# HG changeset patch
# User windel
# Date 1351341118 -7200
# Node ID 60cc36ef5a50e7a41b7895150806fc90a00974f9
# Parent  654c5ac4f2c5c32683b34dc8504f1155946a6e12
Rework in compiler

diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/apps/ide.py
--- a/python/apps/ide.py	Sat Oct 13 16:13:05 2012 +0200
+++ b/python/apps/ide.py	Sat Oct 27 14:31:58 2012 +0200
@@ -1,11 +1,10 @@
-import sys, os
+import sys, os, base64
 if sys.version_info.major != 3:
    print("Needs to be run in python version 3.x")
    sys.exit(1)
 
 from PyQt4.QtCore import *
 from PyQt4.QtGui import *
-import base64
 
 # Compiler imports:
 sys.path.insert(0, os.path.join('..','libs'))
diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/libs/compiler/backends/codegenerator.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python/libs/compiler/backends/codegenerator.py	Sat Oct 27 14:31:58 2012 +0200
@@ -0,0 +1,487 @@
+"""
+  Code generation for 64 bits intel processors
+"""
+
+from .nodes import *
+from .errors import Error
+from .builtin import real, integer, boolean, char
+from .assembler import *
+
+class CodeGenerator:
+   def __init__(self):
+      self.strings = []
+      self.initialize()
+   def initialize(self):
+      # Register descriptors:
+      self.freeregs = 'r8,r9,r10,r11,r12,r13,r14,r15'.split(',')
+      self.usedregs = []
+      # Members to accumulate the result into:
+      # The result is an image of bytecode and global variable space.
+      # Global variables a referenced by RIP relative addressing.
+      self.image = []
+      self.rip = 0 # The current instruction pointer location.
+      # TODO: backpatch list here?
+
+   # Functions to modify the code image
+   def addCode(self, code):
+      assert(type(code) is list)
+      self.image += code
+      self.rip += len(code)
+   def fixCode(self, position, code):
+      self.image[position:position+len(code)] = code
+   def align(self, b):
+      while (self.rip % b) != 0:
+         self.addCode([0])
+
+   def saveAllRegisters(self):
+      regs = list(self.usedregs.keys())
+      for reg in regs:
+         code += self.saveRegister(reg)
+
+   def saveRegister(self, reg):
+      code = []
+      if reg in self.usedregs.keys(): 
+         code.append('mov {0}, {1}'.format(self.usedregs[reg], reg))
+         del self.usedregs[reg]
+         self.freeregs.append(reg)
+
+   def getreg(self, node):
+      """ acquire a working register for a certain node."""
+      # Temporary register bypass action:
+      if len(self.freeregs) > 0:
+         reg = self.freeregs.pop(0)
+         self.usedregs.append(reg)
+      else:
+         Error('No more free regs')
+      node.reg = reg
+
+   def freereg(self, node):
+      reg = node.reg
+      node.reg = None
+      self.freeregs.append(reg)
+      self.usedregs.remove(reg)
+
+   # Helpers to load and retrieve designated objects:
+   def storeRegInDesignator(self, reg, designator):
+      assert(type(reg) is str)
+      assert(type(designator) is Designator)
+      if len(designator.selectors) > 0:
+         self.gencode( designator ) # Load the pointer into some register
+         self.addCode( mov([designator.reg, 0x0], reg) )
+         self.freereg( designator )
+      else:
+         if designator.obj.isLocal:
+            # Relative from rbp register
+            mem = ['rbp', designator.obj.offset]
+            self.addCode( mov(mem, reg) )
+         else:
+            # Relative from RIP after move
+            self.addCode( mov(['RIP', 0x0], reg) )
+            self.fixCode(self.rip - 4, imm32(designator.obj.offset - self.rip) )
+
+   # Code generation functions:
+   def genexprcode(self, node):
+      """ 
+         Generate code for expressions!
+         Recursively evaluates, and ensures a register contains the answer.
+         register is an integer register or a floating point reg
+      """
+      if isinstance(node, Binop):
+         """ Handle a binary operation (two arguments) of some kind """
+         self.genexprcode(node.a)
+         self.genexprcode(node.b)
+
+         if node.op == 'mod':
+            assert(node.typ.isType(integer))
+            self.addCode(mov('rax', node.a.reg))
+            self.addCode(xorreg64('rdx', 'rdx')) # Extend divided number with zeros
+            self.addCode(idivreg64(node.b.reg)) # divide rdx:rax with reg
+            node.reg = node.a.reg
+            self.freereg(node.b) # give up register that contains b
+            self.addCode(mov(node.reg, 'rdx')) # move remainder into result
+         elif node.op == 'div':
+            assert(node.typ.isType(integer))
+            self.addCode(mov('rax', node.a.reg))
+            self.addCode(xorreg64('rdx', 'rdx')) # Extend divided number with zeros
+            self.addCode(idivreg64(node.b.reg)) # divide rdx:rax with reg
+            node.reg = node.a.reg
+            self.freereg(node.b) # give up register that contains b
+            self.addCode(mov(node.reg, 'rax')) # move result into reg
+         elif node.op == '*':
+            if node.typ.isType(integer):
+               self.addCode(imulreg64(node.a.reg, node.b.reg))
+               node.reg = node.a.reg
+               self.freereg(node.b)
+            else:
+               Error('{0} for * not implemented'.format(node.typ))
+         elif node.op == '+':
+            if node.typ.isType(integer):
+               self.addCode(addreg64(node.a.reg, node.b.reg))
+               node.reg = node.a.reg
+               self.freereg(node.b)
+            else:
+               Error('{0} for + not implemented'.format(node.typ))
+         elif node.op == '-':
+            if node.typ.isType(integer):
+               self.addCode(subreg64(node.a.reg, node.b.reg))
+               node.reg = node.a.reg
+               self.freereg(node.b)
+            else:
+               Error('{0} for - not implemented'.format(node.typ))
+         else:
+            Error('Unknown Binop {0}'.format(node.op))
+
+      elif type(node) is Unop:
+         if node.op == 'INTTOREAL':
+            self.genexprcode(node.a)
+            node.reg = node.a.reg
+            # TODO use 'FILD' instruction
+            freg = 12
+            code.append('Unop inttoreal TODO')
+         elif node.op == 'ABS':
+            if isType(node.typ, real):
+               code = [0xD9, 0xE1] # st(0) = fabs st(0)
+               Error('ABS error integer')
+            elif isType(node.typ, integer):
+               code = []
+               Error('ABS error integer')
+            else:
+               Error('ABS error')
+         else:
+            Error('Unknown Unop {0}'.format(node.op))
+
+      elif isinstance(node, Designator):
+         # dereference, array index. Make sure that the result comes into a register
+         if len(node.selectors) > 0:
+            self.gencode(node) # Load the pointer into some register
+
+            # Now we can access the object at location '[node.reg]':
+            if node.typ.isType(integer):
+               self.addCode( mov(node.reg, [node.reg, 0x0]) )
+            else:
+               Error('Only integer types implemented')
+         else:
+            # No selectors, load variable directly
+            if node.obj.typ.isType(integer):
+               if type(node.obj) is Constant:
+                  self.genexprcode(node.obj)
+                  node.reg = node.obj.reg
+               else:
+                  self.getreg(node)
+                  # Get a register to store the integer value
+                  if node.obj.isLocal:
+                     # relative to rbp:
+                     self.addCode( mov(node.reg, ['rbp', node.obj.offset]) )
+                  else:
+                     self.addCode(mov(node.reg, ['RIP', 0x0]))
+                     self.fixCode(self.rip-4, imm32(node.obj.offset - self.rip))
+            else:
+               Error('Cannot load variable type {0}'.format(node.typ))
+
+      elif isinstance(node, Relop):
+         # Create a boolean from operands
+         # TODO create an alternative for expressions used as conditions.
+         self.genexprcode(node.a)
+         self.genexprcode(node.b)
+
+         if node.a.typ.isType(integer):
+            instructions = {'<': 'L', '>': 'G', '<>': 'NE', '>=': 'GE', '<=': 'LE', '=':'E'}
+            if not node.relop in instructions.keys():
+               Error('Unimplemented relop: '+str(node.relop))
+            instr = instructions[node.relop]
+
+            node.reg = node.a.reg
+            self.addCode( cmpreg64(node.a.reg, node.b.reg) )
+            self.addCode( shortjump(0x0, condition=instr) ) # jump over 0 code and jmp
+            fixloc1 = self.rip - 1
+            rip1 = self.rip
+            self.addCode( xorreg64(node.reg, node.reg) )
+            self.addCode( shortjump(0x0) ) # Jump over 1 code
+            fixloc2 = self.rip - 1
+            self.fixCode(fixloc1, imm8(self.rip - rip1))
+            rip2 = self.rip
+            self.addCode( xorreg64(node.reg, node.reg) )
+            self.addCode( increg64(node.reg) )
+            self.fixCode(fixloc2, imm8(self.rip - rip2))
+
+            self.freereg(node.b)
+         else:
+            Error('Relop not implemented for {0}'.format(node.a.typ))
+
+      elif type(node) is Constant:
+         if node.typ.isType(integer):
+            self.getreg(node)
+            self.addCode(mov(node.reg, node.value))
+         elif node.typ.isType(real):
+            code += self.getreg(node)
+            Error('TODO: get real reg')
+            # TODO: get a fixed point reg, and load the variable in there
+         else:
+            Error('Howto generate code for {0}?'.format(node))
+
+      elif type(node) is ProcedureCall:
+         if type(node.proc.obj) is BuiltinProcedure:
+            # Handle builtin procedures different, these not always call
+            # a function, but generate code.
+            bi = node.proc.obj
+            if bi.name == 'chr':
+               arg = node.args[0]
+               self.genexprcode(arg)
+               # Store character in full width register:
+               # TODO: store in char only register
+               node.reg = arg.reg
+            else:
+               Error('Unknown builtin function {0}'.format(bi.name))
+         else:
+            # Use generic procedure call first
+            self.gencode(node)
+            # Retrieve result:
+            if node.typ.isType(integer):
+               # Store result!
+               self.getreg(node)
+               self.addCode( mov(node.reg, 'rax') )
+            else:
+               Error('Return type not supported {0}'.format(node.typ))
+      else:
+         Error('Cannot generate expression code for: {0}'.format(node))
+
+   def gencode(self, node):
+      """ Code generation function for AST nodes """
+      if isinstance(node, Module):
+         # for all imports make a list of pointer to the actual procedures:
+         for imp in node.imports:
+            imp.offset = self.rip
+            self.addCode( [0x0]*8 )
+         # global variable storage allocation
+         variables = node.symtable.getAllLocal(Variable)
+         for var in variables:
+            var.isLocal = False
+            var.offset = self.rip
+            self.addCode( [0x00] * var.typ.size ) # TODO initial values here?
+         self.align(8)
+         # TODO: mark end of data and start of code inside image
+         # TODO: round data to page size to enable protection by loader.
+         # Procedure code generation:
+         procedures = node.symtable.getAllLocal(Procedure)
+         node.procs = procedures
+         for proc in procedures:
+            self.gencode(proc)
+         # Module init code:
+         node.initcodeentry = self.rip
+         self.gencode(node.initcode)
+         self.addCode( ret() )
+         # TODO: how to return from module init code? far return??
+
+      elif type(node) is Procedure:
+        # calculate offsets for local variables and parameters
+        # Variable location relative to 'rbp' register
+        variables = node.symtable.getAllLocal(Variable)
+        offset = 0
+        paramoffset = 16
+        for var in variables:
+           var.isLocal = True
+           if not var.isParameter:
+              offset += var.typ.size
+              # Offset is negative of rbp in stack frame
+              var.offset = -offset
+        node.framesize = offset
+        # Calculate offsets of parameters relative to rbp register
+        for par in reversed(node.typ.parameters):
+           pvar = node.symtable.getLocal(Variable, par.name)
+           pvar.offset = paramoffset
+           paramoffset += pvar.typ.size
+
+        # code generation
+        node.entrypoint = self.rip
+        self.addCode(push('rbp'))
+        self.addCode(mov('rbp', 'rsp')) # Setup the base pointer
+        self.addCode(subreg64('rsp', node.framesize)) # reserve space for locals
+        self.gencode(node.block)
+        if node.retexpr:
+           if node.retexpr.typ.isType(integer):
+              self.genexprcode(node.retexpr)
+              self.addCode( mov('rax', node.retexpr.reg) )
+              self.freereg(node.retexpr)
+           else:
+              Error('Cannot return this kind yet {0}'.format(node.retexpr.typ))
+        self.addCode( addreg64('rsp', node.framesize) )
+        self.addCode( pop('rbp') )
+        self.addCode( ret() )
+        assert(len(self.usedregs) == 0)
+
+      elif isinstance(node, StatementSequence):
+         for s in node.statements:
+            self.gencode(s)
+
+      elif type(node) is ProcedureCall:
+         # Prepare parameters on the stack:
+         stacksize = 0
+         assert(len(node.args) == len(node.proc.typ.parameters))
+         for arg, param in zip(node.args, node.proc.typ.parameters):
+
+            if param.kind == 'value': 
+               self.genexprcode(arg)
+               self.addCode( push(arg.reg) )
+               self.freereg( arg )
+               stacksize += 8
+            else:
+               Error('Parameter kind other than value')
+
+         # Calculate address using designator
+         if type(node.proc.obj) is Procedure:
+            self.addCode( call(0x0) )
+            self.fixCode( self.rip - 4, imm32(node.proc.obj.entrypoint - self.rip))
+         elif type(node.proc.obj) is ImportedSymbol:
+            # Load the entry point of the import table
+            self.getreg(node.proc.obj)
+            # Load the address of the procedure:
+            self.addCode( mov(node.proc.obj.reg, ['RIP', 0x0]) )
+            self.fixCode( self.rip - 4, imm32(node.proc.obj.offset - self.rip) )
+            # Call to the address in register:
+            self.addCode( call(node.proc.obj.reg) )
+            # Free register that holds the address of the object
+            self.freereg( node.proc.obj )
+         elif type(node.proc.obj) is BuiltinProcedure:
+            if node.proc.obj.name == 'chr':
+               print('int to char')
+            else:
+               Error('Unknown builtin function {0}'.format(node.proc.obj.name))
+         else:
+            Error('Cannot call designator of type {0}'.format(node.proc.obj))
+
+         # Restore stack (pop all arguments of):
+         self.addCode(addreg64('rsp', stacksize))
+
+      elif type(node) is Assignment:
+         if node.lval.typ.isType(integer):
+           # TODO if node.rval is Constant of some datatype, move it to mem directly
+           self.genexprcode(node.rval) # Calculate the value that has to be stored.
+           self.storeRegInDesignator(node.rval.reg, node.lval)
+           self.freereg(node.rval)
+         else:
+            Error('Assignments of other types not implemented')
+            # TODO if left and right are designators, do some sort of memcpy.
+
+      elif type(node) is IfStatement:
+        self.genexprcode(node.condition)
+        self.addCode( cmpreg64(node.condition.reg, 1) )
+        self.freereg(node.condition)
+        if node.falsestatement:
+           # If with else clause
+           self.addCode( nearjump(0x0, condition='NE') ) # if Not Equal jump to false
+           rip1 = self.rip
+           fixloc1 = self.rip - 4
+           self.gencode(node.truestatement)
+           self.addCode( nearjump( 0x0 ) ) # jump over false code
+           fixloc2 = self.rip - 4
+           self.fixCode(fixloc1, imm32(self.rip - rip1))
+           rip2 = self.rip
+           self.gencode(node.falsestatement)
+           self.fixCode(fixloc2, imm32(self.rip - rip2))
+        else:
+           # If without else clause
+           self.addCode( nearjump(0x0, condition='NE') ) # if Not Equal jump to false
+           rip1 = self.rip
+           fixloc1 = self.rip - 4
+           self.gencode(node.truestatement)
+           self.fixCode(fixloc1, imm32(self.rip - rip1)) # Fixup near jump over true code.
+
+      elif isinstance(node, WhileStatement):
+        rip1 = self.rip # Store the start of the while loop
+        self.genexprcode(node.condition)
+        self.addCode( cmpreg64(node.condition.reg, 1) ) # Test condition for true-ness
+        self.freereg(node.condition)
+        self.addCode( nearjump(0x0, condition='NE') ) # If Not Equal jump over while code AND jump back (fix later)
+        fixloc1 = self.rip - 4
+        rip2 = self.rip
+        self.gencode(node.dostatements)
+        self.addCode( nearjump(0x0) ) # JMP to condition, fix exact jump position below
+        fixloc2 = self.rip - 4
+        rip3 = self.rip # end of while loop
+        self.fixCode(fixloc2, imm32(rip1 - rip3)) # Fixup jump to start of while loop
+        self.fixCode(fixloc1, imm32(rip3 - rip2)) # Fixup jump out of while loop
+
+      elif type(node) is ForStatement:
+         # Initial load of iterator variable:
+         self.genexprcode(node.begin)
+         self.genexprcode(node.end)
+         # TODO: link reg with variable so that a register is used instead of a variable
+         iterreg = node.begin.reg # Get the register used for the loop
+         #self.addCode(cmpreg64(iterreg, node.endvalue))
+         rip1 = self.rip
+         self.gencode(node.statements)
+         #self.loadDesignatorInReg(node.
+         #self.addCode( addreg64(node.variable, node.increment) )
+         self.addCode(nearjump(0x0))
+         fixloc1 = self.rip - 4
+         rip2 = self.rip
+         self.fixCode(fixloc1, imm32(rip1 - rip2))
+
+         self.freereg(node.begin) # Release register used in loop
+         self.freereg(node.end)
+         Error('No implementation of FOR statement')
+
+      elif type(node) is AsmCode:
+         def processOperand(op):
+            if type(op) is list:
+               if type(op[0]) is Variable:
+                  var = op[0]
+                  if var.isLocal:
+                     return ['rbp', var.offset]
+                  else:
+                     Error('Can only use local variables in inline assembler')
+            return op
+         for asmline in node.asmcode:
+            opcode, operands = asmline
+            operands = [processOperand(opx) for opx in operands]
+            print('assembling', opcode, *operands)
+            func,nargs = opcodes[opcode]
+            code = func(*operands)
+            self.addCode(code)
+
+      elif isinstance(node, EmptyStatement):
+         pass
+
+
+      elif type(node) is StringConstant:
+        self.strings.append(node)
+        self.data.append(node.value) # Add string to the data section
+
+      elif type(node) is Designator:
+         if len(node.selectors) > 0:
+            self.getreg(node)
+            # Load starting address
+            if node.obj.isLocal:
+               self.addCode( leareg64(node.reg, ['rbp', node.obj.offset]) )
+            else:
+               # Global variables need to be relocated...
+               self.addCode(leareg64(node.reg, ['RIP', 0]))
+               self.fixCode(self.rip - 4, imm32(node.obj.offset - self.rip))
+            # Loop over all designators..
+            for selector in node.selectors:
+               if type(selector) is Index:
+                  # Deref an array index
+                  self.genexprcode(selector.index)
+                  self.getreg(selector)
+                  self.addCode( mov(selector.reg, selector.typ.elementType.size) )
+                  self.addCode( imulreg64(selector.reg, selector.index.reg ) )
+                  self.freereg(selector.index)
+                  self.addCode(addreg64(node.reg, selector.reg))
+                  self.freereg(selector)
+               elif type(selector) is Field:
+                  print('Field')
+                  Error('Field not implemented')
+               else:
+                  Error('Unknown selector')
+         else:
+            Error('Can only gencode for designator with selectors')
+
+      else:
+         print('not generating code for {0}'.format(node))
+
+   def generatecode(self, ast):
+     """ code generation front end """
+     self.initialize()
+     self.gencode(ast)
+     ast.image = self.image
+
diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/libs/compiler/codegenerator.py
--- a/python/libs/compiler/codegenerator.py	Sat Oct 13 16:13:05 2012 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,487 +0,0 @@
-"""
-  Code generation for 64 bits intel processors
-"""
-
-from .nodes import *
-from .errors import Error
-from .builtin import real, integer, boolean, char
-from .assembler import *
-
-class CodeGenerator:
-   def __init__(self):
-      self.strings = []
-      self.initialize()
-   def initialize(self):
-      # Register descriptors:
-      self.freeregs = 'r8,r9,r10,r11,r12,r13,r14,r15'.split(',')
-      self.usedregs = []
-      # Members to accumulate the result into:
-      # The result is an image of bytecode and global variable space.
-      # Global variables a referenced by RIP relative addressing.
-      self.image = []
-      self.rip = 0 # The current instruction pointer location.
-      # TODO: backpatch list here?
-
-   # Functions to modify the code image
-   def addCode(self, code):
-      assert(type(code) is list)
-      self.image += code
-      self.rip += len(code)
-   def fixCode(self, position, code):
-      self.image[position:position+len(code)] = code
-   def align(self, b):
-      while (self.rip % b) != 0:
-         self.addCode([0])
-
-   def saveAllRegisters(self):
-      regs = list(self.usedregs.keys())
-      for reg in regs:
-         code += self.saveRegister(reg)
-
-   def saveRegister(self, reg):
-      code = []
-      if reg in self.usedregs.keys(): 
-         code.append('mov {0}, {1}'.format(self.usedregs[reg], reg))
-         del self.usedregs[reg]
-         self.freeregs.append(reg)
-
-   def getreg(self, node):
-      """ acquire a working register for a certain node."""
-      # Temporary register bypass action:
-      if len(self.freeregs) > 0:
-         reg = self.freeregs.pop(0)
-         self.usedregs.append(reg)
-      else:
-         Error('No more free regs')
-      node.reg = reg
-
-   def freereg(self, node):
-      reg = node.reg
-      node.reg = None
-      self.freeregs.append(reg)
-      self.usedregs.remove(reg)
-
-   # Helpers to load and retrieve designated objects:
-   def storeRegInDesignator(self, reg, designator):
-      assert(type(reg) is str)
-      assert(type(designator) is Designator)
-      if len(designator.selectors) > 0:
-         self.gencode( designator ) # Load the pointer into some register
-         self.addCode( mov([designator.reg, 0x0], reg) )
-         self.freereg( designator )
-      else:
-         if designator.obj.isLocal:
-            # Relative from rbp register
-            mem = ['rbp', designator.obj.offset]
-            self.addCode( mov(mem, reg) )
-         else:
-            # Relative from RIP after move
-            self.addCode( mov(['RIP', 0x0], reg) )
-            self.fixCode(self.rip - 4, imm32(designator.obj.offset - self.rip) )
-
-   # Code generation functions:
-   def genexprcode(self, node):
-      """ 
-         Generate code for expressions!
-         Recursively evaluates, and ensures a register contains the answer.
-         register is an integer register or a floating point reg
-      """
-      if isinstance(node, Binop):
-         """ Handle a binary operation (two arguments) of some kind """
-         self.genexprcode(node.a)
-         self.genexprcode(node.b)
-
-         if node.op == 'mod':
-            assert(node.typ.isType(integer))
-            self.addCode(mov('rax', node.a.reg))
-            self.addCode(xorreg64('rdx', 'rdx')) # Extend divided number with zeros
-            self.addCode(idivreg64(node.b.reg)) # divide rdx:rax with reg
-            node.reg = node.a.reg
-            self.freereg(node.b) # give up register that contains b
-            self.addCode(mov(node.reg, 'rdx')) # move remainder into result
-         elif node.op == 'div':
-            assert(node.typ.isType(integer))
-            self.addCode(mov('rax', node.a.reg))
-            self.addCode(xorreg64('rdx', 'rdx')) # Extend divided number with zeros
-            self.addCode(idivreg64(node.b.reg)) # divide rdx:rax with reg
-            node.reg = node.a.reg
-            self.freereg(node.b) # give up register that contains b
-            self.addCode(mov(node.reg, 'rax')) # move result into reg
-         elif node.op == '*':
-            if node.typ.isType(integer):
-               self.addCode(imulreg64(node.a.reg, node.b.reg))
-               node.reg = node.a.reg
-               self.freereg(node.b)
-            else:
-               Error('{0} for * not implemented'.format(node.typ))
-         elif node.op == '+':
-            if node.typ.isType(integer):
-               self.addCode(addreg64(node.a.reg, node.b.reg))
-               node.reg = node.a.reg
-               self.freereg(node.b)
-            else:
-               Error('{0} for + not implemented'.format(node.typ))
-         elif node.op == '-':
-            if node.typ.isType(integer):
-               self.addCode(subreg64(node.a.reg, node.b.reg))
-               node.reg = node.a.reg
-               self.freereg(node.b)
-            else:
-               Error('{0} for - not implemented'.format(node.typ))
-         else:
-            Error('Unknown Binop {0}'.format(node.op))
-
-      elif type(node) is Unop:
-         if node.op == 'INTTOREAL':
-            self.genexprcode(node.a)
-            node.reg = node.a.reg
-            # TODO use 'FILD' instruction
-            freg = 12
-            code.append('Unop inttoreal TODO')
-         elif node.op == 'ABS':
-            if isType(node.typ, real):
-               code = [0xD9, 0xE1] # st(0) = fabs st(0)
-               Error('ABS error integer')
-            elif isType(node.typ, integer):
-               code = []
-               Error('ABS error integer')
-            else:
-               Error('ABS error')
-         else:
-            Error('Unknown Unop {0}'.format(node.op))
-
-      elif isinstance(node, Designator):
-         # dereference, array index. Make sure that the result comes into a register
-         if len(node.selectors) > 0:
-            self.gencode(node) # Load the pointer into some register
-
-            # Now we can access the object at location '[node.reg]':
-            if node.typ.isType(integer):
-               self.addCode( mov(node.reg, [node.reg, 0x0]) )
-            else:
-               Error('Only integer types implemented')
-         else:
-            # No selectors, load variable directly
-            if node.obj.typ.isType(integer):
-               if type(node.obj) is Constant:
-                  self.genexprcode(node.obj)
-                  node.reg = node.obj.reg
-               else:
-                  self.getreg(node)
-                  # Get a register to store the integer value
-                  if node.obj.isLocal:
-                     # relative to rbp:
-                     self.addCode( mov(node.reg, ['rbp', node.obj.offset]) )
-                  else:
-                     self.addCode(mov(node.reg, ['RIP', 0x0]))
-                     self.fixCode(self.rip-4, imm32(node.obj.offset - self.rip))
-            else:
-               Error('Cannot load variable type {0}'.format(node.typ))
-
-      elif isinstance(node, Relop):
-         # Create a boolean from operands
-         # TODO create an alternative for expressions used as conditions.
-         self.genexprcode(node.a)
-         self.genexprcode(node.b)
-
-         if node.a.typ.isType(integer):
-            instructions = {'<': 'L', '>': 'G', '<>': 'NE', '>=': 'GE', '<=': 'LE', '=':'E'}
-            if not node.relop in instructions.keys():
-               Error('Unimplemented relop: '+str(node.relop))
-            instr = instructions[node.relop]
-
-            node.reg = node.a.reg
-            self.addCode( cmpreg64(node.a.reg, node.b.reg) )
-            self.addCode( shortjump(0x0, condition=instr) ) # jump over 0 code and jmp
-            fixloc1 = self.rip - 1
-            rip1 = self.rip
-            self.addCode( xorreg64(node.reg, node.reg) )
-            self.addCode( shortjump(0x0) ) # Jump over 1 code
-            fixloc2 = self.rip - 1
-            self.fixCode(fixloc1, imm8(self.rip - rip1))
-            rip2 = self.rip
-            self.addCode( xorreg64(node.reg, node.reg) )
-            self.addCode( increg64(node.reg) )
-            self.fixCode(fixloc2, imm8(self.rip - rip2))
-
-            self.freereg(node.b)
-         else:
-            Error('Relop not implemented for {0}'.format(node.a.typ))
-
-      elif type(node) is Constant:
-         if node.typ.isType(integer):
-            self.getreg(node)
-            self.addCode(mov(node.reg, node.value))
-         elif node.typ.isType(real):
-            code += self.getreg(node)
-            Error('TODO: get real reg')
-            # TODO: get a fixed point reg, and load the variable in there
-         else:
-            Error('Howto generate code for {0}?'.format(node))
-
-      elif type(node) is ProcedureCall:
-         if type(node.proc.obj) is BuiltinProcedure:
-            # Handle builtin procedures different, these not always call
-            # a function, but generate code.
-            bi = node.proc.obj
-            if bi.name == 'chr':
-               arg = node.args[0]
-               self.genexprcode(arg)
-               # Store character in full width register:
-               # TODO: store in char only register
-               node.reg = arg.reg
-            else:
-               Error('Unknown builtin function {0}'.format(bi.name))
-         else:
-            # Use generic procedure call first
-            self.gencode(node)
-            # Retrieve result:
-            if node.typ.isType(integer):
-               # Store result!
-               self.getreg(node)
-               self.addCode( mov(node.reg, 'rax') )
-            else:
-               Error('Return type not supported {0}'.format(node.typ))
-      else:
-         Error('Cannot generate expression code for: {0}'.format(node))
-
-   def gencode(self, node):
-      """ Code generation function for AST nodes """
-      if isinstance(node, Module):
-         # for all imports make a list of pointer to the actual procedures:
-         for imp in node.imports:
-            imp.offset = self.rip
-            self.addCode( [0x0]*8 )
-         # global variable storage allocation
-         variables = node.symtable.getAllLocal(Variable)
-         for var in variables:
-            var.isLocal = False
-            var.offset = self.rip
-            self.addCode( [0x00] * var.typ.size ) # TODO initial values here?
-         self.align(8)
-         # TODO: mark end of data and start of code inside image
-         # TODO: round data to page size to enable protection by loader.
-         # Procedure code generation:
-         procedures = node.symtable.getAllLocal(Procedure)
-         node.procs = procedures
-         for proc in procedures:
-            self.gencode(proc)
-         # Module init code:
-         node.initcodeentry = self.rip
-         self.gencode(node.initcode)
-         self.addCode( ret() )
-         # TODO: how to return from module init code? far return??
-
-      elif type(node) is Procedure:
-        # calculate offsets for local variables and parameters
-        # Variable location relative to 'rbp' register
-        variables = node.symtable.getAllLocal(Variable)
-        offset = 0
-        paramoffset = 16
-        for var in variables:
-           var.isLocal = True
-           if not var.isParameter:
-              offset += var.typ.size
-              # Offset is negative of rbp in stack frame
-              var.offset = -offset
-        node.framesize = offset
-        # Calculate offsets of parameters relative to rbp register
-        for par in reversed(node.typ.parameters):
-           pvar = node.symtable.getLocal(Variable, par.name)
-           pvar.offset = paramoffset
-           paramoffset += pvar.typ.size
-
-        # code generation
-        node.entrypoint = self.rip
-        self.addCode(push('rbp'))
-        self.addCode(mov('rbp', 'rsp')) # Setup the base pointer
-        self.addCode(subreg64('rsp', node.framesize)) # reserve space for locals
-        self.gencode(node.block)
-        if node.retexpr:
-           if node.retexpr.typ.isType(integer):
-              self.genexprcode(node.retexpr)
-              self.addCode( mov('rax', node.retexpr.reg) )
-              self.freereg(node.retexpr)
-           else:
-              Error('Cannot return this kind yet {0}'.format(node.retexpr.typ))
-        self.addCode( addreg64('rsp', node.framesize) )
-        self.addCode( pop('rbp') )
-        self.addCode( ret() )
-        assert(len(self.usedregs) == 0)
-
-      elif isinstance(node, StatementSequence):
-         for s in node.statements:
-            self.gencode(s)
-
-      elif type(node) is ProcedureCall:
-         # Prepare parameters on the stack:
-         stacksize = 0
-         assert(len(node.args) == len(node.proc.typ.parameters))
-         for arg, param in zip(node.args, node.proc.typ.parameters):
-
-            if param.kind == 'value': 
-               self.genexprcode(arg)
-               self.addCode( push(arg.reg) )
-               self.freereg( arg )
-               stacksize += 8
-            else:
-               Error('Parameter kind other than value')
-
-         # Calculate address using designator
-         if type(node.proc.obj) is Procedure:
-            self.addCode( call(0x0) )
-            self.fixCode( self.rip - 4, imm32(node.proc.obj.entrypoint - self.rip))
-         elif type(node.proc.obj) is ImportedSymbol:
-            # Load the entry point of the import table
-            self.getreg(node.proc.obj)
-            # Load the address of the procedure:
-            self.addCode( mov(node.proc.obj.reg, ['RIP', 0x0]) )
-            self.fixCode( self.rip - 4, imm32(node.proc.obj.offset - self.rip) )
-            # Call to the address in register:
-            self.addCode( call(node.proc.obj.reg) )
-            # Free register that holds the address of the object
-            self.freereg( node.proc.obj )
-         elif type(node.proc.obj) is BuiltinProcedure:
-            if node.proc.obj.name == 'chr':
-               print('int to char')
-            else:
-               Error('Unknown builtin function {0}'.format(node.proc.obj.name))
-         else:
-            Error('Cannot call designator of type {0}'.format(node.proc.obj))
-
-         # Restore stack (pop all arguments of):
-         self.addCode(addreg64('rsp', stacksize))
-
-      elif type(node) is Assignment:
-         if node.lval.typ.isType(integer):
-           # TODO if node.rval is Constant of some datatype, move it to mem directly
-           self.genexprcode(node.rval) # Calculate the value that has to be stored.
-           self.storeRegInDesignator(node.rval.reg, node.lval)
-           self.freereg(node.rval)
-         else:
-            Error('Assignments of other types not implemented')
-            # TODO if left and right are designators, do some sort of memcpy.
-
-      elif type(node) is IfStatement:
-        self.genexprcode(node.condition)
-        self.addCode( cmpreg64(node.condition.reg, 1) )
-        self.freereg(node.condition)
-        if node.falsestatement:
-           # If with else clause
-           self.addCode( nearjump(0x0, condition='NE') ) # if Not Equal jump to false
-           rip1 = self.rip
-           fixloc1 = self.rip - 4
-           self.gencode(node.truestatement)
-           self.addCode( nearjump( 0x0 ) ) # jump over false code
-           fixloc2 = self.rip - 4
-           self.fixCode(fixloc1, imm32(self.rip - rip1))
-           rip2 = self.rip
-           self.gencode(node.falsestatement)
-           self.fixCode(fixloc2, imm32(self.rip - rip2))
-        else:
-           # If without else clause
-           self.addCode( nearjump(0x0, condition='NE') ) # if Not Equal jump to false
-           rip1 = self.rip
-           fixloc1 = self.rip - 4
-           self.gencode(node.truestatement)
-           self.fixCode(fixloc1, imm32(self.rip - rip1)) # Fixup near jump over true code.
-
-      elif isinstance(node, WhileStatement):
-        rip1 = self.rip # Store the start of the while loop
-        self.genexprcode(node.condition)
-        self.addCode( cmpreg64(node.condition.reg, 1) ) # Test condition for true-ness
-        self.freereg(node.condition)
-        self.addCode( nearjump(0x0, condition='NE') ) # If Not Equal jump over while code AND jump back (fix later)
-        fixloc1 = self.rip - 4
-        rip2 = self.rip
-        self.gencode(node.dostatements)
-        self.addCode( nearjump(0x0) ) # JMP to condition, fix exact jump position below
-        fixloc2 = self.rip - 4
-        rip3 = self.rip # end of while loop
-        self.fixCode(fixloc2, imm32(rip1 - rip3)) # Fixup jump to start of while loop
-        self.fixCode(fixloc1, imm32(rip3 - rip2)) # Fixup jump out of while loop
-
-      elif type(node) is ForStatement:
-         # Initial load of iterator variable:
-         self.genexprcode(node.begin)
-         self.genexprcode(node.end)
-         # TODO: link reg with variable so that a register is used instead of a variable
-         iterreg = node.begin.reg # Get the register used for the loop
-         #self.addCode(cmpreg64(iterreg, node.endvalue))
-         rip1 = self.rip
-         self.gencode(node.statements)
-         #self.loadDesignatorInReg(node.
-         #self.addCode( addreg64(node.variable, node.increment) )
-         self.addCode(nearjump(0x0))
-         fixloc1 = self.rip - 4
-         rip2 = self.rip
-         self.fixCode(fixloc1, imm32(rip1 - rip2))
-
-         self.freereg(node.begin) # Release register used in loop
-         self.freereg(node.end)
-         Error('No implementation of FOR statement')
-
-      elif type(node) is AsmCode:
-         def processOperand(op):
-            if type(op) is list:
-               if type(op[0]) is Variable:
-                  var = op[0]
-                  if var.isLocal:
-                     return ['rbp', var.offset]
-                  else:
-                     Error('Can only use local variables in inline assembler')
-            return op
-         for asmline in node.asmcode:
-            opcode, operands = asmline
-            operands = [processOperand(opx) for opx in operands]
-            print('assembling', opcode, *operands)
-            func,nargs = opcodes[opcode]
-            code = func(*operands)
-            self.addCode(code)
-
-      elif isinstance(node, EmptyStatement):
-         pass
-
-
-      elif type(node) is StringConstant:
-        self.strings.append(node)
-        self.data.append(node.value) # Add string to the data section
-
-      elif type(node) is Designator:
-         if len(node.selectors) > 0:
-            self.getreg(node)
-            # Load starting address
-            if node.obj.isLocal:
-               self.addCode( leareg64(node.reg, ['rbp', node.obj.offset]) )
-            else:
-               # Global variables need to be relocated...
-               self.addCode(leareg64(node.reg, ['RIP', 0]))
-               self.fixCode(self.rip - 4, imm32(node.obj.offset - self.rip))
-            # Loop over all designators..
-            for selector in node.selectors:
-               if type(selector) is Index:
-                  # Deref an array index
-                  self.genexprcode(selector.index)
-                  self.getreg(selector)
-                  self.addCode( mov(selector.reg, selector.typ.elementType.size) )
-                  self.addCode( imulreg64(selector.reg, selector.index.reg ) )
-                  self.freereg(selector.index)
-                  self.addCode(addreg64(node.reg, selector.reg))
-                  self.freereg(selector)
-               elif type(selector) is Field:
-                  print('Field')
-                  Error('Field not implemented')
-               else:
-                  Error('Unknown selector')
-         else:
-            Error('Can only gencode for designator with selectors')
-
-      else:
-         print('not generating code for {0}'.format(node))
-
-   def generatecode(self, ast):
-     """ code generation front end """
-     self.initialize()
-     self.gencode(ast)
-     ast.image = self.image
-
diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/libs/compiler/frontends/lexer.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python/libs/compiler/frontends/lexer.py	Sat Oct 27 14:31:58 2012 +0200
@@ -0,0 +1,71 @@
+import collections
+import re
+from .errors import CompilerException
+
+"""
+ Lexical analyzer part. Splits the input character stream into tokens.
+"""
+
+# Token is used in the lexical analyzer:
+Token = collections.namedtuple('Token', 'typ val row col')
+
+keywords = ['and', 'array', 'begin', 'by', 'case', 'const', 'div', 'do', \
+   'else', 'elsif', 'end', 'false', 'for', 'if', 'import', 'in', 'is', \
+   'mod', 'module', 'nil', 'not', 'of', 'or', 'pointer', 'procedure', \
+   'record', 'repeat', 'return', 'then', 'to', 'true', 'type', 'until', 'var', \
+   'while', 'asm' ]
+
+def tokenize(s):
+     """
+       Tokenizer, generates an iterator that
+       returns tokens!
+
+       This GREAT example was taken from python re doc page!
+     """
+     tok_spec = [
+       ('REAL', r'\d+\.\d+'),
+       ('HEXNUMBER', r'0x[\da-fA-F]+'),
+       ('NUMBER', r'\d+'),
+       ('ID', r'[A-Za-z][A-Za-z\d_]*'),
+       ('NEWLINE', r'\n'),
+       ('SKIP', r'[ \t]'),
+       ('COMMENTS', r'{.*}'),
+       ('LEESTEKEN', r':=|[\.,=:;\-+*\[\]/\(\)]|>=|<=|<>|>|<'),
+       ('STRING', r"'.*?'")
+     ]
+     tok_re = '|'.join('(?P<%s>%s)' % pair for pair in tok_spec)
+     gettok = re.compile(tok_re).match
+     line = 1
+     pos = line_start = 0
+     mo = gettok(s)
+     while mo is not None:
+       typ = mo.lastgroup
+       val = mo.group(typ)
+       if typ == 'NEWLINE':
+         line_start = pos
+         line += 1
+       elif typ == 'COMMENTS':
+         pass
+       elif typ != 'SKIP':
+         if typ == 'ID':
+           if val in keywords:
+             typ = val
+         elif typ == 'LEESTEKEN':
+           typ = val
+         elif typ == 'NUMBER':
+           val = int(val)
+         elif typ == 'HEXNUMBER':
+           val = int(val[2:], 16)
+           typ = 'NUMBER'
+         elif typ == 'REAL':
+           val = float(val)
+         elif typ == 'STRING':
+           val = val[1:-1]
+         yield Token(typ, val, line, mo.start()-line_start)
+       pos = mo.end()
+       mo = gettok(s, pos)
+     if pos != len(s):
+       col = pos - line_start
+       raise CompilerException('Unexpected character {0}'.format(s[pos]), line, col)
+     yield Token('END', '', line, 0)
+
diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/libs/compiler/lexer.py
--- a/python/libs/compiler/lexer.py	Sat Oct 13 16:13:05 2012 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,71 +0,0 @@
-import collections
-import re
-from .errors import CompilerException
-
-"""
- Lexical analyzer part. Splits the input character stream into tokens.
-"""
-
-# Token is used in the lexical analyzer:
-Token = collections.namedtuple('Token', 'typ val row col')
-
-keywords = ['and', 'array', 'begin', 'by', 'case', 'const', 'div', 'do', \
-   'else', 'elsif', 'end', 'false', 'for', 'if', 'import', 'in', 'is', \
-   'mod', 'module', 'nil', 'not', 'of', 'or', 'pointer', 'procedure', \
-   'record', 'repeat', 'return', 'then', 'to', 'true', 'type', 'until', 'var', \
-   'while', 'asm' ]
-
-def tokenize(s):
-     """
-       Tokenizer, generates an iterator that
-       returns tokens!
-
-       This GREAT example was taken from python re doc page!
-     """
-     tok_spec = [
-       ('REAL', r'\d+\.\d+'),
-       ('HEXNUMBER', r'0x[\da-fA-F]+'),
-       ('NUMBER', r'\d+'),
-       ('ID', r'[A-Za-z][A-Za-z\d_]*'),
-       ('NEWLINE', r'\n'),
-       ('SKIP', r'[ \t]'),
-       ('COMMENTS', r'{.*}'),
-       ('LEESTEKEN', r':=|[\.,=:;\-+*\[\]/\(\)]|>=|<=|<>|>|<'),
-       ('STRING', r"'.*?'")
-     ]
-     tok_re = '|'.join('(?P<%s>%s)' % pair for pair in tok_spec)
-     gettok = re.compile(tok_re).match
-     line = 1
-     pos = line_start = 0
-     mo = gettok(s)
-     while mo is not None:
-       typ = mo.lastgroup
-       val = mo.group(typ)
-       if typ == 'NEWLINE':
-         line_start = pos
-         line += 1
-       elif typ == 'COMMENTS':
-         pass
-       elif typ != 'SKIP':
-         if typ == 'ID':
-           if val in keywords:
-             typ = val
-         elif typ == 'LEESTEKEN':
-           typ = val
-         elif typ == 'NUMBER':
-           val = int(val)
-         elif typ == 'HEXNUMBER':
-           val = int(val[2:], 16)
-           typ = 'NUMBER'
-         elif typ == 'REAL':
-           val = float(val)
-         elif typ == 'STRING':
-           val = val[1:-1]
-         yield Token(typ, val, line, mo.start()-line_start)
-       pos = mo.end()
-       mo = gettok(s, pos)
-     if pos != len(s):
-       col = pos - line_start
-       raise CompilerException('Unexpected character {0}'.format(s[pos]), line, col)
-     yield Token('END', '', line, 0)
-
diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/libs/compiler/parser.py
--- a/python/libs/compiler/parser.py	Sat Oct 13 16:13:05 2012 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,787 +0,0 @@
-"""
-  This module parses source code into an abstract syntax tree (AST)
-"""
-
-from .symboltable import SymbolTable
-from .nodes import *
-from .errors import CompilerException, Error
-from .modules import loadModule
-from .display import printNode
-from .builtin import *
-from . import assembler
-
-class Parser:
-   def __init__(self, tokens):
-      """ provide the parser with the tokens iterator from the lexer. """
-      self.tokens = tokens
-      self.NextToken()
-      self.errorlist = []
-
-   def Error(self, msg):
-     raise CompilerException(msg, self.token.row, self.token.col)
-
-   # Lexer helpers:
-   def Consume(self, typ=''):
-     if self.token.typ == typ or typ == '':
-       v = self.token.val
-       self.NextToken()
-       return v
-     else:
-       self.Error('Excected: "{0}", got "{1}"'.format(typ, self.token.val))
-
-   def hasConsumed(self, typ):
-      if self.token.typ == typ:
-         self.Consume(typ)
-         return True
-      return False
-     
-   def NextToken(self):
-     self.token = self.tokens.__next__()
-     # TODO: store filename in location?
-     self.location = (self.token.row, self.token.col)
-
-   # Helpers to find location of the error in the code:
-   def setLocation(self, obj, location):
-      obj.location = location
-      return obj
-   def getLocation(self):
-      return self.location
-
-   """
-     Recursive descent parser functions:
-        A set of mutual recursive functions.
-        Starting symbol is the Module.
-   """
-   def parseModule(self):
-       self.imports = []
-       loc = self.getLocation()
-       self.Consume('module')
-       modname = self.Consume('ID')
-       self.Consume(';')
-       mod = Module(modname)
-
-       # Construct a symbol table for this program
-       mod.symtable = SymbolTable()
-       # Add built in types and functions:
-       for x in [real, integer, boolean, char, chr_func]:
-          mod.symtable.addSymbol(x)
-
-       self.cst = mod.symtable
-       self.parseImportList()
-
-       self.parseDeclarationSequence()
-       # Procedures only allowed in this scope
-       self.parseProcedureDeclarations()
-
-       if self.hasConsumed('begin'):
-          mod.initcode = self.parseStatementSequence()
-       else:
-          mod.initcode = EmptyStatement()
-
-       self.Consume('end')
-       endname = self.Consume('ID')
-       if endname != modname:
-          self.Error('end denoter must be module name')
-       self.Consume('.')
-
-       mod.imports = self.imports
-       return self.setLocation(mod, loc)
-
-   # Import part
-   def parseImportList(self):
-      if self.hasConsumed('import'):
-         self.parseImport()
-         while self.hasConsumed(','):
-            self.parseImport()
-         self.Consume(';')
-
-   def parseImport(self):
-      loc = self.getLocation()
-      modname = self.Consume('ID')
-      mod = loadModule(modname)
-      self.setLocation(mod, loc)
-      self.cst.addSymbol(mod)
-
-   # Helper to parse an identifier defenitions
-   def parseIdentDef(self):
-      loc = self.getLocation()
-      name = self.Consume('ID')
-      ispublic = self.hasConsumed('*')
-      # Make a node of this thing:
-      i = Id(name)
-      i.ispublic = ispublic
-      return self.setLocation(i, loc)
-
-   def parseIdentList(self):
-      ids = [ self.parseIdentDef() ]
-      while self.hasConsumed(','):
-         ids.append( self.parseIdentDef() )
-      return ids
-
-   def parseQualIdent(self):
-      """ Parse a qualified identifier """
-      name = self.Consume('ID')
-      if self.cst.has(Module, name):
-         modname = name
-         mod = self.cst.get(Module, modname)
-         self.Consume('.')
-         name = self.Consume('ID')
-         # Try to find existing imported symbol:
-         for imp in self.imports:
-            if imp.modname == modname and imp.name == name:
-               return imp
-         # Try to find the symbol in the modules exports:
-         for sym in mod.exports:
-            if sym.name == name:
-               impsym = ImportedSymbol(modname, name)
-               impsym.typ = sym.typ
-               impsym.signature = mod.signature
-               self.imports.append(impsym)
-               return impsym
-         self.Error("Cannot find symbol {0}".format(name))
-      else:
-         return self.cst.getSymbol(name)
-
-   # Helper to parse a designator
-   def parseDesignator(self):
-      """ A designator designates an object.
-           The base location in memory is denoted by the qualified identifier
-           The actual address depends on the selector.
-      """
-      loc = self.getLocation()
-      obj = self.parseQualIdent()
-      typ = obj.typ
-      selectors = []
-      while self.token.typ in ['.', '[', '^']:
-         if self.hasConsumed('.'):
-            field = self.Consume('ID')
-            if typ is PointerType:
-               selectors.append(Deref())
-               typ = typ.pointedType
-            if not type(typ) is RecordType:
-               self.Error("field reference, type not record but {0}".format(typ))
-            typ = typ.fields[field]
-            selectors.append(Field(field))
-         elif self.hasConsumed('['):
-            indexes = self.parseExpressionList()
-            self.Consume(']')
-            for idx in indexes:
-               if not type(typ) is ArrayType:
-                  self.Error('Cannot index non array type')
-               if not isType(idx.typ, integer):
-                  self.Error('Only integer expressions can be used as an index')
-               selectors.append(Index(idx, typ))
-               typ = typ.elementType
-         elif self.hasConsumed('^'):
-            selectors.append(Deref())
-            typ = typ.pointedType
-      return self.setLocation(Designator(obj, selectors, typ), loc)
-
-   # Declaration sequence
-   def parseDeclarationSequence(self):
-      """ 1. constants, 2. types, 3. variables """
-      self.parseConstantDeclarations()
-      self.parseTypeDeclarations()
-      self.parseVariableDeclarations()
-
-   # Constants
-   def evalExpression(self, expr):
-      if type(expr) is Binop:
-         a = self.evalExpression(expr.a)
-         b = self.evalExpression(expr.b)
-         if expr.op == '+':
-            return a + b
-         elif expr.op == '-':
-            return a - b
-         elif expr.op == '*':
-            return a * b
-         elif expr.op == '/':
-            return float(a) / float(b)
-         elif expr.op == 'mod':
-            return int(a % b)
-         elif expr.op == 'div':
-            return int(a / b)
-         elif expr.op == 'or':
-            return a or b
-         elif expr.op == 'and':
-            return a and b
-         else:
-            self.Error('Cannot evaluate expression with {0}'.format(expr.op))
-      elif type(expr) is Constant:
-         return expr.value
-      elif type(expr) is Designator:
-         if type(expr.obj) is Constant:
-            return self.evalExpression(expr.obj)
-         else:
-            self.Error('Cannot evaluate designated object {0}'.format(expr.obj))
-      elif type(expr) is Unop:
-         a = self.evalExpression(expr.a)
-         if expr.op == 'not':
-            return not a
-         elif expr.op == '-':
-            return -a 
-         else:
-            self.Error('Unimplemented unary operation {0}'.format(expr.op))
-      else:
-         self.Error('Cannot evaluate expression {0}'.format(expr))
-
-   def parseConstExpression(self):
-      e = self.parseExpression()
-      return self.evalExpression(e), e.typ
-
-   def parseConstantDeclarations(self):
-      """ Parse const part of a module """
-      if self.hasConsumed('const'):
-         while self.token.typ == 'ID':
-            i = self.parseIdentDef()
-            self.Consume('=')
-            constvalue, typ = self.parseConstExpression()
-            self.Consume(';')
-            c = Constant(constvalue, typ, name=i.name, public=i.ispublic)
-            self.setLocation(c, i.location)
-            self.cst.addSymbol(c)
-     
-   # Type system
-   def parseTypeDeclarations(self):
-      if self.hasConsumed('type'):
-         while self.token.typ == 'ID':
-            typename, export = self.parseIdentDef()
-            self.Consume('=')
-            typ = self.parseStructuredType()
-            self.Consume(';')
-            t = DefinedType(typename, typ)
-            self.cst.addSymbol(t)
-
-   def parseType(self):
-      if self.token.typ == 'ID':
-         typename = self.Consume('ID')
-         if self.cst.has(Type, typename):
-            typ = self.cst.get(Type, typename)
-            while type(typ) is DefinedType:
-               typ = typ.typ
-            return typ
-         else:
-            self.Error('Cannot find type {0}'.format(typename))
-      else:
-         return self.parseStructuredType()
-
-   def parseStructuredType(self):
-      if self.hasConsumed('array'):
-         dimensions = []
-         dimensions.append( self.parseConstExpression() )
-         while self.hasConsumed(','):
-             dimensions.append( self.parseConstExpression() )
-         self.Consume('of')
-         arr = self.parseType()
-         for dimension, consttyp in reversed(dimensions):
-            if not isType(consttyp, integer):
-               self.Error('array dimension must be an integer type (not {0})'.format(consttyp))
-            if dimension < 2:
-               self.Error('array dimension must be bigger than 1 (not {0})'.format(dimension))
-            arr = ArrayType(dimension, arr)
-         return arr
-      elif self.hasConsumed('record'):
-         fields = {}
-         while self.token.typ == 'ID':
-            # parse a fieldlist:
-            identifiers = self.parseIdentList()
-            self.Consume(':')
-            typ = self.parseType()
-            self.Consume(';')
-            for i in identifiers:
-               if i.name in fields.keys():
-                  self.Error('record field "{0}" multiple defined.'.format(i.name))
-               fields[i.name] = typ
-            # TODO store this in another way, symbol table?
-         self.Consume('end')
-         return RecordType(fields)
-      elif self.hasConsumed('pointer'):
-         self.Consume('to')
-         typ = self.parseType()
-         return PointerType(typ)
-      elif self.hasConsumed('procedure'):
-         parameters, returntype = self.parseFormalParameters()
-         return ProcedureType(parameters, returntype)
-      else:
-         self.Error('Unknown structured type "{0}"'.format(self.token.val))
-
-   # Variable declarations:
-   def parseVariableDeclarations(self):
-      if self.hasConsumed('var'):
-         if self.token.typ == 'ID':
-            while self.token.typ == 'ID':
-               ids = self.parseIdentList()
-               self.Consume(':')
-               typename = self.parseType()
-               self.Consume(';')
-               for i in ids:
-                  v = Variable(i.name, typename, public=i.ispublic)
-                  self.setLocation(v, i.location)
-                  self.cst.addSymbol(v)
-         else:
-            self.Error('Expected ID, got'+str(self.token))
-
-   # Procedures
-   def parseFPsection(self):
-      if self.hasConsumed('const'):
-         kind = 'const'
-      elif self.hasConsumed('var'):
-         kind = 'var'
-      else:
-         kind = 'value'
-      names = [ self.Consume('ID') ]
-      while self.hasConsumed(','):
-         names.append( self.Consume('ID') )
-      self.Consume(':')
-      typ = self.parseType()
-      parameters = [Parameter(kind, name, typ)
-            for name in names]
-      return parameters
-
-   def parseFormalParameters(self):
-      parameters = []
-      self.Consume('(')
-      if not self.hasConsumed(')'):
-         parameters += self.parseFPsection()
-         while self.hasConsumed(';'):
-            parameters += self.parseFPsection()
-         self.Consume(')')
-      if self.hasConsumed(':'):
-         returntype = self.parseQualIdent()
-      else:
-         returntype = void
-      return ProcedureType(parameters, returntype)
-
-   def parseProcedureDeclarations(self):
-     procedures = []
-     while self.token.typ == 'procedure':
-       p = self.parseProcedureDeclaration()
-       procedures.append(p)
-       self.Consume(';')
-     return procedures
-
-   def parseProcedureDeclaration(self):
-     loc = self.getLocation()
-     self.Consume('procedure')
-     i = self.parseIdentDef()
-     procname = i.name
-     proctyp = self.parseFormalParameters()
-     procsymtable = SymbolTable(parent = self.cst)
-     self.cst = procsymtable    # Switch symbol table:
-     # Add parameters as variables to symbol table:
-     for parameter in proctyp.parameters:
-        vname = parameter.name
-        vtyp = parameter.typ
-        if parameter.kind == 'var':
-           vtyp = PointerType(vtyp)
-        variable = Variable(vname, vtyp, False)
-        if parameter.kind == 'const':
-           variable.isReadOnly = True
-        variable.isParameter = True
-        self.cst.addSymbol(variable)
-     self.Consume(';')
-     self.parseDeclarationSequence()
-     # Mark all variables as local:
-     for variable in self.cst.getAllLocal(Variable):
-        variable.isLocal = True
-
-     if self.hasConsumed('begin'):
-        block = self.parseStatementSequence()
-     if self.hasConsumed('return'):
-        returnexpression = self.parseExpression()
-     else:
-        returnexpression = None
-
-     if proctyp.returntype.isType(void):
-        if not returnexpression is None:
-           self.Error('Void procedure cannot return a value')
-     else:
-        if returnexpression is None:
-           self.Error('Procedure must return a value')
-        if not isType(returnexpression.typ, proctyp.returntype):
-           self.Error('Returned type {0} does not match function return type {1}'.format(returnexpression.typ, proctyp.returntype))
-
-     self.Consume('end')
-     endname = self.Consume('ID')
-     if endname != procname:
-        self.Error('endname should match {0}'.format(name))
-     self.cst = procsymtable.parent    # Switch back to parent symbol table
-     proc = Procedure(procname, proctyp, block, procsymtable, returnexpression)
-     self.setLocation(proc, loc)
-     self.cst.addSymbol(proc)
-     proc.public = i.ispublic
-     return proc
-
-   # Statements:
-   def parseAssignment(self, lval):
-      loc = self.getLocation()
-      self.Consume(':=')
-      rval = self.parseExpression()
-      if isType(lval.typ, real) and isType(rval.typ, integer):
-         rval = Unop(rval, 'INTTOREAL', real)
-      if type(rval.typ) is NilType:
-         if not type(lval.typ) is ProcedureType and not type(lval.typ) is PointerType:
-            self.Error('Can assign nil only to pointers or procedure types, not {0}'.format(lval))
-      elif not isType(lval.typ, rval.typ):
-         self.Error('Type mismatch {0} != {1}'.format(lval.typ, rval.typ))
-      return self.setLocation(Assignment(lval, rval), loc)
-
-   def parseExpressionList(self):
-      expressions = [ self.parseExpression() ]
-      while self.hasConsumed(','):
-         expressions.append( self.parseExpression() )
-      return expressions
-
-   def parseProcedureCall(self, procedure):
-      self.Consume('(')
-      if self.token.typ != ')':
-         args = self.parseExpressionList()
-      else:
-         args = []
-      self.Consume(')')
-      parameters = procedure.typ.parameters
-      if len(args) != len(parameters):
-         self.Error("Procedure requires {0} arguments, {1} given".format(len(parameters), len(args)))
-      for arg, param in zip(args, parameters):
-         if not arg.typ.isType(param.typ):
-            print(arg.typ, param.typ)
-            self.Error('Mismatch in parameter')
-      return ProcedureCall(procedure, args)
-
-   def parseIfStatement(self):
-     loc = self.getLocation()
-     self.Consume('if')
-     ifs = []
-     condition = self.parseExpression()
-     if not isType(condition.typ, boolean):
-         self.Error('condition of if statement must be boolean')
-     self.Consume('then')
-     truestatement = self.parseStatementSequence()
-     ifs.append( (condition, truestatement) )
-     while self.hasConsumed('elsif'):
-        condition = self.parseExpression()
-        if not isType(condition.typ, boolean):
-            self.Error('condition of if statement must be boolean')
-        self.Consume('then')
-        truestatement = self.parseStatementSequence()
-        ifs.append( (condition, truestatement) )
-     if self.hasConsumed('else'):
-        statement = self.parseStatementSequence()
-     else:
-        statement = None
-     self.Consume('end')
-     for condition, truestatement in reversed(ifs):
-         statement = IfStatement(condition, truestatement, statement)
-     return self.setLocation(statement, loc)
-
-   def parseCase(self):
-      # TODO
-      pass
-
-   def parseCaseStatement(self):
-      self.Consume('case')
-      expr = self.parseExpression()
-      self.Consume('of')
-      self.parseCase()
-      while self.hasConsumed('|'):
-         self.parseCase()
-      self.Consume('end')
-
-   def parseWhileStatement(self):
-      loc = self.getLocation()
-      self.Consume('while')
-      condition = self.parseExpression()
-      self.Consume('do')
-      statements = self.parseStatementSequence()
-      if self.hasConsumed('elsif'):
-         self.Error('elsif in while not yet implemented')
-      self.Consume('end')
-      return self.setLocation(WhileStatement(condition, statements), loc)
-
-   def parseRepeatStatement(self):
-      self.Consume('repeat')
-      stmt = self.parseStatementSequence()
-      self.Consume('until')
-      cond = self.parseBoolExpression()
-
-   def parseForStatement(self):
-      loc = self.getLocation()
-      self.Consume('for')
-      variable = self.parseDesignator()
-      if not variable.typ.isType(integer):
-         self.Error('loop variable of for statement must have integer type')
-      assert(variable.typ.isType(integer))
-      self.Consume(':=')
-      begin = self.parseExpression()
-      if not begin.typ.isType(integer):
-         self.Error('begin expression of a for statement must have integer type')
-      self.Consume('to')
-      end = self.parseExpression()
-      if not end.typ.isType(integer):
-         self.Error('end expression of a for statement must have integer type')
-      if self.hasConsumed('by'):
-         increment, typ = self.parseConstExpression()
-         if not typ.isType(integer):
-            self.Error('Increment must be integer')
-      else:
-         increment = 1
-      assert(type(increment) is int)
-      self.Consume('do')
-      statements = self.parseStatementSequence()
-      self.Consume('end')
-      return self.setLocation(ForStatement(variable, begin, end, increment, statements), loc)
-
-   def parseAsmcode(self):
-      # TODO: move this to seperate file
-      def parseOpcode():
-         return self.Consume('ID')
-      def parseOperand():
-         if self.hasConsumed('['):
-            memref = []
-            memref.append(parseOperand())
-            self.Consume(']')
-            return memref
-         else:
-            if self.token.typ == 'NUMBER':
-               return self.Consume('NUMBER')
-            else:
-               ID = self.Consume('ID')
-               if self.cst.has(Variable, ID):
-                  return self.cst.get(Variable, ID)
-               else:
-                  return ID
-               
-      def parseOperands(n):
-         operands = []
-         if n > 0:
-            operands.append( parseOperand() )
-            n = n - 1
-            while n > 0:
-               self.Consume(',')
-               operands.append(parseOperand())
-               n = n - 1
-         return operands
-      self.Consume('asm')
-      asmcode = []
-      while self.token.typ != 'end':
-         opcode = parseOpcode()
-         func, numargs = assembler.opcodes[opcode]
-         operands = parseOperands(numargs)
-         asmcode.append( (opcode, operands) )
-         #print('opcode', opcode, operands)
-      self.Consume('end')
-      return AsmCode(asmcode)
-
-   def parseStatement(self):
-     try:
-        # Determine statement type based on the pending token:
-        if self.token.typ == 'if':
-           return self.parseIfStatement()
-        elif self.token.typ == 'case':
-           return self.parseCaseStatement()
-        elif self.token.typ == 'while':
-          return self.parseWhileStatement()
-        elif self.token.typ == 'repeat':
-           return self.parseRepeatStatement()
-        elif self.token.typ == 'for':
-           return self.parseForStatement()
-        elif self.token.typ == 'asm':
-           return self.parseAsmcode()
-        elif self.token.typ == 'ID':
-           # Assignment or procedure call
-           designator = self.parseDesignator()
-           if self.token.typ == '(' and type(designator.typ) is ProcedureType:
-              return self.parseProcedureCall(designator)
-           elif self.token.typ == ':=':
-              return self.parseAssignment(designator)
-           else:
-              self.Error('Unknown statement following designator: {0}'.format(self.token))
-        else:
-           # TODO: return empty statement??:
-           return EmptyStatement()
-           self.Error('Unknown statement {0}'.format(self.token))
-     except CompilerException as e:
-         print(e)
-         self.errorlist.append( (e.row, e.col, e.msg))
-         # Do error recovery by skipping all tokens until next ; or end
-         while not (self.token.typ == ';' or self.token.typ == 'end'):
-            self.Consume(self.token.typ)
-         return EmptyStatement()
-
-   def parseStatementSequence(self):
-       """ Sequence of statements seperated by ';' """
-       statements = [ self.parseStatement() ]
-       while self.hasConsumed(';'):
-         statements.append( self.parseStatement() )
-       return StatementSequence( statements )
-
-   # Parsing expressions:
-   """
-     grammar of expressions:
-     expression       = SimpleExpression [ reloperator SimpleExpression ]
-     reloperator      = '=' | '<=' | '>=' | '<>'
-     Simpleexpression = [ '+' | '-' ] term { addoperator term }
-     addoperator      = '+' | '-' | 'or'
-     term             = factor { muloperator factor }
-     muloperator      = '*' | '/' | 'div' | 'mod' | 'and'
-     factor           = number | nil | true | false | "(" expression ")" | 
-                        designator [ actualparameters ] | 'not' factor
-   """
-   def parseExpression(self):
-      """ The connector between the boolean and expression domain """
-      expr = self.parseSimpleExpression()
-      if self.token.typ in ['>=','<=','<','>','<>','=']:
-         relop = self.Consume()
-         expr2 = self.parseSimpleExpression()
-         # Automatic type convert to reals:
-         if isType(expr.typ, real) and isType(expr2.typ, integer):
-            expr2 = Unop(expr2, 'INTTOREAL', real)
-         if isType(expr2.typ, real) and isType(expr.typ, integer):
-            expr = Unop(expr, 'INTTOREAL', real)
-         # Type check:
-         if not isType(expr.typ, expr2.typ):
-            self.Error('Type mismatch in relop')
-         if isType(expr.typ, real) and relop in ['<>', '=']:
-            self.Error('Cannot check real values for equality')
-
-         expr = Relop(expr, relop, expr2, boolean)
-      return expr
-
-   # Parsing arithmatic expressions:
-   def parseTerm(self):
-       a = self.parseFactor()
-       while self.token.typ in ['*', '/', 'mod', 'div', 'and']:
-           loc = self.getLocation()
-           op = self.Consume()
-           b = self.parseTerm()
-           # Type determination and checking:
-           if op in ['mod', 'div']:
-              if not isType(a.typ, integer):
-                 self.Error('First operand should be integer, not {0}'.format(a.typ))
-              if not isType(b.typ, integer):
-                 self.Error('Second operand should be integer, not {0}'.format(b.typ))
-              typ = integer
-           elif op == '*':
-              if isType(a.typ, integer) and isType(b.typ, integer):
-                 typ = integer
-              elif isType(a.typ, real) or isType(b.typ, real):
-                 if isType(a.typ, integer):
-                    # Automatic type cast
-                    a = Unop(a, 'INTTOREAL', real)
-                 if isType(b.typ, integer):
-                    b = Unop(b, 'INTTOREAL', real)
-                 if not isType(a.typ, real):
-                    self.Error('first operand must be a real!')
-                 if not isType(b.typ, real):
-                    self.Error('second operand must be a real!')
-                 typ = real
-              else:
-                 self.Error('Unknown operands for multiply: {0}, {1}'.format(a, b))
-           elif op == '/':
-              # Division always yields a real result, for integer division use div
-              if isType(a.typ, integer):
-                 # Automatic type cast
-                 a = Unop(a, 'INTTOREAL', real)
-              if isType(b.typ, integer):
-                 b = Unop(b, 'INTTOREAL', real)
-              if not isType(a.typ, real):
-                 self.Error('first operand must be a real!')
-              if not isType(b.typ, real):
-                 self.Error('second operand must be a real!')
-              typ = real
-           elif op == 'and':
-              if not isType(a.typ, boolean):
-                 self.Error('First operand of and must be boolean')
-              if not isType(b.typ, boolean):
-                 self.Error('Second operand of and must be boolean')
-              typ = boolean
-           else:
-              self.Error('Unknown operand {0}'.format(op))
-
-           a = self.setLocation(Binop(a, op, b, typ), loc)
-       return a
-
-   def parseFactor(self):
-      if self.hasConsumed('('):
-         e = self.parseExpression()
-         self.Consume(')')
-         return e
-      elif self.token.typ == 'NUMBER':
-         loc = self.getLocation() 
-         val = self.Consume('NUMBER')
-         return self.setLocation(Constant(val, integer), loc)
-      elif self.token.typ == 'REAL':
-         loc = self.getLocation()
-         val = self.Consume('REAL')
-         return self.setLocation(Constant(val, real), loc)
-      elif self.token.typ == 'CHAR':
-          val = self.Consume('CHAR')
-          return Constant(val, char)
-      elif self.token.typ == 'STRING':
-         txt = self.Consume('STRING')
-         return StringConstant(txt)
-      elif self.token.typ in ['true', 'false']:
-         val = self.Consume()
-         val = True if val == 'true' else False
-         return Constant(val, boolean)
-      elif self.hasConsumed('nil'):
-         return Constant(0, NilType())
-      elif self.hasConsumed('not'):
-         f = self.parseFactor()
-         if not isType(f.typ, boolean):
-            self.Error('argument of boolean negation must be boolean type')
-         return Unop(f, 'not', boolean)
-      elif self.token.typ == 'ID':
-          designator = self.parseDesignator()
-          # TODO: handle functions different here?
-          if self.token.typ == '(' and type(designator.typ) is ProcedureType:
-             return self.parseProcedureCall(designator)
-          else:
-             return designator
-      else:
-         self.Error('Expected NUMBER, ID or ( expr ), got'+str(self.token))
-
-   def parseSimpleExpression(self):
-      """ Arithmatic expression """
-      if self.token.typ in ['+', '-']:
-         # Handle the unary minus
-         op = self.Consume()
-         a = self.parseTerm()
-         typ = a.typ
-         if not isType(typ,real) and not isType(typ, integer):
-            self.Error('Unary minus or plus can be only applied to real or integers')
-         if op == '-':
-            a = Unop(a, op, typ)
-      else:
-         a = self.parseTerm()
-      while self.token.typ in ['+', '-', 'or']:
-           loc = self.getLocation()
-           op = self.Consume()
-           b = self.parseTerm()
-           if op in ['+', '-']:
-              if isType(a.typ, real) or isType(b.typ, real):
-                 typ = real
-                 if isType(a.typ, integer):
-                    # Automatic type cast
-                    a = Unop(a, 'INTTOREAL', real)
-                 if not isType(a.typ, real):
-                    self.Error('first operand must be a real!')
-                 if isType(b.typ, integer):
-                    b = Unop(b, 'INTTOREAL', real)
-                 if not isType(b.typ, real):
-                    self.Error('second operand must be a real!')
-              elif isType(a.typ, integer) and isType(b.typ, integer):
-                 typ = integer
-              else:
-                 self.Error('Invalid types {0} and {1}'.format(a.typ, b.typ))
-           elif op == 'or':
-              if not isType(a.typ, boolean):
-                 self.Error('first operand must be boolean for or operation')
-              if not isType(b.typ, boolean):
-                 self.Error('second operand must be boolean for or operation')
-              typ = boolean
-           else:
-              self.Error('Unknown operand {0}'.format(op))
-           a = self.setLocation(Binop(a, op, b, typ), loc)
-      return a
-
diff -r 654c5ac4f2c5 -r 60cc36ef5a50 python/libs/compiler/parsergen.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python/libs/compiler/parsergen.py	Sat Oct 27 14:31:58 2012 +0200
@@ -0,0 +1,787 @@
+"""
+  This module parses source code into an abstract syntax tree (AST)
+"""
+
+from .symboltable import SymbolTable
+from .nodes import *
+from .errors import CompilerException, Error
+from .modules import loadModule
+from .display import printNode
+from .builtin import *
+from . import assembler
+
+class Parser:
+   def __init__(self, tokens):
+      """ provide the parser with the tokens iterator from the lexer. """
+      self.tokens = tokens
+      self.NextToken()
+      self.errorlist = []
+
+   def Error(self, msg):
+     raise CompilerException(msg, self.token.row, self.token.col)
+
+   # Lexer helpers:
+   def Consume(self, typ=''):
+     if self.token.typ == typ or typ == '':
+       v = self.token.val
+       self.NextToken()
+       return v
+     else:
+       self.Error('Excected: "{0}", got "{1}"'.format(typ, self.token.val))
+
+   def hasConsumed(self, typ):
+      if self.token.typ == typ:
+         self.Consume(typ)
+         return True
+      return False
+     
+   def NextToken(self):
+     self.token = self.tokens.__next__()
+     # TODO: store filename in location?
+     self.location = (self.token.row, self.token.col)
+
+   # Helpers to find location of the error in the code:
+   def setLocation(self, obj, location):
+      obj.location = location
+      return obj
+   def getLocation(self):
+      return self.location
+
+   """
+     Recursive descent parser functions:
+        A set of mutual recursive functions.
+        Starting symbol is the Module.
+   """
+   def parseModule(self):
+       self.imports = []
+       loc = self.getLocation()
+       self.Consume('module')
+       modname = self.Consume('ID')
+       self.Consume(';')
+       mod = Module(modname)
+
+       # Construct a symbol table for this program
+       mod.symtable = SymbolTable()
+       # Add built in types and functions:
+       for x in [real, integer, boolean, char, chr_func]:
+          mod.symtable.addSymbol(x)
+
+       self.cst = mod.symtable
+       self.parseImportList()
+
+       self.parseDeclarationSequence()
+       # Procedures only allowed in this scope
+       self.parseProcedureDeclarations()
+
+       if self.hasConsumed('begin'):
+          mod.initcode = self.parseStatementSequence()
+       else:
+          mod.initcode = EmptyStatement()
+
+       self.Consume('end')
+       endname = self.Consume('ID')
+       if endname != modname:
+          self.Error('end denoter must be module name')
+       self.Consume('.')
+
+       mod.imports = self.imports
+       return self.setLocation(mod, loc)
+
+   # Import part
+   def parseImportList(self):
+      if self.hasConsumed('import'):
+         self.parseImport()
+         while self.hasConsumed(','):
+            self.parseImport()
+         self.Consume(';')
+
+   def parseImport(self):
+      loc = self.getLocation()
+      modname = self.Consume('ID')
+      mod = loadModule(modname)
+      self.setLocation(mod, loc)
+      self.cst.addSymbol(mod)
+
+   # Helper to parse an identifier defenitions
+   def parseIdentDef(self):
+      loc = self.getLocation()
+      name = self.Consume('ID')
+      ispublic = self.hasConsumed('*')
+      # Make a node of this thing:
+      i = Id(name)
+      i.ispublic = ispublic
+      return self.setLocation(i, loc)
+
+   def parseIdentList(self):
+      ids = [ self.parseIdentDef() ]
+      while self.hasConsumed(','):
+         ids.append( self.parseIdentDef() )
+      return ids
+
+   def parseQualIdent(self):
+      """ Parse a qualified identifier """
+      name = self.Consume('ID')
+      if self.cst.has(Module, name):
+         modname = name
+         mod = self.cst.get(Module, modname)
+         self.Consume('.')
+         name = self.Consume('ID')
+         # Try to find existing imported symbol:
+         for imp in self.imports:
+            if imp.modname == modname and imp.name == name:
+               return imp
+         # Try to find the symbol in the modules exports:
+         for sym in mod.exports:
+            if sym.name == name:
+               impsym = ImportedSymbol(modname, name)
+               impsym.typ = sym.typ
+               impsym.signature = mod.signature
+               self.imports.append(impsym)
+               return impsym
+         self.Error("Cannot find symbol {0}".format(name))
+      else:
+         return self.cst.getSymbol(name)
+
+   # Helper to parse a designator
+   def parseDesignator(self):
+      """ A designator designates an object.
+           The base location in memory is denoted by the qualified identifier
+           The actual address depends on the selector.
+      """
+      loc = self.getLocation()
+      obj = self.parseQualIdent()
+      typ = obj.typ
+      selectors = []
+      while self.token.typ in ['.', '[', '^']:
+         if self.hasConsumed('.'):
+            field = self.Consume('ID')
+            if typ is PointerType:
+               selectors.append(Deref())
+               typ = typ.pointedType
+            if not type(typ) is RecordType:
+               self.Error("field reference, type not record but {0}".format(typ))
+            typ = typ.fields[field]
+            selectors.append(Field(field))
+         elif self.hasConsumed('['):
+            indexes = self.parseExpressionList()
+            self.Consume(']')
+            for idx in indexes:
+               if not type(typ) is ArrayType:
+                  self.Error('Cannot index non array type')
+               if not isType(idx.typ, integer):
+                  self.Error('Only integer expressions can be used as an index')
+               selectors.append(Index(idx, typ))
+               typ = typ.elementType
+         elif self.hasConsumed('^'):
+            selectors.append(Deref())
+            typ = typ.pointedType
+      return self.setLocation(Designator(obj, selectors, typ), loc)
+
+   # Declaration sequence
+   def parseDeclarationSequence(self):
+      """ 1. constants, 2. types, 3. variables """
+      self.parseConstantDeclarations()
+      self.parseTypeDeclarations()
+      self.parseVariableDeclarations()
+
+   # Constants
+   def evalExpression(self, expr):
+      if type(expr) is Binop:
+         a = self.evalExpression(expr.a)
+         b = self.evalExpression(expr.b)
+         if expr.op == '+':
+            return a + b
+         elif expr.op == '-':
+            return a - b
+         elif expr.op == '*':
+            return a * b
+         elif expr.op == '/':
+            return float(a) / float(b)
+         elif expr.op == 'mod':
+            return int(a % b)
+         elif expr.op == 'div':
+            return int(a / b)
+         elif expr.op == 'or':
+            return a or b
+         elif expr.op == 'and':
+            return a and b
+         else:
+            self.Error('Cannot evaluate expression with {0}'.format(expr.op))
+      elif type(expr) is Constant:
+         return expr.value
+      elif type(expr) is Designator:
+         if type(expr.obj) is Constant:
+            return self.evalExpression(expr.obj)
+         else:
+            self.Error('Cannot evaluate designated object {0}'.format(expr.obj))
+      elif type(expr) is Unop:
+         a = self.evalExpression(expr.a)
+         if expr.op == 'not':
+            return not a
+         elif expr.op == '-':
+            return -a 
+         else:
+            self.Error('Unimplemented unary operation {0}'.format(expr.op))
+      else:
+         self.Error('Cannot evaluate expression {0}'.format(expr))
+
+   def parseConstExpression(self):
+      e = self.parseExpression()
+      return self.evalExpression(e), e.typ
+
+   def parseConstantDeclarations(self):
+      """ Parse const part of a module """
+      if self.hasConsumed('const'):
+         while self.token.typ == 'ID':
+            i = self.parseIdentDef()
+            self.Consume('=')
+            constvalue, typ = self.parseConstExpression()
+            self.Consume(';')
+            c = Constant(constvalue, typ, name=i.name, public=i.ispublic)
+            self.setLocation(c, i.location)
+            self.cst.addSymbol(c)
+     
+   # Type system
+   def parseTypeDeclarations(self):
+      if self.hasConsumed('type'):
+         while self.token.typ == 'ID':
+            typename, export = self.parseIdentDef()
+            self.Consume('=')
+            typ = self.parseStructuredType()
+            self.Consume(';')
+            t = DefinedType(typename, typ)
+            self.cst.addSymbol(t)
+
+   def parseType(self):
+      if self.token.typ == 'ID':
+         typename = self.Consume('ID')
+         if self.cst.has(Type, typename):
+            typ = self.cst.get(Type, typename)
+            while type(typ) is DefinedType:
+               typ = typ.typ
+            return typ
+         else:
+            self.Error('Cannot find type {0}'.format(typename))
+      else:
+         return self.parseStructuredType()
+
+   def parseStructuredType(self):
+      if self.hasConsumed('array'):
+         dimensions = []
+         dimensions.append( self.parseConstExpression() )
+         while self.hasConsumed(','):
+             dimensions.append( self.parseConstExpression() )
+         self.Consume('of')
+         arr = self.parseType()
+         for dimension, consttyp in reversed(dimensions):
+            if not isType(consttyp, integer):
+               self.Error('array dimension must be an integer type (not {0})'.format(consttyp))
+            if dimension < 2:
+               self.Error('array dimension must be bigger than 1 (not {0})'.format(dimension))
+            arr = ArrayType(dimension, arr)
+         return arr
+      elif self.hasConsumed('record'):
+         fields = {}
+         while self.token.typ == 'ID':
+            # parse a fieldlist:
+            identifiers = self.parseIdentList()
+            self.Consume(':')
+            typ = self.parseType()
+            self.Consume(';')
+            for i in identifiers:
+               if i.name in fields.keys():
+                  self.Error('record field "{0}" multiple defined.'.format(i.name))
+               fields[i.name] = typ
+            # TODO store this in another way, symbol table?
+         self.Consume('end')
+         return RecordType(fields)
+      elif self.hasConsumed('pointer'):
+         self.Consume('to')
+         typ = self.parseType()
+         return PointerType(typ)
+      elif self.hasConsumed('procedure'):
+         parameters, returntype = self.parseFormalParameters()
+         return ProcedureType(parameters, returntype)
+      else:
+         self.Error('Unknown structured type "{0}"'.format(self.token.val))
+
+   # Variable declarations:
+   def parseVariableDeclarations(self):
+      if self.hasConsumed('var'):
+         if self.token.typ == 'ID':
+            while self.token.typ == 'ID':
+               ids = self.parseIdentList()
+               self.Consume(':')
+               typename = self.parseType()
+               self.Consume(';')
+               for i in ids:
+                  v = Variable(i.name, typename, public=i.ispublic)
+                  self.setLocation(v, i.location)
+                  self.cst.addSymbol(v)
+         else:
+            self.Error('Expected ID, got'+str(self.token))
+
+   # Procedures
+   def parseFPsection(self):
+      if self.hasConsumed('const'):
+         kind = 'const'
+      elif self.hasConsumed('var'):
+         kind = 'var'
+      else:
+         kind = 'value'
+      names = [ self.Consume('ID') ]
+      while self.hasConsumed(','):
+         names.append( self.Consume('ID') )
+      self.Consume(':')
+      typ = self.parseType()
+      parameters = [Parameter(kind, name, typ)
+            for name in names]
+      return parameters
+
+   def parseFormalParameters(self):
+      parameters = []
+      self.Consume('(')
+      if not self.hasConsumed(')'):
+         parameters += self.parseFPsection()
+         while self.hasConsumed(';'):
+            parameters += self.parseFPsection()
+         self.Consume(')')
+      if self.hasConsumed(':'):
+         returntype = self.parseQualIdent()
+      else:
+         returntype = void
+      return ProcedureType(parameters, returntype)
+
+   def parseProcedureDeclarations(self):
+     procedures = []
+     while self.token.typ == 'procedure':
+       p = self.parseProcedureDeclaration()
+       procedures.append(p)
+       self.Consume(';')
+     return procedures
+
+   def parseProcedureDeclaration(self):
+     loc = self.getLocation()
+     self.Consume('procedure')
+     i = self.parseIdentDef()
+     procname = i.name
+     proctyp = self.parseFormalParameters()
+     procsymtable = SymbolTable(parent = self.cst)
+     self.cst = procsymtable    # Switch symbol table:
+     # Add parameters as variables to symbol table:
+     for parameter in proctyp.parameters:
+        vname = parameter.name
+        vtyp = parameter.typ
+        if parameter.kind == 'var':
+           vtyp = PointerType(vtyp)
+        variable = Variable(vname, vtyp, False)
+        if parameter.kind == 'const':
+           variable.isReadOnly = True
+        variable.isParameter = True
+        self.cst.addSymbol(variable)
+     self.Consume(';')
+     self.parseDeclarationSequence()
+     # Mark all variables as local:
+     for variable in self.cst.getAllLocal(Variable):
+        variable.isLocal = True
+
+     if self.hasConsumed('begin'):
+        block = self.parseStatementSequence()
+     if self.hasConsumed('return'):
+        returnexpression = self.parseExpression()
+     else:
+        returnexpression = None
+
+     if proctyp.returntype.isType(void):
+        if not returnexpression is None:
+           self.Error('Void procedure cannot return a value')
+     else:
+        if returnexpression is None:
+           self.Error('Procedure must return a value')
+        if not isType(returnexpression.typ, proctyp.returntype):
+           self.Error('Returned type {0} does not match function return type {1}'.format(returnexpression.typ, proctyp.returntype))
+
+     self.Consume('end')
+     endname = self.Consume('ID')
+     if endname != procname:
+        self.Error('endname should match {0}'.format(name))
+     self.cst = procsymtable.parent    # Switch back to parent symbol table
+     proc = Procedure(procname, proctyp, block, procsymtable, returnexpression)
+     self.setLocation(proc, loc)
+     self.cst.addSymbol(proc)
+     proc.public = i.ispublic
+     return proc
+
+   # Statements:
+   def parseAssignment(self, lval):
+      loc = self.getLocation()
+      self.Consume(':=')
+      rval = self.parseExpression()
+      if isType(lval.typ, real) and isType(rval.typ, integer):
+         rval = Unop(rval, 'INTTOREAL', real)
+      if type(rval.typ) is NilType:
+         if not type(lval.typ) is ProcedureType and not type(lval.typ) is PointerType:
+            self.Error('Can assign nil only to pointers or procedure types, not {0}'.format(lval))
+      elif not isType(lval.typ, rval.typ):
+         self.Error('Type mismatch {0} != {1}'.format(lval.typ, rval.typ))
+      return self.setLocation(Assignment(lval, rval), loc)
+
+   def parseExpressionList(self):
+      expressions = [ self.parseExpression() ]
+      while self.hasConsumed(','):
+         expressions.append( self.parseExpression() )
+      return expressions
+
+   def parseProcedureCall(self, procedure):
+      self.Consume('(')
+      if self.token.typ != ')':
+         args = self.parseExpressionList()
+      else:
+         args = []
+      self.Consume(')')
+      parameters = procedure.typ.parameters
+      if len(args) != len(parameters):
+         self.Error("Procedure requires {0} arguments, {1} given".format(len(parameters), len(args)))
+      for arg, param in zip(args, parameters):
+         if not arg.typ.isType(param.typ):
+            print(arg.typ, param.typ)
+            self.Error('Mismatch in parameter')
+      return ProcedureCall(procedure, args)
+
+   def parseIfStatement(self):
+     loc = self.getLocation()
+     self.Consume('if')
+     ifs = []
+     condition = self.parseExpression()
+     if not isType(condition.typ, boolean):
+         self.Error('condition of if statement must be boolean')
+     self.Consume('then')
+     truestatement = self.parseStatementSequence()
+     ifs.append( (condition, truestatement) )
+     while self.hasConsumed('elsif'):
+        condition = self.parseExpression()
+        if not isType(condition.typ, boolean):
+            self.Error('condition of if statement must be boolean')
+        self.Consume('then')
+        truestatement = self.parseStatementSequence()
+        ifs.append( (condition, truestatement) )
+     if self.hasConsumed('else'):
+        statement = self.parseStatementSequence()
+     else:
+        statement = None
+     self.Consume('end')
+     for condition, truestatement in reversed(ifs):
+         statement = IfStatement(condition, truestatement, statement)
+     return self.setLocation(statement, loc)
+
+   def parseCase(self):
+      # TODO
+      pass
+
+   def parseCaseStatement(self):
+      self.Consume('case')
+      expr = self.parseExpression()
+      self.Consume('of')
+      self.parseCase()
+      while self.hasConsumed('|'):
+         self.parseCase()
+      self.Consume('end')
+
+   def parseWhileStatement(self):
+      loc = self.getLocation()
+      self.Consume('while')
+      condition = self.parseExpression()
+      self.Consume('do')
+      statements = self.parseStatementSequence()
+      if self.hasConsumed('elsif'):
+         self.Error('elsif in while not yet implemented')
+      self.Consume('end')
+      return self.setLocation(WhileStatement(condition, statements), loc)
+
+   def parseRepeatStatement(self):
+      self.Consume('repeat')
+      stmt = self.parseStatementSequence()
+      self.Consume('until')
+      cond = self.parseBoolExpression()
+
+   def parseForStatement(self):
+      loc = self.getLocation()
+      self.Consume('for')
+      variable = self.parseDesignator()
+      if not variable.typ.isType(integer):
+         self.Error('loop variable of for statement must have integer type')
+      assert(variable.typ.isType(integer))
+      self.Consume(':=')
+      begin = self.parseExpression()
+      if not begin.typ.isType(integer):
+         self.Error('begin expression of a for statement must have integer type')
+      self.Consume('to')
+      end = self.parseExpression()
+      if not end.typ.isType(integer):
+         self.Error('end expression of a for statement must have integer type')
+      if self.hasConsumed('by'):
+         increment, typ = self.parseConstExpression()
+         if not typ.isType(integer):
+            self.Error('Increment must be integer')
+      else:
+         increment = 1
+      assert(type(increment) is int)
+      self.Consume('do')
+      statements = self.parseStatementSequence()
+      self.Consume('end')
+      return self.setLocation(ForStatement(variable, begin, end, increment, statements), loc)
+
+   def parseAsmcode(self):
+      # TODO: move this to seperate file
+      def parseOpcode():
+         return self.Consume('ID')
+      def parseOperand():
+         if self.hasConsumed('['):
+            memref = []
+            memref.append(parseOperand())
+            self.Consume(']')
+            return memref
+         else:
+            if self.token.typ == 'NUMBER':
+               return self.Consume('NUMBER')
+            else:
+               ID = self.Consume('ID')
+               if self.cst.has(Variable, ID):
+                  return self.cst.get(Variable, ID)
+               else:
+                  return ID
+               
+      def parseOperands(n):
+         operands = []
+         if n > 0:
+            operands.append( parseOperand() )
+            n = n - 1
+            while n > 0:
+               self.Consume(',')
+               operands.append(parseOperand())
+               n = n - 1
+         return operands
+      self.Consume('asm')
+      asmcode = []
+      while self.token.typ != 'end':
+         opcode = parseOpcode()
+         func, numargs = assembler.opcodes[opcode]
+         operands = parseOperands(numargs)
+         asmcode.append( (opcode, operands) )
+         #print('opcode', opcode, operands)
+      self.Consume('end')
+      return AsmCode(asmcode)
+
+   def parseStatement(self):
+     try:
+        # Determine statement type based on the pending token:
+        if self.token.typ == 'if':
+           return self.parseIfStatement()
+        elif self.token.typ == 'case':
+           return self.parseCaseStatement()
+        elif self.token.typ == 'while':
+          return self.parseWhileStatement()
+        elif self.token.typ == 'repeat':
+           return self.parseRepeatStatement()
+        elif self.token.typ == 'for':
+           return self.parseForStatement()
+        elif self.token.typ == 'asm':
+           return self.parseAsmcode()
+        elif self.token.typ == 'ID':
+           # Assignment or procedure call
+           designator = self.parseDesignator()
+           if self.token.typ == '(' and type(designator.typ) is ProcedureType:
+              return self.parseProcedureCall(designator)
+           elif self.token.typ == ':=':
+              return self.parseAssignment(designator)
+           else:
+              self.Error('Unknown statement following designator: {0}'.format(self.token))
+        else:
+           # TODO: return empty statement??:
+           return EmptyStatement()
+           self.Error('Unknown statement {0}'.format(self.token))
+     except CompilerException as e:
+         print(e)
+         self.errorlist.append( (e.row, e.col, e.msg))
+         # Do error recovery by skipping all tokens until next ; or end
+         while not (self.token.typ == ';' or self.token.typ == 'end'):
+            self.Consume(self.token.typ)
+         return EmptyStatement()
+
+   def parseStatementSequence(self):
+       """ Sequence of statements seperated by ';' """
+       statements = [ self.parseStatement() ]
+       while self.hasConsumed(';'):
+         statements.append( self.parseStatement() )
+       return StatementSequence( statements )
+
+   # Parsing expressions:
+   """
+     grammar of expressions:
+     expression       = SimpleExpression [ reloperator SimpleExpression ]
+     reloperator      = '=' | '<=' | '>=' | '<>'
+     Simpleexpression = [ '+' | '-' ] term { addoperator term }
+     addoperator      = '+' | '-' | 'or'
+     term             = factor { muloperator factor }
+     muloperator      = '*' | '/' | 'div' | 'mod' | 'and'
+     factor           = number | nil | true | false | "(" expression ")" | 
+                        designator [ actualparameters ] | 'not' factor
+   """
+   def parseExpression(self):
+      """ The connector between the boolean and expression domain """
+      expr = self.parseSimpleExpression()
+      if self.token.typ in ['>=','<=','<','>','<>','=']:
+         relop = self.Consume()
+         expr2 = self.parseSimpleExpression()
+         # Automatic type convert to reals:
+         if isType(expr.typ, real) and isType(expr2.typ, integer):
+            expr2 = Unop(expr2, 'INTTOREAL', real)
+         if isType(expr2.typ, real) and isType(expr.typ, integer):
+            expr = Unop(expr, 'INTTOREAL', real)
+         # Type check:
+         if not isType(expr.typ, expr2.typ):
+            self.Error('Type mismatch in relop')
+         if isType(expr.typ, real) and relop in ['<>', '=']:
+            self.Error('Cannot check real values for equality')
+
+         expr = Relop(expr, relop, expr2, boolean)
+      return expr
+
+   # Parsing arithmatic expressions:
+   def parseTerm(self):
+       a = self.parseFactor()
+       while self.token.typ in ['*', '/', 'mod', 'div', 'and']:
+           loc = self.getLocation()
+           op = self.Consume()
+           b = self.parseTerm()
+           # Type determination and checking:
+           if op in ['mod', 'div']:
+              if not isType(a.typ, integer):
+                 self.Error('First operand should be integer, not {0}'.format(a.typ))
+              if not isType(b.typ, integer):
+                 self.Error('Second operand should be integer, not {0}'.format(b.typ))
+              typ = integer
+           elif op == '*':
+              if isType(a.typ, integer) and isType(b.typ, integer):
+                 typ = integer
+              elif isType(a.typ, real) or isType(b.typ, real):
+                 if isType(a.typ, integer):
+                    # Automatic type cast
+                    a = Unop(a, 'INTTOREAL', real)
+                 if isType(b.typ, integer):
+                    b = Unop(b, 'INTTOREAL', real)
+                 if not isType(a.typ, real):
+                    self.Error('first operand must be a real!')
+                 if not isType(b.typ, real):
+                    self.Error('second operand must be a real!')
+                 typ = real
+              else:
+                 self.Error('Unknown operands for multiply: {0}, {1}'.format(a, b))
+           elif op == '/':
+              # Division always yields a real result, for integer division use div
+              if isType(a.typ, integer):
+                 # Automatic type cast
+                 a = Unop(a, 'INTTOREAL', real)
+              if isType(b.typ, integer):
+                 b = Unop(b, 'INTTOREAL', real)
+              if not isType(a.typ, real):
+                 self.Error('first operand must be a real!')
+              if not isType(b.typ, real):
+                 self.Error('second operand must be a real!')
+              typ = real
+           elif op == 'and':
+              if not isType(a.typ, boolean):
+                 self.Error('First operand of and must be boolean')
+              if not isType(b.typ, boolean):
+                 self.Error('Second operand of and must be boolean')
+              typ = boolean
+           else:
+              self.Error('Unknown operand {0}'.format(op))
+
+           a = self.setLocation(Binop(a, op, b, typ), loc)
+       return a
+
+   def parseFactor(self):
+      if self.hasConsumed('('):
+         e = self.parseExpression()
+         self.Consume(')')
+         return e
+      elif self.token.typ == 'NUMBER':
+         loc = self.getLocation() 
+         val = self.Consume('NUMBER')
+         return self.setLocation(Constant(val, integer), loc)
+      elif self.token.typ == 'REAL':
+         loc = self.getLocation()
+         val = self.Consume('REAL')
+         return self.setLocation(Constant(val, real), loc)
+      elif self.token.typ == 'CHAR':
+          val = self.Consume('CHAR')
+          return Constant(val, char)
+      elif self.token.typ == 'STRING':
+         txt = self.Consume('STRING')
+         return StringConstant(txt)
+      elif self.token.typ in ['true', 'false']:
+         val = self.Consume()
+         val = True if val == 'true' else False
+         return Constant(val, boolean)
+      elif self.hasConsumed('nil'):
+         return Constant(0, NilType())
+      elif self.hasConsumed('not'):
+         f = self.parseFactor()
+         if not isType(f.typ, boolean):
+            self.Error('argument of boolean negation must be boolean type')
+         return Unop(f, 'not', boolean)
+      elif self.token.typ == 'ID':
+          designator = self.parseDesignator()
+          # TODO: handle functions different here?
+          if self.token.typ == '(' and type(designator.typ) is ProcedureType:
+             return self.parseProcedureCall(designator)
+          else:
+             return designator
+      else:
+         self.Error('Expected NUMBER, ID or ( expr ), got'+str(self.token))
+
+   def parseSimpleExpression(self):
+      """ Arithmatic expression """
+      if self.token.typ in ['+', '-']:
+         # Handle the unary minus
+         op = self.Consume()
+         a = self.parseTerm()
+         typ = a.typ
+         if not isType(typ,real) and not isType(typ, integer):
+            self.Error('Unary minus or plus can be only applied to real or integers')
+         if op == '-':
+            a = Unop(a, op, typ)
+      else:
+         a = self.parseTerm()
+      while self.token.typ in ['+', '-', 'or']:
+           loc = self.getLocation()
+           op = self.Consume()
+           b = self.parseTerm()
+           if op in ['+', '-']:
+              if isType(a.typ, real) or isType(b.typ, real):
+                 typ = real
+                 if isType(a.typ, integer):
+                    # Automatic type cast
+                    a = Unop(a, 'INTTOREAL', real)
+                 if not isType(a.typ, real):
+                    self.Error('first operand must be a real!')
+                 if isType(b.typ, integer):
+                    b = Unop(b, 'INTTOREAL', real)
+                 if not isType(b.typ, real):
+                    self.Error('second operand must be a real!')
+              elif isType(a.typ, integer) and isType(b.typ, integer):
+                 typ = integer
+              else:
+                 self.Error('Invalid types {0} and {1}'.format(a.typ, b.typ))
+           elif op == 'or':
+              if not isType(a.typ, boolean):
+                 self.Error('first operand must be boolean for or operation')
+              if not isType(b.typ, boolean):
+                 self.Error('second operand must be boolean for or operation')
+              typ = boolean
+           else:
+              self.Error('Unknown operand {0}'.format(op))
+           a = self.setLocation(Binop(a, op, b, typ), loc)
+      return a
+