|
1
|
1 """
|
|
|
2 This module parses source code into an abstract syntax tree (AST)
|
|
|
3 """
|
|
|
4
|
|
|
5 import shelve
|
|
|
6 from .symboltable import SymbolTable
|
|
|
7 from .nodes import *
|
|
|
8 from .errors import CompilerException, Error
|
|
|
9 from .modules import loadModule
|
|
|
10 from .display import printNode
|
|
|
11 from .builtin import *
|
|
|
12 from . import assembler
|
|
|
13
|
|
|
14 class Parser:
|
|
|
15 def __init__(self, tokens):
|
|
|
16 """ provide the parser with the tokens iterator from the lexer. """
|
|
|
17 self.tokens = tokens
|
|
|
18 self.NextToken()
|
|
|
19
|
|
|
20 def Error(self, msg):
|
|
|
21 raise CompilerException(msg, self.token.row, self.token.col)
|
|
|
22
|
|
|
23 # Lexer helpers:
|
|
|
24 def Consume(self, typ=''):
|
|
|
25 if self.token.typ == typ or typ == '':
|
|
|
26 v = self.token.val
|
|
|
27 self.NextToken()
|
|
|
28 return v
|
|
|
29 else:
|
|
|
30 self.Error('Excected: "{0}", got "{1}"'.format(typ, self.token))
|
|
|
31
|
|
|
32 def hasConsumed(self, typ):
|
|
|
33 if self.token.typ == typ:
|
|
|
34 self.Consume(typ)
|
|
|
35 return True
|
|
|
36 return False
|
|
|
37
|
|
|
38 def NextToken(self):
|
|
|
39 self.token = self.tokens.__next__()
|
|
|
40
|
|
|
41 def setLocation(self):
|
|
|
42 pass
|
|
|
43 def attachLocation(self, node):
|
|
|
44 node.row, node.col = self.token.row, self.token.col
|
|
|
45 return node
|
|
|
46 """
|
|
|
47 Recursive descent parser functions:
|
|
|
48 A set of mutual recursive functions.
|
|
|
49 Starting symbol is the Module.
|
|
|
50 """
|
|
|
51
|
|
|
52 def parseModule(self):
|
|
|
53 self.imports = []
|
|
|
54 self.Consume('module')
|
|
|
55 modname = self.Consume('ID')
|
|
|
56 self.Consume(';')
|
|
|
57 mod = Module(modname)
|
|
|
58
|
|
|
59 # Construct a symbol table for this program
|
|
|
60 mod.symtable = SymbolTable()
|
|
|
61 # Add built in types and functions:
|
|
|
62 for x in [real, integer, boolean, char, chr_func]:
|
|
|
63 mod.symtable.addSymbol(x)
|
|
|
64
|
|
|
65 self.cst = mod.symtable
|
|
|
66 self.parseImportList()
|
|
|
67
|
|
|
68 self.parseDeclarationSequence()
|
|
|
69 # Procedures only allowed in this scope
|
|
|
70 self.parseProcedureDeclarations()
|
|
|
71
|
|
|
72 if self.hasConsumed('begin'):
|
|
|
73 mod.initcode = self.parseStatementSequence()
|
|
|
74 else:
|
|
|
75 mod.initcode = EmptyStatement()
|
|
|
76
|
|
|
77 self.Consume('end')
|
|
|
78 endname = self.Consume('ID')
|
|
|
79 if endname != modname:
|
|
|
80 self.Error('end denoter must be module name')
|
|
|
81 self.Consume('.')
|
|
|
82
|
|
|
83 mod.imports = self.imports
|
|
|
84 return mod
|
|
|
85
|
|
|
86 # Import part
|
|
|
87 def parseImportList(self):
|
|
|
88 if self.hasConsumed('import'):
|
|
|
89 self.parseImport()
|
|
|
90 while self.hasConsumed(','):
|
|
|
91 self.parseImport()
|
|
|
92 self.Consume(';')
|
|
|
93
|
|
|
94 def parseImport(self):
|
|
|
95 modname = self.Consume('ID')
|
|
|
96 mod = loadModule(modname)
|
|
|
97 self.cst.addSymbol(mod)
|
|
|
98
|
|
|
99 # Helper to parse an identifier defenitions
|
|
|
100 def parseIdentDef(self):
|
|
|
101 name = self.Consume('ID')
|
|
|
102 ispublic = self.hasConsumed('*')
|
|
|
103 return (name, ispublic)
|
|
|
104
|
|
|
105 def parseIdentList(self):
|
|
|
106 ids = [ self.parseIdentDef() ]
|
|
|
107 while self.hasConsumed(','):
|
|
|
108 ids.append( self.parseIdentDef() )
|
|
|
109 return ids
|
|
|
110
|
|
|
111 def parseQualIdent(self):
|
|
|
112 """ Parse a qualified identifier """
|
|
|
113 name = self.Consume('ID')
|
|
|
114 if self.cst.has(Module, name):
|
|
|
115 modname = name
|
|
|
116 mod = self.cst.get(Module, modname)
|
|
|
117 self.Consume('.')
|
|
|
118 name = self.Consume('ID')
|
|
|
119 # Try to find existing imported symbol:
|
|
|
120 for imp in self.imports:
|
|
|
121 if imp.modname == modname and imp.name == name:
|
|
|
122 return imp
|
|
|
123 # Try to find the symbol in the modules exports:
|
|
|
124 for sym in mod.exports:
|
|
|
125 if sym.name == name:
|
|
|
126 impsym = ImportedSymbol(modname, name)
|
|
|
127 impsym.typ = sym.typ
|
|
|
128 impsym.signature = mod.signature
|
|
|
129 self.imports.append(impsym)
|
|
|
130 return impsym
|
|
|
131 self.Error("Cannot find symbol {0}".format(name))
|
|
|
132 else:
|
|
|
133 return self.cst.getSymbol(name)
|
|
|
134
|
|
|
135 # Helper to parse a designator
|
|
|
136 def parseDesignator(self):
|
|
|
137 """ A designator designates an object.
|
|
|
138 The base location in memory is denoted by the qualified identifier
|
|
|
139 The actual address depends on the selector.
|
|
|
140 """
|
|
|
141 obj = self.parseQualIdent()
|
|
|
142 typ = obj.typ
|
|
|
143 selectors = []
|
|
|
144 while self.token.typ in ['.', '[', '^']:
|
|
|
145 if self.hasConsumed('.'):
|
|
|
146 field = self.Consume('ID')
|
|
|
147 if typ is PointerType:
|
|
|
148 selectors.append(Deref())
|
|
|
149 typ = typ.pointedType
|
|
|
150 if not type(typ) is RecordType:
|
|
|
151 self.Error("field reference, type not record but {0}".format(typ))
|
|
|
152 typ = typ.fields[field]
|
|
|
153 selectors.append(Field(field))
|
|
|
154 elif self.hasConsumed('['):
|
|
|
155 indexes = self.parseExpressionList()
|
|
|
156 self.Consume(']')
|
|
|
157 for idx in indexes:
|
|
|
158 if not type(typ) is ArrayType:
|
|
|
159 self.Error('Cannot index non array type')
|
|
|
160 if not isType(idx.typ, integer):
|
|
|
161 self.Error('Only integer expressions can be used as an index')
|
|
|
162 selectors.append(Index(idx, typ))
|
|
|
163 typ = typ.elementType
|
|
|
164 elif self.hasConsumed('^'):
|
|
|
165 selectors.append(Deref())
|
|
|
166 typ = typ.pointedType
|
|
|
167 return Designator(obj, selectors, typ)
|
|
|
168
|
|
|
169 # Declaration sequence
|
|
|
170 def parseDeclarationSequence(self):
|
|
|
171 """ 1. constants, 2. types, 3. variables """
|
|
|
172 self.parseConstantDeclarations()
|
|
|
173 self.parseTypeDeclarations()
|
|
|
174 self.parseVariableDeclarations()
|
|
|
175
|
|
|
176 # Constants
|
|
|
177 def evalExpression(self, expr):
|
|
|
178 if type(expr) is Binop:
|
|
|
179 a = self.evalExpression(expr.a)
|
|
|
180 b = self.evalExpression(expr.b)
|
|
|
181 if expr.op == '+':
|
|
|
182 return a + b
|
|
|
183 elif expr.op == '-':
|
|
|
184 return a - b
|
|
|
185 elif expr.op == '*':
|
|
|
186 return a * b
|
|
|
187 elif expr.op == '/':
|
|
|
188 return float(a) / float(b)
|
|
|
189 elif expr.op == 'mod':
|
|
|
190 return int(a % b)
|
|
|
191 elif expr.op == 'div':
|
|
|
192 return int(a / b)
|
|
|
193 elif expr.op == 'or':
|
|
|
194 return a or b
|
|
|
195 elif expr.op == 'and':
|
|
|
196 return a and b
|
|
|
197 else:
|
|
|
198 self.Error('Cannot evaluate expression with {0}'.format(expr.op))
|
|
|
199 elif type(expr) is Constant:
|
|
|
200 return expr.value
|
|
|
201 elif type(expr) is Designator:
|
|
|
202 if type(expr.obj) is Constant:
|
|
|
203 return self.evalExpression(expr.obj)
|
|
|
204 else:
|
|
|
205 self.Error('Cannot evaluate designated object {0}'.format(expr.obj))
|
|
|
206 elif type(expr) is Unop:
|
|
|
207 a = self.evalExpression(expr.a)
|
|
|
208 if expr.op == 'not':
|
|
|
209 return not a
|
|
|
210 elif expr.op == '-':
|
|
|
211 return -a
|
|
|
212 else:
|
|
|
213 self.Error('Unimplemented unary operation {0}'.format(expr.op))
|
|
|
214 else:
|
|
|
215 self.Error('Cannot evaluate expression {0}'.format(expr))
|
|
|
216
|
|
|
217 def parseConstExpression(self):
|
|
|
218 e = self.parseExpression()
|
|
|
219 return self.evalExpression(e), e.typ
|
|
|
220
|
|
|
221 def parseConstantDeclarations(self):
|
|
|
222 """ Parse const part of a module """
|
|
|
223 if self.hasConsumed('const'):
|
|
|
224 while self.token.typ == 'ID':
|
|
|
225 name, ispublic = self.parseIdentDef()
|
|
|
226 self.Consume('=')
|
|
|
227 constvalue, typ = self.parseConstExpression()
|
|
|
228 self.Consume(';')
|
|
|
229 c = Constant(constvalue, typ, name=name, public=ispublic)
|
|
|
230 self.cst.addSymbol(c)
|
|
|
231
|
|
|
232 # Type system
|
|
|
233 def parseTypeDeclarations(self):
|
|
|
234 if self.hasConsumed('type'):
|
|
|
235 while self.token.typ == 'ID':
|
|
|
236 typename, export = self.parseIdentDef()
|
|
|
237 self.Consume('=')
|
|
|
238 typ = self.parseStructuredType()
|
|
|
239 self.Consume(';')
|
|
|
240 t = DefinedType(typename, typ)
|
|
|
241 self.cst.addSymbol(t)
|
|
|
242
|
|
|
243 def parseType(self):
|
|
|
244 if self.token.typ == 'ID':
|
|
|
245 typename = self.Consume('ID')
|
|
|
246 if self.cst.has(Type, typename):
|
|
|
247 typ = self.cst.get(Type, typename)
|
|
|
248 while type(typ) is DefinedType:
|
|
|
249 typ = typ.typ
|
|
|
250 return typ
|
|
|
251 else:
|
|
|
252 self.Error('Cannot find type {0}'.format(typename))
|
|
|
253 else:
|
|
|
254 return self.parseStructuredType()
|
|
|
255
|
|
|
256 def parseStructuredType(self):
|
|
|
257 if self.hasConsumed('array'):
|
|
|
258 dimensions = []
|
|
|
259 dimensions.append( self.parseConstExpression() )
|
|
|
260 while self.hasConsumed(','):
|
|
|
261 dimensions.append( self.parseConstExpression() )
|
|
|
262 self.Consume('of')
|
|
|
263 arr = self.parseType()
|
|
|
264 for dimension, consttyp in reversed(dimensions):
|
|
|
265 if not isType(consttyp, integer):
|
|
|
266 self.Error('array dimension must be an integer type (not {0})'.format(consttyp))
|
|
|
267 if dimension < 2:
|
|
|
268 self.Error('array dimension must be bigger than 1 (not {0})'.format(dimension))
|
|
|
269 arr = ArrayType(dimension, arr)
|
|
|
270 return arr
|
|
|
271 elif self.hasConsumed('record'):
|
|
|
272 fields = {}
|
|
|
273 while self.token.typ == 'ID':
|
|
|
274 # parse a fieldlist:
|
|
|
275 identifiers = self.parseIdentList()
|
|
|
276 self.Consume(':')
|
|
|
277 typ = self.parseType()
|
|
|
278 self.Consume(';')
|
|
|
279 for id, public in identifiers:
|
|
|
280 if id in fields.keys():
|
|
|
281 self.Error('record field "{0}" multiple defined.'.format(id))
|
|
|
282 fields[id] = typ
|
|
|
283 # TODO store this in another way, symbol table?
|
|
|
284 self.Consume('end')
|
|
|
285 return RecordType(fields)
|
|
|
286 elif self.hasConsumed('pointer'):
|
|
|
287 self.Consume('to')
|
|
|
288 typ = self.parseType()
|
|
|
289 return PointerType(typ)
|
|
|
290 elif self.hasConsumed('procedure'):
|
|
|
291 parameters, returntype = self.parseFormalParameters()
|
|
|
292 return ProcedureType(parameters, returntype)
|
|
|
293 else:
|
|
|
294 self.Error('Unknown structured type "{0}"'.format(self.token.val))
|
|
|
295
|
|
|
296 # Variable declarations:
|
|
|
297 def parseVariableDeclarations(self):
|
|
|
298 if self.hasConsumed('var'):
|
|
|
299 if self.token.typ == 'ID':
|
|
|
300 while self.token.typ == 'ID':
|
|
|
301 ids = self.parseIdentList()
|
|
|
302 self.Consume(':')
|
|
|
303 typename = self.parseType()
|
|
|
304 self.Consume(';')
|
|
|
305 for name, ispublic in ids:
|
|
|
306 v = Variable(name, typename, public=ispublic)
|
|
|
307 self.cst.addSymbol(v)
|
|
|
308 else:
|
|
|
309 self.Error('Expected ID, got'+str(self.token))
|
|
|
310
|
|
|
311 # Procedures
|
|
|
312 def parseFPsection(self):
|
|
|
313 if self.hasConsumed('const'):
|
|
|
314 kind = 'const'
|
|
|
315 elif self.hasConsumed('var'):
|
|
|
316 kind = 'var'
|
|
|
317 else:
|
|
|
318 kind = 'value'
|
|
|
319 names = [ self.Consume('ID') ]
|
|
|
320 while self.hasConsumed(','):
|
|
|
321 names.append( self.Consume('ID') )
|
|
|
322 self.Consume(':')
|
|
|
323 typ = self.parseType()
|
|
|
324 parameters = [Parameter(kind, name, typ)
|
|
|
325 for name in names]
|
|
|
326 return parameters
|
|
|
327
|
|
|
328 def parseFormalParameters(self):
|
|
|
329 parameters = []
|
|
|
330 self.Consume('(')
|
|
|
331 if not self.hasConsumed(')'):
|
|
|
332 parameters += self.parseFPsection()
|
|
|
333 while self.hasConsumed(';'):
|
|
|
334 parameters += self.parseFPsection()
|
|
|
335 self.Consume(')')
|
|
|
336 if self.hasConsumed(':'):
|
|
|
337 returntype = self.parseQualIdent()
|
|
|
338 else:
|
|
|
339 returntype = void
|
|
|
340 return ProcedureType(parameters, returntype)
|
|
|
341
|
|
|
342 def parseProcedureDeclarations(self):
|
|
|
343 procedures = []
|
|
|
344 while self.token.typ == 'procedure':
|
|
|
345 p = self.parseProcedureDeclaration()
|
|
|
346 procedures.append(p)
|
|
|
347 self.Consume(';')
|
|
|
348 return procedures
|
|
|
349
|
|
|
350 def parseProcedureDeclaration(self):
|
|
|
351 self.Consume('procedure')
|
|
|
352 name, ispublic = self.parseIdentDef()
|
|
|
353 proctyp = self.parseFormalParameters()
|
|
|
354 procsymtable = SymbolTable(parent = self.cst)
|
|
|
355 self.cst = procsymtable # Switch symbol table:
|
|
|
356 # Add parameters as variables to symbol table:
|
|
|
357 for parameter in proctyp.parameters:
|
|
|
358 vname = parameter.name
|
|
|
359 vtyp = parameter.typ
|
|
|
360 if parameter.kind == 'var':
|
|
|
361 vtyp = PointerType(vtyp)
|
|
|
362 variable = Variable(vname, vtyp, False)
|
|
|
363 if parameter.kind == 'const':
|
|
|
364 variable.isReadOnly = True
|
|
|
365 variable.isParameter = True
|
|
|
366 self.cst.addSymbol(variable)
|
|
|
367 self.Consume(';')
|
|
|
368 self.parseDeclarationSequence()
|
|
|
369 # Mark all variables as local:
|
|
|
370 for variable in self.cst.getAllLocal(Variable):
|
|
|
371 variable.isLocal = True
|
|
|
372
|
|
|
373 if self.hasConsumed('begin'):
|
|
|
374 block = self.parseStatementSequence()
|
|
|
375 if self.hasConsumed('return'):
|
|
|
376 returnexpression = self.parseExpression()
|
|
|
377 else:
|
|
|
378 returnexpression = None
|
|
|
379
|
|
|
380 if proctyp.returntype.isType(void):
|
|
|
381 if not returnexpression is None:
|
|
|
382 self.Error('Void procedure cannot return a value')
|
|
|
383 else:
|
|
|
384 if returnexpression is None:
|
|
|
385 self.Error('Procedure must return a value')
|
|
|
386 if not isType(returnexpression.typ, proctyp.returntype):
|
|
|
387 self.Error('Returned type {0} does not match function return type {1}'.format(returnexpression.typ, proctyp.returntype))
|
|
|
388
|
|
|
389 self.Consume('end')
|
|
|
390 endname = self.Consume('ID')
|
|
|
391 if endname != name:
|
|
|
392 self.Error('endname should match {0}'.format(name))
|
|
|
393 self.cst = procsymtable.parent # Switch back to parent symbol table
|
|
|
394 proc = Procedure(name, proctyp, block, procsymtable, returnexpression)
|
|
|
395 self.cst.addSymbol(proc)
|
|
|
396 proc.public = ispublic
|
|
|
397 return proc
|
|
|
398
|
|
|
399 # Statements:
|
|
|
400 def parseAssignment(self, lval):
|
|
|
401 self.Consume(':=')
|
|
|
402 rval = self.parseExpression()
|
|
|
403 if isType(lval.typ, real) and isType(rval.typ, integer):
|
|
|
404 rval = Unop(rval, 'INTTOREAL', real)
|
|
|
405 if type(rval.typ) is NilType:
|
|
|
406 if not type(lval.typ) is ProcedureType and not type(lval.typ) is PointerType:
|
|
|
407 self.Error('Can assign nil only to pointers or procedure types, not {0}'.format(lval))
|
|
|
408 elif not isType(lval.typ, rval.typ):
|
|
|
409 self.Error('Type mismatch {0} != {1}'.format(lval.typ, rval.typ))
|
|
|
410 return Assignment(lval, rval)
|
|
|
411
|
|
|
412 def parseExpressionList(self):
|
|
|
413 expressions = [ self.parseExpression() ]
|
|
|
414 while self.hasConsumed(','):
|
|
|
415 expressions.append( self.parseExpression() )
|
|
|
416 return expressions
|
|
|
417
|
|
|
418 def parseProcedureCall(self, procedure):
|
|
|
419 self.Consume('(')
|
|
|
420 if self.token.typ != ')':
|
|
|
421 args = self.parseExpressionList()
|
|
|
422 else:
|
|
|
423 args = []
|
|
|
424 self.Consume(')')
|
|
|
425 parameters = procedure.typ.parameters
|
|
|
426 if len(args) != len(parameters):
|
|
|
427 self.Error("Procedure requires {0} arguments, {1} given".format(len(parameters), len(args)))
|
|
|
428 for arg, param in zip(args, parameters):
|
|
|
429 if not arg.typ.isType(param.typ):
|
|
|
430 print(arg.typ, param.typ)
|
|
|
431 self.Error('Mismatch in parameter')
|
|
|
432 return ProcedureCall(procedure, args)
|
|
|
433
|
|
|
434 def parseIfStatement(self):
|
|
|
435 self.Consume('if')
|
|
|
436 ifs = []
|
|
|
437 condition = self.parseExpression()
|
|
|
438 if not isType(condition.typ, boolean):
|
|
|
439 self.Error('condition of if statement must be boolean')
|
|
|
440 self.Consume('then')
|
|
|
441 truestatement = self.parseStatementSequence()
|
|
|
442 ifs.append( (condition, truestatement) )
|
|
|
443 while self.hasConsumed('elsif'):
|
|
|
444 condition = self.parseExpression()
|
|
|
445 if not isType(condition.typ, boolean):
|
|
|
446 self.Error('condition of if statement must be boolean')
|
|
|
447 self.Consume('then')
|
|
|
448 truestatement = self.parseStatementSequence()
|
|
|
449 ifs.append( (condition, truestatement) )
|
|
|
450 if self.hasConsumed('else'):
|
|
|
451 statement = self.parseStatementSequence()
|
|
|
452 else:
|
|
|
453 statement = None
|
|
|
454 self.Consume('end')
|
|
|
455 for condition, truestatement in reversed(ifs):
|
|
|
456 statement = IfStatement(condition, truestatement, statement)
|
|
|
457 return statement
|
|
|
458
|
|
|
459 def parseCase(self):
|
|
|
460 # TODO
|
|
|
461 pass
|
|
|
462
|
|
|
463 def parseCaseStatement(self):
|
|
|
464 self.Consume('case')
|
|
|
465 expr = self.parseExpression()
|
|
|
466 self.Consume('of')
|
|
|
467 self.parseCase()
|
|
|
468 while self.hasConsumed('|'):
|
|
|
469 self.parseCase()
|
|
|
470 self.Consume('end')
|
|
|
471
|
|
|
472 def parseWhileStatement(self):
|
|
|
473 self.Consume('while')
|
|
|
474 condition = self.parseExpression()
|
|
|
475 self.Consume('do')
|
|
|
476 statements = self.parseStatementSequence()
|
|
|
477 if self.hasConsumed('elsif'):
|
|
|
478 self.Error('elsif in while not yet implemented')
|
|
|
479 self.Consume('end')
|
|
|
480 return WhileStatement(condition, statements)
|
|
|
481
|
|
|
482 def parseRepeatStatement(self):
|
|
|
483 self.Consume('repeat')
|
|
|
484 stmt = self.parseStatementSequence()
|
|
|
485 self.Consume('until')
|
|
|
486 cond = self.parseBoolExpression()
|
|
|
487
|
|
|
488 def parseForStatement(self):
|
|
|
489 self.Consume('for')
|
|
|
490 variable = self.parseDesignator()
|
|
|
491 if not variable.typ.isType(integer):
|
|
|
492 self.Error('loop variable of for statement must have integer type')
|
|
|
493 assert(variable.typ.isType(integer))
|
|
|
494 self.Consume(':=')
|
|
|
495 begin = self.parseExpression()
|
|
|
496 if not begin.typ.isType(integer):
|
|
|
497 self.Error('begin expression of a for statement must have integer type')
|
|
|
498 self.Consume('to')
|
|
|
499 end = self.parseExpression()
|
|
|
500 if not end.typ.isType(integer):
|
|
|
501 self.Error('end expression of a for statement must have integer type')
|
|
|
502 if self.hasConsumed('by'):
|
|
|
503 increment, typ = self.parseConstExpression()
|
|
|
504 if not typ.isType(integer):
|
|
|
505 self.Error('Increment must be integer')
|
|
|
506 else:
|
|
|
507 increment = 1
|
|
|
508 assert(type(increment) is int)
|
|
|
509 self.Consume('do')
|
|
|
510 statements = self.parseStatementSequence()
|
|
|
511 self.Consume('end')
|
|
|
512 return ForStatement(variable, begin, end, increment, statements)
|
|
|
513
|
|
|
514 def parseAsmcode(self):
|
|
|
515 def parseOpcode():
|
|
|
516 return self.Consume('ID')
|
|
|
517 def parseOperand():
|
|
|
518 if self.hasConsumed('['):
|
|
|
519 memref = []
|
|
|
520 memref.append(parseOperand())
|
|
|
521 self.Consume(']')
|
|
|
522 return memref
|
|
|
523 else:
|
|
|
524 if self.token.typ == 'NUMBER':
|
|
|
525 return self.Consume('NUMBER')
|
|
|
526 else:
|
|
|
527 ID = self.Consume('ID')
|
|
|
528 if self.cst.has(Variable, ID):
|
|
|
529 return self.cst.get(Variable, ID)
|
|
|
530 else:
|
|
|
531 return ID
|
|
|
532
|
|
|
533 def parseOperands(n):
|
|
|
534 operands = []
|
|
|
535 if n > 0:
|
|
|
536 operands.append( parseOperand() )
|
|
|
537 n = n - 1
|
|
|
538 while n > 0:
|
|
|
539 self.Consume(',')
|
|
|
540 operands.append(parseOperand())
|
|
|
541 n = n - 1
|
|
|
542 return operands
|
|
|
543 self.Consume('asm')
|
|
|
544 asmcode = []
|
|
|
545 while self.token.typ != 'end':
|
|
|
546 opcode = parseOpcode()
|
|
|
547 func, numargs = assembler.opcodes[opcode]
|
|
|
548 operands = parseOperands(numargs)
|
|
|
549 asmcode.append( (opcode, operands) )
|
|
|
550 #print('opcode', opcode, operands)
|
|
|
551 self.Consume('end')
|
|
|
552 return AsmCode(asmcode)
|
|
|
553
|
|
|
554 def parseStatement(self):
|
|
|
555 # Determine statement type based on the pending token:
|
|
|
556 if self.token.typ == 'if':
|
|
|
557 return self.parseIfStatement()
|
|
|
558 elif self.token.typ == 'case':
|
|
|
559 return self.parseCaseStatement()
|
|
|
560 elif self.token.typ == 'while':
|
|
|
561 return self.parseWhileStatement()
|
|
|
562 elif self.token.typ == 'repeat':
|
|
|
563 return self.parseRepeatStatement()
|
|
|
564 elif self.token.typ == 'for':
|
|
|
565 return self.parseForStatement()
|
|
|
566 elif self.token.typ == 'asm':
|
|
|
567 return self.parseAsmcode()
|
|
|
568 elif self.token.typ == 'ID':
|
|
|
569 # Assignment or procedure call
|
|
|
570 designator = self.parseDesignator()
|
|
|
571 if self.token.typ == '(' and type(designator.typ) is ProcedureType:
|
|
|
572 return self.parseProcedureCall(designator)
|
|
|
573 elif self.token.typ == ':=':
|
|
|
574 return self.parseAssignment(designator)
|
|
|
575 else:
|
|
|
576 self.Error('Unknown statement following designator: {0}'.format(self.token))
|
|
|
577 else:
|
|
|
578 # TODO: return empty statement??:
|
|
|
579 return EmptyStatement()
|
|
|
580 self.Error('Unknown statement {0}'.format(self.token))
|
|
|
581
|
|
|
582 def parseStatementSequence(self):
|
|
|
583 """ Sequence of statements seperated by ';' """
|
|
|
584 statements = [ self.parseStatement() ]
|
|
|
585 while self.hasConsumed(';'):
|
|
|
586 statements.append( self.parseStatement() )
|
|
|
587 return StatementSequence( statements )
|
|
|
588
|
|
|
589 # Parsing expressions:
|
|
|
590 """
|
|
|
591 grammar of expressions:
|
|
|
592 expression = SimpleExpression [ reloperator SimpleExpression ]
|
|
|
593 reloperator = '=' | '<=' | '>=' | '<>'
|
|
|
594 Simpleexpression = [ '+' | '-' ] term { addoperator term }
|
|
|
595 addoperator = '+' | '-' | 'or'
|
|
|
596 term = factor { muloperator factor }
|
|
|
597 muloperator = '*' | '/' | 'div' | 'mod' | 'and'
|
|
|
598 factor = number | nil | true | false | "(" expression ")" |
|
|
|
599 designator [ actualparameters ] | 'not' factor
|
|
|
600 """
|
|
|
601 def parseExpression(self):
|
|
|
602 """ The connector between the boolean and expression domain """
|
|
|
603 expr = self.parseSimpleExpression()
|
|
|
604 if self.token.typ in ['>=','<=','<','>','<>','=']:
|
|
|
605 relop = self.Consume()
|
|
|
606 expr2 = self.parseSimpleExpression()
|
|
|
607 # Automatic type convert to reals:
|
|
|
608 if isType(expr.typ, real) and isType(expr2.typ, integer):
|
|
|
609 expr2 = Unop(expr2, 'INTTOREAL', real)
|
|
|
610 if isType(expr2.typ, real) and isType(expr.typ, integer):
|
|
|
611 expr = Unop(expr, 'INTTOREAL', real)
|
|
|
612 # Type check:
|
|
|
613 if not isType(expr.typ, expr2.typ):
|
|
|
614 self.Error('Type mismatch in relop')
|
|
|
615 if isType(expr.typ, real) and relop in ['<>', '=']:
|
|
|
616 self.Error('Cannot check real values for equality')
|
|
|
617
|
|
|
618 expr = Relop(expr, relop, expr2, boolean)
|
|
|
619 return expr
|
|
|
620
|
|
|
621 # Parsing arithmatic expressions:
|
|
|
622 def parseTerm(self):
|
|
|
623 a = self.parseFactor()
|
|
|
624 while self.token.typ in ['*', '/', 'mod', 'div', 'and']:
|
|
|
625 op = self.Consume()
|
|
|
626 b = self.parseTerm()
|
|
|
627 # Type determination and checking:
|
|
|
628 if op in ['mod', 'div']:
|
|
|
629 if not isType(a.typ, integer):
|
|
|
630 self.Error('First operand should be integer, not {0}'.format(a.typ))
|
|
|
631 if not isType(b.typ, integer):
|
|
|
632 self.Error('Second operand should be integer, not {0}'.format(b.typ))
|
|
|
633 typ = integer
|
|
|
634 elif op == '*':
|
|
|
635 if isType(a.typ, integer) and isType(b.typ, integer):
|
|
|
636 typ = integer
|
|
|
637 elif isType(a.typ, real) or isType(b.typ, real):
|
|
|
638 if isType(a.typ, integer):
|
|
|
639 # Automatic type cast
|
|
|
640 a = Unop(a, 'INTTOREAL', real)
|
|
|
641 if isType(b.typ, integer):
|
|
|
642 b = Unop(b, 'INTTOREAL', real)
|
|
|
643 if not isType(a.typ, real):
|
|
|
644 self.Error('first operand must be a real!')
|
|
|
645 if not isType(b.typ, real):
|
|
|
646 self.Error('second operand must be a real!')
|
|
|
647 typ = real
|
|
|
648 else:
|
|
|
649 self.Error('Unknown operands for multiply: {0}, {1}'.format(a, b))
|
|
|
650 elif op == '/':
|
|
|
651 # Division always yields a real result, for integer division use div
|
|
|
652 if isType(a.typ, integer):
|
|
|
653 # Automatic type cast
|
|
|
654 a = Unop(a, 'INTTOREAL', real)
|
|
|
655 if isType(b.typ, integer):
|
|
|
656 b = Unop(b, 'INTTOREAL', real)
|
|
|
657 if not isType(a.typ, real):
|
|
|
658 self.Error('first operand must be a real!')
|
|
|
659 if not isType(b.typ, real):
|
|
|
660 self.Error('second operand must be a real!')
|
|
|
661 typ = real
|
|
|
662 elif op == 'and':
|
|
|
663 if not isType(a.typ, boolean):
|
|
|
664 self.Error('First operand of and must be boolean')
|
|
|
665 if not isType(b.typ, boolean):
|
|
|
666 self.Error('Second operand of and must be boolean')
|
|
|
667 typ = boolean
|
|
|
668 else:
|
|
|
669 self.Error('Unknown operand {0}'.format(op))
|
|
|
670
|
|
|
671 a = Binop(a, op, b, typ)
|
|
|
672 return a
|
|
|
673
|
|
|
674 def parseFactor(self):
|
|
|
675 if self.hasConsumed('('):
|
|
|
676 e = self.parseExpression()
|
|
|
677 self.Consume(')')
|
|
|
678 return e
|
|
|
679 elif self.token.typ == 'NUMBER':
|
|
|
680 val = self.Consume('NUMBER')
|
|
|
681 return Constant(val, integer)
|
|
|
682 elif self.token.typ == 'REAL':
|
|
|
683 val = self.Consume('REAL')
|
|
|
684 return Constant(val, real)
|
|
|
685 elif self.token.typ == 'CHAR':
|
|
|
686 val = self.Consume('CHAR')
|
|
|
687 return Constant(val, char)
|
|
|
688 elif self.token.typ == 'STRING':
|
|
|
689 txt = self.Consume('STRING')
|
|
|
690 return StringConstant(txt)
|
|
|
691 elif self.token.typ in ['true', 'false']:
|
|
|
692 val = self.Consume()
|
|
|
693 val = True if val == 'true' else False
|
|
|
694 return Constant(val, boolean)
|
|
|
695 elif self.hasConsumed('nil'):
|
|
|
696 return Constant(0, NilType())
|
|
|
697 elif self.hasConsumed('not'):
|
|
|
698 f = self.parseFactor()
|
|
|
699 if not isType(f.typ, boolean):
|
|
|
700 self.Error('argument of boolean negation must be boolean type')
|
|
|
701 return Unop(f, 'not', boolean)
|
|
|
702 elif self.token.typ == 'ID':
|
|
|
703 designator = self.parseDesignator()
|
|
|
704 # TODO: handle functions different here?
|
|
|
705 if self.token.typ == '(' and type(designator.typ) is ProcedureType:
|
|
|
706 return self.parseProcedureCall(designator)
|
|
|
707 else:
|
|
|
708 return designator
|
|
|
709 else:
|
|
|
710 self.Error('Expected NUMBER, ID or ( expr ), got'+str(self.token))
|
|
|
711
|
|
|
712 def parseSimpleExpression(self):
|
|
|
713 """ Arithmatic expression """
|
|
|
714 if self.token.typ in ['+', '-']:
|
|
|
715 # Handle the unary minus
|
|
|
716 op = self.Consume()
|
|
|
717 a = self.parseTerm()
|
|
|
718 typ = a.typ
|
|
|
719 if not isType(typ,real) and not isType(typ, integer):
|
|
|
720 self.Error('Unary minus or plus can be only applied to real or integers')
|
|
|
721 if op == '-':
|
|
|
722 a = Unop(a, op, typ)
|
|
|
723 else:
|
|
|
724 a = self.parseTerm()
|
|
|
725 while self.token.typ in ['+', '-', 'or']:
|
|
|
726 op = self.Consume()
|
|
|
727 b = self.parseTerm()
|
|
|
728 if op in ['+', '-']:
|
|
|
729 if isType(a.typ, real) or isType(b.typ, real):
|
|
|
730 typ = real
|
|
|
731 if isType(a.typ, integer):
|
|
|
732 # Automatic type cast
|
|
|
733 a = Unop(a, 'INTTOREAL', real)
|
|
|
734 if not isType(a.typ, real):
|
|
|
735 self.Error('first operand must be a real!')
|
|
|
736 if isType(b.typ, integer):
|
|
|
737 b = Unop(b, 'INTTOREAL', real)
|
|
|
738 if not isType(b.typ, real):
|
|
|
739 self.Error('second operand must be a real!')
|
|
|
740 elif isType(a.typ, integer) and isType(b.typ, integer):
|
|
|
741 typ = integer
|
|
|
742 else:
|
|
|
743 self.Error('Invalid types {0} and {1}'.format(a.typ, b.typ))
|
|
|
744 elif op == 'or':
|
|
|
745 if not isType(a.typ, boolean):
|
|
|
746 self.Error('first operand must be boolean for or operation')
|
|
|
747 if not isType(b.typ, boolean):
|
|
|
748 self.Error('second operand must be boolean for or operation')
|
|
|
749 typ = boolean
|
|
|
750 else:
|
|
|
751 self.Error('Unknown operand {0}'.format(op))
|
|
|
752 a = Binop(a, op, b, typ)
|
|
|
753 return a
|
|
|
754
|
