--- a/python/ppci/common.py	Mon Dec 16 12:49:24 2013 +0100
+++ b/python/ppci/common.py	Mon Dec 16 17:58:15 2013 +0100
@@ -1,5 +1,11 @@
 from collections import namedtuple
+import logging
 
+"""
+   Error handling routines
+   Diagnostic utils
+   Source location structures
+"""
 
 # Token is used in the lexical analyzer:
 class Token:
@@ -27,3 +33,79 @@
 
 
 SourceRange = namedtuple('SourceRange', ['p1', 'p2'])
+
+
+class CompilerError(Exception):
+    def __init__(self, msg, loc=None):
+        self.msg = msg
+        self.loc = loc
+        if loc:
+            assert type(loc) is SourceLocation, \
+                   '{0} must be SourceLocation'.format(type(loc))
+            self.row = loc.row
+            self.col = loc.col
+        else:
+            self.row = self.col = 0
+
+    def __repr__(self):
+        return '"{}"'.format(self.msg)
+
+
+class DiagnosticsManager:
+    def __init__(self):
+        self.diags = []
+        self.sources = {}
+        self.logger = logging.getLogger('diagnostics')
+
+    def addSource(self, name, src):
+        self.logger.info('Adding source {}'.format(name))
+        self.sources[name] = src
+
+    def addDiag(self, d):
+        #self.logger.warning(str(d.msg))
+        self.diags.append(d)
+
+    def error(self, msg, loc):
+        self.addDiag(CompilerError(msg, loc))
+
+    def clear(self):
+        del self.diags[:]
+        self.sources.clear()
+
+    def printErrors(self):
+        if len(self.diags) > 0:
+            print('{0} Errors'.format(len(self.diags)))
+            for d in self.diags:
+                self.printError(d)
+
+    def printError(self, e):
+        def printLine(row, txt):
+            print(str(row)+':'+txt)
+        print('==============')
+        if not e.loc:
+            print('Error: {0}'.format(e))
+        else:
+            if e.loc.filename not in self.sources:
+                print('Error: {0}'.format(e))
+                return
+            print("File: {}".format(e.loc.filename))
+            source = self.sources[e.loc.filename]
+            lines = source.split('\n')
+            ro, co = e.row, e.col
+            prerow = ro - 2
+            if prerow < 1:
+               prerow = 1
+            afterrow = ro + 3
+            if afterrow > len(lines):
+               afterrow = len(lines)
+
+            # print preceding source lines:
+            for r in range(prerow, ro):
+               printLine(r, lines[r-1])
+            # print source line containing error:
+            printLine(ro, lines[ro-1])
+            print(' '*(len(str(ro)+':')+co-1) + '^ Error: {0}'.format(e.msg))
+            # print trailing source line:
+            for r in range(ro+1, afterrow+1):
+              printLine(r, lines[r-1])
+        print('==============')