Augment ParseException str() output to include what character was found at the error location, to help diagnose errors.

2 files changed, 26 insertions, 4 deletions

diff --git a/CHANGES b/CHANGES
index f02d2e7..6478072 100644
--- a/CHANGES
+++ b/CHANGES
@@ -58,6 +58,20 @@ Version 2.4.1 - July, 2019
 
   This form is only valid when used with the '|' operator.
 
+- Improved exception messages to show what was actually found, not
+  just what was expected.
+
+    word = pp.Word(pp.alphas)
+    pp.OneOrMore(word).parseString("aaa bbb 123", parseAll=True)
+
+  Former exception message:
+
+    pyparsing.ParseException: Expected end of text (at char 8), (line:1, col:9)
+
+  New exception message:
+
+    pyparsing.ParseException: Expected end of text, found '1' (at char 8), (line:1, col:9)
+
 - Added ParseResults.from_dict classmethod, to simplify creation
   of a ParseResults with results names. May be called with a dict
   argument, or with a series of named arguments (or both). This
@@ -104,7 +118,8 @@ Version 2.4.1 - July, 2019
   delegate to it to model state-specific properties and behavior.
 
 - Added example nested_markup.py, showing a simple wiki markup with
-  nested markup directives.
+  nested markup directives, and illustrating the use of '...' for
+  skipping over input to match the next expression.
 
 - Rewrote delta_time.py example (renamed from deltaTime.py) to
   fix some omitted formats and upgrade to latest pyparsing idioms,
diff --git a/pyparsing.py b/pyparsing.py
index 27df353..eabfead 100644
--- a/pyparsing.py
+++ b/pyparsing.py
@@ -96,7 +96,7 @@ classes inherit from. Use the docstrings for examples of how to:
 """
 
 __version__ = "2.4.1"
-__versionTime__ = "07 Jul 2019 06:35 UTC"
+__versionTime__ = "08 Jul 2019 02:00 UTC"
 __author__ = "Paul McGuire <ptmcg@users.sourceforge.net>"
 
 import string
@@ -290,8 +290,15 @@ class ParseBaseException(Exception):
             raise AttributeError(aname)
 
     def __str__( self ):
-        return "%s (at char %d), (line:%d, col:%d)" % \
-                ( self.msg, self.loc, self.lineno, self.column )
+        if self.pstr:
+            if self.loc >= len(self.pstr):
+                foundstr = ', found end of text'
+            else:
+                foundstr = ', found %r' % self.pstr[self.loc:self.loc+1]
+        else:
+            foundstr = ''
+        return "%s%s  (at char %d), (line:%d, col:%d)" % \
+                ( self.msg, foundstr, self.loc, self.lineno, self.column )
     def __repr__( self ):
         return _ustr(self)
     def markInputline( self, markerString = ">!<" ):