1 files changed, 78 insertions, 0 deletions
diff --git a/src/examples/indentedGrammarExample.py b/src/examples/indentedGrammarExample.py
new file mode 100644
index 0000000..e7b8cb7
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+++ b/src/examples/indentedGrammarExample.py
@@ -0,0 +1,78 @@
+# indentedGrammarExample.py
+#
+# Copyright (c) 2006, Paul McGuire
+#
+# A sample of a pyparsing grammar using indentation for 
+# grouping (like Python does).
+#
+
+from pyparsing import *
+
+data = """\
+def A(z):
+  A1
+  B = 100
+  G = A2
+  A2
+  A3
+B
+def BB(a,b,c):
+  BB1
+  def BBA():
+    bba1
+    bba2
+    bba3
+C
+D
+def spam(x,y):
+     def eggs(z):
+         pass
+"""
+
+indentStack = [1]
+
+def checkPeerIndent(s,l,t):
+    curCol = col(l,s)
+    if curCol != indentStack[-1]:
+        if (not indentStack) or curCol > indentStack[-1]:
+            raise ParseFatalException(s,l,"illegal nesting")
+        raise ParseException(s,l,"not a peer entry")
+
+def checkSubIndent(s,l,t):
+    curCol = col(l,s)
+    if curCol > indentStack[-1]:
+        indentStack.append( curCol )
+    else:
+        raise ParseException(s,l,"not a subentry")
+
+def checkUnindent(s,l,t):
+    if l >= len(s): return
+    curCol = col(l,s)
+    if not(curCol < indentStack[-1] and curCol <= indentStack[-2]):
+        raise ParseException(s,l,"not an unindent")
+
+def doUnindent():
+    indentStack.pop()
+    
+INDENT = lineEnd.suppress() + empty + empty.copy().setParseAction(checkSubIndent)
+UNDENT = FollowedBy(empty).setParseAction(checkUnindent)
+UNDENT.setParseAction(doUnindent)
+
+stmt = Forward()
+suite = Group( OneOrMore( empty + stmt.setParseAction( checkPeerIndent ) )  )
+
+identifier = Word(alphas, alphanums)
+funcDecl = ("def" + identifier + Group( "(" + Optional( delimitedList(identifier) ) + ")" ) + ":")
+funcDef = Group( funcDecl + INDENT + suite + UNDENT )
+
+rvalue = Forward()
+funcCall = Group(identifier + "(" + Optional(delimitedList(rvalue)) + ")")
+rvalue << (funcCall | identifier | Word(nums))
+assignment = Group(identifier + "=" + rvalue)
+stmt << ( funcDef | assignment | identifier )
+
+print data
+parseTree = suite.parseString(data)
+
+import pprint
+pprint.pprint( parseTree.asList() )