text: # indentedGrammarExample.py
  #
  # Copyright (c) 2006, Paul McGuire
  #
  # A sample of a pyparsing grammar using indentation for 
  # grouping (like Python does).
  #
  
  from pyparsingOD 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() )
  