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# 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() )
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