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+#
+# left_recursion.py
+#
+# Example code illustrating use of left-recursion in Pyparsing.
+#
+import pyparsing as pp
+
+# comment out this line to see the effects without LR parsing enabled
+pp.ParserElement.enableLeftRecursion()
+
+item_list = pp.Forward()
+
+# a common left-recursion definition
+# define a list of items as 'list + item | item'
+# BNF:
+# item_list := item_list item | item
+# item := word of alphas
+item = pp.Word(pp.alphas)
+item_list <<= item_list + item | item
+
+item_list.runTests("""\
+ To parse or not to parse that is the question
+ """)
+
+# Define a parser for an expression that can be an identifier, a quoted string, or a
+# function call that starts with an expression
+# BNF:
+# expr := function_call | name | string | '(' expr ')'
+# function_call := expr '(' expr,... ')'
+# name := Python identifier
+# string := a quoted string
+# from https://stackoverflow.com/questions/32809389/parse-python-code-using-pyparsing/32822575#32822575
+
+LPAR, RPAR = map(pp.Suppress, "()")
+expr = pp.Forward()
+string = pp.quotedString
+function_call = expr + pp.Group(LPAR + pp.Optional(pp.delimitedList(expr)) + RPAR)
+name = pp.Word(pp.alphas + '_', pp.alphanums + '_')
+# left recursion - call starts with an expr
+expr <<= function_call | string | name | pp.Group(LPAR + expr + RPAR)
+
+expr.runTests("""\
+ print("Hello, World!")
+ (lookup_function("fprintf"))(stderr, "Hello, World!")
+ """, fullDump=False)