From b2c3ade75384efe76b8774b607e17fe98fab92ef Mon Sep 17 00:00:00 2001
From: ptmcg <ptmcg@9bf210a0-9d2d-494c-87cf-cfb32e7dff7b>
Date: Tue, 9 Aug 2016 00:23:49 +0000
Subject: TagTag for 2.1.6 release

git-svn-id: svn://svn.code.sf.net/p/pyparsing/code/tags/pyparsing_2.1.6@402 9bf210a0-9d2d-494c-87cf-cfb32e7dff7b
---
 trunk/src/examples/macroExpander.py | 60 +++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 trunk/src/examples/macroExpander.py

(limited to 'trunk/src/examples/macroExpander.py')

diff --git a/trunk/src/examples/macroExpander.py b/trunk/src/examples/macroExpander.py
new file mode 100644
index 0000000..327976c
--- /dev/null
+++ b/trunk/src/examples/macroExpander.py
@@ -0,0 +1,60 @@
+# macroExpander.py
+#
+# Example pyparsing program for performing macro expansion, similar to 
+# the C pre-processor.  This program is not as fully-featured, simply
+# processing macros of the form:
+#     #def xxx yyyyy
+# and replacing xxx with yyyyy in the rest of the input string.  Macros
+# can also be composed using other macros, such as
+#     #def zzz xxx+1
+# Since xxx was previously defined as yyyyy, then zzz will be replaced
+# with yyyyy+1.
+#
+# Copyright 2007 by Paul McGuire
+#
+from pyparsing import *
+
+# define the structure of a macro definition (the empty term is used 
+# to advance to the next non-whitespace character)
+identifier = Word(alphas+"_",alphanums+"_")
+macroDef = "#def" + identifier("macro") + empty + restOfLine("value")
+                
+# define a placeholder for defined macros - initially nothing
+macroExpr = Forward()
+macroExpr << NoMatch()
+
+# global dictionary for macro definitions
+macros = {}
+
+# parse action for macro definitions
+def processMacroDefn(s,l,t):
+    macroVal = macroExpander.transformString(t.value)
+    macros[t.macro] = macroVal
+    macroExpr << MatchFirst(map(Keyword, macros.keys()))
+    return "#def " + t.macro + " " + macroVal
+
+# parse action to replace macro references with their respective definition
+def processMacroRef(s,l,t):
+    return macros[t[0]]
+
+# attach parse actions to expressions
+macroExpr.setParseAction(processMacroRef)
+macroDef.setParseAction(processMacroDefn)
+
+# define pattern for scanning through the input string
+macroExpander = macroExpr | macroDef
+
+
+
+# test macro substitution using transformString
+testString = """
+    #def A 100
+    #def ALEN A+1
+
+    char Astring[ALEN];
+    char AA[A];
+    typedef char[ALEN] Acharbuf;
+    """
+
+print(macroExpander.transformString(testString))
+print(macros)
-- 
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