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Diffstat (limited to 'trunk/src/examples/pythonGrammarParser.py')
| -rw-r--r-- | trunk/src/examples/pythonGrammarParser.py | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/trunk/src/examples/pythonGrammarParser.py b/trunk/src/examples/pythonGrammarParser.py new file mode 100644 index 0000000..f0631b8 --- /dev/null +++ b/trunk/src/examples/pythonGrammarParser.py @@ -0,0 +1,220 @@ +# pythonGrammarParser.py
+#
+# Copyright, 2006, by Paul McGuire
+#
+
+from pyparsing import *
+
+# should probably read this from the Grammar file provided with the Python source, but
+# this just skips that step and inlines the bnf text directly - this grammar was taken from
+# Python 2.4.1
+#
+grammar = """
+# Grammar for Python
+
+# Note: Changing the grammar specified in this file will most likely
+# require corresponding changes in the parser module
+# (../Modules/parsermodule.c). If you can't make the changes to
+# that module yourself, please co-ordinate the required changes
+# with someone who can; ask around on python-dev for help. Fred
+# Drake <fdrake@acm.org> will probably be listening there.
+
+# Commands for Kees Blom's railroad program
+#diagram:token NAME
+#diagram:token NUMBER
+#diagram:token STRING
+#diagram:token NEWLINE
+#diagram:token ENDMARKER
+#diagram:token INDENT
+#diagram:output\input python.bla
+#diagram:token DEDENT
+#diagram:output\textwidth 20.04cm\oddsidemargin 0.0cm\evensidemargin 0.0cm
+#diagram:rules
+
+# Start symbols for the grammar:
+# single_input is a single interactive statement;
+# file_input is a module or sequence of commands read from an input file;
+# eval_input is the input for the eval() and input() functions.
+# NB: compound_stmt in single_input is followed by extra NEWLINE!
+single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
+file_input: (NEWLINE | stmt)* ENDMARKER
+eval_input: testlist NEWLINE* ENDMARKER
+
+decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
+decorators: decorator+
+funcdef: [decorators] 'def' NAME parameters ':' suite
+parameters: '(' [varargslist] ')'
+varargslist: (fpdef ['=' test] ',')* ('*' NAME [',' '**' NAME] | '**' NAME) | fpdef ['=' test] (',' fpdef ['=' test])* [',']
+fpdef: NAME | '(' fplist ')'
+fplist: fpdef (',' fpdef)* [',']
+
+stmt: simple_stmt | compound_stmt
+simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
+small_stmt: expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt | import_stmt | global_stmt | exec_stmt | assert_stmt
+expr_stmt: testlist (augassign testlist | ('=' testlist)*)
+augassign: '+=' | '-=' | '*=' | '/=' | '%=' | '&=' | '|=' | '^=' | '<<=' | '>>=' | '**=' | '//='
+# For normal assignments, additional restrictions enforced by the interpreter
+print_stmt: 'print' ( [ test (',' test)* [','] ] | '>>' test [ (',' test)+ [','] ] )
+del_stmt: 'del' exprlist
+pass_stmt: 'pass'
+flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt
+break_stmt: 'break'
+continue_stmt: 'continue'
+return_stmt: 'return' [testlist]
+yield_stmt: 'yield' testlist
+raise_stmt: 'raise' [test [',' test [',' test]]]
+import_stmt: import_name | import_from
+import_name: 'import' dotted_as_names
+import_from: 'from' dotted_name 'import' ('*' | '(' import_as_names ')' | import_as_names)
+import_as_name: NAME [NAME NAME]
+dotted_as_name: dotted_name [NAME NAME]
+import_as_names: import_as_name (',' import_as_name)* [',']
+dotted_as_names: dotted_as_name (',' dotted_as_name)*
+dotted_name: NAME ('.' NAME)*
+global_stmt: 'global' NAME (',' NAME)*
+exec_stmt: 'exec' expr ['in' test [',' test]]
+assert_stmt: 'assert' test [',' test]
+#35
+compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | funcdef | classdef
+if_stmt: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
+while_stmt: 'while' test ':' suite ['else' ':' suite]
+for_stmt: 'for' exprlist 'in' testlist ':' suite ['else' ':' suite]
+try_stmt: ('try' ':' suite (except_clause ':' suite)+ #diagram:break
+ ['else' ':' suite] | 'try' ':' suite 'finally' ':' suite)
+# NB compile.c makes sure that the default except clause is last
+except_clause: 'except' [test [',' test]]
+suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT
+
+test: and_test ('or' and_test)* | lambdef
+and_test: not_test ('and' not_test)*
+not_test: 'not' not_test | comparison
+comparison: expr (comp_op expr)*
+comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
+expr: xor_expr ('|' xor_expr)*
+xor_expr: and_expr ('^' and_expr)*
+and_expr: shift_expr ('&' shift_expr)*
+shift_expr: arith_expr (('<<'|'>>') arith_expr)*
+arith_expr: term (('+'|'-') term)*
+term: factor (('*'|'/'|'%'|'//') factor)*
+factor: ('+'|'-'|'~') factor | power
+power: atom trailer* ['**' factor]
+atom: '(' [testlist_gexp] ')' | '[' [listmaker] ']' | '{' [dictmaker] '}' | '`' testlist1 '`' | NAME | NUMBER | STRING+
+listmaker: test ( list_for | (',' test)* [','] )
+testlist_gexp: test ( gen_for | (',' test)* [','] )
+lambdef: 'lambda' [varargslist] ':' test
+trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
+subscriptlist: subscript (',' subscript)* [',']
+subscript: '.' '.' '.' | test | [test] ':' [test] [sliceop]
+sliceop: ':' [test]
+exprlist: expr (',' expr)* [',']
+testlist: test (',' test)* [',']
+testlist_safe: test [(',' test)+ [',']]
+dictmaker: test ':' test (',' test ':' test)* [',']
+
+classdef: 'class' NAME ['(' testlist ')'] ':' suite
+
+arglist: (argument ',')* (argument [',']| '*' test [',' '**' test] | '**' test)
+argument: [test '='] test [gen_for] # Really [keyword '='] test
+
+list_iter: list_for | list_if
+list_for: 'for' exprlist 'in' testlist_safe [list_iter]
+list_if: 'if' test [list_iter]
+
+gen_iter: gen_for | gen_if
+gen_for: 'for' exprlist 'in' test [gen_iter]
+gen_if: 'if' test [gen_iter]
+
+testlist1: test (',' test)*
+
+# not used in grammar, but may appear in "node" passed from Parser to Compiler
+encoding_decl: NAME
+"""
+
+class SemanticGroup(object):
+ def __init__(self,contents):
+ self.contents = contents
+ while self.contents[-1].__class__ == self.__class__:
+ self.contents = self.contents[:-1] + self.contents[-1].contents
+
+ def __str__(self):
+ return "%s(%s)" % (self.label,
+ " ".join([isinstance(c,str) and c or str(c) for c in self.contents]) )
+
+class OrList(SemanticGroup):
+ label = "OR"
+ pass
+
+class AndList(SemanticGroup):
+ label = "AND"
+ pass
+
+class OptionalGroup(SemanticGroup):
+ label = "OPT"
+ pass
+
+class Atom(SemanticGroup):
+ def __init__(self,contents):
+ if len(contents) > 1:
+ self.rep = contents[1]
+ else:
+ self.rep = ""
+ if isinstance(contents,str):
+ self.contents = contents
+ else:
+ self.contents = contents[0]
+
+ def __str__(self):
+ return "%s%s" % (self.rep, self.contents)
+
+def makeGroupObject(cls):
+ def groupAction(s,l,t):
+ try:
+ return cls(t[0].asList())
+ except:
+ return cls(t)
+ return groupAction
+
+
+# bnf punctuation
+LPAREN = Suppress("(")
+RPAREN = Suppress(")")
+LBRACK = Suppress("[")
+RBRACK = Suppress("]")
+COLON = Suppress(":")
+ALT_OP = Suppress("|")
+
+# bnf grammar
+ident = Word(alphanums+"_")
+bnfToken = Word(alphanums+"_") + ~FollowedBy(":")
+repSymbol = oneOf("* +")
+bnfExpr = Forward()
+optionalTerm = Group(LBRACK + bnfExpr + RBRACK).setParseAction(makeGroupObject(OptionalGroup))
+bnfTerm = ( (bnfToken | quotedString | optionalTerm | ( LPAREN + bnfExpr + RPAREN )) + Optional(repSymbol) ).setParseAction(makeGroupObject(Atom))
+andList = Group(bnfTerm + OneOrMore(bnfTerm)).setParseAction(makeGroupObject(AndList))
+bnfFactor = andList | bnfTerm
+orList = Group( bnfFactor + OneOrMore( ALT_OP + bnfFactor ) ).setParseAction(makeGroupObject(OrList))
+bnfExpr << ( orList | bnfFactor )
+bnfLine = ident + COLON + bnfExpr
+
+bnfComment = "#" + restOfLine
+
+# build return tokens as a dictionary
+bnf = Dict(OneOrMore(Group(bnfLine)))
+bnf.ignore(bnfComment)
+
+# bnf is defined, parse the grammar text
+bnfDefs = bnf.parseString(grammar)
+
+# correct answer is 78
+expected = 78
+assert len(bnfDefs) == expected, \
+ "Error, found %d BNF defns, expected %d" % (len(bnfDefs), expected)
+
+# list out defns in order they were parsed (to verify accuracy of parsing)
+for k,v in bnfDefs:
+ print(k,"=",v)
+print()
+
+# list out parsed grammar defns (demonstrates dictionary access to parsed tokens)
+for k in list(bnfDefs.keys()):
+ print(k,"=",bnfDefs[k])
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