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author | Gabe Black <gblack@eecs.umich.edu> | 2007-05-25 19:29:32 -0700 |
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committer | Gabe Black <gblack@eecs.umich.edu> | 2007-05-25 19:29:32 -0700 |
commit | a3ae9486d543f23cd4203381e7bcf2ce86c51389 (patch) | |
tree | d66d3b9851f3002d0746c7af830062480f83773d /ext/ply/example/newclasscalc/calc.py | |
parent | ad02a59f89139a75dfcfaa7a79498e54f7ce7e5d (diff) | |
parent | 44ebb8d3e27329e9f0b501897585359b4ab696f2 (diff) | |
download | gem5-a3ae9486d543f23cd4203381e7bcf2ce86c51389.tar.xz |
Merge zizzer.eecs.umich.edu:/bk/newmem
into doughnut.mwconnections.com:/home/gblack/m5/newmem-x86
--HG--
extra : convert_revision : 276d00a73b1834d5262129c3f7e0f7fae18e23bc
Diffstat (limited to 'ext/ply/example/newclasscalc/calc.py')
-rw-r--r-- | ext/ply/example/newclasscalc/calc.py | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/ext/ply/example/newclasscalc/calc.py b/ext/ply/example/newclasscalc/calc.py new file mode 100644 index 000000000..7f29bc821 --- /dev/null +++ b/ext/ply/example/newclasscalc/calc.py @@ -0,0 +1,155 @@ +#!/usr/bin/env python + +# ----------------------------------------------------------------------------- +# calc.py +# +# A simple calculator with variables. This is from O'Reilly's +# "Lex and Yacc", p. 63. +# +# Class-based example contributed to PLY by David McNab. +# +# Modified to use new-style classes. Test case. +# ----------------------------------------------------------------------------- + +import sys +sys.path.insert(0,"../..") + +import readline +import ply.lex as lex +import ply.yacc as yacc +import os + +class Parser(object): + """ + Base class for a lexer/parser that has the rules defined as methods + """ + tokens = () + precedence = () + + + def __init__(self, **kw): + self.debug = kw.get('debug', 0) + self.names = { } + try: + modname = os.path.split(os.path.splitext(__file__)[0])[1] + "_" + self.__class__.__name__ + except: + modname = "parser"+"_"+self.__class__.__name__ + self.debugfile = modname + ".dbg" + self.tabmodule = modname + "_" + "parsetab" + #print self.debugfile, self.tabmodule + + # Build the lexer and parser + lex.lex(module=self, debug=self.debug) + yacc.yacc(module=self, + debug=self.debug, + debugfile=self.debugfile, + tabmodule=self.tabmodule) + + def run(self): + while 1: + try: + s = raw_input('calc > ') + except EOFError: + break + if not s: continue + yacc.parse(s) + + +class Calc(Parser): + + tokens = ( + 'NAME','NUMBER', + 'PLUS','MINUS','EXP', 'TIMES','DIVIDE','EQUALS', + 'LPAREN','RPAREN', + ) + + # Tokens + + t_PLUS = r'\+' + t_MINUS = r'-' + t_EXP = r'\*\*' + t_TIMES = r'\*' + t_DIVIDE = r'/' + t_EQUALS = r'=' + t_LPAREN = r'\(' + t_RPAREN = r'\)' + t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*' + + def t_NUMBER(self, t): + r'\d+' + try: + t.value = int(t.value) + except ValueError: + print "Integer value too large", t.value + t.value = 0 + #print "parsed number %s" % repr(t.value) + return t + + t_ignore = " \t" + + def t_newline(self, t): + r'\n+' + t.lexer.lineno += t.value.count("\n") + + def t_error(self, t): + print "Illegal character '%s'" % t.value[0] + t.lexer.skip(1) + + # Parsing rules + + precedence = ( + ('left','PLUS','MINUS'), + ('left','TIMES','DIVIDE'), + ('left', 'EXP'), + ('right','UMINUS'), + ) + + def p_statement_assign(self, p): + 'statement : NAME EQUALS expression' + self.names[p[1]] = p[3] + + def p_statement_expr(self, p): + 'statement : expression' + print p[1] + + def p_expression_binop(self, p): + """ + expression : expression PLUS expression + | expression MINUS expression + | expression TIMES expression + | expression DIVIDE expression + | expression EXP expression + """ + #print [repr(p[i]) for i in range(0,4)] + if p[2] == '+' : p[0] = p[1] + p[3] + elif p[2] == '-': p[0] = p[1] - p[3] + elif p[2] == '*': p[0] = p[1] * p[3] + elif p[2] == '/': p[0] = p[1] / p[3] + elif p[2] == '**': p[0] = p[1] ** p[3] + + def p_expression_uminus(self, p): + 'expression : MINUS expression %prec UMINUS' + p[0] = -p[2] + + def p_expression_group(self, p): + 'expression : LPAREN expression RPAREN' + p[0] = p[2] + + def p_expression_number(self, p): + 'expression : NUMBER' + p[0] = p[1] + + def p_expression_name(self, p): + 'expression : NAME' + try: + p[0] = self.names[p[1]] + except LookupError: + print "Undefined name '%s'" % p[1] + p[0] = 0 + + def p_error(self, p): + print "Syntax error at '%s'" % p.value + +if __name__ == '__main__': + calc = Calc() + calc.run() |