ext/ply/ply/lex.py: ext/ply/ply/yacc.py: ext/ply/CHANGES: ext/ply/README: ext/ply/TODO: ext/ply/doc/ply.html: ext/ply/example/ansic/clex.py: ext/ply/example/ansic/cparse.py: ext/ply/example/calc/calc.py: ext/ply/example/hedit/hedit.py: ext/ply/example/optcalc/calc.py: ext/ply/test/README: ext/ply/test/calclex.py: ext/ply/test/lex_doc1.exp: ext/ply/test/lex_doc1.py: ext/ply/test/lex_dup1.exp: ext/ply/test/lex_dup1.py: ext/ply/test/lex_dup2.exp: ext/ply/test/lex_dup2.py: ext/ply/test/lex_dup3.exp: ext/ply/test/lex_dup3.py: ext/ply/test/lex_empty.py: ext/ply/test/lex_error1.py: ext/ply/test/lex_error2.py: ext/ply/test/lex_error3.exp: ext/ply/test/lex_error3.py: ext/ply/test/lex_error4.exp: ext/ply/test/lex_error4.py: ext/ply/test/lex_hedit.exp: ext/ply/test/lex_hedit.py: ext/ply/test/lex_ignore.exp: ext/ply/test/lex_ignore.py: ext/ply/test/lex_re1.exp: ext/ply/test/lex_re1.py: ext/ply/test/lex_rule1.py: ext/ply/test/lex_token1.py: ext/ply/test/lex_token2.py: ext/ply/test/lex_token3.py: ext/ply/test/lex_token4.py: ext/ply/test/lex_token5.exp: ext/ply/test/lex_token5.py: ext/ply/test/yacc_badargs.exp: ext/ply/test/yacc_badargs.py: ext/ply/test/yacc_badprec.exp: ext/ply/test/yacc_badprec.py: ext/ply/test/yacc_badprec2.exp: ext/ply/test/yacc_badprec2.py: ext/ply/test/yacc_badrule.exp: ext/ply/test/yacc_badrule.py: ext/ply/test/yacc_badtok.exp: ext/ply/test/yacc_badtok.py: ext/ply/test/yacc_dup.exp: ext/ply/test/yacc_dup.py: ext/ply/test/yacc_error1.exp: ext/ply/test/yacc_error1.py: ext/ply/test/yacc_error2.exp: ext/ply/test/yacc_error2.py: ext/ply/test/yacc_error3.exp: ext/ply/test/yacc_error3.py: ext/ply/test/yacc_inf.exp: ext/ply/test/yacc_inf.py: ext/ply/test/yacc_missing1.exp: ext/ply/test/yacc_missing1.py: ext/ply/test/yacc_nodoc.exp: ext/ply/test/yacc_nodoc.py: ext/ply/test/yacc_noerror.exp: ext/ply/test/yacc_noerror.py: ext/ply/test/yacc_nop.exp: ext/ply/test/yacc_nop.py: ext/ply/test/yacc_notfunc.exp: ext/ply/test/yacc_notfunc.py: ext/ply/test/yacc_notok.exp: ext/ply/test/yacc_notok.py: ext/ply/test/yacc_rr.exp: ext/ply/test/yacc_rr.py: ext/ply/test/yacc_simple.exp: ext/ply/test/yacc_simple.py: ext/ply/test/yacc_sr.exp: ext/ply/test/yacc_sr.py: ext/ply/test/yacc_term1.exp: ext/ply/test/yacc_term1.py: ext/ply/test/yacc_unused.exp: ext/ply/test/yacc_unused.py: ext/ply/test/yacc_uprec.exp: ext/ply/test/yacc_uprec.py: Import patch ply.diff src/arch/isa_parser.py: everything is now within the ply package --HG-- rename : ext/ply/lex.py => ext/ply/ply/lex.py rename : ext/ply/yacc.py => ext/ply/ply/yacc.py extra : convert_revision : fca8deabd5c095bdeabd52a1f236ae1404ef106e
114 lines
2.4 KiB
Python
114 lines
2.4 KiB
Python
# -----------------------------------------------------------------------------
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# calc.py
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#
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# A simple calculator with variables. This is from O'Reilly's
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# "Lex and Yacc", p. 63.
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#
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# This example uses unicode strings for tokens, docstrings, and input.
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# -----------------------------------------------------------------------------
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import sys
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sys.path.insert(0,"../..")
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tokens = (
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'NAME','NUMBER',
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'PLUS','MINUS','TIMES','DIVIDE','EQUALS',
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'LPAREN','RPAREN',
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)
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# Tokens
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t_PLUS = ur'\+'
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t_MINUS = ur'-'
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t_TIMES = ur'\*'
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t_DIVIDE = ur'/'
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t_EQUALS = ur'='
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t_LPAREN = ur'\('
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t_RPAREN = ur'\)'
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t_NAME = ur'[a-zA-Z_][a-zA-Z0-9_]*'
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def t_NUMBER(t):
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ur'\d+'
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try:
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t.value = int(t.value)
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except ValueError:
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print "Integer value too large", t.value
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t.value = 0
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return t
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t_ignore = u" \t"
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def t_newline(t):
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ur'\n+'
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t.lexer.lineno += t.value.count("\n")
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def t_error(t):
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print "Illegal character '%s'" % t.value[0]
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t.lexer.skip(1)
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# Build the lexer
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import ply.lex as lex
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lex.lex()
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# Parsing rules
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precedence = (
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('left','PLUS','MINUS'),
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('left','TIMES','DIVIDE'),
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('right','UMINUS'),
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)
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# dictionary of names
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names = { }
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def p_statement_assign(p):
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'statement : NAME EQUALS expression'
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names[p[1]] = p[3]
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def p_statement_expr(p):
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'statement : expression'
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print p[1]
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def p_expression_binop(p):
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'''expression : expression PLUS expression
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| expression MINUS expression
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| expression TIMES expression
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| expression DIVIDE expression'''
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if p[2] == u'+' : p[0] = p[1] + p[3]
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elif p[2] == u'-': p[0] = p[1] - p[3]
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elif p[2] == u'*': p[0] = p[1] * p[3]
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elif p[2] == u'/': p[0] = p[1] / p[3]
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def p_expression_uminus(p):
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'expression : MINUS expression %prec UMINUS'
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p[0] = -p[2]
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def p_expression_group(p):
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'expression : LPAREN expression RPAREN'
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p[0] = p[2]
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def p_expression_number(p):
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'expression : NUMBER'
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p[0] = p[1]
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def p_expression_name(p):
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'expression : NAME'
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try:
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p[0] = names[p[1]]
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except LookupError:
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print "Undefined name '%s'" % p[1]
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p[0] = 0
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def p_error(p):
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print "Syntax error at '%s'" % p.value
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import ply.yacc as yacc
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yacc.yacc()
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while 1:
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try:
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s = raw_input('calc > ')
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except EOFError:
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break
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if not s: continue
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yacc.parse(unicode(s))
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