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diff ply-3.8/example/calcdebug/calc.py @ 7267:343ff337a19b
<ais523> ` tar -xf ply-3.8.tar.gz
author | HackBot |
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date | Wed, 23 Mar 2016 02:40:16 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ply-3.8/example/calcdebug/calc.py Wed Mar 23 02:40:16 2016 +0000 @@ -0,0 +1,113 @@ +# ----------------------------------------------------------------------------- +# calc.py +# +# This example shows how to run the parser in a debugging mode +# with output routed to a logging object. +# ----------------------------------------------------------------------------- + +import sys +sys.path.insert(0,"../..") + +if sys.version_info[0] >= 3: + raw_input = input + +tokens = ( + 'NAME','NUMBER', + ) + +literals = ['=','+','-','*','/', '(',')'] + +# Tokens + +t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*' + +def t_NUMBER(t): + r'\d+' + t.value = int(t.value) + return t + +t_ignore = " \t" + +def t_newline(t): + r'\n+' + t.lexer.lineno += t.value.count("\n") + +def t_error(t): + print("Illegal character '%s'" % t.value[0]) + t.lexer.skip(1) + +# Build the lexer +import ply.lex as lex +lex.lex() + +# Parsing rules + +precedence = ( + ('left','+','-'), + ('left','*','/'), + ('right','UMINUS'), + ) + +# dictionary of names +names = { } + +def p_statement_assign(p): + 'statement : NAME "=" expression' + names[p[1]] = p[3] + +def p_statement_expr(p): + 'statement : expression' + print(p[1]) + +def p_expression_binop(p): + '''expression : expression '+' expression + | expression '-' expression + | expression '*' expression + | expression '/' expression''' + 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] + +def p_expression_uminus(p): + "expression : '-' expression %prec UMINUS" + p[0] = -p[2] + +def p_expression_group(p): + "expression : '(' expression ')'" + p[0] = p[2] + +def p_expression_number(p): + "expression : NUMBER" + p[0] = p[1] + +def p_expression_name(p): + "expression : NAME" + try: + p[0] = names[p[1]] + except LookupError: + print("Undefined name '%s'" % p[1]) + p[0] = 0 + +def p_error(p): + if p: + print("Syntax error at '%s'" % p.value) + else: + print("Syntax error at EOF") + +import ply.yacc as yacc +yacc.yacc() + +import logging +logging.basicConfig( + level=logging.INFO, + filename="parselog.txt" +) + +while 1: + try: + s = raw_input('calc > ') + except EOFError: + break + if not s: continue + yacc.parse(s,debug=logging.getLogger())