calc.py revision 6498
17585SAli.Saidi@arm.com# ----------------------------------------------------------------------------- 27585SAli.Saidi@arm.com# calc.py 37585SAli.Saidi@arm.com# 47585SAli.Saidi@arm.com# This example shows how to run the parser in a debugging mode 57585SAli.Saidi@arm.com# with output routed to a logging object. 67585SAli.Saidi@arm.com# ----------------------------------------------------------------------------- 77585SAli.Saidi@arm.com 87585SAli.Saidi@arm.comimport sys 97585SAli.Saidi@arm.comsys.path.insert(0,"../..") 107585SAli.Saidi@arm.com 117585SAli.Saidi@arm.comif sys.version_info[0] >= 3: 127585SAli.Saidi@arm.com raw_input = input 137585SAli.Saidi@arm.com 147585SAli.Saidi@arm.comtokens = ( 157585SAli.Saidi@arm.com 'NAME','NUMBER', 167585SAli.Saidi@arm.com ) 177585SAli.Saidi@arm.com 187585SAli.Saidi@arm.comliterals = ['=','+','-','*','/', '(',')'] 197585SAli.Saidi@arm.com 207585SAli.Saidi@arm.com# Tokens 217585SAli.Saidi@arm.com 227585SAli.Saidi@arm.comt_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*' 237585SAli.Saidi@arm.com 247585SAli.Saidi@arm.comdef t_NUMBER(t): 257585SAli.Saidi@arm.com r'\d+' 267585SAli.Saidi@arm.com t.value = int(t.value) 277585SAli.Saidi@arm.com return t 287585SAli.Saidi@arm.com 297585SAli.Saidi@arm.comt_ignore = " \t" 307585SAli.Saidi@arm.com 317585SAli.Saidi@arm.comdef t_newline(t): 327585SAli.Saidi@arm.com r'\n+' 337585SAli.Saidi@arm.com t.lexer.lineno += t.value.count("\n") 347585SAli.Saidi@arm.com 357585SAli.Saidi@arm.comdef t_error(t): 367585SAli.Saidi@arm.com print("Illegal character '%s'" % t.value[0]) 377585SAli.Saidi@arm.com t.lexer.skip(1) 387585SAli.Saidi@arm.com 397585SAli.Saidi@arm.com# Build the lexer 407585SAli.Saidi@arm.comimport ply.lex as lex 417585SAli.Saidi@arm.comlex.lex() 427585SAli.Saidi@arm.com 437585SAli.Saidi@arm.com# Parsing rules 447585SAli.Saidi@arm.com 457585SAli.Saidi@arm.comprecedence = ( 467723SAli.Saidi@ARM.com ('left','+','-'), 477585SAli.Saidi@arm.com ('left','*','/'), 487585SAli.Saidi@arm.com ('right','UMINUS'), 497723SAli.Saidi@ARM.com ) 508143SAli.Saidi@ARM.com 517585SAli.Saidi@arm.com# dictionary of names 527585SAli.Saidi@arm.comnames = { } 537585SAli.Saidi@arm.com 548143SAli.Saidi@ARM.comdef p_statement_assign(p): 557585SAli.Saidi@arm.com 'statement : NAME "=" expression' 567585SAli.Saidi@arm.com names[p[1]] = p[3] 577585SAli.Saidi@arm.com 587585SAli.Saidi@arm.comdef p_statement_expr(p): 597585SAli.Saidi@arm.com 'statement : expression' 607585SAli.Saidi@arm.com print(p[1]) 617585SAli.Saidi@arm.com 627585SAli.Saidi@arm.comdef p_expression_binop(p): 637585SAli.Saidi@arm.com '''expression : expression '+' expression 647585SAli.Saidi@arm.com | expression '-' expression 657585SAli.Saidi@arm.com | expression '*' expression 667585SAli.Saidi@arm.com | expression '/' expression''' 677585SAli.Saidi@arm.com if p[2] == '+' : p[0] = p[1] + p[3] 687585SAli.Saidi@arm.com elif p[2] == '-': p[0] = p[1] - p[3] 697585SAli.Saidi@arm.com elif p[2] == '*': p[0] = p[1] * p[3] 707585SAli.Saidi@arm.com elif p[2] == '/': p[0] = p[1] / p[3] 717585SAli.Saidi@arm.com 727585SAli.Saidi@arm.comdef p_expression_uminus(p): 737585SAli.Saidi@arm.com "expression : '-' expression %prec UMINUS" 747585SAli.Saidi@arm.com p[0] = -p[2] 757585SAli.Saidi@arm.com 767585SAli.Saidi@arm.comdef p_expression_group(p): 777585SAli.Saidi@arm.com "expression : '(' expression ')'" 787585SAli.Saidi@arm.com p[0] = p[2] 797585SAli.Saidi@arm.com 807585SAli.Saidi@arm.comdef p_expression_number(p): 817585SAli.Saidi@arm.com "expression : NUMBER" 827585SAli.Saidi@arm.com p[0] = p[1] 837585SAli.Saidi@arm.com 847585SAli.Saidi@arm.comdef p_expression_name(p): 857585SAli.Saidi@arm.com "expression : NAME" 867585SAli.Saidi@arm.com try: 877585SAli.Saidi@arm.com p[0] = names[p[1]] 887585SAli.Saidi@arm.com except LookupError: 897585SAli.Saidi@arm.com print("Undefined name '%s'" % p[1]) 907585SAli.Saidi@arm.com p[0] = 0 917585SAli.Saidi@arm.com 927585SAli.Saidi@arm.comdef p_error(p): 937585SAli.Saidi@arm.com if p: 947723SAli.Saidi@ARM.com print("Syntax error at '%s'" % p.value) 957585SAli.Saidi@arm.com else: 967585SAli.Saidi@arm.com print("Syntax error at EOF") 977585SAli.Saidi@arm.com 987585SAli.Saidi@arm.comimport ply.yacc as yacc 997585SAli.Saidi@arm.comyacc.yacc() 1007585SAli.Saidi@arm.com 1018143SAli.Saidi@ARM.comimport logging 1028143SAli.Saidi@ARM.comlogging.basicConfig( 1038143SAli.Saidi@ARM.com level=logging.INFO, 1048143SAli.Saidi@ARM.com filename="parselog.txt" 1058143SAli.Saidi@ARM.com) 1068143SAli.Saidi@ARM.com 1078143SAli.Saidi@ARM.comwhile 1: 1088143SAli.Saidi@ARM.com try: 1098143SAli.Saidi@ARM.com s = raw_input('calc > ') 1108143SAli.Saidi@ARM.com except EOFError: 1118143SAli.Saidi@ARM.com break 1128143SAli.Saidi@ARM.com if not s: continue 1138143SAli.Saidi@ARM.com yacc.parse(s,debug=logging.getLogger()) 1148143SAli.Saidi@ARM.com