yacc_nodoc.py (1501B)
1# ----------------------------------------------------------------------------- 2# yacc_nodoc.py 3# 4# Rule with a missing doc-string 5# ----------------------------------------------------------------------------- 6import sys 7sys.tracebacklimit = 0 8 9sys.path.insert(0,"..") 10import ply.yacc as yacc 11 12from calclex import tokens 13 14# Parsing rules 15precedence = ( 16 ('left','PLUS','MINUS'), 17 ('left','TIMES','DIVIDE'), 18 ('right','UMINUS'), 19 ) 20 21# dictionary of names 22names = { } 23 24def p_statement_assign(t): 25 'statement : NAME EQUALS expression' 26 names[t[1]] = t[3] 27 28def p_statement_expr(t): 29 print t[1] 30 31def p_expression_binop(t): 32 '''expression : expression PLUS expression 33 | expression MINUS expression 34 | expression TIMES expression 35 | expression DIVIDE expression''' 36 if t[2] == '+' : t[0] = t[1] + t[3] 37 elif t[2] == '-': t[0] = t[1] - t[3] 38 elif t[2] == '*': t[0] = t[1] * t[3] 39 elif t[3] == '/': t[0] = t[1] / t[3] 40 41def p_expression_uminus(t): 42 'expression : MINUS expression %prec UMINUS' 43 t[0] = -t[2] 44 45def p_expression_group(t): 46 'expression : LPAREN expression RPAREN' 47 t[0] = t[2] 48 49def p_expression_number(t): 50 'expression : NUMBER' 51 t[0] = t[1] 52 53def p_expression_name(t): 54 'expression : NAME' 55 try: 56 t[0] = names[t[1]] 57 except LookupError: 58 print "Undefined name '%s'" % t[1] 59 t[0] = 0 60 61def p_error(t): 62 print "Syntax error at '%s'" % t.value 63 64yacc.yacc() 65 66 67 68