yacc_badtok.py (4479:61d3ed46e373) | yacc_badtok.py (6498:e21e9ab5fad0) |
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1# ----------------------------------------------------------------------------- 2# yacc_badtok.py 3# 4# A grammar, but tokens is a bad datatype 5# ----------------------------------------------------------------------------- 6 7import sys | 1# ----------------------------------------------------------------------------- 2# yacc_badtok.py 3# 4# A grammar, but tokens is a bad datatype 5# ----------------------------------------------------------------------------- 6 7import sys |
8sys.tracebacklimit = 0 9 10sys.path.insert(0,"..") | 8if ".." not in sys.path: sys.path.insert(0,"..") |
11import ply.yacc as yacc 12 13tokens = "Hello" 14 15# Parsing rules 16precedence = ( 17 ('left','PLUS','MINUS'), 18 ('left','TIMES','DIVIDE'), --- 4 unchanged lines hidden (view full) --- 23names = { } 24 25def p_statement_assign(t): 26 'statement : NAME EQUALS expression' 27 names[t[1]] = t[3] 28 29def p_statement_expr(t): 30 'statement : expression' | 9import ply.yacc as yacc 10 11tokens = "Hello" 12 13# Parsing rules 14precedence = ( 15 ('left','PLUS','MINUS'), 16 ('left','TIMES','DIVIDE'), --- 4 unchanged lines hidden (view full) --- 21names = { } 22 23def p_statement_assign(t): 24 'statement : NAME EQUALS expression' 25 names[t[1]] = t[3] 26 27def p_statement_expr(t): 28 'statement : expression' |
31 print t[1] | 29 print(t[1]) |
32 33def p_expression_binop(t): 34 '''expression : expression PLUS expression 35 | expression MINUS expression 36 | expression TIMES expression 37 | expression DIVIDE expression''' 38 if t[2] == '+' : t[0] = t[1] + t[3] 39 elif t[2] == '-': t[0] = t[1] - t[3] 40 elif t[2] == '*': t[0] = t[1] * t[3] | 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] |
41 elif t[3] == '/': t[0] = t[1] / t[3] | 39 elif t[2] == '/': t[0] = t[1] / t[3] |
42 43def p_expression_uminus(t): 44 'expression : MINUS expression %prec UMINUS' 45 t[0] = -t[2] 46 47def p_expression_group(t): 48 'expression : LPAREN expression RPAREN' 49 t[0] = t[2] 50 51def p_expression_number(t): 52 'expression : NUMBER' 53 t[0] = t[1] 54 55def p_expression_name(t): 56 'expression : NAME' 57 try: 58 t[0] = names[t[1]] 59 except LookupError: | 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: |
60 print "Undefined name '%s'" % t[1] | 58 print("Undefined name '%s'" % t[1]) |
61 t[0] = 0 62 63def p_error(t): | 59 t[0] = 0 60 61def p_error(t): |
64 print "Syntax error at '%s'" % t.value | 62 print("Syntax error at '%s'" % t.value) |
65 66yacc.yacc() 67 68 69 70 | 63 64yacc.yacc() 65 66 67 68 |