yacc_simple.py (4479:61d3ed46e373) | yacc_simple.py (6498:e21e9ab5fad0) |
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1# ----------------------------------------------------------------------------- 2# yacc_simple.py 3# 4# A simple, properly specifier grammar 5# ----------------------------------------------------------------------------- 6import sys | 1# ----------------------------------------------------------------------------- 2# yacc_simple.py 3# 4# A simple, properly specifier grammar 5# ----------------------------------------------------------------------------- 6import sys |
7sys.tracebacklimit = 0 | |
8 | 7 |
9sys.path.insert(0,"..") | 8if ".." not in sys.path: sys.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'), --- 4 unchanged lines hidden (view full) --- 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 'statement : expression' | 9import ply.yacc as yacc 10 11from calclex import tokens 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' |
30 print t[1] | 29 print(t[1]) |
31 32def p_expression_binop(t): 33 '''expression : expression PLUS expression 34 | expression MINUS expression 35 | expression TIMES expression 36 | expression DIVIDE expression''' 37 if t[2] == '+' : t[0] = t[1] + t[3] 38 elif t[2] == '-': t[0] = t[1] - t[3] 39 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] |
40 elif t[3] == '/': t[0] = t[1] / t[3] | 39 elif t[2] == '/': t[0] = t[1] / t[3] |
41 42def p_expression_uminus(t): 43 'expression : MINUS expression %prec UMINUS' 44 t[0] = -t[2] 45 46def p_expression_group(t): 47 'expression : LPAREN expression RPAREN' 48 t[0] = t[2] 49 50def p_expression_number(t): 51 'expression : NUMBER' 52 t[0] = t[1] 53 54def p_expression_name(t): 55 'expression : NAME' 56 try: 57 t[0] = names[t[1]] 58 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: |
59 print "Undefined name '%s'" % t[1] | 58 print("Undefined name '%s'" % t[1]) |
60 t[0] = 0 61 62def p_error(t): | 59 t[0] = 0 60 61def p_error(t): |
63 print "Syntax error at '%s'" % t.value | 62 print("Syntax error at '%s'" % t.value) |
64 65yacc.yacc() 66 67 68 69 | 63 64yacc.yacc() 65 66 67 68 |