ext/ply/test/yacc_noerror.py

   1 # -----------------------------------------------------------------------------
   2 # yacc_noerror.py
   3 #
   4 # No p_error() rule defined.
   5 # -----------------------------------------------------------------------------
   6 import sys
   7 sys.tracebacklimit = 0
   8
   9 sys.path.insert(0,"..")
  10 import ply.yacc as yacc
  11
  12 from calclex import tokens
  13
  14 # Parsing rules
  15 precedence = (
  16     ('left','PLUS','MINUS'),
  17     ('left','TIMES','DIVIDE'),
  18     ('right','UMINUS'),
  19     )
  20
  21 # dictionary of names
  22 names = { }
  23
  24 def p_statement_assign(t):
  25     'statement : NAME EQUALS expression'
  26     names[t[1]] = t[3]
  27
  28 def p_statement_expr(t):
  29     'statement : expression'
  30     print t[1]
  31
  32 def 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]
  40     elif t[3] == '/': t[0] = t[1] / t[3]
  41
  42 def p_expression_uminus(t):
  43     'expression : MINUS expression %prec UMINUS'
  44     t[0] = -t[2]
  45
  46 def p_expression_group(t):
  47     'expression : LPAREN expression RPAREN'
  48     t[0] = t[2]
  49
  50 def p_expression_number(t):
  51     'expression : NUMBER'
  52     t[0] = t[1]
  53
  54 def p_expression_name(t):
  55     'expression : NAME'
  56     try:
  57         t[0] = names[t[1]]
  58     except LookupError:
  59         print "Undefined name '%s'" % t[1]
  60         t[0] = 0
  61
  62
  63 yacc.yacc()
  64
  65
  66
  67