Attempt at a vba parser

vbaparser.py

import ply.lex as lex
import ply.yacc as yacc
 
tokens = (
        "DOUBLE",
        "IDENTIFIER",
        "INT",
        "TYPE",
        "BOOLEAN",
        "DIM",
        "AS",
        "ASSIGN",
)
 
t_INT = "\d+"
t_DOUBLE = r"-?\d+\.\d+([e|E][+-]?\d+)?"
t_IDENTIFIER = r"[a-z]+"
t_TYPE = "Double|Integer|Boolean|Byte"
t_BOOLEAN = "True|False"
t_DIM = "DIM"
t_AS = "AS"
t_ASSIGN = "="
t_ignore = ' \t'
 
# Ignore comments
def t_comment(t):
    r"['|REM][^\n]*"
    pass
 
def t_newline(t):
    r"\n+"
    t.lexer.lineno += len(t.value)
    pass
 
def t_error(t):
    raise TypeError("%d:%d: Unknown text '%s'" % (t.lineno, find_column(self.text, t), t.value,))
 
lex.lex()
 
 
class Identifier:
    def __init__(self, t, name):
        self.t = t # type
        self.name = name
        if (t == "BOOLEAN"):
            self.value = "False"
        else:
            self.value = "0"
 
    def __repr__(self):
        return self.t + " " + self.name + " = " + repr(self.value)
 
identifiers = {}
 
def p_statement(p):
    '''statement : declaration
                | assignment'''
    print p[1]
 
def p_declaration(p):
    "declaration : DIM IDENTIFIER AS TYPE"
    identifiers[p[2]] = Identifier(p[4], p[2])
    p[0] = identifiers[p[2]]
 
 
def p_assignment(p):
    '''assignment : IDENTIFIER ASSIGN BOOLEAN
                 | IDENTIFIER ASSIGN DOUBLE
                 | IDENTIFIER ASSIGN INT'''
    id = identifiers.get(p[1], None)
    if (not id):
        raise TypeError("%d: Undeclared IDENTIFIER '%s'." % (p.lineno(1), p[1]))
 
 
    if ((id.t == "Boolean" and p[3].type != "BOOLEAN") or
        (id.t == "Integer" and p[3].type != "INT") or
        (id.t == "Double" and p[3].type == "BOOLEAN") or
        (id.t == "Byte" and p[3].type != "INT")):
        print("%d: Type mismatch. Trying to assign (%s) to identifier '%s' which is of type %s" % (p.lineno(3), p[3], p[1], p[3].type))
 
    id.value = p[3]
 
 
def p_error(p):
    if p:
        raise TypeError("line %d: Syntax error near '%s': Unexpected %s found." % (p.lineno, p.value, p.type))
    else:
        print "Syntax error: Reached end ouf output."
 
 
yacc.yacc()
yacc.parse("DIM a AS Integer\na = 3")
print "Identifiers(" + repr(len(identifiers)) + ")"
for k,v in identifiers.iteritems():
    print repr(v)