用ply创建c解析器

Question

我想在python中创建解析器。我创建了词汇部分，现在我想为c语言创建简单的解析器，我不知道如何为if或for创建语法，我也不知道如何通过通过词法分析器检测标记到层中的解析器以及如何使用简单的字符串测试它（解析器）？

这是我的Lexer：

import ply.lex as lex
import ply.yacc as yacc
#
# List of token names.   This is always required
tokens = [
   'NUMBER',
   'PLUS',
   'MINUS',
   'MULT',
   'DIVIDE',
   'LPAREN',
   'RPAREN',
   'ID',
   'COMMA',
   'SEMICOLON',
   'LEFTBRACE',
   'RIGHTBRACE',
   'ASSIGN',
   'EQUAL',
]

reserved={
    'while' : 'WHILE',
    'else' : 'ELSE',
    'if' : 'IF',
    'for' : 'FOR',
    'switch':'SWITCH',
    'case':'CASE',
    'do' : 'DO',
    'break': 'BREAK',
    'return' : 'RETURN',
    'int' : 'INT',
    'float' : 'FLOAT',
    'double' : 'DOUBLE',
    'continue' : 'CONTINUE',
    'struct' : 'STRUCT',
    'union' : 'UNION',
    'char' : 'CHAR',
    'printf':'PRINTF',
    'scanf' : 'SCANF',
}
tokens += reserved.values()
# Regular expression rules for simple tokens
t_CONTINUE = r'continue'
t_CASE = r'case'
t_ELSE = r'else'
t_BREAK = r'break'
t_INT = r'int'
t_SCANF = r'scanf'
t_UNION = r'union'
t_PRINTF = r'printf'
t_CHAR = r'char'
t_ASSIGN = r'='
t_EQUAL = r'=='
t_LEFTBRACE = r'{'
t_RIGHTBRACE = r'}'
t_PLUS = r'\+'
t_MINUS   = r'-'
t_MULT   = r'\*'
t_DIVIDE  = r'/'
t_LPAREN  = r'\('
t_RPAREN  = r'\)'
t_COMMA = r','
t_SEMICOLON = r';'
t_FOR = r'for'
t_WHILE = r'while'
t_SWITCH = r'switch'
t_STRUCT = r'struct'
t_RETURN = r'return'
t_IF = r'if'
t_DO = r'do'
t_FLOAT = 'float'
t_DOUBLE = r'double'
# A regular expression rule with some action code
#
def t_ID(t):
    r'[a-zA-Z_][a-zA-Z0-9_]*'
    if t.value in reserved:
        t.type = reserved[ t.value ]
    return t
#
def t_NUMBER(t):
  r'\d+'
  try:
    t.value = int(t.value)
  except ValueError:
    print("Line %d: Number %s is too large!" ,(t.lineno,t.value))
    t.value = 0
  return t
#
# Define a rule so we can track line numbers
def t_newline(t):
  r'\n+'
  t.lexer.lineno += len(t.value)

# A string containing ignored characters (spaces and tabs)
t_ignore  = ' \t'

# Error handling rule
def t_error(t):
  print ("Illegal character '%s'" , t.value[0])
  t.lexer.skip(1)
def t_COMMENT(t):
    r'\#.*'
    pass
# No return value. Token discarded
# Build the lexer
lexer=lex.lex()

# Test it out
data = "3 + 4"
data1="int gcd(int u, int v){ if(v==2) return u; else return gcd(v,u-u/v*v);}"
# Give the lexer some input
lexer.input(data)

# Tokenize
while 1:
   tok = lexer.token()
   if not tok: break      # No more input
   print("This is a token: (" , tok.type,", ",tok.value,")")

感谢您的帮助。