Python之根据类型将字符过滤到结构中

几天来我一直在努力反对这个问题，尝试了多种方法，但似乎没有一种方法能以我可以使用的方式工作......

问题。

我得到了一个任意字节流。字节中隐藏了一些语义元素。有花括号、方括号和方括号。这些表示三个不同的东西 - {} 是一个没有。字节范围，例如{17} 是 17 个字节。 [] 是一个字节值，例如[90:95] 是字节 x90、x91、x92、x93、x94、x95。 () 是字节值 'OR' 选项，例如(46|47) 表示 x46 或 x47。

我还必须检测其他语法结构，“!”、“*”、“?”和 ”:”。

字节流示例:524946(46|58){4}434452367672736E

我试图过滤它，所以我得到类似的东西:

1 string 524946 
2 token (46|58) 
3 token {4} 
4 string 434452367672736E 

拆分后，我可以进一步处理它。

我最接近它的工作(它丑陋丑陋的丑陋代码......):http://pastebin.com/XLg2H0PW

我尝试使用一些正则表达式，但我可以让它不将语法单元内的字符串字节计为普通字符串元素:

range_masks_list =  [(m_mask1.span()) for m_mask1 in re.finditer("\{([0-9]+|[0-9]+-[0-9]+|[0-9]+-\*)\}",sequence)] ## looks for {int}, {int-int} and {int-*} 
byte_masks_list =  [(m_mask2.span()) for m_mask2 in re.finditer("\[[a-fA-F0-9]{2}:[a-fA-F0-9]{2}]",sequence)] ## looks for [a:b] where a and b are byte ranges 
options_sets_list = [(m_mask3.span()) for m_mask3 in re.finditer("\(([a-fA-F0-9]{2})+\|([a-fA-F0-9]{2})+(\|([a-fA-F0-9]{2})+)*\)",sequence)] ## looks for regex or clauses e.g. (a|b) 
string_chunk_list = [(m_mask4.span()) for m_mask4 in re.finditer("([a-fA-F0-9]{2})+",sequence)] ## looks for uninterrupted hex byte spans  

看起来像:

def do_fragmenter(self,sequence): 
    """ converts the grep grammer normalised string into a set of fragments and offsets for sig population""" 
    sequence = sequence.replace(" ","") 
    range_masks_list =  [(m_mask1.span()) for m_mask1 in re.finditer("\{([0-9]+|[0-9]+-[0-9]+|[0-9]+-\*)\}",sequence)] ## looks for {int}, {int-int} and {int-*} 
    byte_masks_list =  [(m_mask2.span()) for m_mask2 in re.finditer("\[[a-fA-F0-9]{2}:[a-fA-F0-9]{2}]",sequence)] ## looks for [a:b] where a and b are byte ranges 
    options_sets_list = [(m_mask3.span()) for m_mask3 in re.finditer("\(([a-fA-F0-9]{2})+\|([a-fA-F0-9]{2})+(\|([a-fA-F0-9]{2})+)*\)",sequence)] ## looks for regex or clauses e.g. (a|b) 
    string_chunk_list = [(m_mask4.span()) for m_mask4 in re.finditer("([a-fA-F0-9]{2})+",sequence)] ## looks for uninterupted hex byte spans  
    string_chunks = [] 
    string_chunks_len = [] 
    for pair in string_chunk_list: 
        string_chunks.append(sequence[pair[0]:pair[1]]) 
        string_chunks_len.append(len(sequence[pair[0]:pair[1]])) 
    print zip(string_chunks,string_chunks_len)  

请您参考如下方法:

只要考虑到您定义的语法元素，您就可以使用这样的东西(用您需要的处理替换打印品):

#! /usr/bin/python3.2 
 
import re 
 
a = '524946(46|58){4}434452[22:33]367672736E' 
patterns = [ ('([0-9a-fA-F]+)', 'Sequence '), 
    ('(\\([0-9a-fA-F]+\\|[0-9a-fA-F]+\\))', 'Option '), 
    ('({[0-9a-fA-F]+})', 'Curly '), 
    ('(\\[[0-9a-fA-F]+:[0-9a-fA-F]+\\])', 'Slice ') ] 
 
while a: 
    found = False 
    for pattern, name in patterns: 
        m = re.match (pattern, a) 
        if m: 
            m = m.groups () [0] 
            print (name + m) 
            a = a [len (m):] 
            found = True 
            break 
    if not found: raise Exception ('Unrecognized sequence') 

产量:

Sequence 524946 
Option (46|58) 
Curly {4} 
Sequence 434452 
Slice [22:33] 
Sequence 367672736E