正则表达式排除表达式中的字符串和属性 [英] Regex to exclude string and attribute within expression

问题描述

我有一个正则表达式，可以将 {{expression}} 转换为 {％print expression％} 是 {{function（）}} 或 {{object.function（）}} 或 {{a + b}} ，但在获得 {{var}} 或 {{object.attribute}} 。

I have a regex which will convert {{ expression }} into {% print expression %} when expression is {{ function() }} or {{ object.function() }} or arithmetic operation like {{ a+b }} but will not convert when it will get {{ var }} or {{ object.attribute }}.

正则表达式存在的问题是它会转换字符串表达式 {{ string}} 或 {{ function（）}} 或 {{ {{var}} }} 放入 {％print string％} 或 {％print function（）％} 或 {％print {％print var％}％}

The issue with regex I have is it convert string expression {{ "string" }} or {{ "function()" }} or {{ "{{ var}}" }} into {% print "string" %} or {% print "function()" %} or {% print "{% print var %}" %}

import re

def replacement(val):
    content = val.group(1)
    if re.match('^\s*[\w\.]+\s*$', content):
        return "{{%s}}" % content
    else:
        return "{%% print %s %%}" % content

string_obj = """{{ var }} {{ object.var }} {{ func()}} {{ object.function() }} {{ a+b }} {{ "string" }} {{ "{{ var }}" }} {{ "function()" }} {{ "a+b" }}"""

print(re.sub("{{(\s*.*?\s*)}}", replacement, string_obj))

输出：

'{{var}} {{object.var} } {％print func（）％} {％print
object.function（）％} {％print a + b％} {％print string％} {％print {{var}}％ } {％print
function（）％} {％print a + b％}'

'{{ var }} {{ object.var }} {%print func()%} {% print object.function() %} {% print a+b %} {% print "string" %} {% print "{{ var }}" %} {% print "function()" %} {% print "a+b" %}'

输出我想要的是：

'{{var}} {{object.var}} {％print func（）％} { ％print
object.function（）％} {％print a + b％} {{ string}} {{ {{var}}}} {{ function（）
}} {{ a + b}}'

'{{ var }} {{ object.var }} {%print func()%} {% print object.function() %} {% print a+b %} {{ "string" }} {{ "{{ var }}" }} {{ "function()" }} {{ "a+b" }}'

注意：，这里的一个条件是表达式在 {{}} 之间可以使用 {{}} 这样的字符串表达式，即用双引号或 {{''string'}} 即单引号。

Note: The one condition here is expression in between {{ }} can have string expression like {{ "string" }} i.e. with double quotes or {{ 'string' }} i.e. with single quotes.

推荐答案

代码

对于更漂亮的打印，我只需在开头和结尾处去除空格。

Code

For prettier printing I just strip the whitespace at beginning and end. It just simplifies the regex, too.

import re

def replacement(val):
    content = val.group(1).strip()
    if re.match('^\w[^\.\(\+\*\/\-\|]*\.?\w[^\.\(\+\*\/\-\|]*$', content):
        return "{{ %s }}" % content
    else:
        return "{%% print %s %%}" % content

def maskString(templateString):
    stringChars = ['"', "'"]
    a = 0
    start = None
    maskedList = []
    while a < len(templateString):
        l = templateString[a]
        if l in stringChars and start is None and a-1 >=0 and templateString[a-1] != '\\':
            start = {'l' : l, 's' : a}
        elif start is not None and l is start['l'] and a-1 >=0 and templateString[a-1] != '\\':
            start['e'] = a + 1
            stringToMask = templateString[start['s']:start['e']]
            templateString = templateString[:start['s']] + ("_" * len(stringToMask)) + templateString[start['e']:]
            maskedList.append(stringToMask)
            start = None
        a += 1
    return (templateString, maskedList)

def unmaskString(templateString, maskedList):
    for string in maskedList:
        templateString = templateString.replace("_" * len(string), string,1)
    return templateString

def templateMatcher(templateString):
    p = re.compile('("[^"]*)"')
    templateString, maskedList = maskString(templateString)
    templateString = re.sub("{{(\s*.*?\s*)}}", replacement, templateString)
    return unmaskString(templateString, maskedList)

string_obj = """{{ var }} {{ object.var }} {{ func()}} {{ object.function() }} {{ a+b }} {{ "string" }} {{ "{{ var }}" }} {{ "function()" }} {{ "a+b" }}"""
string_obj_2 = """{{ a+b*c-d/100}} {{ 1 * 2 }} {{ 20/10 }} {{ 5-4 }}"""
string_obj_3 = """{{ "another {{ mask" }} {{ func() }}, {{ a+b }} , {{ "string with \\""|filter }}"""

print(templateMatcher(string_obj))
print(templateMatcher(string_obj_2))
print(templateMatcher(string_obj_3))

为字符串添加了高级屏蔽，因此 \假设变量永远不能仅由 _ 和''将被识别为字符串。 c $ c>。字符串的开头和结尾字符位于变量 stringChars 中。因此，如果您不喜欢'，只需将其从此处删除。

Added an advanced masking for the strings so "\"" and '"' will be recognized as string, assuming that a variable could never consists only of _. Strings start and endcharacter are in the variable stringChars. So if you don't like the ' just remove it from there.

{{ var }} {{ object.var }} {% print func() %} {% print object.function() %} {% print a+b %} {{ "string" }} {{ "{{ var }}" }} {{ "function()" }} {{ "a+b" }}
{% print a+b*c-d/100 %} {% print 1 * 2 %} {% print 20/10 %} {% print 5-4 %}
{{ "another {{ mask" }} {% print func() %}, {% print a+b %} , {% print "string with \""|filter %}

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