Python 按规则解析并替换字符串中的变量及函数(示例代码)

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import re
REGEX_PATTERN_FOR_DYNAMIC =  re.compile('(\${\s*.+\s*})', re.DOTALL) # 用于获取动态值中的表达式
REGEX_PATTERN_FOR_VAR = re.compile('(\${\s*[^{}]+s*})', re.DOTALL) # 用于获取动态值中的变量表达式
REGEX_PATTERN_FOR_FUNC_DEFINITION = re.compile('\${\s*__.+?\(.*?\)\s*}', re.DOTALL) # 用于获取函数表达式中的函数名称及其参数
REGEX_PATTERN_FOR_FUNC_NAME_WITH_ARGS = re.compile('\${\s*(__.+?)\((.*?)\)\s*}', re.DOTALL) # 用于获取函数表达式中的函数名称及其参数
def test_func1():
    print('-----func1 called-----')
def test_func2(arg1, arg2):
    print('-----func2 called-----')
    print('arg1:', arg1, 'arg2:', arg2)
    print()
    return "func2"
def test_func3(arg1, arg2):
    print('-----func3 called-----')
    print('arg1:', arg1, 'arg2:', arg2)
    print()
    return 999
def test_func4(arg1, arg2):
    print('-----func4 called-----')
    print('arg1:', arg1, 'arg2:', arg2)
    print()
    return 9.99
def test_func5(arg1, arg2):
    print('-----func5 called-----')
    print('arg1:', arg1, 'arg2:', arg2)
    print()
    return ['e1', 'e2']
def test_func6(arg1, arg2):
    print('-----func6 called-----')
    print('arg1:', arg1, 'arg2:', arg2)
    print()
    return False
def test_func7(*args, **kwargs):
    print('-----func7 called-----')
    for i, arg in enumerate(args):
        print('arg%s = %s' % (i, arg))
    for i, kwargs in enumerate(kwargs):
        print('kwarg%s = ' % i, kwargs)
user_name = 'shouke'
addr = 'unknown'
int_var = 3
def evaluate_dynamic_value(dynamic_value):
    '''解析动态值
    @params: dynamic_value 动态值，如果是字符串类型，带双引号、单引号
    '''
    if REGEX_PATTERN_FOR_VAR.search(dynamic_value):
        pattern = REGEX_PATTERN_FOR_VAR
    elif REGEX_PATTERN_FOR_FUNC_DEFINITION.search(dynamic_value):
        pattern = REGEX_PATTERN_FOR_FUNC_DEFINITION
    else:
        return dynamic_value
    var_express_value = None
    match_res = pattern.findall(dynamic_value)
    for var_express in match_res:
        var_name = var_express[2:-1].strip()
        if var_name.startswith('__'): # 函数
            function_mateched = REGEX_PATTERN_FOR_FUNC_DEFINITION.findall(var_express)
            for function in function_mateched:
                func_info_matched = REGEX_PATTERN_FOR_FUNC_NAME_WITH_ARGS.findall(var_express)
                for func_info in func_info_matched:
                    func_name, func_args = func_info
                    # print('---',func_name, func_args)
                    if REGEX_PATTERN_FOR_DYNAMIC.search(func_args):
                        func_args = evaluate_dynamic_value(func_args)
                    func_value = eval('{func_name}({func_args})'.format(func_name=func_name.lstrip('_'), func_args=func_args))
                    if func_value is None:
                        func_value = ''
                    var_express_value = var_express.replace(function, str(func_value))
        else: # 变量，不支持嵌套，直接取值
            var_express_value = globals().get(var_name, '')
        if var_express_value is not None:
            dynamic_value = dynamic_value.replace(var_express, str(var_express_value))
            if REGEX_PATTERN_FOR_DYNAMIC.search(dynamic_value): # 替换后的动态值，还是可能存在动态值
                dynamic_value = evaluate_dynamic_value(dynamic_value)
    return dynamic_value
# 测试验证
print(evaluate_dynamic_value('${ user_name }')) # 输出：shouke
print(evaluate_dynamic_value('${ addr }')) # 输出：unknown
print(evaluate_dynamic_value('username:${ user_name } addr:${ addr }')) # 输出：username:shouke addr:unknown
print(evaluate_dynamic_value('${ __test_func1() }'))
#调用输出：
#-----func1 called-----
print(evaluate_dynamic_value('${ __test_func2("user", "shouke") }')) # 输出：func2
#调用输出：
#-----func2 called-----
# arg1: user arg2: shouke
#
print(evaluate_dynamic_value('test_func1 return: ${ __test_func1() }, test_func2 return: ${ __test_func2("user", "shouke") }')) # 输出：test_func1 return: , test_func2 return: func2
# 调用输出：
#-----func1 called-----
#-----func2 called-----
#arg1: user arg2: shouke
#
print(evaluate_dynamic_value('${ __test_func7("addr", "sz") }'))
#-----func7 called-----
#调用输出：
#arg0 = addr
#arg1 = sz
print(evaluate_dynamic_value('${ __test_func7(110,'
                             ' 11.56, '
                             '"test", '
                             '[1, 3, 5], '
                             '["2", "4", "6"], '
                             '1 == 1, '
                             'True, '
                             '{"username": "shouke", "age": "unknown"},'
                             'position="sz",'
                             'hobby="pingpong",'
                             'books=["unkonwn"]) }'))
#调用输出：
# -----func7 called-----
# arg0 = 110
# arg1 = 11.56
# arg2 = test
# arg3 = [1, 3, 5]
# arg4 = ['2', '4', '6']
# arg5 = True
# arg6 = True
# arg7 = {'username': 'shouke', 'age': 'unknown'}
# kwarg0 =  position
# kwarg1 =  hobby
# kwarg2 =  books
print(evaluate_dynamic_value('${ __test_func7("${user_name}", ${int_var})}'))
#调用输出：
#-----func7 called-----
#arg0 = shouke
#arg1 = 3
print(evaluate_dynamic_value('var: ${addr} function: ${ __test_func7( ${__test_func6("${user_name}", ${int_var})}, ${__test_func5( ${__test_func4("${int_var}", "func4")}, ${__test_func3(\'${__test_func2("func2", True)}\', \'func3\')} )})}')) # 返回 var: unknown function:
#调用输出：
#-----func6 called-----
#arg1: shouke arg2: 3
#
#-----func4 called-----
#arg1: 3 arg2: func4
#
#-----func2 called-----
#arg1: func2 arg2: True
#
#-----func3 called-----
#arg1: func2 arg2: func3
#
#-----func5 called-----
#arg1: 9.99 arg2: 999
#
#-----func7 called-----
#arg0 = False
#arg1 = ['e1', 'e2']
#-----func2 called-----
#arg1: func2 arg2: True
#
#-----func4 called-----
#arg1: 3 arg2: func4
#
#-----func2 called-----
#arg1: func2 arg2: True
#
#-----func2 called-----
#arg1: func2 arg2: True
#
#-----func2 called-----
#arg1: func2 arg2: True
#
#-----func2 called-----
#arg1: func2 arg2: True
#
print(evaluate_dynamic_value('${ __test_func7(set([1, 2, 3]))}'))
#调用输出：
# -----func7 called-----
# arg0 = {1, 2, 3}