Python加載帶有註釋的Json文件

由於json文件不支持註釋，所以如果在json文件中標記了註釋，則使用python中的json.dump()無法加載該json文件。
本文旨在解決當定義“//”爲json註釋時，如何正確解析有註釋的json文件。

程序實現

# encoding: utf-8

import json
import re
import sys

reload(sys)
sys.setdefaultencoding('utf8')

CAUTION_PRINT_HEAD = 'caution: '

# 創建一個xstr類，用於處理從文件中讀出的字符串
class xstr:
    def __init__(self, instr):
        self.instr = instr

    # 刪除“//”標誌後的註釋
    def rmCmt(self): 
        qtCnt = cmtPos = slashPos = 0
        rearLine = self.instr
        # rearline: 前一個“//”之後的字符串，
        # 雙引號裏的“//”不是註釋標誌，所以遇到這種情況，仍需繼續查找後續的“//”
        while rearLine.find('//') >= 0: # 查找“//”
            slashPos = rearLine.find('//')
            cmtPos += slashPos
            # print 'slashPos: ' + str(slashPos)
            headLine = rearLine[:slashPos]
            while headLine.find('"') >= 0: # 查找“//”前的雙引號
                qtPos = headLine.find('"')
                if not self.isEscapeOpr(headLine[:qtPos]): # 如果雙引號沒有被轉義
                    qtCnt += 1 # 雙引號的數量加1
                headLine = headLine[qtPos+1:]
                # print qtCnt
            if qtCnt % 2 == 0: # 如果雙引號的數量爲偶數，則說明“//”是註釋標誌
                # print self.instr[:cmtPos]
                return self.instr[:cmtPos]
            rearLine = rearLine[slashPos+2:]
            # print rearLine
            cmtPos += 2
        # print self.instr
        return self.instr

    # 判斷是否爲轉義字符
    def isEscapeOpr(self, instr):
        if len(instr) <= 0:
            return False
        cnt = 0
        while instr[-1] == '\\':
            cnt += 1
            instr = instr[:-1]
        if cnt % 2 == 1:
            return True
        else:
            return False


# 從json文件的路徑JsonPath讀取該文件，返回json對象
def loadJson(JsonPath):
    try:
        srcJson = open(JsonPath, 'r')
    except:
        print CAUTION_PRINT_HEAD + 'cannot open ' + JsonPath
        quit()

    dstJsonStr = ''
    for line in srcJson.readlines():
        if not re.match(r'\s*//', line) and not re.match(r'\s*\n', line):
            xline = xstr(line)
            dstJsonStr += xline.rmCmt()

    # print dstJsonStr
    dstJson = {}
    try:
        dstJson = json.loads(dstJsonStr)
        return dstJson
    except:
        print CAUTION_PRINT_HEAD + JsonPath + ' is not a valid json file'
        quit()

# 帶縮進地在屏幕輸出json字符串
def printRes(resStr):
    resStr = resStr.replace(',', ',\n')
    resStr = resStr.replace('{', '{\n')
    resStr = resStr.replace(':{', ':\n{')
    resStr = resStr.replace('}', '\n}')
    resStr = resStr.replace('[', '\n[\n')
    resStr = resStr.replace(']', '\n]')
    resStr = resStr
    resArray = resStr.split('\n')
    preBlank = ''
    for line in resArray:
        if len(line) == 0:
            continue
        lastChar = line[len(line)-1]
        lastTwoChars = line[len(line)-2:]

        if lastChar in {'}', ']'} or lastTwoChars in {'},', '],'}:
            preBlank = preBlank[:len(preBlank)-2]
        try:
            print preBlank + line.decode('utf-8')
        except:
            print(preBlank + '[%This line cannot be decoded%]')

        if lastChar == '{' or lastChar == '[':
            preBlank += ' '*2