/core/externals/google-toolbox-for-mac/Foundation/GTMNSScanner+JSON.m

 1//
 2//  GTMNSScanner+JSON.m
 3//
 4//  Copyright 2009 Google Inc.
 5//
 6//  Licensed under the Apache License, Version 2.0 (the "License"); you may not
 7//  use this file except in compliance with the License.  You may obtain a copy
 8//  of the License at
 9// 
10//  http://www.apache.org/licenses/LICENSE-2.0
11// 
12//  Unless required by applicable law or agreed to in writing, software
13//  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
14//  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
15//  License for the specific language governing permissions and limitations under
16//  the License.
17//
18
19#import "GTMDefines.h"
20#import "GTMNSScanner+JSON.h"
21
22@implementation NSScanner (GTMNSScannerJSONAdditions)
23
24- (BOOL)gtm_scanJSONString:(NSString **)jsonString 
25                 startChar:(unichar)startChar 
26                   endChar:(unichar)endChar {
27  BOOL isGood = NO;
28  NSRange jsonRange = { NSNotFound, 0 };
29  NSString *scanString = [self string];
30  NSUInteger startLocation = [self scanLocation];
31  NSUInteger length = [scanString length];
32  NSUInteger blockOpen = 0;
33  NSCharacterSet *charsToSkip = [self charactersToBeSkipped];
34  BOOL inQuoteMode = NO;
35  NSUInteger i;
36  for (i = startLocation; i < length; ++i) {
37    unichar jsonChar = [scanString characterAtIndex:i];
38    if (jsonChar == startChar && !inQuoteMode) {
39      if (blockOpen == 0) {
40        jsonRange.location = i;
41      }
42      blockOpen += 1;
43    } else if (blockOpen == 0) {
44      // If we haven't opened our block skip over any characters in
45      // charsToSkip.
46      if (![charsToSkip characterIsMember:jsonChar]) {
47        break;
48      }
49    } else if (jsonChar == endChar && !inQuoteMode) {
50      blockOpen -= 1;
51      if (blockOpen == 0) {
52        i += 1; // Move onto next character
53        jsonRange.length = i - jsonRange.location;
54        break;
55      }
56    } else {
57      if (jsonChar == '"') {
58        inQuoteMode = !inQuoteMode;
59      } else if (inQuoteMode && jsonChar == '\\') {
60        // Skip the escaped character if it isn't the last one
61        if (i < length - 1) ++i;
62      }
63    }
64  }
65  [self setScanLocation:i];
66  if (blockOpen == 0 && jsonRange.location != NSNotFound) {
67    isGood = YES;
68    if (jsonString) {
69      *jsonString = [scanString substringWithRange:jsonRange];
70    }
71  }
72  return isGood;
73}
74
75- (BOOL)gtm_scanJSONObjectString:(NSString **)jsonString {
76  return [self gtm_scanJSONString:jsonString startChar:'{' endChar:'}'];  
77}
78
79- (BOOL)gtm_scanJSONArrayString:(NSString**)jsonString {
80  return [self gtm_scanJSONString:jsonString startChar:'[' endChar:']'];  
81}
82
83@end