[Author: iwade]

Added GTMStringEncoding which is a generic base 2-128 encoder/decoder with support for custom character maps.

R=thomasvl
APPROVED=thomasvl
DELTA=723  (723 added, 0 deleted, 0 changed)

1 files changed, 88 insertions, 0 deletions

diff --git a/Foundation/GTMStringEncoding.h b/Foundation/GTMStringEncoding.h
new file mode 100644
index 0000000..b74f2d9
--- /dev/null
+++ b/Foundation/GTMStringEncoding.h
@@ -0,0 +1,88 @@
+//
+//  GTMStringEncoding.h
+//
+//  Copyright 2010 Google Inc.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License"); you may not
+//  use this file except in compliance with the License.  You may obtain a copy
+//  of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+//  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+//  License for the specific language governing permissions and limitations under
+//  the License.
+//
+
+#import <Foundation/Foundation.h>
+#import "GTMDefines.h"
+
+// A generic class for arbitrary base-2 to 128 string encoding and decoding.
+@interface GTMStringEncoding : NSObject {
+ @private
+  NSData *charMapData_;
+  char *charMap_;
+  int reverseCharMap_[128];
+  int shift_;
+  int mask_;
+  BOOL doPad_;
+  char paddingChar_;
+  int padLen_;
+}
+
+// Create a new, autoreleased GTMStringEncoding object with a standard encoding.
++ (id)binaryStringEncoding;
++ (id)hexStringEncoding;
++ (id)rfc4648Base32StringEncoding;
++ (id)rfc4648Base32HexStringEncoding;
++ (id)crockfordBase32StringEncoding;
++ (id)rfc4648Base64StringEncoding;
++ (id)rfc4648Base64WebsafeStringEncoding;
+
+// Create a new, autoreleased GTMStringEncoding object with the given string,
+// as described below.
++ (id)stringEncodingWithString:(NSString *)string;
+
+// Initialize a new GTMStringEncoding object with the string.
+//
+// The length of the string must be a power of 2, at least 2 and at most 128.
+// Only 7-bit ASCII characters are permitted in the string.
+//
+// These characters are the canonical set emitted during encoding.
+// If the characters have alternatives (e.g. case, easily transposed) then use
+// addDecodeSynonyms: to configure them.
+- (id)initWithString:(NSString *)string;
+
+// Add decoding synonyms as specified in the synonyms argument.
+//
+// It should be a sequence of one previously reverse mapped character,
+// followed by one or more non-reverse mapped character synonyms.
+// Only 7-bit ASCII characters are permitted in the string.
+//
+// e.g. If a GTMStringEncoder object has already been initialised with a set
+// of characters excluding I, L and O (to avoid confusion with digits) and you
+// want to accept them as digits you can call addDecodeSynonyms:@"0oO1iIlL".
+- (void)addDecodeSynonyms:(NSString *)synonyms;
+
+// A sequence of characters to ignore if they occur during encoding.
+// Only 7-bit ASCII characters are permitted in the string.
+- (void)ignoreCharacters:(NSString *)chars;
+
+// Indicates whether padding is performed during encoding.
+- (BOOL)doPad;
+- (void)setDoPad:(BOOL)doPad;
+
+// Sets the padding character to use during encoding.
+- (void)setPaddingChar:(char)c;
+
+// Encode a raw binary buffer to a 7-bit ASCII string.
+- (NSString *)encode:(NSData *)data;
+- (NSString *)encodeString:(NSString *)string;
+
+// Decode a 7-bit ASCII string to a raw binary buffer.
+- (NSData *)decode:(NSString *)string;
+- (NSString *)stringByDecoding:(NSString *)string;
+
+@end