Adds a modified copy of talk/base to webrtc/base. It is the first step in migrating talk/base to webrtc/base.

BUG=N/A
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12199004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6107 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/base64.h

@@ -0,0 +1,104 @@
+
+//*********************************************************************
+//* C_Base64 - a simple base64 encoder and decoder.
+//*
+//*     Copyright (c) 1999, Bob Withers - bwit@pobox.com
+//*
+//* This code may be freely used for any purpose, either personal
+//* or commercial, provided the authors copyright notice remains
+//* intact.
+//*********************************************************************
+
+#ifndef WEBRTC_BASE_BASE64_H__
+#define WEBRTC_BASE_BASE64_H__
+
+#include <string>
+#include <vector>
+
+namespace rtc {
+
+class Base64
+{
+public:
+  enum DecodeOption {
+    DO_PARSE_STRICT =  1,  // Parse only base64 characters
+    DO_PARSE_WHITE  =  2,  // Parse only base64 and whitespace characters
+    DO_PARSE_ANY    =  3,  // Parse all characters
+    DO_PARSE_MASK   =  3,
+
+    DO_PAD_YES      =  4,  // Padding is required
+    DO_PAD_ANY      =  8,  // Padding is optional
+    DO_PAD_NO       = 12,  // Padding is disallowed
+    DO_PAD_MASK     = 12,
+
+    DO_TERM_BUFFER  = 16,  // Must termiante at end of buffer
+    DO_TERM_CHAR    = 32,  // May terminate at any character boundary
+    DO_TERM_ANY     = 48,  // May terminate at a sub-character bit offset
+    DO_TERM_MASK    = 48,
+
+    // Strictest interpretation
+    DO_STRICT = DO_PARSE_STRICT | DO_PAD_YES | DO_TERM_BUFFER,
+
+    DO_LAX    = DO_PARSE_ANY | DO_PAD_ANY | DO_TERM_CHAR,
+  };
+  typedef int DecodeFlags;
+
+  static bool IsBase64Char(char ch);
+
+  // Get the char next to the |ch| from the Base64Table.
+  // If the |ch| is the last one in the Base64Table then returns
+  // the first one from the table.
+  // Expects the |ch| be a base64 char.
+  // The result will be saved in |next_ch|.
+  // Returns true on success.
+  static bool GetNextBase64Char(char ch, char* next_ch);
+
+  // Determines whether the given string consists entirely of valid base64
+  // encoded characters.
+  static bool IsBase64Encoded(const std::string& str);
+
+  static void EncodeFromArray(const void* data, size_t len,
+                              std::string* result);
+  static bool DecodeFromArray(const char* data, size_t len, DecodeFlags flags,
+                              std::string* result, size_t* data_used);
+  static bool DecodeFromArray(const char* data, size_t len, DecodeFlags flags,
+                              std::vector<char>* result, size_t* data_used);
+
+  // Convenience Methods
+  static inline std::string Encode(const std::string& data) {
+    std::string result;
+    EncodeFromArray(data.data(), data.size(), &result);
+    return result;
+  }
+  static inline std::string Decode(const std::string& data, DecodeFlags flags) {
+    std::string result;
+    DecodeFromArray(data.data(), data.size(), flags, &result, NULL);
+    return result;
+  }
+  static inline bool Decode(const std::string& data, DecodeFlags flags,
+                            std::string* result, size_t* data_used)
+  {
+    return DecodeFromArray(data.data(), data.size(), flags, result, data_used);
+  }
+  static inline bool Decode(const std::string& data, DecodeFlags flags,
+                            std::vector<char>* result, size_t* data_used)
+  {
+    return DecodeFromArray(data.data(), data.size(), flags, result, data_used);
+  }
+
+private:
+  static const char Base64Table[];
+  static const unsigned char DecodeTable[];
+
+  static size_t GetNextQuantum(DecodeFlags parse_flags, bool illegal_pads,
+                               const char* data, size_t len, size_t* dpos,
+                               unsigned char qbuf[4], bool* padded);
+  template<typename T>
+  static bool DecodeFromArrayTemplate(const char* data, size_t len,
+                                      DecodeFlags flags, T* result,
+                                      size_t* data_used);
+};
+
+} // namespace rtc
+
+#endif // WEBRTC_BASE_BASE64_H__