src: Add StringBytes static util class

Four functions:

- StringBytes::StorageSize()
- StringBytes::Size()
- StringBytes::Write()
- StringBytes::Encode()

src/string_bytes.h

@@ -0,0 +1,65 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#ifndef SRC_STRING_BYTES_H_
+#define SRC_STRING_BYTES_H_
+
+// Decodes a v8::Handle<v8::String> or Buffer to a raw char*
+
+#include "v8.h"
+#include "node.h"
+
+namespace node {
+
+using v8::Handle;
+using v8::Local;
+using v8::String;
+using v8::Value;
+
+class StringBytes {
+ public:
+  // Fast, but can be 2 bytes oversized for Base64, and
+  // as much as triple UTF-8 strings <= 65536 chars in length
+  static size_t StorageSize(Handle<Value> val, enum encoding enc);
+
+  // Precise byte count, but slightly slower for Base64 and
+  // very much slower for UTF-8
+  static size_t Size(Handle<Value> val, enum encoding enc);
+
+  // Write the bytes from the string or buffer into the char*
+  // returns the number of bytes written, which will always be
+  // <= buflen.  Use StorageSize/Size first to know how much
+  // memory to allocate.
+  static size_t Write(char* buf,
+                      size_t buflen,
+                      Handle<Value> val,
+                      enum encoding enc,
+                      int* chars_written = NULL);
+
+  // Take the bytes in the src, and turn it into a Buffer or String.
+  static Local<Value> Encode(const char* buf,
+                             size_t buflen,
+                             enum encoding encoding);
+};
+
+}  // namespace node
+
+#endif  // SRC_STRING_BYTES_H_