buffer: move Buffer prototype wiring into internal/buffer.js

Instead of exposing the Buffer prototype methods through an
object in `internal/buffer.js` and then iterating over it
to put the methods on the prototype, create a function
in `internal/buffer.js` to do this.

Also moves the creaton of the `FastBuffer` class into
`internal/buffer.js` and expose it directly instead of
writing it onto that module later.

PR-URL: #25292
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/buffer.js

@@ -36,21 +36,7 @@ const {
   swap64: _swap64,
   kMaxLength,
   kStringMaxLength,
-  zeroFill: bindingZeroFill,
-
-  // Additional Buffer methods
-  asciiSlice,
-  base64Slice,
-  latin1Slice,
-  hexSlice,
-  ucs2Slice,
-  utf8Slice,
-  asciiWrite,
-  base64Write,
-  latin1Write,
-  hexWrite,
-  ucs2Write,
-  utf8Write
+  zeroFill: bindingZeroFill
 } = internalBinding('buffer');
 const {
   getOwnNonIndexProperties,
@@ -88,30 +74,14 @@ const {
 } = require('internal/errors').codes;
 const { validateString } = require('internal/validators');
 
-const internalBuffer = require('internal/buffer');
+const {
+  FastBuffer,
+  addBufferPrototypeMethods
+} = require('internal/buffer');
 
-class FastBuffer extends Uint8Array {}
 FastBuffer.prototype.constructor = Buffer;
-internalBuffer.FastBuffer = FastBuffer;
-
 Buffer.prototype = FastBuffer.prototype;
-
-for (const [name, method] of Object.entries(internalBuffer.readWrites)) {
-  Buffer.prototype[name] = method;
-}
-
-Buffer.prototype.asciiSlice = asciiSlice;
-Buffer.prototype.base64Slice = base64Slice;
-Buffer.prototype.latin1Slice = latin1Slice;
-Buffer.prototype.hexSlice = hexSlice;
-Buffer.prototype.ucs2Slice = ucs2Slice;
-Buffer.prototype.utf8Slice = utf8Slice;
-Buffer.prototype.asciiWrite = asciiWrite;
-Buffer.prototype.base64Write = base64Write;
-Buffer.prototype.latin1Write = latin1Write;
-Buffer.prototype.hexWrite = hexWrite;
-Buffer.prototype.ucs2Write = ucs2Write;
-Buffer.prototype.utf8Write = utf8Write;
+addBufferPrototypeMethods(Buffer.prototype);
 
 const constants = Object.defineProperties({}, {
   MAX_LENGTH: {

lib/internal/buffer.js

@@ -6,6 +6,20 @@ const {
   ERR_OUT_OF_RANGE
 } = require('internal/errors').codes;
 const { validateNumber } = require('internal/validators');
+const {
+  asciiSlice,
+  base64Slice,
+  latin1Slice,
+  hexSlice,
+  ucs2Slice,
+  utf8Slice,
+  asciiWrite,
+  base64Write,
+  latin1Write,
+  hexWrite,
+  ucs2Write,
+  utf8Write
+} = internalBinding('buffer');
 
 // Temporary buffers to convert numbers.
 const float32Array = new Float32Array(1);
@@ -771,45 +785,63 @@ function writeFloatBackwards(val, offset = 0) {
   return offset;
 }
 
-// FastBuffer wil be inserted here by lib/buffer.js
+class FastBuffer extends Uint8Array {}
+
+function addBufferPrototypeMethods(proto) {
+  proto.readUIntLE = readUIntLE;
+  proto.readUInt32LE = readUInt32LE;
+  proto.readUInt16LE = readUInt16LE;
+  proto.readUInt8 = readUInt8;
+  proto.readUIntBE = readUIntBE;
+  proto.readUInt32BE = readUInt32BE;
+  proto.readUInt16BE = readUInt16BE;
+  proto.readIntLE = readIntLE;
+  proto.readInt32LE = readInt32LE;
+  proto.readInt16LE = readInt16LE;
+  proto.readInt8 = readInt8;
+  proto.readIntBE = readIntBE;
+  proto.readInt32BE = readInt32BE;
+  proto.readInt16BE = readInt16BE;
+
+  proto.writeUIntLE = writeUIntLE;
+  proto.writeUInt32LE = writeUInt32LE;
+  proto.writeUInt16LE = writeUInt16LE;
+  proto.writeUInt8 = writeUInt8;
+  proto.writeUIntBE = writeUIntBE;
+  proto.writeUInt32BE = writeUInt32BE;
+  proto.writeUInt16BE = writeUInt16BE;
+  proto.writeIntLE = writeIntLE;
+  proto.writeInt32LE = writeInt32LE;
+  proto.writeInt16LE = writeInt16LE;
+  proto.writeInt8 = writeInt8;
+  proto.writeIntBE = writeIntBE;
+  proto.writeInt32BE = writeInt32BE;
+  proto.writeInt16BE = writeInt16BE;
+
+  proto.readFloatLE = bigEndian ? readFloatBackwards : readFloatForwards;
+  proto.readFloatBE = bigEndian ? readFloatForwards : readFloatBackwards;
+  proto.readDoubleLE = bigEndian ? readDoubleBackwards : readDoubleForwards;
+  proto.readDoubleBE = bigEndian ? readDoubleForwards : readDoubleBackwards;
+  proto.writeFloatLE = bigEndian ? writeFloatBackwards : writeFloatForwards;
+  proto.writeFloatBE = bigEndian ? writeFloatForwards : writeFloatBackwards;
+  proto.writeDoubleLE = bigEndian ? writeDoubleBackwards : writeDoubleForwards;
+  proto.writeDoubleBE = bigEndian ? writeDoubleForwards : writeDoubleBackwards;
+
+  proto.asciiSlice = asciiSlice;
+  proto.base64Slice = base64Slice;
+  proto.latin1Slice = latin1Slice;
+  proto.hexSlice = hexSlice;
+  proto.ucs2Slice = ucs2Slice;
+  proto.utf8Slice = utf8Slice;
+  proto.asciiWrite = asciiWrite;
+  proto.base64Write = base64Write;
+  proto.latin1Write = latin1Write;
+  proto.hexWrite = hexWrite;
+  proto.ucs2Write = ucs2Write;
+  proto.utf8Write = utf8Write;
+}
+
 module.exports = {
-  // Container to export all read write functions.
-  readWrites: {
-    readUIntLE,
-    readUInt32LE,
-    readUInt16LE,
-    readUInt8,
-    readUIntBE,
-    readUInt32BE,
-    readUInt16BE,
-    readIntLE,
-    readInt32LE,
-    readInt16LE,
-    readInt8,
-    readIntBE,
-    readInt32BE,
-    readInt16BE,
-    writeUIntLE,
-    writeUInt32LE,
-    writeUInt16LE,
-    writeUInt8,
-    writeUIntBE,
-    writeUInt32BE,
-    writeUInt16BE,
-    writeIntLE,
-    writeInt32LE,
-    writeInt16LE,
-    writeInt8,
-    writeIntBE,
-    writeInt32BE,
-    writeInt16BE,
-    readFloatLE: bigEndian ? readFloatBackwards : readFloatForwards,
-    readFloatBE: bigEndian ? readFloatForwards : readFloatBackwards,
-    readDoubleLE: bigEndian ? readDoubleBackwards : readDoubleForwards,
-    readDoubleBE: bigEndian ? readDoubleForwards : readDoubleBackwards,
-    writeFloatLE: bigEndian ? writeFloatBackwards : writeFloatForwards,
-    writeFloatBE: bigEndian ? writeFloatForwards : writeFloatBackwards,
-    writeDoubleLE: bigEndian ? writeDoubleBackwards : writeDoubleForwards,
-    writeDoubleBE: bigEndian ? writeDoubleForwards : writeDoubleBackwards
-  }
+  FastBuffer,
+  addBufferPrototypeMethods
 };