fd-slicer - npm Package Compare versions

Comparing version 0.3.2 to 0.4.0

index.js

@@ -6,2 +6,3 @@ var fs = require('fs');
 var Writable = stream.Writable;
+var PassThrough = stream.PassThrough;
 var Pend = require('pend');
@@ -11,2 +12,4 @@ var EventEmitter = require('events').EventEmitter;
 module.exports = FdSlicer;
+FdSlicer.BufferSlicer = BufferSlicer;
+FdSlicer.createFromBuffer = createFromBuffer;
 
@@ -86,3 +89,3 @@ util.inherits(FdSlicer, EventEmitter);
   this.start = options.start || 0;
-  this.end = options.end;
+  this.endOffset = options.end;
   this.pos = this.start;
@@ -97,4 +100,4 @@ this.destroyed = false;
   var toRead = Math.min(self._readableState.highWaterMark, n);
-  if (self.end != null) {
-    toRead = Math.min(toRead, self.end - self.pos);
+  if (self.endOffset != null) {
+    toRead = Math.min(toRead, self.endOffset - self.pos);
   }
@@ -185,1 +188,89 @@ if (toRead <= 0) {
 };
+
+util.inherits(BufferSlicer, EventEmitter);
+function BufferSlicer(buffer) {
+  EventEmitter.call(this);
+
+  this.refCount = 0;
+  this.buffer = buffer;
+}
+
+BufferSlicer.prototype.read = function(buffer, offset, length, position, callback) {
+  var end = position + length;
+  var delta = end - this.buffer.length;
+  var written = (delta > 0) ? delta : length;
+  this.buffer.copy(buffer, offset, position, end);
+  process.nextTick(function() {
+    callback(null, written);
+  });
+};
+
+BufferSlicer.prototype.write = function(buffer, offset, length, position, callback) {
+  buffer.copy(this.buffer, position, offset, offset + length);
+  setImmediate(function() {
+    callback(null, length, buffer);
+  });
+};
+
+BufferSlicer.prototype.createReadStream = function(options) {
+  options = options || {};
+  var readStream = new PassThrough(options);
+  readStream.start = options.start || 0;
+  readStream.endOffset = options.end;
+  readStream.pos = readStream.endOffset || this.buffer.length; // yep, we're already done
+  readStream.destroyed = false;
+  readStream.write(this.buffer.slice(readStream.start, readStream.pos));
+  readStream.end();
+  readStream.destroy = function() {
+    readStream.destroyed = true;
+  };
+  return readStream;
+};
+
+BufferSlicer.prototype.createWriteStream = function(options) {
+  var bufferSlicer = this;
+  options = options || {};
+  var writeStream = new WriteStream(options);
+  writeStream.start = options.start || 0;
+  writeStream.endOffset = options.end || Infinity;
+  writeStream.bytesWritten = 0;
+  writeStream.pos = writeStream.start;
+  writeStream.destroyed = false;
+  writeStream._write = function(buffer, encoding, callback) {
+    if (writeStream.destroyed) return;
+
+    var end = writeStream.pos + buffer.length;
+    if (end > writeStream.endOffset) {
+      var err = new Error("maximum file length exceeded");
+      err.code = 'ETOOBIG';
+      writeStream.destroyed = true;
+      callback(err);
+      return;
+    }
+    buffer.copy(bufferSlicer.buffer, writeStream.pos, 0, buffer.length);
+
+    writeStream.bytesWritten += buffer.length;
+    writeStream.pos = end;
+    writeStream.emit('progress');
+  };
+  writeStream.destroy = function() {
+    writeStream.destroyed = true;
+  };
+  return writeStream;
+};
+
+BufferSlicer.prototype.ref = function() {
+  this.refCount += 1;
+};
+
+BufferSlicer.prototype.unref = function() {
+  this.refCount -= 1;
+
+  if (this.refCount < 0) {
+    throw new Error("invalid unref");
+  }
+};
+
+function createFromBuffer(buffer) {
+  return new BufferSlicer(buffer);
+}

package.json

 {
   "name": "fd-slicer",
-  "version": "0.3.2",
+  "version": "0.4.0",
   "description": "safely create multiple ReadStream or WriteStream objects from the same file descriptor",
@@ -5,0 +5,0 @@ "main": "index.js",

README.md

@@ -39,2 +39,4 @@ # fd-slicer
  * Ability to set a maximum size and emit an error if this size is exceeded.
+ * Ability to create an `FdSlicer` instance from a `Buffer`. This enables you
+   to provide API for handling files as well as buffers using the same API.
 
@@ -59,5 +61,18 @@ ## Usage
 
+You can also create from a buffer:
+
+```js
+var FdSlicer = require('fd-slicer');
+var fdSlicer = FdSlicer.createFromBuffer(someBuffer);
+var firstPart = fdSlicer.createReadStream({start: 0, end: 100});
+var secondPart = fdSlicer.createReadStream({start: 100});
+var firstOut = fs.createWriteStream("first.txt");
+var secondOut = fs.createWriteStream("second.txt");
+firstPart.pipe(firstOut);
+secondPart.pipe(secondOut);
+```
+
 ## API Documentation
 
-### FdSlicer(fd, [options])
+### new FdSlicer(fd, [options])
 
@@ -84,2 +99,10 @@ ```js
 
+### FdSlicer.createFromBuffer(buffer)
+
+```js
+var FdSlicer = require('fd-slicer');
+var fdSlicer = FdSlicer.createFromBuffer(someBuffer);
+// ...
+```
+
 #### Properties
@@ -89,3 +112,3 @@
 
-The file descriptor passed in.
+The file descriptor passed in. `undefined` if created from a buffer.
 
@@ -166,2 +189,3 @@ #### Methods
 
-Emitted when fd-slicer closes the file descriptor due to `autoClose`.
+Emitted when fd-slicer closes the file descriptor due to `autoClose`. Never
+emitted if created from a buffer.

No alert changes

Improved metrics

Total package byte prevSize

24306

increased by16.54%

Lines of code

473

increased by20.05%

Number of lines in readme file

187

increased by14.72%

No dependency changes