#Cahier

Cahier is a high performance static file reading module, without the network stuf.

Cahier will handle file convertion, compression and cacheing in both memory and on HDD. It is totally stream based, but allow you to use both buffers and strings if needed. It also protects your filesystem, since it won't allow to read below the specifed source directory.

##Installation

npm install cahier

##Example

var cahier = require('cahier');

// The cahier compiler require a source path, a cache path
// and a state filepath. The ready callback will be execute once
// the state file is read and the necessary are created
var convert = cahier({
  'source': path.resolve('./source'),
  'cache': path.resolve('./cache'),
  'state': path.resolve('./state.json')
}, ready);

// Cahier allow you to attach handlers to filetypes
// This is an example of how to compress json files
convert.handle('json', 'string', function (content, next) {
  next( JSON.stringify(JSON.parse(content)) );
});

// Cahier also supports streams
// In this example cahier will gzip selected txt files
var zlib = require('zlib');
convert.handle(['json', 'js', 'css'], 'stream', function (stream, next) {
  var gzip = zlib.createGzip();
      gzip.pause();

  next( stream.pipe(gzip) );
  stream.resume();
});

// cahier is now ready
function ready(error) {
  if (error) throw error;

  // for high performance you can precompile all source files,
  // the compiled files will be stored in the cache directory
  convert.compile(function (error) {
    if (error) throw error;

    // files there hasn't been compiled will be compiled on
    // runtime and allready compiled files will be read from cache.
    var filestream = convert.read('/file.json');
        filestream.pipe(process.stdout);
        filestream.resume();
  });
}

##API documentation

cahier = Cahier(options, callback)

require('cahier') will return function there when executed returns a new cahier instance. The function require two arguments options and callback.

options is an object there must contains the following properties:

• source: an absolute path to the directory where the umcompiled source files exist.
• cache: an absolute path to the directroy where the compiled files should be stored.
• state: an absolute filepath to a JSON file, there will contain the cache state.

callback is an function there will be execute with an error argument. If error is null no error occurred.

cahier.handle([filetype], usetype, handler)

This method allow you to attach an filehandler function to one or more filetypes. The .handle method require three arguments filetype, usetype and handler.

filetype this can be a single filetype given by a string, or multiply filetypes listed in an array. The value of the array items or string should only be the file extension name. Note that if filetype is not specified the handle function will attached to all filetypes.

handler is a function there is executed with three arguments content and next and file:

• content: is the current content of the file, this can be a stream a buffer or a string. The type depend on the usetype argument.
• next: is a function that you must call with a output stream, buffer or string. You can also execute it with an error object, in that case all future filehandlers will be skiped, and the error be emitted in the returned stream object from cahier.read(filetype).
• file is an object containing a path property its value is an relative path to handled file. Note that file argument is rarely need, but can be useful in debugging and edgecases.

usetype must be a string or an object, the object must contain two properties:

• input: the type of the first argument that the handle function is called with.
• output: the result type that the next function is called with.

The value of the properties can be stream, buffer or string and must reflect the usecase. In case usetype is a string both the input and output type will be the value of this string.

In case that you decide to use stream, you must manually resume the input stream and pause output stream, before executeing the stream.pause().

cahier.read(filepath)

This method returns a ReadStream there can be piped to any WritStream. The method must be executed with a relative filepath argument. The filepath argument may start with / indicating an absolute but it will be threaded as an path relative to the source path given in cahier(options).

Any ../ or ./ will be handled correctly, but cahier won't allow the user to read files below the source directory. Any extra ../ indicating that will simply be skiped.

Note that the returned ReadStream object may emit an error event, if any error was cached durrying the reading or compileing of the file. Also note that no data will be emitted from the stream, before you manually resume the ReadStream.

Along with the normal ReadStream events and method, the stream will also emit a stat event. Once emitted a stream.mtime property will be set, this contains a Date object pointing to the stat.mtime of the source file.

cahier.ignore(filename)

When reading a file using cahier.read(filepath) it will first match again an ignore list. The match can be relative in terms of a filename or an absloute filepath.

This method adds filepaths or filenames to the ignore list. If the filename argument starts with / it will be threaded as an absolute filepath, if not it will be threaded as a filename.

If a filepath match the ignore list, the returned stream object by cahier.read(filepath) will simply emit an error as if the file didn't exist. However the error object will have an extra ignore property set to true.

cahier.compile(callback)

The current implementation will remove all files from cache directory and compile all files from the source directory. When all files are compiled the callback will be executed. If any error occurred the callback will be execute with this error as its first argument, otherwise it will be null.

Note: in the future this function may cache so only non-compiled or updated files will compiled.

cahier.watch()

When executed cahier will check the file stat for any modification and determin if the file should be recompiled or just read from cached. This affect performance, but is highly useful in development.

cahier.memory(size)

Highly used files will be cached in a memory buffer, the total buffer size do approximately match the given size argument, but since cahier is stream based, the compiled and compressed size can not be preknown with absolute certainty.

The size argument can be Infinity a number defining the size in bytes, or a simple string like 10 MB.

##License

The software is license under "MIT"

Copyright (c) 2012 Andreas Madsen

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.