nixfilter/reader.coffee

Simplify the development of (UNIX) "Filters"

'use strict'

bytes_reader = ->
	(callback) ->
		callback

byte_reader = ->
	(callback) ->
		bytes_reader() (input_bytes) ->
			for input_byte in input_bytes
				callback(input_byte)
			return

# Import the "StringDecoder" class from the "string_decoder" module
StringDecoder = require('string_decoder').StringDecoder

characters_reader = (encoding) ->
	encoding = (encoding or 'utf8')
	(callback) ->
		string_decoder = new StringDecoder(encoding)
		(input_bytes) ->
			input_characters = string_decoder.write(input_bytes)
			if (input_characters.length > 0)
				callback(input_characters)
			return

character_reader = (encoding) ->
	(callback) ->
		characters_reader(encoding) (input_characters) ->
			for input_character in input_characters
				callback(input_character)
			return

line_reader = (encoding) ->
	(callback) ->
		line_buffer = []
		character_reader(encoding) (input_character) ->
			if (input_character is '\n')
				callback(line_buffer.join(''))
				line_buffer = []
			else
				line_buffer.push(input_character)
			return

json_line_reader = (encoding) ->
	(callback) ->
		line_reader(encoding) (input_line) ->
			callback(JSON.parse(input_line))
			return

# What this module exports
module.exports =
	byte: byte_reader
	bytes: bytes_reader
	character: character_reader
	characters: characters_reader
	json_line: json_line_reader
	line: line_reader