114 lines
2.9 KiB
JavaScript
114 lines
2.9 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
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var isObject = require( '@stdlib/assert/is-plain-object' );
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var isFunction = require( '@stdlib/assert/is-function' );
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var readFile = require( './../../read-file' );
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var removeBOM = require( '@stdlib/string/remove-utf8-bom' );
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var parseJSON = require( '@stdlib/utils/parse-json' );
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var instanceOf = require( '@stdlib/assert/instance-of' );
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// MAIN //
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/**
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* Asynchronously reads a file as JSON.
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*
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* @param {(string|Buffer|integer)} file - file path or file descriptor
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* @param {(Options|string)} [options] - options
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* @param {(string|null)} [options.encoding] - file encoding
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* @param {string} [options.flag] - file status flag
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* @param {Function} [options.reviver] - JSON reviver
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* @param {Callback} clbk - callback
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* @throws {TypeError} options argument must be either a string or an object
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* @throws {TypeError} callback argument must be a function
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*
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* @example
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* var resolve = require( 'path' ).resolve;
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*
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* readJSON( resolve( __dirname, '..', 'package.json' ), onJSON );
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*
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* function onJSON( error, data ) {
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* if ( error ) {
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* throw error;
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* }
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* console.dir( data );
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* }
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*/
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function readJSON( file, options, clbk ) {
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var opts;
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var done;
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if ( arguments.length < 3 ) {
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opts = {};
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done = options;
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} else {
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if ( isString( options ) ) {
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opts = {
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'encoding': options
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};
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} else {
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if ( !isObject( options ) ) {
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throw new TypeError( 'invalid argument. Options argument must be either a string or an object. Value: `' + options + '`.' );
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}
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opts = options;
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}
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done = clbk;
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}
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if ( !isFunction( done ) ) {
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throw new TypeError( 'invalid argument. Callback argument must be a function. Value: `' + done + '`.' );
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}
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readFile( file, opts, onRead );
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/**
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* Callback invoked upon reading a file.
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*
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* @private
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* @param {(Error|null)} error - error object
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* @param {(Buffer|string)} file - file contents
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* @returns {void}
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*/
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function onRead( error, file ) {
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if ( error ) {
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return done( error );
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}
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file = file.toString();
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if ( opts.encoding === 'utf8' ) {
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file = removeBOM( file );
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}
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if ( opts.reviver ) {
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file = parseJSON( file, opts.reviver );
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} else {
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file = parseJSON( file );
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}
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if ( instanceOf( file, Error ) ) {
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return done( file );
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}
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done( null, file );
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}
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}
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// EXPORTS //
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module.exports = readJSON;
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