cli (2157B)
1 #!/usr/bin/env node 2 3 /** 4 * @license Apache-2.0 5 * 6 * Copyright (c) 2020 The Stdlib Authors. 7 * 8 * Licensed under the Apache License, Version 2.0 (the "License"); 9 * you may not use this file except in compliance with the License. 10 * You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 21 'use strict'; 22 23 // MODULES // 24 25 var resolve = require( 'path' ).resolve; 26 var readFileSync = require( '@stdlib/fs/read-file' ).sync; 27 var CLI = require( '@stdlib/cli/ctor' ); 28 var stdin = require( '@stdlib/process/read-stdin' ); 29 var stdinStream = require( '@stdlib/streams/node/stdin' ); 30 var codePointAt = require( './../lib' ); 31 32 33 // MAIN // 34 35 /** 36 * Main execution sequence. 37 * 38 * @private 39 * @returns {void} 40 */ 41 function main() { 42 var flags; 43 var args; 44 var cli; 45 var pos; 46 47 // Create a command-line interface: 48 cli = new CLI({ 49 'pkg': require( './../package.json' ), 50 'options': require( './../etc/cli_opts.json' ), 51 'help': readFileSync( resolve( __dirname, '..', 'docs', 'usage.txt' ), { 52 'encoding': 'utf8' 53 }) 54 }); 55 56 // Get any provided command-line options: 57 flags = cli.flags(); 58 if ( flags.help || flags.version ) { 59 return; 60 } 61 pos = parseInt( flags.pos, 10 ); 62 63 // Get any provided command-line arguments: 64 args = cli.args(); 65 66 // Check if we are receiving data from `stdin`... 67 if ( stdinStream.isTTY ) { 68 return console.log( codePointAt( args[ 0 ], pos, flags.backward ) ); // eslint-disable-line no-console 69 } 70 return stdin( onRead ); 71 72 /** 73 * Callback invoked upon reading from `stdin`. 74 * 75 * @private 76 * @param {(Error|null)} error - error object 77 * @param {Buffer} data - data 78 * @returns {void} 79 */ 80 function onRead( error, data ) { 81 if ( error ) { 82 return cli.error( error ); 83 } 84 console.log( codePointAt( data.toString(), pos, flags.backward ) ); // eslint-disable-line no-console 85 } 86 } 87 88 main();