/* *************************************************************************************
* copyright: Copyright (c) 2021 Lowell D. Thomas, all rights reserved
* license: BSD-2-Clause (https://opensource.org/licenses/BSD-2-Clause)
* ********************************************************************************* */This is a demonstration of the using the back reference operators.
module.exports = function main(args) {
/* display the program arguments */
console.log('back-reference args');
console.dir(args);
/* the help screen */
let desc = '';
desc += 'The "back-reference" example is a demonstration of using back referencing\n';
desc += 'in pattern matching.\n';
desc +=
'Examine or run a debugger on this module, "apg-js-examples/src/back-reference/main.js" to study the example.\n';
let help = '';
help += 'Usage: npm run back-reference [-- arg]\n';
help += ' arg: help (or no arg) to display this help screen.\n';
help += ' branch-fail back-reference not matched (see the trace output)\n';
help += ' parent demonstrate parent-mode back reference to match HTML tags\n';
help += ' universal a very simple demonstration of universal-mode back referencing\n';
help += ' all all demonstrations\n';
if (!args[0]) {
/* display the help screen and exit */
console.log(desc);
console.log(help);
return;
}
if (args[0] === 'help') {
console.log(help);
return;
}
let input;
let grammar;
let displayname;
let doTrace;
const setup = require('./setup');
console.log();
console.log('Demonstration of using back referencing.');
console.log();
const fnFail = function fnFail() {
input = 'ayaa';
grammar = new (require('./branch-fail-grammar'))();
displayname = 'branch-fail';
doTrace = true;
setup(input, grammar, displayname, doTrace);
};
const fnParent = function fnParent() {
input = '<ROOT><next><ToP>...</ToP></next></ROOT>';
grammar = new (require('./parent-mode-grammar'))();
displayname = 'parent-mode matched';
doTrace = true;
setup(input, grammar, displayname, doTrace);
input = '<root><next><top>...</top></next></notroot>';
displayname = 'parent-mode not matched';
setup(input, grammar, displayname, doTrace);
};
const fnUniversal = function fnUniversal() {
input = 'xXXx';
grammar = new (require('./universal-mode-grammar'))();
displayname = 'universal-mode';
doTrace = true;
setup(input, grammar, displayname, doTrace);
};
switch (args[0]) {
case 'branch-fail':
fnFail();
break;
case 'parent':
fnParent();
break;
case 'universal':
fnUniversal();
break;
case 'all':
fnFail();
fnParent();
fnUniversal();
break;
default:
console.log(`unrecognized argument: ${args[0]}`);
console.log(help);return;
}setup(input, grammar, displayname, doTrace);
};