apg-js-examples/src/apg-exp/unicode.js

Examples of using the suite of apg-js applications and libraries.

/*  *************************************************************************************
 *   copyright: Copyright (c) 2021 Lowell D. Thomas, all rights reserved
 *     license: BSD-2-Clause (https://opensource.org/licenses/BSD-2-Clause)
 *   ********************************************************************************* */
// With the Unicode flag, `u`, set, `apg-exp` returns its matched phrases as arrays of character codes rather than
// Javascript strings.
// This module gives a short demonstration of how one might take advantage of that to deal with Unicode text.
// I don't read or speak Greek, but I took a couple of phrases from [here](http://www.omniglot.com/language/phrases/greek.php)
// to experiment with.
//
// Here I will simply define a Greek word as any string of Unicode characters from the
// [Greek and Coptic range](http://www.unicode.org/charts/PDF/U0370.pdf) U+0370-03FF.
// The exercise will be to find and display any Greeks word fitting this loose description.
(function unicode() {
  try {
    const { apgExp: ApgExp, apgLib } = require('apg-js');
    const writeHtml = require('../writeHtml');
    const grammar = new (require('./grammars/greek-words'))();

    //   const apgJs = require('apg-js');
    //     const { apgExp } = apgJs;
    //     const { apgLib } = apgJs;
    let result;
    let str;
    let html;
    const flags = 'ug';
    const exp = new ApgExp(grammar, flags);
    console.log();
    console.log('Demonstrate Unicode mode with the "u" flag.');
    console.log();
    console.log('SABNF grammar:');
    console.log(exp.sourceToText());
    str = '';
    str += 'The word for "yes" is \u039d\u03b1\u03b9\n';
    str += 'The word for "no" is \u038c\u03c7\u03b9\n';
    str += 'The word for "maybe" is \u038a\u03c3\u03c9\u03c2\n';
    console.log();
    console.log('input string:');
    console.log(str);
    html = '';
    html += '<h3>Greek words found</h3>\n';
    const TRUE = true;
    while (TRUE) {
      result = exp.exec(str);
      if (result == null) {
        break;
      }
      const greek = result.rules['greek-word'];
      // When a Greek word is found, its character codes are converted to HTML entities for web page display.
      if (greek) {
        /* generate text output for the console */
        /* (displays Greek characters on my Ubuntu console) */
        const txt = apgLib.utils.charsToString(greek[0].phrase);
        console.log(`Greek word found: ${txt}`);
        /* convert the characters to HTML entities for page display */
        html += 'Greek word: ';
        for (let i = 0; i < greek[0].phrase.length; i += 1) {
          html += `&#${greek[0].phrase[i]};`;
        }
        html += '<br>\n';
      }
    }
    /* display the greek words, represented as HTML entities, on a page */
    const page = apgLib.utils.htmlToPage(html);
    const htmlName = 'unicode-words';
    writeHtml(page, htmlName);
  } catch (e) {
    console.log(`EXCEPTION: ${e.message}`);
  }
})();