Feature Request: Ability to initialise lazily and detect if language is already initalised

[yahya-uddin]

Requirements

• I want to initialise the highlighter language when it is required
• I do not want re-load something that is already loaded

Problem

There is no way to detect if the langauge is already initalised. Also re-initalising unfortunatley re-loads the files, even when already initialised.

Solution

Currently the initialise method looks like:

 static Future<void> initialize(List<String> languages) async {
    for (var language in languages) {
      var json = await rootBundle.loadString(
        'packages/syntax_highlight/grammars/$language.json',
      );
      _cache[language] = Grammar.fromJson(jsonDecode(json));
    }
  }

This can be adjusted so it does not replace already loaded languages:

  static Future<void> initialize(List<String> languages, {bool forceReplace = false}) async {
    for (var language in languages) {
      if (forceReplace || !_cache.containsKey(language) {
         var json = await rootBundle.loadString(
           'packages/syntax_highlight/grammars/$language.json',
         );
         _cache[language] = Grammar.fromJson(jsonDecode(json));
      }
    }
  }

if forceReplace = true, then there will be no breaking changes.
If it is false this will be a minor breaking change.

We could optionally also add some utility methods like:

static bool isLanguageInitalised(String name) {
    return _cache.containsKey(name);
}

// Slightly different to addLanguage
static Future<void> loadLanguage(String name, String language) {
   var json = await rootBundle.loadString(
       'packages/syntax_highlight/grammars/$language.json',
    );
    _cache.putIfAbsent(name, () => Grammar.fromJson(jsonDecode(json)));
  }