Visual Studio Code / Atom Editor - Syntax Highlighting via program not regex grammars

Is it possible to write a plugin for language syntax support programmatically? I mean to get the content of current open file into my program and give back a tokenized syntax data structure? Something like:

editor.onChange((fileContent) => {
    return tokenizeForVSCode(fileContent);
    // return tokenizeForAtome(fileContent);
});

from Visual Studio Code / Atom Editor - Syntax Highlighting via program not regex grammars