[Langium Grammar] How best to implement section headings?

[ym-han]

What's the best way to implement optional section headings (much like Markdown's) like

SECTION 1: Introduction

<... stuff ...>

SECTION 2

<... stuff ...>

where there aren't super-explicit closing delimiters?

I see from #153 that one way to do it is to use EOL --- is that the best way?

Thanks very much in advance!

[msujew]

Hey @ym-han,

sorry for the late response. You can use a parser rule like this to identify the end of section headings:

Section: 'SECTION' content=TEXT (EOL+ | EOF); // EOF is a builtin keyword that matches the end of a file

terminal EOL: /\r?\n/;
terminal TEXT: [^\n\r]+;

A general word of warning: Markdown like languages are very difficult to parse using LL based parsers (like Langium). Parsers for those languages are usually handwritten due to very specific behavior wrt to stuff like line endings, ambiguity detection and error recovery. It can work, but it's often a lot more effort than necessary.

[ym-han]

Gotcha, thank you! Sounds like there's no way to do it without using EOL then!