Feature proposal: Accept OffsetOrPosition that denotes end of line

[sealer3]

Clear and concise description of the problem

I would like to decorate (for example) lines 75 and 76 with Shiki. Currently that means I must also know the precise length of line 76, which means I have to split lines myself to determine what the line length is in order to produce a Position for the DecorationItem's start and end positions. This is something Shiki already has to do. Adding this feature would make things easier from a library user point of view.

Suggested solution

Can we have some way of describing "I want to highlight the whole line"? A simple solution would be to accept a negative character index as a Position and treat that as line.length + character. So if you want to highlight lines 75 and 76, you would use

...
start: {
    line: 75,
    character: 0,
  },
end: {
    line: 76,
    character: -1,
}

We would just need to modify this bit to accept it:

shiki/packages/core/src/transformer-decorations.ts

Lines 41 to 52 in d25afc2

	else {
	const line = converter.lines[p.line]
	if (line === undefined)
	throw new ShikiError(`Invalid decoration position ${JSON.stringify(p)}. Lines length: ${converter.lines.length}`)
	if (p.character < 0 || p.character > line.length)
	throw new ShikiError(`Invalid decoration position ${JSON.stringify(p)}. Line ${p.line} length: ${line.length}`)
	return {
	...p,
	offset: converter.posToIndex(p.line, p.character),
	}
	}

Alternative

Alternatively, we can derive some other object that accounts for an entire line.

Additional context

I'd be happy to make a PR for this simple change myself if I get the OK from a maintainer.

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[sealer3]

Closed by #1051.