syncPast

syncPast combinator consumes input until sync matches, consuming the match as well, or stops at the end of input if sync never matches. Resolves to null and never fails.

Like syncTo it advances by whole code points and applies sync speculatively, so surrogate pairs are never split and the sync parser's own commitments and errors don't leak into the surrounding parse. The only difference is where it leaves the position: syncTo stops before the match, syncPast stops after it.

Consuming the match means it always advances unless the cursor is already at the end of the input, which is what guarantees a recover inside a repetition combinator makes progress.

Use it as a recover strategy when sync terminates the malformed construct rather than starting the next one, such as the ; ending a statement.

The error recovery guide works through choosing between the two on a real grammar.

Usage

const Parser = syncPast(string(';'))

Success

run(Parser).with('abc;rest')

{
  isOk: true,
  start: 0,
  end: 4,
  pos: 4,
  value: null
}

---

run(Parser).with('abc')

{
  isOk: true,
  start: 0,
  end: 3,
  pos: 3,
  value: null
}

On ;; the resynchronisation point sits at the entry position, so only that first ; is consumed.

Success

run(Parser).with(';;')

{
  isOk: true,
  start: 0,
  end: 1,
  pos: 1,
  value: null
}