add an exception to the for-each-of lint rule for interval iteration

[michaelficarra]

Fixes #708

[bakkot]

Suggested change

	!/^ in the (?:inclusive )?interval from\b/.test(next.contents)
	!/^ in the (?:inclusive )?interval\b/.test(next.contents)

No need to mandate the "from"; e.g. one might say "in the interval defined by..." or whatever.

[michaelficarra]

All of our allowed interval forms use from: https://tc39.es/ecma262/#interval

[gibson042]

I second @bakkot's suggestion to stop after "interval". And if we consider it in scope, also adopting the early-exit pattern from above this loop:

  // Find the loop variable (underscore), then check the text after it
  for (let i = 1; i < stepSeq.items.length - 1; i++) {
    const item = stepSeq.items[i];
    if (item.name !== 'underscore') {
      continue;
    }

    const next = stepSeq.items[i + 1];
    const over = next.name === 'text'
      ? next.contents.match(/^ in (the (?:inclusive)? interval )?/)
      : undefined;
    if (over && !over[1]) {
      report({
        ruleId,
        ...offsetToLineAndColumn(algorithmSource, next.location.start.offset + 1),
        message: 'expected "of" instead of "in" in "for each"',
      });
    }
    break;
  }

[bakkot]

All of our allowed interval forms use from: https://tc39.es/ecma262/#interval

This rule is not intended to enforce a specific style for declaring intervals. You could have such a rule if you really wanted, but I would still want this rule not to enforce it; writing "in the interval defined by..." shouldn't lead to an error complaining about using in instead of of even if there's some other error that complains about some other thing.

[gibson042]

LGTM even without accepting the suggestion(s).

[gibson042]

I second @bakkot's suggestion to stop after "interval". And if we consider it in scope, also adopting the early-exit pattern from above this loop:

  // Find the loop variable (underscore), then check the text after it
  for (let i = 1; i < stepSeq.items.length - 1; i++) {
    const item = stepSeq.items[i];
    if (item.name !== 'underscore') {
      continue;
    }

    const next = stepSeq.items[i + 1];
    const over = next.name === 'text'
      ? next.contents.match(/^ in (the (?:inclusive)? interval )?/)
      : undefined;
    if (over && !over[1]) {
      report({
        ruleId,
        ...offsetToLineAndColumn(algorithmSource, next.location.start.offset + 1),
        message: 'expected "of" instead of "in" in "for each"',
      });
    }
    break;
  }