Function checkSelector

javascript/selenium-webdriver/project_bidi_schema.mjs:541–571

(name, selector, has)

// selector has distinct values and at most one default, a structural selector
// dispatches on something. Keeps a malformed selector from shipping silently.
function checkSelector(name, selector, has) {
  const errors = []
  if (!selector) return [`${name}: union has no selector`]
  if (selector.correlated) return [] // resolved by request id, not the payload — nothing to dispatch
  if (selector.by) {
    const values = selector.variants.map((v) => JSON.stringify(v.value))
    if (new Set(values).size !== values.length) errors.push(`${name}: selector has duplicate discriminator values`)
    for (const v of selector.variants)
      if (!has(v.ref)) errors.push(`${name}: selector variant ${v.ref} does not resolve`)
    if (selector.default && !has(selector.default))
      errors.push(`${name}: selector default ${selector.default} does not resolve`)
  } else if (selector.ordered) {
    // A structural selector must actually dispatch from the payload: every arm needs
    // a distinguishing required field, and no arm's `requires` may be a subset of a
    // later arm's — that would shadow the later arm under first-match. A union that
    // cannot satisfy this is not payload-dispatchable and must be `correlated`.
    selector.ordered.forEach((v, i) => {
      if (!has(v.ref)) errors.push(`${name}: selector variant ${v.ref} does not resolve`)
      if (!v.requires.length)
        errors.push(`${name}: structural selector arm ${v.ref} has no required fields to dispatch on`)
      for (let j = i + 1; j < selector.ordered.length; j++) {
        const w = selector.ordered[j]
        if (v.requires.length && w.requires.length && v.requires.every((k) => w.requires.includes(k)))
          errors.push(`${name}: structural selector arm ${v.ref} shadows ${w.ref} (requires is a subset)`)
      }
    })
  } else {
    errors.push(`${name}: selector is neither discriminated, structural, nor correlated`)
  }
  return errors
}

// ============================================================
// CLI: raw ast + model → flat schema (validated)