getHookNameForLocation.js — react Source File

Source Code

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict-local
 */

import type {
  HookMap,
  HookMapEntry,
  HookMapLine,
  HookMapMappings,
} from './generateHookMap';
import type {Position} from './astUtils';
import {NO_HOOK_NAME} from './astUtils';

/**
 * Finds the Hook name assigned to a given location in the source code,
 * and a HookMap extracted from an extended source map.
 * The given location must correspond to the location in the *original*
 * source code (i.e. *not* the generated one).
 *
 * Note that all locations in the source code are guaranteed to map
 * to a name, including a sentinel value that represents a missing
 * Hook name: '<no-hook>'.
 *
 * For more details on the format of the HookMap, see generateHookMap
 * and the tests for that function and this function.
 */
export function getHookNameForLocation(
  location: Position,
  hookMap: HookMap,
): string | null {
  const {names, mappings} = hookMap;

  // The HookMap mappings are grouped by lines, so first we look up
  // which line of mappings covers the target location.
  // Note that we expect to find a line since all the locations in the
  // source code are guaranteed to map to a name, including a '<no-hook>'
  // name.
  const foundLine = binSearch(location, mappings, compareLinePositions);
  if (foundLine == null) {
    throw new Error(
      `Expected to find a line in the HookMap that covers the target location at line: ${location.line}, column: ${location.column}`,
    );
  }

  let foundEntry;
  const foundLineNumber = getLineNumberFromLine(foundLine);
  // The line found in the mappings will never be larger than the target
  // line, and vice-versa, so if the target line doesn't match the found
  // line, we immediately know that it must correspond to the last mapping
  // entry for that line.
  if (foundLineNumber !== location.line) {
    foundEntry = foundLine[foundLine.length - 1];
  } else {
    foundEntry = binSearch(location, foundLine, compareColumnPositions);
  }
// ... (215 more lines)