RenameVariables.ts — 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.
 */

import {ProgramContext} from '..';
import {CompilerError} from '../CompilerError';
import {
  DeclarationId,
  GeneratedSource,
  Identifier,
  IdentifierName,
  InstructionId,
  Place,
  PrunedReactiveScopeBlock,
  ReactiveBlock,
  ReactiveFunction,
  ReactiveScopeBlock,
  ReactiveValue,
  ValidIdentifierName,
  isPromotedJsxTemporary,
  isPromotedTemporary,
  makeIdentifierName,
} from '../HIR/HIR';
import {collectReferencedGlobals} from './CollectReferencedGlobals';
import {ReactiveFunctionVisitor, visitReactiveFunction} from './visitors';

/**
 * Ensures that each named variable in the given function has a unique name
 * that does not conflict with any other variables in the same block scope.
 * Note that the scoping is based on the final inferred blocks, not the
 * block scopes that were present in the original source. Thus variables
 * that shadowed in the original source may end up with unique names in the
 * output, if Forget would merge those two blocks into a single scope.
 *
 * Variables are renamed using their original name followed by a number,
 * starting with 0 and incrementing until a unique name is found. Eg if the
 * compiler collapses three scopes that each had their own `foo` declaration,
 * they will be renamed to `foo`, `foo0`, and `foo1`, assuming that no conflicts'
 * exist for `foo0` and `foo1`.
 *
 * For temporary values that are promoted to named variables, the starting name
 * is "T0" for values that appear in JSX tag position and "t0" otherwise. If this
 * name conflicts, the number portion increments until the name is unique (t1, t2, etc).
 *
 * Returns a Set of all the unique variable names in the function after renaming.
 */
export function renameVariables(fn: ReactiveFunction): Set<string> {
  const globals = collectReferencedGlobals(fn);
  const scopes = new Scopes(globals, fn.env.programContext);
  renameVariablesImpl(fn, new Visitor(), scopes);
  return new Set([...scopes.names, ...globals]);
}

function renameVariablesImpl(
  fn: ReactiveFunction,
  visitor: Visitor,
  scopes: Scopes,
// ... (133 more lines)