ValidateUseMemo.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 {
  CompilerDiagnostic,
  CompilerError,
  ErrorCategory,
} from '../CompilerError';
import {
  FunctionExpression,
  HIRFunction,
  IdentifierId,
  SourceLocation,
} from '../HIR';
import {
  eachInstructionValueOperand,
  eachTerminalOperand,
} from '../HIR/visitors';
import {Result} from '../Utils/Result';

export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
  const errors = new CompilerError();
  const voidMemoErrors = new CompilerError();
  const useMemos = new Set<IdentifierId>();
  const react = new Set<IdentifierId>();
  const functions = new Map<IdentifierId, FunctionExpression>();
  const unusedUseMemos = new Map<IdentifierId, SourceLocation>();
  for (const [, block] of fn.body.blocks) {
    for (const {lvalue, value} of block.instructions) {
      if (unusedUseMemos.size !== 0) {
        /**
         * Most of the time useMemo results are referenced immediately. Don't bother
         * scanning instruction operands for useMemos unless there is an as-yet-unused
         * useMemo.
         */
        for (const operand of eachInstructionValueOperand(value)) {
          unusedUseMemos.delete(operand.identifier.id);
        }
      }
      switch (value.kind) {
        case 'LoadGlobal': {
          if (value.binding.name === 'useMemo') {
            useMemos.add(lvalue.identifier.id);
          } else if (value.binding.name === 'React') {
            react.add(lvalue.identifier.id);
          }
          break;
        }
        case 'PropertyLoad': {
          if (react.has(value.object.identifier.id)) {
            if (value.property === 'useMemo') {
              useMemos.add(lvalue.identifier.id);
            }
          }
          break;
        }
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