emitSelectorFn() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/Optimization/LowerContextAccess.ts lines 219–291

function emitSelectorFn(env: Environment, keys: Array<string>): Instruction {
  const obj: Place = createTemporaryPlace(env, GeneratedSource);
  promoteTemporary(obj.identifier);
  const instr: Array<Instruction> = [];
  const elements = [];
  for (const key of keys) {
    const {instructions, element: prop} = emitPropertyLoad(env, obj, key);
    instr.push(...instructions);
    elements.push(prop);
  }

  const arrayInstr = emitArrayInstr(elements, env);
  instr.push(arrayInstr);

  const block: BasicBlock = {
    kind: 'block',
    id: makeBlockId(0),
    instructions: instr,
    terminal: {
      id: makeInstructionId(0),
      kind: 'return',
      returnVariant: 'Explicit',
      loc: GeneratedSource,
      value: arrayInstr.lvalue,
      effects: null,
    },
    preds: new Set(),
    phis: new Set(),
  };

  const fn: HIRFunction = {
    loc: GeneratedSource,
    id: null,
    nameHint: null,
    fnType: 'Other',
    env,
    params: [obj],
    returnTypeAnnotation: null,
    returns: createTemporaryPlace(env, GeneratedSource),
    context: [],
    body: {
      entry: block.id,
      blocks: new Map([[block.id, block]]),
    },
    generator: false,
    async: false,
    directives: [],
    aliasingEffects: [],
  };

  reversePostorderBlocks(fn.body);
  markInstructionIds(fn.body);
  enterSSA(fn);
  inferTypes(fn);

  const fnInstr: Instruction = {
    id: makeInstructionId(0),
    value: {
      kind: 'FunctionExpression',
      name: null,
      nameHint: null,
      loweredFunc: {
        func: fn,
      },
      type: 'ArrowFunctionExpression',
      loc: GeneratedSource,
    },
    lvalue: createTemporaryPlace(env, GeneratedSource),
    effects: null,
    loc: GeneratedSource,
  };
  return fnInstr;
}