insertNewOutlinedFunctionNode() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts lines 283–329

function insertNewOutlinedFunctionNode(
  program: NodePath<t.Program>,
  originalFn: BabelFn,
  compiledFn: CodegenFunction,
): BabelFn {
  switch (originalFn.type) {
    case 'FunctionDeclaration': {
      return originalFn.insertAfter(
        createNewFunctionNode(originalFn, compiledFn),
      )[0]!;
    }
    /**
     * We can't just append the outlined function as a sibling of the original function if it is an
     * (Arrow)FunctionExpression parented by a VariableDeclaration, as this would cause its parent
     * to become a SequenceExpression instead which breaks a bunch of assumptions elsewhere in the
     * plugin.
     *
     * To get around this, we always synthesize a new FunctionDeclaration for the outlined function
     * and insert it as a true sibling to the original function.
     */
    case 'ArrowFunctionExpression':
    case 'FunctionExpression': {
      const fn: t.FunctionDeclaration = {
        type: 'FunctionDeclaration',
        id: compiledFn.id,
        loc: originalFn.node.loc ?? null,
        async: compiledFn.async,
        generator: compiledFn.generator,
        params: compiledFn.params,
        body: compiledFn.body,
      };
      const insertedFuncDecl = program.pushContainer('body', [fn])[0]!;
      CompilerError.invariant(insertedFuncDecl.isFunctionDeclaration(), {
        reason: 'Expected inserted function declaration',
        description: `Got: ${insertedFuncDecl}`,
        loc: insertedFuncDecl.node?.loc ?? GeneratedSource,
      });
      return insertedFuncDecl;
    }
    default: {
      assertExhaustive(
        originalFn,
        `Inserting unhandled function: ${originalFn}`,
      );
    }
  }
}