How to use babel-macros - 3 common examples

// ast-pretty-print is really handy :)
const printAST = require('ast-pretty-print')
const {createMacro} = require('babel-macros')

module.exports = createMacro(greetingMacro)

function greetingMacro({references, babel}) {
  const {default: hello = [], goodbye = []} = references
  hello.forEach(reference => {
    // console.log(printAST(reference))
    reference.replaceWith(babel.types.stringLiteral('hi there'))
  })
  goodbye.forEach(reference => {
    // console.log(printAST(reference))
    reference.replaceWith(babel.types.stringLiteral('goodbye friend'))
  })
}

(TEMP_VAR = NODE, UNWRAP)
`);

const createUnwrapExpression = (id) =>
  buildUnwrapExpression({
    WRAPPED: id
  });

const createUnwrapSequence = (id, node) =>
  buildUnwrapSequence({
    TEMP_VAR: id,
    NODE: node,
    UNWRAP: createUnwrapExpression(id)
  });

module.exports = createMacro(({ references }) => {
  const refs = references.default.slice(0).reverse();
  refs.forEach(path => {
    const id = t.identifier('_wrappedValue');
    const maybeValueNode = path.parentPath.node.arguments[0];
    const valueNode = maybeValueNode !== undefined ?
      maybeValueNode :
      t.identifier('undefined');
    if (valueNode.type === 'Identifier') {
      path.parentPath.replaceWith(
        createUnwrapExpression(valueNode)
      );
    } else {
      path.parentPath.replaceWith(
        createUnwrapSequence(id, valueNode)
      );
      ensureVar(id, path);

};

const macro = ({ references, state }) => {
  const paths = getPaths(state.file.opts.filename);

  Object.keys(paths).forEach(key => {
    const value = (key === 'default' ? paths['base'] : paths[key]) || '';
    const list = references[key] || [];

    list.forEach(reference => {
      reference.replaceWithSourceString(JSON.stringify(value));
    });
  })
};

module.exports = createMacro(macro);