ember-cli-htmlbars/lib/colocated-babel-plugin.js

A library for adding htmlbars to ember CLI

// For ease of debuggin / tweaking:
// https://astexplorer.net/#/gist/bcca584efdab6c981a75618642c76a22/1e1d262eaeb47b7da66150e0781a02b96e597b25
module.exports = function (babel) {
  let t = babel.types;

  function makeSetComponentTemplateExpression(state) {
    return state._colocationEnsureImport(
      'setComponentTemplate',
      '@ember/component',
    );
  }

  function makeColocatedTemplateIdentifier() {
    return t.identifier('__COLOCATED_TEMPLATE__');
  }

  return {
    name: 'ember-cli-htmlbars-colocation-template',

    visitor: {
      Program(path, state) {
        let allAddedImports = {};

        state._colocationEnsureImport = (exportName, moduleName) => {
          let addedImports = (allAddedImports[moduleName] =
            allAddedImports[moduleName] || {});

          if (addedImports[exportName])
            return t.identifier(addedImports[exportName].name);

          let importDeclarations = path
            .get('body')
            .filter((n) => n.type === 'ImportDeclaration');

          let preexistingImportDeclaration = importDeclarations.find(
            (n) => n.get('source').get('value').node === moduleName,
          );

          if (preexistingImportDeclaration) {
            let importSpecifier = preexistingImportDeclaration
              .get('specifiers')
              .find(({ node }) => {
                return exportName === 'default'
                  ? t.isImportDefaultSpecifier(node)
                  : node.imported && node.imported.name === exportName;
              });

            if (importSpecifier) {
              addedImports[exportName] = importSpecifier.node.local;
            }
          }

          if (!addedImports[exportName]) {
            let uid = path.scope.generateUidIdentifier(
              exportName === 'default' ? moduleName : exportName,
            );
            addedImports[exportName] = uid;

            let newImportSpecifier =
              exportName === 'default'
                ? t.importDefaultSpecifier(uid)
                : t.importSpecifier(uid, t.identifier(exportName));

            let newImport = t.importDeclaration(
              [newImportSpecifier],
              t.stringLiteral(moduleName),
            );
            path.unshiftContainer('body', newImport);
          }

          return t.identifier(addedImports[exportName].name);
        };
      },

      VariableDeclarator(path, state) {
        if (path.node.id.name === '__COLOCATED_TEMPLATE__') {
          state.colocatedTemplateFound = true;
        }
      },

      ExportDefaultDeclaration(path, state) {
        let defaultExportDeclarationPath = path.get('declaration');
        let defaultExportIsExpressionOrClass =
          defaultExportDeclarationPath.isClass() ||
          defaultExportDeclarationPath.isExpression() ||
          defaultExportDeclarationPath.isFunction();

        if (
          state.colocatedTemplateFound !== true ||
          state.setComponentTemplateInjected === true ||
          !defaultExportIsExpressionOrClass
        ) {
          return;
        }

        state.setComponentTemplateInjected = true;
        let defaultExportDeclaration = path.node.declaration;
        let setComponentTemplateMemberExpression =
          makeSetComponentTemplateExpression(state);
        let colocatedTemplateIdentifier = makeColocatedTemplateIdentifier();

        if (defaultExportDeclaration.type === 'ClassDeclaration') {
          // when the default export is a ClassDeclaration with an `id`,
          // wrapping it in a CallExpression would remove that class from the
          // local scope which would cause issues for folks using the declared
          // name _after_ the export
          if (defaultExportDeclaration.id !== null) {
            path.parent.body.push(
              t.expressionStatement(
                t.callExpression(setComponentTemplateMemberExpression, [
                  colocatedTemplateIdentifier,
                  defaultExportDeclaration.id,
                ]),
              ),
            );
          } else {
            path.node.declaration = t.callExpression(
              setComponentTemplateMemberExpression,
              [
                colocatedTemplateIdentifier,
                t.classExpression(
                  null,
                  defaultExportDeclaration.superClass,
                  defaultExportDeclaration.body,
                ),
              ],
            );
          }
        } else {
          path.node.declaration = t.callExpression(
            setComponentTemplateMemberExpression,
            [colocatedTemplateIdentifier, defaultExportDeclaration],
          );
        }
      },

      ExportNamedDeclaration(path, state) {
        if (
          state.colocatedTemplateFound !== true ||
          state.setComponentTemplateInjected === true
        ) {
          return;
        }

        let defaultSpecifier = path.node.specifiers.find(
          (spec) => spec.exported.name === 'default',
        );
        if (defaultSpecifier) {
          state.setComponentTemplateInjected = true;
          path.parent.body.push(
            t.expressionStatement(
              t.callExpression(makeSetComponentTemplateExpression(state), [
                makeColocatedTemplateIdentifier(),
                defaultSpecifier.local,
              ]),
            ),
          );
        }
      },
    },
  };
};