100 lines
2.1 KiB
JavaScript
100 lines
2.1 KiB
JavaScript
/* @flow */
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import cloneDeep from "lodash/lang/cloneDeep";
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import has from "lodash/object/has";
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import traverse from "babel-traverse";
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import * as babylon from "babylon";
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import * as t from "babel-types";
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let FROM_TEMPLATE = "_fromTemplate"; //Symbol(); // todo: probably wont get copied over
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let TEMPLATE_SKIP = Symbol();
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export default function (code: string): Function {
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// since we lazy parse the template, we get the current stack so we have the
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// original stack to append if it errors when parsing
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let stack = new Error().stack.split("\n").slice(1).join("\n");
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let getAst = function () {
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let ast;
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try {
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ast = babylon.parse(code, {
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allowReturnOutsideFunction: true,
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allowSuperOutsideMethod: true
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});
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ast = traverse.removeProperties(ast);
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traverse.cheap(ast, function (node) {
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node[FROM_TEMPLATE] = true;
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});
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} catch (err) {
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err.stack = `${err.stack}from\n${stack}`;
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throw err;
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}
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getAst = function () {
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return ast;
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};
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return ast;
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};
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return function (...args) {
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return useTemplate(getAst(), args);
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};
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}
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function useTemplate(ast, nodes?: Array<Object>) {
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ast = cloneDeep(ast);
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let { program } = ast;
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if (nodes.length) {
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traverse(ast, templateVisitor, null, nodes);
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}
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if (program.body.length > 1) {
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return program.body;
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} else {
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return program.body[0];
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}
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}
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let templateVisitor = {
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// 360
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noScope: true,
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enter(path, args) {
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let { node } = path;
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if (node[TEMPLATE_SKIP]) return path.skip();
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if (t.isExpressionStatement(node)) {
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node = node.expression;
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}
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let replacement;
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if (t.isIdentifier(node) && node[FROM_TEMPLATE]) {
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if (has(args[0], node.name)) {
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replacement = args[0][node.name];
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} else if (node.name[0] === "$") {
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let i = +node.name.slice(1);
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if (args[i]) replacement = args[i];
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}
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}
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if (replacement === null) {
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path.remove();
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}
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if (replacement) {
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replacement[TEMPLATE_SKIP] = true;
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path.replaceInline(replacement);
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}
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},
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exit({ node }) {
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traverse.clearNode(node);
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}
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};
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