2017-03-04 10:46:01 -05:00

112 lines
2.5 KiB
JavaScript

import cloneDeep from "lodash/cloneDeep";
import has from "lodash/has";
import traverse from "babel-traverse";
import * as babylon from "babylon";
import * as t from "babel-types";
const FROM_TEMPLATE = "_fromTemplate"; //Symbol(); // todo: probably wont get copied over
const TEMPLATE_SKIP = Symbol();
export default function (code: string, opts?: Object): Function {
// since we lazy parse the template, we get the current stack so we have the
// original stack to append if it errors when parsing
let stack;
try {
// error stack gets populated in IE only on throw
// (https://msdn.microsoft.com/en-us/library/hh699850(v=vs.94).aspx)
throw new Error();
} catch (error) {
if (error.stack) {
// error.stack does not exists in IE <= 9
stack = error.stack.split("\n").slice(1).join("\n");
}
}
opts = Object.assign({
allowReturnOutsideFunction: true,
allowSuperOutsideMethod: true,
preserveComments: false,
}, opts);
let getAst = function () {
let ast;
try {
ast = babylon.parse(code, opts);
ast = traverse.removeProperties(ast, { preserveComments: opts.preserveComments });
traverse.cheap(ast, function (node) {
node[FROM_TEMPLATE] = true;
});
} catch (err) {
err.stack = `${err.stack}from\n${stack}`;
throw err;
}
getAst = function () {
return ast;
};
return ast;
};
return function (...args) {
return useTemplate(getAst(), args);
};
}
function useTemplate(ast, nodes?: Array<Object>) {
ast = cloneDeep(ast);
const { program } = ast;
if (nodes.length) {
traverse(ast, templateVisitor, null, nodes);
}
if (program.body.length > 1) {
return program.body;
} else {
return program.body[0];
}
}
const templateVisitor = {
// 360
noScope: true,
enter(path, args) {
let { node } = path;
if (node[TEMPLATE_SKIP]) return path.skip();
if (t.isExpressionStatement(node)) {
node = node.expression;
}
let replacement;
if (t.isIdentifier(node) && node[FROM_TEMPLATE]) {
if (has(args[0], node.name)) {
replacement = args[0][node.name];
} else if (node.name[0] === "$") {
const i = +node.name.slice(1);
if (args[i]) replacement = args[i];
}
}
if (replacement === null) {
path.remove();
}
if (replacement) {
replacement[TEMPLATE_SKIP] = true;
path.replaceInline(replacement);
}
},
exit({ node }) {
if (!node.loc)
{traverse.clearNode(node);}
},
};