107 lines
2.9 KiB
JavaScript
107 lines
2.9 KiB
JavaScript
import * as t from "babel-types";
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import template from "babel-template";
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import traverse from "babel-traverse";
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let buildForAwait = template(`
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function* wrapper() {
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var ITERATOR_COMPLETION = true;
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var ITERATOR_HAD_ERROR_KEY = false;
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var ITERATOR_ERROR_KEY = undefined;
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try {
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for (
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var ITERATOR_KEY = GET_ITERATOR(OBJECT), STEP_KEY, STEP_VALUE;
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(
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STEP_KEY = yield AWAIT(ITERATOR_KEY.next()),
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ITERATOR_COMPLETION = STEP_KEY.done,
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STEP_VALUE = yield AWAIT(STEP_KEY.value),
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!ITERATOR_COMPLETION
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);
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ITERATOR_COMPLETION = true) {
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}
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} catch (err) {
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ITERATOR_HAD_ERROR_KEY = true;
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ITERATOR_ERROR_KEY = err;
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} finally {
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try {
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if (!ITERATOR_COMPLETION && ITERATOR_KEY.return) {
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yield AWAIT(ITERATOR_KEY.return());
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}
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} finally {
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if (ITERATOR_HAD_ERROR_KEY) {
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throw ITERATOR_ERROR_KEY;
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}
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}
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}
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}
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`);
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let forAwaitVisitor = {
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noScope: true,
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Identifier(path, replacements) {
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if (path.node.name in replacements) {
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path.replaceInline(replacements[path.node.name]);
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}
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},
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CallExpression(path, replacements) {
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let callee = path.node.callee;
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// if no await wrapping is being applied, unwrap the call expression
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if (t.isIdentifier(callee) && callee.name === "AWAIT" && !replacements.AWAIT) {
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path.replaceWith(path.node.arguments[0]);
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}
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}
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};
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export default function (path, helpers) {
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let { node, scope, parent } = path;
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let stepKey = scope.generateUidIdentifier("step");
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let stepValue = scope.generateUidIdentifier("value");
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let left = node.left;
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let declar;
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if (t.isIdentifier(left) || t.isPattern(left) || t.isMemberExpression(left)) {
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// for await (i of test), for await ({ i } of test)
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declar = t.expressionStatement(t.assignmentExpression("=", left, stepValue));
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} else if (t.isVariableDeclaration(left)) {
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// for await (let i of test)
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declar = t.variableDeclaration(left.kind, [
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t.variableDeclarator(left.declarations[0].id, stepValue)
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]);
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}
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let template = buildForAwait();
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traverse(template, forAwaitVisitor, null, {
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ITERATOR_HAD_ERROR_KEY: scope.generateUidIdentifier("didIteratorError"),
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ITERATOR_COMPLETION: scope.generateUidIdentifier("iteratorNormalCompletion"),
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ITERATOR_ERROR_KEY: scope.generateUidIdentifier("iteratorError"),
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ITERATOR_KEY: scope.generateUidIdentifier("iterator"),
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GET_ITERATOR: helpers.getAsyncIterator,
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OBJECT: node.right,
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STEP_VALUE: stepValue,
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STEP_KEY: stepKey,
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AWAIT: helpers.wrapAwait
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});
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// remove generator function wrapper
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template = template.body.body;
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let isLabeledParent = t.isLabeledStatement(parent);
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let tryBody = template[3].block.body;
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let loop = tryBody[0];
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if (isLabeledParent) {
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tryBody[0] = t.labeledStatement(parent.label, loop);
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}
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return {
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replaceParent: isLabeledParent,
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node: template,
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declar,
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loop
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};
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}
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