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Edit File: degenerator.js

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.degenerator = void 0;
const util_1 = require("util");
const escodegen_1 = require("escodegen");
const esprima_1 = require("esprima");
const ast_types_1 = require("ast-types");
/**
 * Compiles sync JavaScript code into JavaScript with async Functions.
 *
 * @param {String} code JavaScript string to convert
 * @param {Array} names Array of function names to add `await` operators to
 * @return {String} Converted JavaScript string with async/await injected
 * @api public
 */
function degenerator(code, _names) {
    if (!Array.isArray(_names)) {
        throw new TypeError('an array of async function "names" is required');
    }
    // Duplicate the `names` array since it's rude to augment the user args
    const names = _names.slice(0);
    const ast = (0, esprima_1.parseScript)(code);
    // First pass is to find the `function` nodes and turn them into async or
    // generator functions only if their body includes `CallExpressions` to
    // function in `names`. We also add the names of the functions to the `names`
    // array. We'll iterate several time, as every iteration might add new items
    // to the `names` array, until no new names were added in the iteration.
    let lastNamesLength = 0;
    do {
        lastNamesLength = names.length;
        (0, ast_types_1.visit)(ast, {
            visitVariableDeclaration(path) {
                if (path.node.declarations) {
                    for (let i = 0; i < path.node.declarations.length; i++) {
                        const declaration = path.node.declarations[i];
                        if (ast_types_1.namedTypes.VariableDeclarator.check(declaration) &&
                            ast_types_1.namedTypes.Identifier.check(declaration.init) &&
                            ast_types_1.namedTypes.Identifier.check(declaration.id) &&
                            checkName(declaration.init.name, names) &&
                            !checkName(declaration.id.name, names)) {
                            names.push(declaration.id.name);
                        }
                    }
                }
                return false;
            },
            visitAssignmentExpression(path) {
                if (ast_types_1.namedTypes.Identifier.check(path.node.left) &&
                    ast_types_1.namedTypes.Identifier.check(path.node.right) &&
                    checkName(path.node.right.name, names) &&
                    !checkName(path.node.left.name, names)) {
                    names.push(path.node.left.name);
                }
                return false;
            },
            visitFunction(path) {
                if (path.node.id) {
                    let shouldDegenerate = false;
                    (0, ast_types_1.visit)(path.node, {
                        visitCallExpression(path) {
                            if (checkNames(path.node, names)) {
                                shouldDegenerate = true;
                            }
                            return false;
                        },
                    });
                    if (!shouldDegenerate) {
                        return false;
                    }
                    // Got a "function" expression/statement,
                    // convert it into an async function
                    path.node.async = true;
                    // Add function name to `names` array
                    if (!checkName(path.node.id.name, names)) {
                        names.push(path.node.id.name);
                    }
                }
                this.traverse(path);
            },
        });
    } while (lastNamesLength !== names.length);
    // Second pass is for adding `await` statements to any function
    // invocations that match the given `names` array.
    (0, ast_types_1.visit)(ast, {
        visitCallExpression(path) {
            if (checkNames(path.node, names)) {
                // A "function invocation" expression,
                // we need to inject an `AwaitExpression`
                const delegate = false;
                const { name, parent: { node: pNode }, } = path;
                const expr = ast_types_1.builders.awaitExpression(path.node, delegate);
                if (ast_types_1.namedTypes.CallExpression.check(pNode)) {
                    pNode.arguments[name] = expr;
                }
                else {
                    pNode[name] = expr;
                }
            }
            this.traverse(path);
        },
    });
    return (0, escodegen_1.generate)(ast);
}
exports.degenerator = degenerator;
/**
 * Returns `true` if `node` has a matching name to one of the entries in the
 * `names` array.
 *
 * @param {types.Node} node
 * @param {Array} names Array of function names to return true for
 * @return {Boolean}
 * @api private
 */
function checkNames({ callee }, names) {
    let name;
    if (ast_types_1.namedTypes.Identifier.check(callee)) {
        name = callee.name;
    }
    else if (ast_types_1.namedTypes.MemberExpression.check(callee)) {
        if (ast_types_1.namedTypes.Identifier.check(callee.object) &&
            ast_types_1.namedTypes.Identifier.check(callee.property)) {
            name = `${callee.object.name}.${callee.property.name}`;
        }
        else {
            return false;
        }
    }
    else if (ast_types_1.namedTypes.FunctionExpression.check(callee)) {
        if (callee.id) {
            name = callee.id.name;
        }
        else {
            return false;
        }
    }
    else {
        throw new Error(`Don't know how to get name for: ${callee.type}`);
    }
    return checkName(name, names);
}
function checkName(name, names) {
    // now that we have the `name`, check if any entries match in the `names` array
    for (let i = 0; i < names.length; i++) {
        const n = names[i];
        if (util_1.types.isRegExp(n)) {
            if (n.test(name)) {
                return true;
            }
        }
        else if (name === n) {
            return true;
        }
    }
    return false;
}
//# sourceMappingURL=degenerator.js.map

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