02511bff1c
js: Automatically convert _.each to for…of.
...
This commit was automatically generated by the following script,
followed by lint --fix and a few small manual lint-related cleanups.
import * as babelParser from "recast/parsers/babel";
import * as recast from "recast";
import * as tsParser from "recast/parsers/typescript";
import { builders as b, namedTypes as n } from "ast-types";
import { Context } from "ast-types/lib/path-visitor";
import K from "ast-types/gen/kinds";
import { NodePath } from "ast-types/lib/node-path";
import assert from "assert";
import fs from "fs";
import path from "path";
import process from "process";
const checkExpression = (node: n.Node): node is K.ExpressionKind =>
n.Expression.check(node);
const checkStatement = (node: n.Node): node is K.StatementKind =>
n.Statement.check(node);
for (const file of process.argv.slice(2)) {
console.log("Parsing", file);
const ast = recast.parse(fs.readFileSync(file, { encoding: "utf8" }), {
parser: path.extname(file) === ".ts" ? tsParser : babelParser,
});
let changed = false;
let inLoop = false;
let replaceReturn = false;
const visitLoop = (...args: string[]) =>
function(this: Context, path: NodePath) {
for (const arg of args) {
this.visit(path.get(arg));
}
const old = { inLoop };
inLoop = true;
this.visit(path.get("body"));
inLoop = old.inLoop;
return false;
};
recast.visit(ast, {
visitDoWhileStatement: visitLoop("test"),
visitExpressionStatement(path) {
const { expression, comments } = path.node;
let valueOnly;
if (
n.CallExpression.check(expression) &&
n.MemberExpression.check(expression.callee) &&
!expression.callee.computed &&
n.Identifier.check(expression.callee.object) &&
expression.callee.object.name === "_" &&
n.Identifier.check(expression.callee.property) &&
["each", "forEach"].includes(expression.callee.property.name) &&
[2, 3].includes(expression.arguments.length) &&
checkExpression(expression.arguments[0]) &&
(n.FunctionExpression.check(expression.arguments[1]) ||
n.ArrowFunctionExpression.check(expression.arguments[1])) &&
[1, 2].includes(expression.arguments[1].params.length) &&
n.Identifier.check(expression.arguments[1].params[0]) &&
((valueOnly = expression.arguments[1].params[1] === undefined) ||
n.Identifier.check(expression.arguments[1].params[1])) &&
(expression.arguments[2] === undefined ||
n.ThisExpression.check(expression.arguments[2]))
) {
const old = { inLoop, replaceReturn };
inLoop = false;
replaceReturn = true;
this.visit(
path
.get("expression")
.get("arguments")
.get(1)
.get("body")
);
inLoop = old.inLoop;
replaceReturn = old.replaceReturn;
const [right, { body, params }] = expression.arguments;
const loop = b.forOfStatement(
b.variableDeclaration("let", [
b.variableDeclarator(
valueOnly ? params[0] : b.arrayPattern([params[1], params[0]])
),
]),
valueOnly
? right
: b.callExpression(
b.memberExpression(right, b.identifier("entries")),
[]
),
checkStatement(body) ? body : b.expressionStatement(body)
);
loop.comments = comments;
path.replace(loop);
changed = true;
}
this.traverse(path);
},
visitForStatement: visitLoop("init", "test", "update"),
visitForInStatement: visitLoop("left", "right"),
visitForOfStatement: visitLoop("left", "right"),
visitFunction(path) {
this.visit(path.get("params"));
const old = { replaceReturn };
replaceReturn = false;
this.visit(path.get("body"));
replaceReturn = old.replaceReturn;
return false;
},
visitReturnStatement(path) {
if (replaceReturn) {
assert(!inLoop); // could use labeled continue if this ever fires
const { argument, comments } = path.node;
if (argument === null) {
const s = b.continueStatement();
s.comments = comments;
path.replace(s);
} else {
const s = b.expressionStatement(argument);
s.comments = comments;
path.replace(s, b.continueStatement());
}
return false;
}
this.traverse(path);
},
visitWhileStatement: visitLoop("test"),
});
if (changed) {
console.log("Writing", file);
fs.writeFileSync(file, recast.print(ast).code, { encoding: "utf8" });
}
}
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
2020-02-07 14:09:47 -08:00
Anders Kaseorg
Steve Howell