mirror of https://github.com/sveltejs/svelte
chore: simplify assignments in server code (#12614)
Also fixes an uncovered bug where store `+=/-=` etc assignments were not serialized correctly on the serverpull/12619/head
Rich Harris
4 months ago
committed by
GitHub
parent
993fff0045
commit
97d5cf178f
@ -0,0 +1,5 @@
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---
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'svelte': patch
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---
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fix: correctly update stores when reassigning with operator other than `=`
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@ -1,11 +1,118 @@
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/** @import { AssignmentExpression } from 'estree' */
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/** @import { Context } from '../types.js' */
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import { serialize_set_binding } from './shared/utils.js';
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/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Node, Pattern } from 'estree' */
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/** @import { SvelteNode } from '#compiler' */
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/** @import { Context, ServerTransformState } from '../types.js' */
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import * as b from '../../../../utils/builders.js';
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import { extract_paths } from '../../../../utils/ast.js';
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import { serialize_get_binding } from './shared/utils.js';
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/**
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* @param {AssignmentExpression} node
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* @param {Context} context
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*/
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export function AssignmentExpression(node, context) {
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return serialize_set_binding(node, context, context.next);
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const parent = /** @type {Node} */ (context.path.at(-1));
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const is_standalone = parent.type.endsWith('Statement');
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if (
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node.left.type === 'ArrayPattern' ||
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node.left.type === 'ObjectPattern' ||
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node.left.type === 'RestElement'
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) {
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const value = /** @type {Expression} */ (context.visit(node.right));
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const should_cache = value.type !== 'Identifier';
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const rhs = should_cache ? b.id('$$value') : value;
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let changed = false;
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const assignments = extract_paths(node.left).map((path) => {
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const value = path.expression?.(rhs);
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let assignment = serialize_assignment('=', path.node, value, context);
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if (assignment !== null) changed = true;
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return assignment ?? b.assignment('=', path.node, value);
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});
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if (!changed) {
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// No change to output -> nothing to transform -> we can keep the original assignment
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return context.next();
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}
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const sequence = b.sequence(assignments);
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if (!is_standalone) {
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// this is part of an expression, we need the sequence to end with the value
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sequence.expressions.push(rhs);
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}
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if (should_cache) {
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// the right hand side is a complex expression, wrap in an IIFE to cache it
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return b.call(b.arrow([rhs], sequence), value);
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}
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return sequence;
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}
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return serialize_assignment(node.operator, node.left, node.right, context) || context.next();
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}
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/**
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* Only returns an expression if this is not a `$store` assignment, as others can be kept as-is
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* @param {AssignmentOperator} operator
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* @param {Pattern} left
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* @param {Expression} right
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* @param {import('zimmerframe').Context<SvelteNode, ServerTransformState>} context
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* @returns {Expression | null}
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*/
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function serialize_assignment(operator, left, right, context) {
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let object = left;
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while (object.type === 'MemberExpression') {
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// @ts-expect-error
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object = object.object;
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}
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if (object.type !== 'Identifier' || !is_store_name(object.name)) {
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return null;
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}
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const name = object.name.slice(1);
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if (!context.state.scope.get(name)) {
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return null;
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}
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if (object === left) {
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let value = /** @type {Expression} */ (context.visit(right));
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if (operator !== '=') {
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// turn `x += 1` into `x = x + 1`
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value = b.binary(
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/** @type {BinaryOperator} */ (operator.slice(0, -1)),
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serialize_get_binding(left, context.state),
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value
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);
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}
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return b.call('$.store_set', b.id(name), value);
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}
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return b.call(
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'$.store_mutate',
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b.assignment('??=', b.id('$$store_subs'), b.object([])),
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b.literal(object.name),
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b.id(name),
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b.assignment(
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operator,
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/** @type {Pattern} */ (context.visit(left)),
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/** @type {Expression} */ (context.visit(right))
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)
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);
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}
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/**
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* @param {string} name
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*/
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function is_store_name(name) {
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return name[0] === '$' && /[A-Za-z_]/.test(name[1]);
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}
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@ -0,0 +1,5 @@
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import { test } from '../../test';
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export default test({
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html: '<p>3</p>'
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});
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@ -0,0 +1,11 @@
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<script>
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import { writable } from 'svelte/store';
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const count = writable(0);
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$count += 1;
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$count += 1;
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$count += 1;
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</script>
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<p>{$count}</p>
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