mirror of https://github.com/sveltejs/svelte
Rich Harris
2 years ago
parent
a16e0c105d
commit
44076f736c
@ -1,11 +1,137 @@
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/** @import { AssignmentExpression } from 'estree' */
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/** @import { AssignmentExpression, BinaryOperator, Expression, Node, Pattern } from 'estree' */
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/** @import { Context } from '../types.js' */
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/** @import { SvelteNode } from '#compiler' */
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import { serialize_set_binding } from './shared/utils.js';
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/** @import { Context, ServerTransformState } from '../types.js' */
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import { extract_paths } from '../../../../utils/ast.js';
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import * as b from '../../../../utils/builders.js';
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import { serialize_get_binding } from './shared/utils.js';
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/**
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/**
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* @param {AssignmentExpression} node
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* @param {AssignmentExpression} node
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* @param {Context} context
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* @param {Context} context
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*/
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*/
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export function AssignmentExpression(node, context) {
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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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return serialize_assignment(node, context, is_standalone, context.next);
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}
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/**
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* @param {AssignmentExpression} node
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* @param {import('zimmerframe').Context<SvelteNode, ServerTransformState>} context
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* @param {boolean} is_standalone
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* @param {() => any} fallback
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* @returns {Expression}
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*/
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function serialize_assignment(node, context, is_standalone, fallback) {
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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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/** @type {Expression[]} */
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const assignments = [];
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let should_transform = false;
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for (const path of extract_paths(node.left)) {
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const assignment = b.assignment('=', path.node, path.expression?.(rhs));
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let changed = true;
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assignments.push(
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serialize_assignment(assignment, context, false, () => {
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changed = false;
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return assignment;
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})
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);
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should_transform ||= changed;
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}
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if (!should_transform) {
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// No change to output -> nothing to transform -> we can keep the original assignment
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return fallback();
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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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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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if (node.left.type !== 'Identifier' && node.left.type !== 'MemberExpression') {
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throw new Error(`Unexpected assignment type ${node.left.type}`);
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}
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let left = node.left;
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while (left.type === 'MemberExpression') {
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// @ts-expect-error
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left = left.object;
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}
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if (left.type !== 'Identifier' || !is_store_name(left.name)) {
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return fallback();
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}
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const name = left.name.slice(1);
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if (!context.state.scope.get(name)) {
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// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
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return fallback();
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}
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if (left === node.left) {
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return b.call('$.store_set', b.id(name), /** @type {Expression} */ (context.visit(node.right)));
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}
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return b.call(
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'$.mutate_store',
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b.assignment('??=', b.id('$$store_subs'), b.object([])),
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b.literal(left.name),
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b.id(name),
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b.assignment(
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node.operator,
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/** @type {Pattern} */ (context.visit(node.left)),
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get_assignment_value(node, context)
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)
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);
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}
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/**
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* @param {AssignmentExpression} node
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* @param {Pick<import('zimmerframe').Context<SvelteNode, ServerTransformState>, 'visit' | 'state'>} context
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*/
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function get_assignment_value(node, { state, visit }) {
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if (node.left.type === 'Identifier') {
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const operator = node.operator;
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return operator === '='
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? /** @type {Expression} */ (visit(node.right))
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: // turn something like x += 1 into x = x + 1
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b.binary(
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/** @type {BinaryOperator} */ (operator.slice(0, -1)),
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serialize_get_binding(node.left, state),
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/** @type {Expression} */ (visit(node.right))
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);
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}
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return /** @type {Expression} */ (visit(node.right));
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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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}
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