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paoloricciutiRich-Harris
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Rich-Harris
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feat: allow generics on snippets (#15915)
* feat: allow generics on snippets * chore: fix lint * reuse bracket matching logic * remove some unused stuff * chore: update name, test and types * chore: fix lint --------- Co-authored-by: Rich Harris <[email protected]>
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-103
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‎.changeset/ten-colts-grab.md‎

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---
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'svelte': minor
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---
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feat: allow generics on snippets

‎packages/svelte/src/compiler/phases/1-parse/read/context.js‎

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/** @import { Location } from 'locate-character' */
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/** @import { Pattern } from 'estree' */
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/** @import { Parser } from '../index.js' */
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import { is_bracket_open, is_bracket_close, get_bracket_close } from '../utils/bracket.js';
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import { match_bracket } from '../utils/bracket.js';
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import { parse_expression_at } from '../acorn.js';
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import { regex_not_newline_characters } from '../../patterns.js';
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import * as e from '../../../errors.js';
@@ -33,7 +33,9 @@ export default function read_pattern(parser) {
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};
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}
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if (!is_bracket_open(parser.template[i])) {
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const char = parser.template[i];
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if (char !== '{' && char !== '[') {
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e.expected_pattern(i);
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}
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@@ -71,75 +73,6 @@ export default function read_pattern(parser) {
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}
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}
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/**
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* @param {Parser} parser
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* @param {number} start
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*/
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function match_bracket(parser, start) {
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const bracket_stack = [];
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let i = start;
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while (i < parser.template.length) {
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let char = parser.template[i++];
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if (char === "'" || char === '"' || char === '`') {
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i = match_quote(parser, i, char);
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continue;
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}
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if (is_bracket_open(char)) {
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bracket_stack.push(char);
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} else if (is_bracket_close(char)) {
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const popped = /** @type {string} */ (bracket_stack.pop());
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const expected = /** @type {string} */ (get_bracket_close(popped));
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if (char !== expected) {
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e.expected_token(i - 1, expected);
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}
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if (bracket_stack.length === 0) {
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return i;
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}
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}
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}
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e.unexpected_eof(parser.template.length);
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}
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/**
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* @param {Parser} parser
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* @param {number} start
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* @param {string} quote
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*/
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function match_quote(parser, start, quote) {
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let is_escaped = false;
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let i = start;
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while (i < parser.template.length) {
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const char = parser.template[i++];
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if (is_escaped) {
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is_escaped = false;
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continue;
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}
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if (char === quote) {
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return i;
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}
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if (char === '\\') {
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is_escaped = true;
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}
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if (quote === '`' && char === '$' && parser.template[i] === '{') {
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i = match_bracket(parser, i);
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}
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}
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e.unterminated_string_constant(start);
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}
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/**
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* @param {Parser} parser
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* @returns {any}

‎packages/svelte/src/compiler/phases/1-parse/state/tag.js‎

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@@ -8,9 +8,12 @@ import { parse_expression_at } from '../acorn.js';
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import read_pattern from '../read/context.js';
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import read_expression, { get_loose_identifier } from '../read/expression.js';
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import { create_fragment } from '../utils/create.js';
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import { match_bracket } from '../utils/bracket.js';
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const regex_whitespace_with_closing_curly_brace = /^\s*}/;
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const pointy_bois = { '<': '>' };
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/** @param {Parser} parser */
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export default function tag(parser) {
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const start = parser.index;
@@ -351,6 +354,22 @@ function open(parser) {
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const params_start = parser.index;
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// snippets could have a generic signature, e.g. `#snippet foo<T>(...)`
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/** @type {string | undefined} */
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let type_params;
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// if we match a generic opening
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if (parser.ts && parser.match('<')) {
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const start = parser.index;
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const end = match_bracket(parser, start, pointy_bois);
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type_params = parser.template.slice(start + 1, end - 1);
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parser.index = end;
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}
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parser.allow_whitespace();
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const matched = parser.eat('(', true, false);
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if (matched) {
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end: name_end,
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name
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},
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typeParams: type_params,
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parameters: function_expression.params,
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body: create_fragment(),
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metadata: {

‎packages/svelte/src/compiler/phases/1-parse/utils/bracket.js‎

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const SQUARE_BRACKET_OPEN = '[';
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const SQUARE_BRACKET_CLOSE = ']';
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const CURLY_BRACKET_OPEN = '{';
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const CURLY_BRACKET_CLOSE = '}';
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const PARENTHESES_OPEN = '(';
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const PARENTHESES_CLOSE = ')';
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/** @param {string} char */
9-
export function is_bracket_open(char) {
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return char === SQUARE_BRACKET_OPEN || char === CURLY_BRACKET_OPEN;
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}
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/** @param {string} char */
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export function is_bracket_close(char) {
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return char === SQUARE_BRACKET_CLOSE || char === CURLY_BRACKET_CLOSE;
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}
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/** @param {string} open */
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export function get_bracket_close(open) {
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if (open === SQUARE_BRACKET_OPEN) {
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return SQUARE_BRACKET_CLOSE;
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}
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if (open === CURLY_BRACKET_OPEN) {
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return CURLY_BRACKET_CLOSE;
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}
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if (open === PARENTHESES_OPEN) {
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return PARENTHESES_CLOSE;
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}
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}
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/** @import { Parser } from '../index.js' */
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import * as e from '../../../errors.js';
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/**
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* @param {number} num
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* @returns {number | undefined} The index of the closing bracket, or undefined if not found.
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*/
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export function find_matching_bracket(template, index, open) {
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const close = get_bracket_close(open);
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const close = default_brackets[open];
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let brackets = 1;
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let i = index;
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while (brackets > 0 && i < template.length) {
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}
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return undefined;
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}
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/** @type {Record<string, string>} */
138+
const default_brackets = {
139+
'{': '}',
140+
'(': ')',
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'[': ']'
142+
};
143+
144+
/**
145+
* @param {Parser} parser
146+
* @param {number} start
147+
* @param {Record<string, string>} brackets
148+
*/
149+
export function match_bracket(parser, start, brackets = default_brackets) {
150+
const close = Object.values(brackets);
151+
const bracket_stack = [];
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let i = start;
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while (i < parser.template.length) {
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let char = parser.template[i++];
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if (char === "'" || char === '"' || char === '`') {
159+
i = match_quote(parser, i, char);
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continue;
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}
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if (char in brackets) {
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bracket_stack.push(char);
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} else if (close.includes(char)) {
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const popped = /** @type {string} */ (bracket_stack.pop());
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const expected = /** @type {string} */ (brackets[popped]);
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if (char !== expected) {
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e.expected_token(i - 1, expected);
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}
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if (bracket_stack.length === 0) {
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return i;
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}
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}
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}
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e.unexpected_eof(parser.template.length);
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}
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/**
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* @param {Parser} parser
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* @param {number} start
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* @param {string} quote
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*/
187+
function match_quote(parser, start, quote) {
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let is_escaped = false;
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let i = start;
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while (i < parser.template.length) {
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const char = parser.template[i++];
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if (is_escaped) {
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is_escaped = false;
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continue;
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}
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if (char === quote) {
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return i;
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}
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if (char === '\\') {
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is_escaped = true;
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}
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if (quote === '`' && char === '$' && parser.template[i] === '{') {
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i = match_bracket(parser, i);
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}
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}
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e.unterminated_string_constant(start);
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}

‎packages/svelte/src/compiler/types/template.d.ts‎

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@@ -468,6 +468,7 @@ export namespace AST {
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type: 'SnippetBlock';
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expression: Identifier;
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parameters: Pattern[];
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typeParams?: string;
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body: Fragment;
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/** @internal */
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metadata: {

‎packages/svelte/tests/parser-modern/samples/generic-snippets/input.svelte‎

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<script lang="ts">
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</script>
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{#snippet generic<T extends string>(val: T)}
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{val}
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{/snippet}
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{#snippet complex_generic<T extends { bracket: "<" } | "<" | Set<"<>">>(val: T)}
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{val}
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{/snippet}

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