chore: use codePointAt instead of implementing it ourselves

Author: Rich-Harris

packages/svelte/src/compiler/phases/1-parse/index.js

@@ -3,7 +3,6 @@
 import { isIdentifierStart, isIdentifierChar } from 'acorn';
 import fragment from './state/fragment.js';
 import { regex_whitespace } from '../patterns.js';
-import full_char_code_at from './utils/full_char_code_at.js';
 import * as e from '../../errors.js';
 import { create_fragment } from './utils/create.js';
 import read_options from './read/options.js';
@@ -214,6 +213,11 @@ export class Parser {
 		}
 	}
 
+	/** @param {number} i */
+	code_point_at(i) {
+		return /** @type {number} */ (this.template.codePointAt(i));
+	}
+
 	/**
 	 * Search for a regex starting at the current index and return the result if it matches
 	 * @param {RegExp} pattern  Should have a ^ anchor at the start so the regex doesn't search past the beginning, resulting in worse performance
@@ -230,13 +234,13 @@ export class Parser {
 
 		let i = this.index;
 
-		const code = full_char_code_at(this.template, i);
+		const code = this.code_point_at(i);
 		if (!isIdentifierStart(code, true)) return null;
 
 		i += code <= 0xffff ? 1 : 2;
 
 		while (i < this.template.length) {
-			const code = full_char_code_at(this.template, i);
+			const code = this.code_point_at(i);
 
 			if (!isIdentifierChar(code, true)) break;
 			i += code <= 0xffff ? 1 : 2;

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

@@ -3,7 +3,6 @@
 /** @import { Parser } from '../index.js' */
 // @ts-expect-error acorn type definitions are borked in the release we use
 import { isIdentifierStart } from 'acorn';
-import full_char_code_at from '../utils/full_char_code_at.js';
 import {
 	is_bracket_open,
 	is_bracket_close,
@@ -23,7 +22,8 @@ export default function read_pattern(parser) {
 	const start = parser.index;
 	let i = parser.index;
 
-	const code = full_char_code_at(parser.template, i);
+	const code = parser.code_point_at(i);
+
 	if (isIdentifierStart(code, true)) {
 		const name = /** @type {string} */ (parser.read_identifier());
 		const annotation = read_type_annotation(parser);
@@ -49,7 +49,8 @@ export default function read_pattern(parser) {
 	i += code <= 0xffff ? 1 : 2;
 
 	while (i < parser.template.length) {
-		const code = full_char_code_at(parser.template, i);
+		const code = parser.code_point_at(i);
+
 		if (is_bracket_open(code)) {
 			bracket_stack.push(code);
 		} else if (is_bracket_close(code)) {

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

@@ -1,5 +1,3 @@
-import full_char_code_at from './full_char_code_at.js';
-
 const SQUARE_BRACKET_OPEN = '['.charCodeAt(0);
 const SQUARE_BRACKET_CLOSE = ']'.charCodeAt(0);
 const CURLY_BRACKET_OPEN = '{'.charCodeAt(0);
@@ -132,7 +130,7 @@ function count_leading_backslashes(string, search_start_index) {
  * @returns {number | undefined} The index of the closing bracket, or undefined if not found.
  */
 export function find_matching_bracket(template, index, open) {
-	const open_code = full_char_code_at(open, 0);
+	const open_code = open.charCodeAt(0);
 	const close_code = get_bracket_close(open_code);
 	let brackets = 1;
 	let i = index;
@@ -159,7 +157,7 @@ export function find_matching_bracket(template, index, open) {
 				continue;
 			}
 			default: {
-				const code = full_char_code_at(template, i);
+				const code = template.codePointAt(i);
 				if (code === open_code) {
 					brackets++;
 				} else if (code === close_code) {