Extract string parsing to a separate package

babel.config.js

@@ -209,6 +209,7 @@ module.exports = function (api) {
         test: [
           "packages/babel-generator",
           "packages/babel-plugin-proposal-decorators",
+          "packages/babel-helper-string-parser",
         ].map(normalize),
         plugins: ["babel-plugin-transform-charcodes"],
       },

lib/babel-packages.js.flow

@@ -220,3 +220,85 @@ declare module "@babel/plugin-transform-classes" {
 declare module "@babel/helper-compilation-targets" {
   declare module.exports: any;
 }
+
+declare module "@babel/helper-string-parser" {
+  declare export type StringContentsErrorHandlers = EscapedCharErrorHandlers & {
+    unterminated(
+      initialPos: number,
+      initialLineStart: number,
+      initialCurLine: number
+    ): void,
+  };
+  declare export function readStringContents(
+    type: "single" | "double" | "template",
+    input: string,
+    pos: number,
+    lineStart: number,
+    curLine: number,
+    errors: StringContentsErrorHandlers
+  ): {
+    pos: number,
+    str: string,
+    containsInvalid: boolean,
+    lineStart: number,
+    curLine: number,
+  };
+
+  declare export type EscapedCharErrorHandlers = HexCharErrorHandlers &
+    CodePointErrorHandlers & {
+      strictNumericEscape(pos: number): void,
+    };
+
+  declare export function readEscapedChar(
+    input: string,
+    pos: number,
+    lineStart: number,
+    curLine: number,
+    inTemplate: boolean,
+    errors: EscapedCharErrorHandlers
+  ): {
+    pos: number,
+    ch: string | null,
+    lineStart: number,
+    curLine: number,
+  };
+
+  declare type HexCharErrorHandlers = IntErrorHandlers & {
+    invalidEscapeSequence(pos: number, startPos: number): void,
+  };
+
+  declare export type IntErrorHandlers = {
+    numericSeparatorInEscapeSequence(pos: number): void,
+    unexpectedNumericSeparator(pos: number): void,
+    // It can return "true" to indicate that the error was handled
+    // and the int parsing should continue.
+    invalidDigit(pos: number, radix: number): boolean,
+  };
+
+  declare export function readInt(
+    input: string,
+    pos: number,
+    radix: number,
+    len?: number,
+    forceLen: boolean,
+    allowNumSeparator: boolean | "bail",
+    errors: IntErrorHandlers
+  ): {
+    n: null | number,
+    pos: number,
+  };
+
+  declare export type CodePointErrorHandlers = HexCharErrorHandlers & {
+    invalidCodePoint(pos: number): void,
+  };
+
+  declare export function readCodePoint(
+    input: string,
+    pos: number,
+    throwOnInvalid: boolean,
+    errors: CodePointErrorHandlers
+  ): {
+    code: any,
+    pos: number,
+  };
+}

packages/babel-helper-string-parser/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-helper-string-parser/README.md

@@ -0,0 +1,19 @@
+# @babel/helper-string-parser
+
+> A utility package to parse strings
+
+See our website [@babel/helper-string-parser](https://babeljs.io/docs/en/babel-helper-string-parser) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save @babel/helper-string-parser
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/helper-string-parser
+```

packages/babel-helper-string-parser/package.json

@@ -0,0 +1,36 @@
+{
+  "name": "@babel/helper-string-parser",
+  "version": "7.18.6",
+  "description": "A utility package to parse strings",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-helper-string-parser"
+  },
+  "homepage": "https://babel.dev/docs/en/next/babel-helper-string-parser",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./lib/index.js",
+  "devDependencies": {
+    "charcodes": "^0.2.0"
+  },
+  "engines": {
+    "node": ">=6.9.0"
+  },
+  "author": "The Babel Team (https://babel.dev/team)",
+  "conditions": {
+    "USE_ESM": [
+      {
+        "type": "module"
+      },
+      null
+    ]
+  },
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
+  },
+  "type": "commonjs"
+}