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// Copyright (c) 2022-2023 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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import assert from "node:assert";
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import ts from "typescript";
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export const SourcesMap = Map<string, string>;
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export type SourcesMap = InstanceType<typeof SourcesMap>;
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const defaultCompilerOpts = ts.getDefaultCompilerOptions();
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// Creates a TypeScript program from in-memory source files. Accepts a Map of
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// fully-resolved "virtual" paths to source code.
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export function createMemoryProgram(
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  sources: SourcesMap,
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  host?: ts.CompilerHost,
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  compilerOpts = defaultCompilerOpts,
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  // Provide additional lib files to TypeScript. These should all be prefixed with
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  // `/node_modules/typescript/lib` (e.g. `/node_modules/typescript/lib/lib.esnext.d.ts`)
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  lib?: SourcesMap
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): ts.Program {
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  const sourceFiles = new Map<string, ts.SourceFile>();
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  for (const [sourcePath, source] of [...sources, ...(lib ?? [])]) {
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    const sourceFile = ts.createSourceFile(
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      sourcePath,
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      source,
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      ts.ScriptTarget.ESNext,
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      false,
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      ts.ScriptKind.TS
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    );
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    sourceFiles.set(sourcePath, sourceFile);
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  }
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  host ??= {
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    getCurrentDirectory(): string {
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      return "/";
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    },
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    getCanonicalFileName(fileName: string): string {
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      return fileName;
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    },
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    getDefaultLibFileName(_options: ts.CompilerOptions): string {
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      return "";
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    },
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    getDefaultLibLocation(): string {
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      return "/node_modules/typescript/lib";
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    },
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    getNewLine(): string {
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      return "\n";
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    },
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    useCaseSensitiveFileNames(): boolean {
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      return true;
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    },
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    fileExists(fileName: string): boolean {
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      return sourceFiles.has(fileName);
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    },
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    readFile(_path: string): string | undefined {
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      assert.fail("readFile() not implemented");
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    },
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    writeFile(
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      _path: string,
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      _data: string,
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      _writeByteOrderMark?: boolean
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    ): void {
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      assert.fail("writeFile() not implemented");
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    },
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    getSourceFile(
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      fileName: string,
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      _languageVersionOrOptions: ts.ScriptTarget | ts.CreateSourceFileOptions,
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      _onError?: (message: string) => void,
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      _shouldCreateNewSourceFile?: boolean
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    ): ts.SourceFile | undefined {
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      return sourceFiles.get(fileName);
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    },
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  };
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  const rootNames = Array.from(sources.keys());
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  return ts.createProgram(rootNames, compilerOpts, host);
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}