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const { open, Buffer } = Deno;type Reader = Deno.Reader;import { stringsReader } from 'https://deno.land/std/io/util.ts';import { BufReader } from 'https://deno.land/std/io/bufio.ts';import escape from 'https://deno.land/x/lodash/escape.js';
const globalEval = eval;const window = globalEval('this');
Object.defineProperty(window, '$$ESCAPE', {  value: escape,  writable: false,});
export interface Params {  [key: string]: any;}
enum ReadMode {  Normal,  Escaped,  Raw,  Comment,  Evaluate,}
enum Codes {  Begin = 60, // <  End = 62, // >  Percent = 37, // %  Escaped = 61, // =  Raw = 45, // -  Comment = 35, // #}
interface Template {  (params: Params): Promise<Reader>;}
function genRandomID(): string {  return (    Math.random()      .toString(36)      .substring(2) +    Math.random()      .toString(36)      .substring(2)  );}
async function include(path: string, params: Params): Promise<string> {  const result = await renderFile(path, params);  const buf = new Buffer();  await buf.readFrom(result);  return buf.toString();}
function NewTemplate(script: string): Template {  return async (params: Params): Promise<Reader> => {    const output: Array<string> = [];    const scopeID = '$$' + genRandomID();    await new Promise(resolve => {      const scope = {        ...params,        $$OUTPUT: output,        include,        $$FINISHED: resolve,      };      window[scopeID] = scope;
      const header = Object.keys(scope)        .map(k => `const ${k} = ${scopeID}.${k};`)        .join('\n');
      const src = `(async() => {        ${header}        ${script}        $$FINISHED();      })();`;      globalEval(src);    });
    delete window[scopeID];    return stringsReader(output.join(''));  };}
export async function compile(reader: Reader): Promise<Template> {  const src = new BufReader(reader);  const buf: Array<number> = [];  const statements: Array<string> = [];  const statementBuf = new Buffer();  let readMode: ReadMode = ReadMode.Normal;  const statementBufWrite = async (byte: number): Promise<number> =>    await statementBuf.write(new Uint8Array([byte]));
  while (true) {    const byte = await src.readByte();    if (byte === Deno.EOF) {      break;    }
    buf.push(byte);    if (buf.length < 3) {      continue;    }
    if (readMode === ReadMode.Normal) {      // Detect ReadMode      if (buf[0] === Codes.Begin && buf[1] === Codes.Percent) {        switch (buf[2]) {          case Codes.Escaped:            readMode = ReadMode.Escaped;            break;          case Codes.Raw:            readMode = ReadMode.Raw;            break;          case Codes.Comment:            readMode = ReadMode.Comment;            break;          default:            readMode = ReadMode.Evaluate;            break;        }        statements.push(`$$OUTPUT.push(\`${statementBuf.toString()}\`);`);        statementBuf.reset();        buf.splice(0);        continue;      }      if (buf.length > 2) {        await statementBufWrite(buf.shift() as number);      }      continue;    }
    // Finish current ReadMode    if (buf[1] === Codes.Percent && buf[2] === Codes.End) {      statementBufWrite(buf.shift() as number);      buf.splice(0);      // Don't execute if ReadMode is Comment.      if (readMode !== ReadMode.Comment) {        switch (readMode) {          case ReadMode.Raw:            statements.push(`$$OUTPUT.push(${statementBuf.toString()});`);            break;          case ReadMode.Escaped:            statements.push(              `$$OUTPUT.push($$ESCAPE(${statementBuf.toString()}));`            );            break;          case ReadMode.Evaluate:            statements.push(statementBuf.toString());            break;        }      }      statementBuf.reset();      readMode = ReadMode.Normal;      continue;    }    await statementBufWrite(buf.shift() as number);  }
  // Flush buffer  while (buf.length > 0) {    await statementBufWrite(buf.shift() as number);  }  statements.push(`$$OUTPUT.push(\`${statementBuf.toString()}\`);`);  statementBuf.reset();
  return await NewTemplate(statements.join(''));}
export async function render(body: string, params: Params): Promise<Reader> {  const reader = stringsReader(body);  const template = await compile(reader);  return template(params);}
export async function renderFile(  path: string,  params: Params): Promise<Reader> {  const file = await open(path);  const template = await compile(file);  file.close();  return template(params);}