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mod.ts
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mod.ts
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const { open, Buffer } = Deno;
type Reader = Deno.Reader;
import { stringsReader } from './vendor/https/deno.land/std/io/util.ts';
import { BufReader } from './vendor/https/deno.land/std/io/bufio.ts';
import escape from './vendor/https/deno.land/x/lodash/escape.js';
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>;
}
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> = [];
await new Promise(resolve => {
const $$CONSTANTS = {
...params,
include,
$$OUTPUT: output,
$$FINISHED: resolve,
$$ESCAPE: escape,
};
const header = Object.keys($$CONSTANTS)
.map(k => `const ${k} = $$CONSTANTS.${k};`)
.join('\n');
const src = `(async() => {
${header}
${script}
$$FINISHED();
})();`;
eval(src);
});
return stringsReader(output.join(''));
};
}
export async function compile(reader: Reader): Promise<Template> {
const src = new BufReader(reader);
const buf: Array<number> = [];
const statements: Array<string> = [];
const statementBuf = new Buffer();
let readMode: ReadMode = ReadMode.Normal;
const statementBufWrite = async (byte: number): Promise<number> =>
await statementBuf.write(new Uint8Array([byte]));
while (true) {
const byte = await src.readByte();
if (byte === Deno.EOF) {
break;
}
buf.push(byte);
if (buf.length < 3) {
continue;
}
if (readMode === ReadMode.Normal) {
// Detect ReadMode
if (buf[0] === Codes.Begin && buf[1] === Codes.Percent) {
switch (buf[2]) {
case Codes.Escaped:
readMode = ReadMode.Escaped;
break;
case Codes.Raw:
readMode = ReadMode.Raw;
break;
case Codes.Comment:
readMode = ReadMode.Comment;
break;
default:
readMode = ReadMode.Evaluate;
break;
}
statements.push(`$$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);
}