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159 lines
3 KiB
Markdown
159 lines
3 KiB
Markdown
# std/io
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## Bufio
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**Uses:**
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### readLines
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Read reader[like file], line by line:
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```ts title="readLines"
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import { readLines } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
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import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
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const filename = path.join(Deno.cwd(), "std/io/README.md");
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let fileReader = await Deno.open(filename);
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for await (let line of readLines(fileReader)) {
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console.log(line);
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}
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```
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**Output:**
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````text
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# std/io
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## readLines
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```ts
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import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
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## Rest of the file
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````
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### readStringDelim
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Read reader`[like file]` chunk by chunk, splitting based on delimiter.
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```ts title="readStringDelim"
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import { readStringDelim } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
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import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
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const filename = path.join(Deno.cwd(), "std/io/README.md");
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let fileReader = await Deno.open(filename);
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for await (let line of readStringDelim(fileReader, "\n")) {
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console.log(line);
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}
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```
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**Output:**
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````text
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# std/io
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## readLines
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```ts
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import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
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## Rest of the file
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````
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## Reader
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### StringReader
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Create a `Reader` object for `string`.
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```ts
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import { StringReader } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
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const data = new Uint8Array(6);
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const r = new StringReader("abcdef");
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const res0 = await r.read(data);
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const res1 = await r.read(new Uint8Array(6));
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// Number of bytes read
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console.log(res0); // 6
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console.log(res1); // null, no byte left to read. EOL
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// text
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console.log(new TextDecoder().decode(data)); // abcdef
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```
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**Output:**
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```text
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6
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null
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abcdef
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```
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## Writer
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### StringWriter
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Create a `Writer` object for `string`.
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```ts
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import {
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copyN,
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StringReader,
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StringWriter,
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} from "https://deno.land/std@$STD_VERSION/io/mod.ts";
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const w = new StringWriter("base");
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const r = new StringReader("0123456789");
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await copyN(r, w, 4); // copy 4 bytes
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// Number of bytes read
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console.log(w.toString()); //base0123
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await Deno.copy(r, w); // copy all
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console.log(w.toString()); // base0123456789
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```
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**Output:**
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```text
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base0123
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base0123456789
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```
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## Streams
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### fromStreamReader
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Creates a `Reader` from a `ReadableStreamDefaultReader`.
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```ts
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import { fromStreamReader } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
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const res = await fetch("https://deno.land");
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const file = await Deno.open("./deno.land.html", { create: true, write: true });
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const reader = fromStreamReader(res.body!.getReader());
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await Deno.copy(reader, file);
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file.close();
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```
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### fromStreamWriter
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Creates a `Writer` from a `WritableStreamDefaultWriter`.
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```ts
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import { fromStreamWriter } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
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const file = await Deno.open("./deno.land.html", { read: true });
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const writableStream = new WritableStream({
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write(chunk): void {
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console.log(chunk);
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},
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});
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const writer = fromStreamWriter(writableStream.getWriter());
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await Deno.copy(file, writer);
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file.close();
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```
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