285 lines
8.1 KiB
Markdown
285 lines
8.1 KiB
Markdown
# Mhysa
|
|
|
|
**Dependency-free stream utils for Node.js**
|
|
|
|
<sub>Released under the [MIT](https://github.com/Wenzil/Mhysa/blob/master/LICENSE) license.</sub>
|
|
|
|
```sh
|
|
yarn add mhysa
|
|
```
|
|
|
|
<sub>Tested with Node.js versions 8+</sub>
|
|
|
|
## fromArray(array)
|
|
Convert an array into a `Readable` stream of its elements
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `array` | `T[]` | Array of elements to stream |
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "b"])
|
|
.pipe(process.stdout);
|
|
// ab is printed out
|
|
```
|
|
|
|
|
|
## map(mapper, options)
|
|
Return a `ReadWrite` stream that maps streamed chunks
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `mapper` | `(chunk: T, encoding: string) => R` | Mapper function, mapping each (chunk, encoding) to a new chunk (or a promise of such) |
|
|
| `options` | `object` | |
|
|
| `options.readableObjectMode` | `boolean` | Whether this stream should behave as a readable stream of objects |
|
|
| `options.writableObjectMode` | `boolean` | Whether this stream should behave as a writable stream of objects |
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "b"])
|
|
.pipe(Mhysa.map(s => s.toUpperCase()))
|
|
.pipe(process.stdout);
|
|
// AB is printed out
|
|
```
|
|
|
|
|
|
## flatMap(mapper, options)
|
|
Return a `ReadWrite` stream that flat maps streamed chunks
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `mapper` | `(chunk: T, encoding: string) => R[]` | Mapper function, mapping each (chunk, encoding) to an array of new chunks (or a promise of such) |
|
|
| `options` | `object` | |
|
|
| `options.readableObjectMode` | `boolean` | Whether this stream should behave as a readable stream of objects |
|
|
| `options.writableObjectMode` | `boolean` | Whether this stream should behave as a writable stream of objects |
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "AA"])
|
|
.pipe(Mhysa.flatMap(s => new Array(s.length).fill(s)))
|
|
.pipe(process.stdout);
|
|
// aAAAA is printed out
|
|
```
|
|
|
|
|
|
## filter(predicate, options)
|
|
Return a `ReadWrite` stream that filters out streamed chunks for which the predicate does not hold
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `predicate` | `(chunk: T, encoding: string) => boolean` | Predicate with which to filter scream chunks |
|
|
| `options` | `object` | |
|
|
| `options.objectMode` | `boolean` | `boolean` | Whether this stream should behave as a stream of objects |
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "b", "c"])
|
|
.pipe(Mhysa.filter(s => s !== "b"))
|
|
.pipe(process.stdout);
|
|
// ac is printed out
|
|
```
|
|
|
|
|
|
## reduce(iteratee, initialValue, options)
|
|
Return a `ReadWrite` stream that reduces streamed chunks down to a single value and yield that
|
|
value
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `iteratee` | `(chunk: T, encoding: string) => R` | Reducer function to apply on each streamed chunk |
|
|
| `initialValue` | `T` | Initial value |
|
|
| `options` | `object` | |
|
|
| `options.readableObjectMode` | `boolean` | Whether this stream should behave as a readable stream of objects |
|
|
| `options.writableObjectMode` | `boolean` | Whether this stream should behave as a writable stream of objects |
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "b", "cc"])
|
|
.pipe(Mhysa.reduce((acc, s) => ({ ...acc, [s]: s.length }), {}))
|
|
.pipe(Mhysa.stringify())
|
|
.pipe(process.stdout);
|
|
// {"a":1,"b":1","c":2} is printed out
|
|
```
|
|
|
|
|
|
## split(separator)
|
|
Return a `ReadWrite` stream that splits streamed chunks using the given separator
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `separator` | `string` | Separator to split by, defaulting to `"\n"` |
|
|
| `options` | `object` | |
|
|
| `options.encoding` | `string` | Character encoding to use for decoding chunks. Defaults to utf8
|
|
|
|
```js
|
|
Mhysa.fromArray(["a,b", "c,d"])
|
|
.pipe(Mhysa.split(","))
|
|
.pipe(Mhysa.join("|"))
|
|
.pipe(process.stdout);
|
|
// a|bc|d is printed out
|
|
```
|
|
|
|
|
|
## join(separator)
|
|
Return a `ReadWrite` stream that joins streamed chunks using the given separator
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `separator` | `string` | Separator to join with |
|
|
| `options` | `object` | |
|
|
| `options.encoding` | `string` | Character encoding to use for decoding chunks. Defaults to utf8
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "b", "c"])
|
|
.pipe(Mhysa.join(","))
|
|
.pipe(process.stdout);
|
|
// a,b,c is printed out
|
|
```
|
|
|
|
|
|
## replace(searchValue, replaceValue)
|
|
Return a `ReadWrite` stream that replaces occurrences of the given string or regular expression in
|
|
the streamed chunks with the specified replacement string
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `searchValue` | `string \| RegExp` | Search string to use |
|
|
| `replaceValue` | `string` | Replacement string to use |
|
|
| `options` | `object` | |
|
|
| `options.encoding` | `string` | Character encoding to use for decoding chunks. Defaults to utf8
|
|
|
|
```js
|
|
Mhysa.fromArray(["a1", "b22", "c333"])
|
|
.pipe(Mhysa.replace(/b\d+/, "B"))
|
|
.pipe(process.stdout);
|
|
// a1Bc333 is printed out
|
|
```
|
|
|
|
|
|
## parse()
|
|
Return a `ReadWrite` stream that parses the streamed chunks as JSON
|
|
|
|
```js
|
|
Mhysa.fromArray(['{ "a": "b" }'])
|
|
.pipe(Mhysa.parse())
|
|
.once("data", object => console.log(object));
|
|
// { a: 'b' } is printed out
|
|
```
|
|
|
|
|
|
## stringify()
|
|
Return a `ReadWrite` stream that stringifies the streamed chunks to JSON
|
|
|
|
```js
|
|
Mhysa.fromArray([{ a: "b" }])
|
|
.pipe(Mhysa.stringify())
|
|
.pipe(process.stdout);
|
|
// {"a":"b"} is printed out
|
|
```
|
|
|
|
|
|
## collect(options)
|
|
Return a `ReadWrite` stream that collects streamed chunks into an array or buffer
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `options` | `object` | |
|
|
| `options.objectMode` | `boolean` | Whether this stream should behave as a stream of objects |
|
|
|
|
```js
|
|
Mhysa.fromArray(["a", "b", "c"])
|
|
.pipe(Mhysa.collect({ objectMode: true }))
|
|
.once("data", object => console.log(object));
|
|
// [ 'a', 'b', 'c' ] is printed out
|
|
```
|
|
|
|
|
|
## concat(streams)
|
|
Return a `Readable` stream of readable streams concatenated together
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `streams` | `...Readable[]` | Readable streams to concatenate |
|
|
|
|
```js
|
|
const source1 = new Readable();
|
|
const source2 = new Readable();
|
|
Mhysa.concat(source1, source2).pipe(process.stdout)
|
|
source1.push("a1 ");
|
|
source2.push("c3 ");
|
|
source1.push("b2 ");
|
|
source2.push("d4 ");
|
|
source1.push(null);
|
|
source2.push(null);
|
|
// a1 b2 c3 d4 is printed out
|
|
```
|
|
|
|
|
|
## merge(streams)
|
|
Return a `Readable` stream of readable streams merged together in chunk arrival order
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `streams` | `...Readable[]` | Readable streams to merge |
|
|
|
|
```js
|
|
const source1 = new Readable({ read() {} });
|
|
const source2 = new Readable({ read() {} });
|
|
Mhysa.merge(source1, source2).pipe(process.stdout);
|
|
source1.push("a1 ");
|
|
setTimeout(() => source2.push("c3 "), 10);
|
|
setTimeout(() => source1.push("b2 "), 20);
|
|
setTimeout(() => source2.push("d4 "), 30);
|
|
setTimeout(() => source1.push(null), 40);
|
|
setTimeout(() => source2.push(null), 50);
|
|
// a1 c3 b2 d4 is printed out
|
|
```
|
|
|
|
|
|
## duplex(writable, readable)
|
|
Return a `Duplex` stream from a writable stream that is assumed to somehow, when written to,
|
|
cause the given readable stream to yield chunks
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `writable` | `Writable` | Writable stream assumed to cause the readable stream to yield chunks when written to |
|
|
| `readable` | `Readable` | Readable stream assumed to yield chunks when the writable stream is written to |
|
|
|
|
```js
|
|
const catProcess = require("child_process").exec("grep -o ab");
|
|
Mhysa.fromArray(["a", "b", "c"])
|
|
.pipe(Mhysa.duplex(catProcess.stdin, catProcess.stdout))
|
|
.pipe(process.stdout);
|
|
// ab is printed out
|
|
```
|
|
|
|
|
|
## child(childProcess)
|
|
Return a `Duplex` stream from a child process' stdin and stdout
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| childProcess | `ChildProcess` | Child process from which to create duplex stream |
|
|
|
|
```js
|
|
const catProcess = require("child_process").exec("grep -o ab");
|
|
Mhysa.fromArray(["a", "b", "c"])
|
|
.pipe(Mhysa.child(catProcess))
|
|
.pipe(process.stdout);
|
|
// ab is printed out
|
|
```
|
|
|
|
|
|
## last(readable)
|
|
Return a `Promise` resolving to the last streamed chunk of the given readable stream, after it has
|
|
ended
|
|
|
|
| Param | Type | Description |
|
|
| --- | --- | --- |
|
|
| `readable` | `Readable` | Readable stream to wait on |
|
|
|
|
```js
|
|
let f = async () => {
|
|
const source = Mhysa.fromArray(["a", "b", "c"]);
|
|
console.log(await Mhysa.last(source));
|
|
};
|
|
f();
|
|
// c is printed out
|
|
```
|