https://github.com/xpl/meta-fields
Meta-annotations for data structures in JavaScript
https://github.com/xpl/meta-fields
Last synced: 11 months ago
JSON representation
Meta-annotations for data structures in JavaScript
- Host: GitHub
- URL: https://github.com/xpl/meta-fields
- Owner: xpl
- License: unlicense
- Created: 2017-04-06T04:09:11.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2017-05-26T10:10:44.000Z (about 9 years ago)
- Last Synced: 2025-07-05T09:41:55.906Z (about 1 year ago)
- Language: JavaScript
- Homepage: https://www.npmjs.com/package/meta-fields
- Size: 6.84 KB
- Stars: 2
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Meta-annotations for data structures in JavaScript
```javascript
it ('Importing', () => {
Meta = require ('./meta-fields')
})
it ('Defining tags', () => {
$foo = Meta.tag ('foo'),
$bar = Meta.tag ('bar')
})
it ("Defining tags in global namespace", () => {
Meta.globalTag ('qux')
})
it ('Tag is a function, accepting random data', () => {
$foo (42) // returns 42 tagged with $foo
$foo ($bar (42)) // returns 42 tagged with $foo and $bar
})
it ('It returns a wrapper holding the metadata and the original value', () => {
const x = $foo (42)
assert (Meta.is (x), true)
assert ( x, { wrapped: 42, __meta__: { foo: true } })
assert ( $bar (x), { wrapped: 42, __meta__: { foo: true, bar: true } })
assert ($qux ($bar (x)), { wrapped: 42, __meta__: { foo: true, bar: true, qux: true } })
})
it ("Order/redundancy is irrelevant", () => {
assert ($foo ($bar (42)), $bar ($foo ($foo (42))))
})
it ("Supplying additional metadata along with a tag", () => {
assert ($foo ('some data', $bar (42)), { wrapped: 42, __meta__: { foo: 'some data', bar: true } })
})
it ("Explicit way of adding tags", () => {
assert (Meta.setTags (42, { foo: true }), $foo (42))
})
it ("Accessing the original value", () => {
assert (Meta.unwrap ($foo ($bar (42))), 42)
assert (Meta.unwrap (42), 42)
})
it ("Modifying tagged value while keeping the original tags intact (can also add new tags this way)", () => {
assert (Meta.modify ( 42, x => x + 1), 43)
assert (Meta.modify ($foo (42), x => x + 1), $foo ( 43))
assert (Meta.modify ($foo (42), x => $bar (x + 1)), $foo ($bar (43)))
})
it ("Tagging 'nothing' is legal. And it is not the same as tagging 'undefined'...", () => {
assert ($foo (), { __meta__: { foo: true } })
assert ($foo (undefined), { __meta__: { foo: true }, wrapped: undefined })
assert (Meta.hasValue ($foo ()) , false)
assert (Meta.hasValue ($foo (undefined)), true)
})
it ("Checking for a specific tag presence", () => {
assert ($foo.is ( 42), false)
assert ($foo.is ($foo (42)), true)
assert ($foo.is ($bar (42)), false)
assert (Meta.hasTag ($foo (42), 'foo'), true)
})
it ("Obtaining a value associated with a tag", () => {
assert ($foo.read ( 42), undefined)
assert ($foo.read ($foo ( 42)), true)
assert ($foo.read ($foo ('data', 42)), 'data')
assert (Meta.readTag ($foo ('data', 42), 'foo'), 'data')
})
it ("Getting all tags", () => {
assert (Meta.tags ($foo ($bar ($qux (42)))), { 'qux': true, 'bar': true, 'foo': true })
assert (Meta.tags ( 42), {})
})
it ("Enumerating tags", () => {
const calls = []
Meta.eachTag ($foo ($bar ($qux (42))), (tag, value) => calls.push ([tag, value]))
assert (calls, [['qux', true], ['bar', true], ['foo', true]])
})
it ("Removing tags", () => {
assert (Meta.omitTags ($foo ($bar (7)), 'foo'), $bar ( 7))
assert (Meta.omitTags ( 7, 'foo'), 7)
})
it ("Using with string.ify (if available)", () => {
const stringify = require ('string.ify'),
pretty = require ('string.ify').configure ({ pretty: true })
assert (stringify ( { foo: $foo ($qux ({ bar: 7 }, 1)) }),
'{ foo: $foo ($qux ({ bar: 7 }, 1)) }')
assert (pretty ( { foo: $foo ($qux ([ 7, 8 ])) }),
'{ foo: $foo ($qux ([ 7,' + '\n' +
' 8 ])) }')
})
```