From c28fa78963f1d2c23c8b73db9d0a025ab5bffa18 Mon Sep 17 00:00:00 2001
From: Julien Fontanet <julien.fontanet@isonoe.net>
Date: Thu, 10 Feb 2022 16:55:15 +0100
Subject: [PATCH] feat(@vates/predicates): utils to compose predicates

---
 @vates/predicates/.npmignore   |  1 +
 @vates/predicates/README.md    | 90 ++++++++++++++++++++++++++++++++++
 @vates/predicates/USAGE.md     | 57 +++++++++++++++++++++
 @vates/predicates/index.js     | 69 ++++++++++++++++++++++++++
 @vates/predicates/package.json | 36 ++++++++++++++
 CHANGELOG.unreleased.md        |  1 +
 6 files changed, 254 insertions(+)
 create mode 120000 @vates/predicates/.npmignore
 create mode 100644 @vates/predicates/README.md
 create mode 100644 @vates/predicates/USAGE.md
 create mode 100644 @vates/predicates/index.js
 create mode 100644 @vates/predicates/package.json

diff --git a/@vates/predicates/.npmignore b/@vates/predicates/.npmignore
new file mode 120000
index 000000000..008d1b9b9
--- /dev/null
+++ b/@vates/predicates/.npmignore
@@ -0,0 +1 @@
+../../scripts/npmignore
\ No newline at end of file
diff --git a/@vates/predicates/README.md b/@vates/predicates/README.md
new file mode 100644
index 000000000..b83161a3b
--- /dev/null
+++ b/@vates/predicates/README.md
@@ -0,0 +1,90 @@
+<!-- DO NOT EDIT MANUALLY, THIS FILE HAS BEEN GENERATED -->
+
+# @vates/predicates
+
+[![Package Version](https://badgen.net/npm/v/@vates/predicates)](https://npmjs.org/package/@vates/predicates) ![License](https://badgen.net/npm/license/@vates/predicates) [![PackagePhobia](https://badgen.net/bundlephobia/minzip/@vates/predicates)](https://bundlephobia.com/result?p=@vates/predicates) [![Node compatibility](https://badgen.net/npm/node/@vates/predicates)](https://npmjs.org/package/@vates/predicates)
+
+> Utilities to compose predicates
+
+## Install
+
+Installation of the [npm package](https://npmjs.org/package/@vates/predicates):
+
+```
+> npm install --save @vates/predicates
+```
+
+## Usage
+
+`undefined` predicates are ignored and `undefined` is returned if all predicates are `undefined`, this permits the most efficient composition:
+
+```js
+const compositePredicate = every(undefined, some(predicate2, undefined))
+
+// ends up as
+
+const compositePredicate = predicate2
+```
+
+Predicates can also be passed wrapped in an array:
+
+```js
+const compositePredicate = every([predicate1, some([predicate2, predicate3])])
+```
+
+`this` and all arguments are passed to the nested predicates.
+
+### `every(predicates)`
+
+> Returns a predicate that returns `true` iff every predicate returns `true`.
+
+```js
+const isBetween3And7 = every(
+  n => n >= 3,
+  n => n <= 7
+)
+
+isBetween3And10(0)
+// → false
+
+isBetween3And10(5)
+// → true
+
+isBetween3And10(10)
+// → false
+```
+
+### `some(predicates)`
+
+> Returns a predicate that returns `true` iff some predicate returns `true`.
+
+```js
+const isAliceOrBob = some(
+  name => name === 'Alice',
+  name => name === 'Bob'
+)
+
+isAliceOrBob('Alice')
+// → true
+
+isAliceOrBob('Bob')
+// → true
+
+isAliceOrBob('Oscar')
+// → false
+```
+
+## Contributions
+
+Contributions are _very_ welcomed, either on the documentation or on
+the code.
+
+You may:
+
+- report any [issue](https://github.com/vatesfr/xen-orchestra/issues)
+  you've encountered;
+- fork and create a pull request.
+
+## License
+
+[ISC](https://spdx.org/licenses/ISC) © [Vates SAS](https://vates.fr)
diff --git a/@vates/predicates/USAGE.md b/@vates/predicates/USAGE.md
new file mode 100644
index 000000000..be38f3ceb
--- /dev/null
+++ b/@vates/predicates/USAGE.md
@@ -0,0 +1,57 @@
+`undefined` predicates are ignored and `undefined` is returned if all predicates are `undefined`, this permits the most efficient composition:
+
+```js
+const compositePredicate = every(undefined, some(predicate2, undefined))
+
+// ends up as
+
+const compositePredicate = predicate2
+```
+
+Predicates can also be passed wrapped in an array:
+
+```js
+const compositePredicate = every([predicate1, some([predicate2, predicate3])])
+```
+
+`this` and all arguments are passed to the nested predicates.
+
+### `every(predicates)`
+
+> Returns a predicate that returns `true` iff every predicate returns `true`.
+
+```js
+const isBetween3And7 = every(
+  n => n >= 3,
+  n => n <= 7
+)
+
+isBetween3And10(0)
+// → false
+
+isBetween3And10(5)
+// → true
+
+isBetween3And10(10)
+// → false
+```
+
+### `some(predicates)`
+
+> Returns a predicate that returns `true` iff some predicate returns `true`.
+
+```js
+const isAliceOrBob = some(
+  name => name === 'Alice',
+  name => name === 'Bob'
+)
+
+isAliceOrBob('Alice')
+// → true
+
+isAliceOrBob('Bob')
+// → true
+
+isAliceOrBob('Oscar')
+// → false
+```
diff --git a/@vates/predicates/index.js b/@vates/predicates/index.js
new file mode 100644
index 000000000..b7ba215a7
--- /dev/null
+++ b/@vates/predicates/index.js
@@ -0,0 +1,69 @@
+const {
+  isArray,
+  prototype: { filter },
+} = Array
+
+class InvalidPredicate extends TypeError {
+  constructor(value) {
+    super('not a valid predicate')
+    this.value = value
+  }
+}
+
+function isDefinedPredicate(value) {
+  if (value === undefined) {
+    return false
+  }
+
+  if (typeof value !== 'function') {
+    throw new InvalidPredicate(value)
+  }
+
+  return true
+}
+
+function handleArgs() {
+  let predicates
+  if (!(arguments.length === 1 && isArray((predicates = arguments[0])))) {
+    predicates = arguments
+  }
+  return filter.call(predicates, isDefinedPredicate)
+}
+
+exports.every = function every() {
+  const predicates = handleArgs.apply(this, arguments)
+  const n = predicates.length
+  if (n === 0) {
+    return
+  }
+  if (n === 1) {
+    return predicates[0]
+  }
+  return function everyPredicate() {
+    for (let i = 0; i < n; ++i) {
+      if (!predicates[0].apply(this, arguments)) {
+        return false
+      }
+    }
+    return true
+  }
+}
+
+exports.some = function some() {
+  const predicates = handleArgs.apply(this, arguments)
+  const n = predicates.length
+  if (n === 0) {
+    return
+  }
+  if (n === 1) {
+    return predicates[0]
+  }
+  return function somePredicate() {
+    for (let i = 0; i < n; ++i) {
+      if (predicates[0].apply(this, arguments)) {
+        return true
+      }
+    }
+    return false
+  }
+}
diff --git a/@vates/predicates/package.json b/@vates/predicates/package.json
new file mode 100644
index 000000000..101dda0b7
--- /dev/null
+++ b/@vates/predicates/package.json
@@ -0,0 +1,36 @@
+{
+  "private": false,
+  "name": "@vates/predicates",
+  "description": "Utilities to compose predicates",
+  "keywords": [
+    "and",
+    "combine",
+    "compose",
+    "every",
+    "function",
+    "functions",
+    "or",
+    "predicate",
+    "predicates",
+    "some"
+  ],
+  "homepage": "https://github.com/vatesfr/xen-orchestra/tree/master/@vates/predicates",
+  "bugs": "https://github.com/vatesfr/xen-orchestra/issues",
+  "repository": {
+    "directory": "@vates/predicates",
+    "type": "git",
+    "url": "https://github.com/vatesfr/xen-orchestra.git"
+  },
+  "author": {
+    "name": "Vates SAS",
+    "url": "https://vates.fr"
+  },
+  "license": "ISC",
+  "version": "0.0.0",
+  "engines": {
+    "node": ">=6"
+  },
+  "scripts": {
+    "postversion": "npm publish --access public"
+  }
+}
diff --git a/CHANGELOG.unreleased.md b/CHANGELOG.unreleased.md
index c8dc96246..65b1a44bc 100644
--- a/CHANGELOG.unreleased.md
+++ b/CHANGELOG.unreleased.md
@@ -28,6 +28,7 @@
 >
 > In case of conflict, the highest (lowest in previous list) `$version` wins.
 
+- @vates/predicates major
 - @xen-orchestra/mixins minor
 - @xen-orchestra/backups patch
 - @xen-orchestra/proxy patch