Add Seq::map() and Filter\Chain::yieldRules()

src/Filter/Chain.php

@@ -4,6 +4,7 @@
 
 use ArrayIterator;
 use Countable;
+use Generator;
 use IteratorAggregate;
 use OutOfBoundsException;
 use Traversable;
@@ -56,6 +57,22 @@ public function getIterator(): Traversable
         return new ArrayIterator($this->rules);
     }
 
+    /**
+     * Yield all rules of this and nested chains in a flat sequence
+     *
+     * @return Generator<Rule>
+     */
+    public function yieldRules(): Generator
+    {
+        foreach ($this->rules as $rule) {
+            if ($rule instanceof self) {
+                yield from $rule->yieldRules();
+            } else {
+                yield $rule;
+            }
+        }
+    }
+
     /**
      * Add a rule to this chain
      *

src/Seq.php

@@ -3,6 +3,7 @@
 namespace ipl\Stdlib;
 
 use Closure;
+use Generator;
 
 /**
  * Collection of utilities for traversables
@@ -113,4 +114,19 @@ public static function findValue(iterable $traversable, mixed $needle, bool $cas
 
         return null;
     }
+
+    /**
+     * Apply the callback to all elements of the given traversable, while preserving keys
+     *
+     * @param iterable $traversable
+     * @param callable $callback
+     *
+     * @return Generator
+     */
+    public static function map(iterable $traversable, callable $callback): Generator
+    {
+        foreach ($traversable as $key => $value) {
+            yield $key => $callback($value);
+        }
+    }
 }

tests/FilterChainTest.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace ipl\Tests\Stdlib;
+
+use ipl\Stdlib\Filter;
+
+class FilterChainTest extends \PHPUnit\Framework\TestCase
+{
+    public function testYieldRules()
+    {
+        $filter = Filter::all(
+            Filter::equal('a', 'b'),
+            Filter::any(
+                Filter::equal('c', 'd'),
+                Filter::equal('e', 'f'),
+                Filter::none(
+                    Filter::equal('g', 'h')
+                )
+            )
+        );
+
+        $flat = [];
+        foreach ($filter->yieldRules() as $rule) {
+            $flat[] = $rule;
+        }
+
+        $this->assertCount(4, $flat);
+        $this->assertContainsOnlyInstancesOf(Filter\Rule::class, $flat);
+    }
+}

tests/SeqTest.php

@@ -129,4 +129,89 @@ public function testFindWithFunctionName()
             )
         );
     }
+
+    public function testMapWithSequencedArray()
+    {
+        $arr = [1, 2, 3];
+
+        $result = [];
+        foreach (Seq::map($arr, fn ($v) => $v + 1) as $k => $v) {
+            $result[$k] = $v;
+        }
+
+        $this->assertSame(
+            [2, 3, 4],
+            $result
+        );
+    }
+
+    public function testMapWithKeyedArray()
+    {
+        $arr = [
+            'one' => 1,
+            'two' => 2,
+            'three' => 3
+        ];
+
+        $result = [];
+        foreach (Seq::map($arr, fn ($v) => $v + 1) as $k => $v) {
+            $result[$k] = $v;
+        }
+
+        $this->assertSame(
+            [
+                'one' => 2,
+                'two' => 3,
+                'three' => 4
+            ],
+            $result
+        );
+    }
+
+    public function testMapWithGenerators()
+    {
+        $generator = function () {
+            foreach ([1, 2, 3] as $v) {
+                yield $v;
+            }
+        };
+
+        $result = [];
+        foreach (Seq::map($generator(), fn ($v) => $v + 1) as $k => $v) {
+            $result[$k] = $v;
+        }
+
+        $this->assertSame(
+            [2, 3, 4],
+            $result
+        );
+    }
+
+    public function testMapWithKeyedGenerators()
+    {
+        $generator = function () {
+            $arr = [
+                'one' => 1,
+                'two' => 2,
+                'three' => 3
+            ];
+            foreach ($arr as $k => $v) {
+                yield $k => $v;
+            }
+        };
+
+        $result = [];
+        foreach (Seq::map($generator(), fn ($v) => $v + 1) as $k => $v) {
+            $result[$k] = $v;
+        }
+
+        $this->assertSame(
+            [
+                'one' => 2,
+                'two' => 3,
+                'three' => 4
+            ],
+            $result
+        );
+    }
 }