docs: added Count rule

Author: andrepimpao

docs/03-rules_count.md

@@ -0,0 +1,110 @@
+# Count
+
+Validates that the number of elements of an `array`, or object implementing `\Countable`, is between a minimum and maximum value.
+
+```php
+Count(
+    ?int $min = null, 
+    ?int $max = null,
+    ?string $minMessage = null,
+    ?string $maxMessage = null,
+    ?string $exactMessage = null
+);
+```
+
+## Basic Usage
+
+```php
+// min value
+Validator::count(min: 1)->validate(['a', 'b', 'c']); // true
+Validator::count(min: 5)->validate(['a', 'b', 'c']); // false
+
+// max value
+Validator::count(max: 5)->validate(['a', 'b', 'c']); // true
+Validator::count(max: 1)->validate(['a', 'b', 'c']); // false
+
+// min and max value
+Validator::count(min: 2, max: 4)->validate(['a', 'b', 'c']); // true
+
+// exact value
+Validator::count(min: 3, max: 3)->validate(['a', 'b', 'c']); // true
+```
+
+> [!NOTE]
+> An `UnexpectedValueException` will be thrown when either `min` or `max` options are not given.
+
+> [!NOTE]
+> An `UnexpectedValueException` will be thrown when the input value is not an `array` or an object implementing `\Countable`.
+
+> [!NOTE]
+> An `UnexpectedValueException` will be thrown when the `min` value is greater than the `max` value.
+
+## Options
+
+### `min`
+
+type: `?int` default: `null`
+
+It defines the minimum number of elements required.
+
+For example, if `min` is 2, the input value must have at least 2 elements.
+
+### `max`
+
+type: `?int` default: `null`
+
+It defines the maximum number of elements required.
+
+For example, if `max` is 2, the input value must have at most 2 elements.
+
+### `minMessage`
+
+type: `?string` default: `The {{ name }} value should contain {{ min }} elements or more, {{ numElements }} elements given.`
+
+Message that will be shown when the input value has fewer elements than the defined in `min`.
+
+The following parameters are available:
+
+| Parameter           | Description                            |
+|---------------------|----------------------------------------|
+| `{{ value }}`       | The current invalid value              |
+| `{{ name }}`        | Name of the invalid value              |
+| `{{ min }}`         | The minimum number of valid elements   |
+| `{{ max }}`         | The maximum number of valid elements   |
+| `{{ numElements }}` | The current invalid number of elements |
+
+### `maxMessage`
+
+type: `?string` default: `The {{ name }} value should contain {{ max }} elements or less, {{ numElements }} elements given.`
+
+Message that will be shown when the input value has more elements than the defined in `max`.
+
+The following parameters are available:
+
+| Parameter           | Description                            |
+|---------------------|----------------------------------------|
+| `{{ value }}`       | The current invalid value              |
+| `{{ name }}`        | Name of the invalid value              |
+| `{{ min }}`         | The minimum number of valid elements   |
+| `{{ max }}`         | The maximum number of valid elements   |
+| `{{ numElements }}` | The current invalid number of elements |
+
+### `exactMessage`
+
+type: `?string` default: `The {{ name }} value should contain exactly {{ min }} elements, {{ numElements }} elements given.`
+
+Message that will be shown when `min` and `max` options have the same value and the input value has a different number of elements.
+
+The following parameters are available:
+
+| Parameter           | Description                            |
+|---------------------|----------------------------------------|
+| `{{ value }}`       | The current invalid value              |
+| `{{ name }}`        | Name of the invalid value              |
+| `{{ min }}`         | The minimum number of valid elements   |
+| `{{ max }}`         | The maximum number of valid elements   |
+| `{{ numElements }}` | The current invalid number of elements |
+
+## Changelog
+
+- `0.7.0` Created