[PHP知识库]LARAVEL框架Arr函数

<?php

namespace Illuminate\Support;

use ArrayAccess;
use Illuminate\Support\Traits\Macroable;
use InvalidArgumentException;

class Arr
{
    use Macroable;

    /**
     * Determine whether the given value is array accessible.
     *验证这个给定的值是否是数组或者继承ArrayAccess的对象
     * @param  mixed  $value
     * @return bool
     */
    public static function accessible($value)
    {
        return is_array($value) || $value instanceof ArrayAccess;
    }

    /**
     * Add an element to an array using "dot" notation if it doesn't exist.
     * 对数组添加一个指定下标的元素， 如果该下标存在的话，返回这个数组
     * @param  array  $array
     * @param  string  $key
     * @param  mixed  $value
     * @return array
     */
    public static function add($array, $key, $value)
    {
        if (is_null(static::get($array, $key))) {
            static::set($array, $key, $value);
        }

        return $array;
    }

    /**
     * Collapse an array of arrays into a single array.
     * 将多个数组合并成一个
     * @param  iterable  $array
     * @return array
     */
    public static function collapse($array)
    {
        $results = [];

        foreach ($array as $values) {
            if ($values instanceof Collection) {
                $values = $values->all();
            } elseif (! is_array($values)) {
                continue;
            }

            $results[] = $values;
        }

        return array_merge([], ...$results);
    }

    /**
     * Cross join the given arrays, returning all possible permutations.
     * 函数交叉连接给定的数组，返回具有所有可能排列的笛卡尔乘积：
     * @param  iterable  ...$arrays
     * @return array
     */
    public static function crossJoin(...$arrays)
    {
        $results = [[]];

        foreach ($arrays as $index => $array) {
            $append = [];

            foreach ($results as $product) {
                foreach ($array as $item) {
                    $product[$index] = $item;

                    $append[] = $product;
                }
            }

            $results = $append;
        }

        return $results;
    }

    /**
     * Divide an array into two arrays. One with keys and the other with values.
     * 获取数组的键和值， 组成一个新的数组
     * @param  array  $array
     * @return array
     */
    public static function divide($array)
    {
        return [array_keys($array), array_values($array)];
    }

    /**
     * Flatten a multi-dimensional associative array with dots.
     * 将多维数组使用点构建成键， 作为一个数组返回
     * @param  iterable  $array
     * @param  string  $prepend
     * @return array
     */
    public static function dot($array, $prepend = '')
    {
        $results = [];

        foreach ($array as $key => $value) {
            if (is_array($value) && ! empty($value)) {
                $results = array_merge($results, static::dot($value, $prepend.$key.'.'));
            } else {
                $results[$prepend.$key] = $value;
            }
        }

        return $results;
    }

    /**
     * Get all of the given array except for a specified array of keys.
     * 获取数组除了$keys之外的元素
     * @param  array  $array
     * @param  array|string  $keys
     * @return array
     */
    public static function except($array, $keys)
    {
        static::forget($array, $keys);

        return $array;
    }

    /**
     * Determine if the given key exists in the provided array.
     * 判断数组中是否存在下标为key的元素
     * @param  \ArrayAccess|array  $array
     * @param  string|int  $key
     * @return bool
     */
    public static function exists($array, $key)
    {
        if ($array instanceof Enumerable) {
            return $array->has($key);
        }

        if ($array instanceof ArrayAccess) {
            return $array->offsetExists($key);
        }

        return array_key_exists($key, $array);
    }

    /**
     * Return the first element in an array passing a given truth test.
     * 返回数组中经过测试成功的第一个元素
     * 1. 如果没有测试函数， 那么返回数组第一个元素
     * 2. 如果没有测试函数，也没有数组元素，则返回默认值
     * 3. 如果有测试函数，则返回第一个测试成功的元素
     * 4. 如果有测试函数，但是测试都是不通过，则返回默认值
     * @param  iterable  $array
     * @param  callable|null  $callback
     * @param  mixed  $default
     * @return mixed
     */
    public static function first($array, callable $callback = null, $default = null)
    {
        if (is_null($callback)) {
            if (empty($array)) {
                return value($default);
            }

            foreach ($array as $item) {
                return $item;
            }
        }

        foreach ($array as $key => $value) {
            if ($callback($value, $key)) {
                return $value;
            }
        }

        return value($default);
    }

    /**
     * Return the last element in an array passing a given truth test.
     * 返回数组中经过测试成功的最后一个元素
     * 1. 如果没有测试函数， 那么返回数组最后一个元素
     * 2. 如果没有测试函数，也没有数组元素，则返回默认值
     * 3. 如果有测试函数，则返回最后一个测试成功的元素
     * 4. 如果有测试函数，但是测试都是不通过，则返回默认值
     * @param  array  $array
     * @param  callable|null  $callback
     * @param  mixed  $default
     * @return mixed
     */
    public static function last($array, callable $callback = null, $default = null)
    {
        if (is_null($callback)) {
            return empty($array) ? value($default) : end($array);
        }

        return static::first(array_reverse($array, true), $callback, $default);
    }

    /**
     * Flatten a multi-dimensional array into a single level.
     *将一个多维数组变成为单层， 指定过滤数组的层级
     * @param  iterable  $array
     * @param  int  $depth
     * @return array
     */
    public static function flatten($array, $depth = INF)
    {
        $result = [];

        foreach ($array as $item) {
            $item = $item instanceof Collection ? $item->all() : $item;

            if (! is_array($item)) {
                $result[] = $item;
            } else {
                $values = $depth === 1
                    ? array_values($item)
                    : static::flatten($item, $depth - 1);

                foreach ($values as $value) {
                    $result[] = $value;
                }
            }
        }

        return $result;
    }

    /**
     * Remove one or many array items from a given array using "dot" notation.
     * 对传递的数组进行移除指定的keys
     * @param  array  $array
     * @param  array|string  $keys
     * @return void
     */
    public static function forget(&$array, $keys)
    {
        $original = &$array;

        $keys = (array) $keys;

        if (count($keys) === 0) {
            return;
        }

        foreach ($keys as $key) {
            // if the exact key exists in the top-level, remove it
            if (static::exists($array, $key)) {
                unset($array[$key]);

                continue;
            }

            $parts = explode('.', $key);

            // clean up before each pass
            $array = &$original;

            while (count($parts) > 1) {
                $part = array_shift($parts);

                if (isset($array[$part]) && is_array($array[$part])) {
                    $array = &$array[$part];
                } else {
                    continue 2;
                }
            }

            unset($array[array_shift($parts)]);
        }
    }

    /**
     * Get an item from an array using "dot" notation.
     * 获取数组某个键的值，不存在则返回默认值； 如果键不可访问，则返回数组
     * @param  \ArrayAccess|array  $array
     * @param  string|int|null  $key
     * @param  mixed  $default
     * @return mixed
     */
    public static function get($array, $key, $default = null)
    {
        if (! static::accessible($array)) {
            return value($default);
        }

        if (is_null($key)) {
            return $array;
        }

        if (static::exists($array, $key)) {
            return $array[$key];
        }

        if (strpos($key, '.') === false) {
            return $array[$key] ?? value($default);
        }

        foreach (explode('.', $key) as $segment) {
            if (static::accessible($array) && static::exists($array, $segment)) {
                $array = $array[$segment];
            } else {
                return value($default);
            }
        }

        return $array;
    }

    /**
     * Check if an item or items exist in an array using "dot" notation.
     * 判断给定数组是否存在指定的键值
     * @param  \ArrayAccess|array  $array
     * @param  string|array  $keys
     * @return bool
     */
    public static function has($array, $keys)
    {
        $keys = (array) $keys;

        if (! $array || $keys === []) {
            return false;
        }

        foreach ($keys as $key) {
            $subKeyArray = $array;

            if (static::exists($array, $key)) {
                continue;
            }

            foreach (explode('.', $key) as $segment) {
                if (static::accessible($subKeyArray) && static::exists($subKeyArray, $segment)) {
                    $subKeyArray = $subKeyArray[$segment];
                } else {
                    return false;
                }
            }
        }

        return true;
    }

    /**
     * Determine if any of the keys exist in an array using "dot" notation.
     * 是否存在key列表中的某一个或都有且值不为空
     * @param  \ArrayAccess|array  $array
     * @param  string|array  $keys
     * @return bool
     */
    public static function hasAny($array, $keys)
    {
        if (is_null($keys)) {
            return false;
        }

        $keys = (array) $keys;

        if (! $array) {
            return false;
        }

        if ($keys === []) {
            return false;
        }

        foreach ($keys as $key) {
            if (static::has($array, $key)) {
                return true;
            }
        }

        return false;
    }

    /**
     * Determines if an array is associative.
     *
     * An array is "associative" if it doesn't have sequential numerical keys beginning with zero.
     *是否是一个有键的数组
     * @param  array  $array
     * @return bool
     */
    public static function isAssoc(array $array)
    {
        $keys = array_keys($array);

        return array_keys($keys) !== $keys;
    }

    /**
     * Determines if an array is a list.
     *确定数组是否为列表
     * An array is a "list" if all array keys are sequential integers starting from 0 with no gaps in between.
     *如果所有数组键都是从0开始的连续整数，且其间没有间隙，则数组就是“列表”
     * @param  array  $array
     * @return bool
     */
    public static function isList($array)
    {
        return ! self::isAssoc($array);
    }

    /**
     * Get a subset of the items from the given array.
     * 获取数组中指定的keys
     * @param  array  $array
     * @param  array|string  $keys
     * @return array
     */
    public static function only($array, $keys)
    {
        return array_intersect_key($array, array_flip((array) $keys));
    }

    /**
     * Pluck an array of values from an array.
     * 从数组中提取指定键值数组。
     * @param  iterable  $array
     * @param  string|array|int|null  $value
     * @param  string|array|null  $key
     * @return array
     */
    public static function pluck($array, $value, $key = null)
    {
        $results = [];

        [$value, $key] = static::explodePluckParameters($value, $key);

        foreach ($array as $item) {
            $itemValue = data_get($item, $value);

            // If the key is "null", we will just append the value to the array and keep
            // looping. Otherwise we will key the array using the value of the key we
            // received from the developer. Then we'll return the final array form.
            if (is_null($key)) {
                $results[] = $itemValue;
            } else {
                $itemKey = data_get($item, $key);

                if (is_object($itemKey) && method_exists($itemKey, '__toString')) {
                    $itemKey = (string) $itemKey;
                }

                $results[$itemKey] = $itemValue;
            }
        }

        return $results;
    }

    /**
     * Explode the "value" and "key" arguments passed to "pluck".
     * 分解传递给“pull”的“value”和“key”参数。
     * @param  string|array  $value
     * @param  string|array|null  $key
     * @return array
     */
    protected static function explodePluckParameters($value, $key)
    {
        $value = is_string($value) ? explode('.', $value) : $value;

        $key = is_null($key) || is_array($key) ? $key : explode('.', $key);

        return [$value, $key];
    }

    /**
     * Push an item onto the beginning of an array.
     * 将指定数据推送到数组的开头。
     * @param  array  $array
     * @param  mixed  $value
     * @param  mixed  $key
     * @return array
     */
    public static function prepend($array, $value, $key = null)
    {
        if (func_num_args() == 2) {
            array_unshift($array, $value);
        } else {
            $array = [$key => $value] + $array;
        }

        return $array;
    }

    /**
     * Get a value from the array, and remove it.
     * 从数组中获取一个值，并将其删除。
     * @param  array  $array
     * @param  string  $key
     * @param  mixed  $default
     * @return mixed
     */
    public static function pull(&$array, $key, $default = null)
    {
        $value = static::get($array, $key, $default);

        static::forget($array, $key);

        return $value;
    }

    /**
     * Convert the array into a query string.
     *将数组转换为查询字符串。
     * @param  array  $array
     * @return string
     */
    public static function query($array)
    {
        return http_build_query($array, '', '&', PHP_QUERY_RFC3986);
    }

    /**
     * Get one or a specified number of random values from an array.
     * 从数组中获取一个或指定数量的随机值。
     * @param  array  $array
     * @param  int|null  $number
     * @param  bool|false  $preserveKeys
     * @return mixed
     *
     * @throws \InvalidArgumentException
     */
    public static function random($array, $number = null, $preserveKeys = false)
    {
        $requested = is_null($number) ? 1 : $number;

        $count = count($array);

        if ($requested > $count) {
            throw new InvalidArgumentException(
                "You requested {$requested} items, but there are only {$count} items available."
            );
        }

        if (is_null($number)) {
            return $array[array_rand($array)];
        }

        if ((int) $number === 0) {
            return [];
        }

        $keys = array_rand($array, $number);

        $results = [];

        if ($preserveKeys) {
            foreach ((array) $keys as $key) {
                $results[$key] = $array[$key];
            }
        } else {
            foreach ((array) $keys as $key) {
                $results[] = $array[$key];
            }
        }

        return $results;
    }

    /**
     * Set an array item to a given value using "dot" notation.
     *设置数组中一个值
     * If no key is given to the method, the entire array will be replaced.
     *
     * @param  array  $array
     * @param  string|null  $key
     * @param  mixed  $value
     * @return array
     */
    public static function set(&$array, $key, $value)
    {
        if (is_null($key)) {
            return $array = $value;
        }

        $keys = explode('.', $key);

        foreach ($keys as $i => $key) {
            if (count($keys) === 1) {
                break;
            }

            unset($keys[$i]);

            // If the key doesn't exist at this depth, we will just create an empty array
            // to hold the next value, allowing us to create the arrays to hold final
            // values at the correct depth. Then we'll keep digging into the array.
            if (! isset($array[$key]) || ! is_array($array[$key])) {
                $array[$key] = [];
            }

            $array = &$array[$key];
        }

        $array[array_shift($keys)] = $value;

        return $array;
    }

    /**
     * Shuffle the given array and return the result.
     *打乱数组，并且返回数组
     * @param  array  $array
     * @param  int|null  $seed
     * @return array
     */
    public static function shuffle($array, $seed = null)
    {
        if (is_null($seed)) {
            shuffle($array);
        } else {
            mt_srand($seed);
            shuffle($array);
            mt_srand();
        }

        return $array;
    }

    /**
     * Sort the array using the given callback or "dot" notation.
     *使用回调函数进行排序
     * @param  array  $array
     * @param  callable|array|string|null  $callback
     * @return array
     */
    public static function sort($array, $callback = null)
    {
        return Collection::make($array)->sortBy($callback)->all();
    }

    /**
     * Recursively sort an array by keys and values.
     * 递归的排序,如果有键，则通过键排序,否则通过值排序
     * @param  array  $array
     * @param  int  $options
     * @param  bool  $descending
     * @return array
     */
    public static function sortRecursive($array, $options = SORT_REGULAR, $descending = false)
    {
        foreach ($array as &$value) {
            if (is_array($value)) {
                $value = static::sortRecursive($value, $options, $descending);
            }
        }

        if (static::isAssoc($array)) {
            $descending
                    ? krsort($array, $options)
                    : ksort($array, $options);
        } else {
            $descending
                    ? rsort($array, $options)
                    : sort($array, $options);
        }

        return $array;
    }

    /**
     * Conditionally compile classes from an array into a CSS class list.
     * 有条件地将数组中的类编译到CSS类列表中。
     * @param  array  $array
     * @return string
     */
    public static function toCssClasses($array)
    {
        $classList = static::wrap($array);

        $classes = [];

        foreach ($classList as $class => $constraint) {
            if (is_numeric($class)) {
                $classes[] = $constraint;
            } elseif ($constraint) {
                $classes[] = $class;
            }
        }

        return implode(' ', $classes);
    }

    /**
     * Filter the array using the given callback.
     * 使用回调函数进行过滤
     * @param  array  $array
     * @param  callable  $callback
     * @return array
     */
    public static function where($array, callable $callback)
    {
        return array_filter($array, $callback, ARRAY_FILTER_USE_BOTH);
    }

    /**
     * If the given value is not an array and not null, wrap it in one.
     * 对value进行包装称为一个数组
     * @param  mixed  $value
     * @return array
     */
    public static function wrap($value)
    {
        if (is_null($value)) {
            return [];
        }

        return is_array($value) ? $value : [$value];
    }
}