? ??? ???? ?? ???? ?? ?? ?? ????.

? ???? 1?? ?? ???? ??? ??????? ???? ??? ??? ?? ??????.¹

??? ??²? ? ???? ???(??? UTF-8 ??? ??? ???)? ?????.³ ?? ??? ????.

• 1 1
• //article[@title="foobar"]//image
• .items[].foo|select(.bar = "foo")
• a.comments > 1 and a.category not in ["misc"]

?? ??(?? DSL⁴)? ?? ??? ????.

• JQ
• Kibana ?? ??
• XPath ??
• ??? ?? ??

???? ?? ??? ??? ??? ?????? ? ? ?? ?? ????? ????! ? ?, ? ?, ??? ??? ???? ????. 1?? ????? ? ??? ??? ??????!⁵

ProCalc2000

??? 2000? ??? ?? ??? ???? ?? ???? ProCalc2000 ??? ??? ??? ????.

1 1, 1 2 ?? ???? ???? 1 3 2 / 2 ?? ?? ??? ??? ? ????.

??? ??(?: 1, 2)? ???( , -, )? ?????. ??? ????(?? I ??)? ???? ???? ????*.

????? ???? ??, ??, ??? ???, ???, ??? ??, ??? (Godzilla? ??? ???) ??? ?? ??? ???? ?? ??? ?????.

One?? ??? ??????

??? ???? ???? ??? ?? ??? ??? ???? ?????, ?? ? ???? ???????.

<code>              +-----------+  tokens  +--------+  ast  +-----------+ 
EXPRESSION ==>| Tokenizer |--------->| Parser |------>| Evaluator | => VALUE
              +-----------+          +--------+       +-----------+</code>

?????

?? ?? ?????? ???. ? ???? ???? ????? ??? ???? ????.

class Tokenizer
{
    public function tokenize(string $expression): Tokens
    {
        // ...
    }
}

?? ?? 1 2 3? 5?? ??? ?????.

<code>Token(Integer, 1)
Token(Plus)
Token(Integer, 2)
Token(Plus)
Token(Integer, 3)</code>

?????? ???? ????? ???? ?? ??? , - ? * ???? ?? ???? ???? ?????. ??? ?????. ?? ??? ??? ??????. ?? ??? ??, ???, ??, ??????.

?????? ???? ???? ???? ????. ??? ?????.⁶ ??? ??? ?????.

??

??? ??? ???? AST(?? ?? ??)? ?????.

<code>              +-----------+  tokens  +--------+  ast  +-----------+ 
EXPRESSION ==>| Tokenizer |--------->| Parser |------>| Evaluator | => VALUE
              +-----------+          +--------+       +-----------+</code>

?? ??? ???? ??? ??? ?? ??? AST? ?????. ? ??? ?? ??? ??????. ?? ??? BinaryOp ? Integer???.

?? ???? ? ?? ????? ????(?: foo or bar? BinaryOp(Variable('foo'), 'or', Variable('bar'))? ? ??).

?? ???? ????? ?? ????(?: -1).

?? ???? ? ?? ????? ????(?: foo ? bar : baz).

1 1 / 5 ???? ???? ???? BinaryOp???. ???? ? ??? 1?? ?? ??? ? ?? BinaryOp(1 / 5)???.

class Tokenizer
{
    public function tokenize(string $expression): Tokens
    {
        // ...
    }
}

???

???? ??? ???? ?(???? ??)? ?????. ??????????.

<code>Token(Integer, 1)
Token(Plus)
Token(Integer, 2)
Token(Plus)
Token(Integer, 3)</code>

??? ?????

? ??? ?? ???(???? ???)? ?? ??? PHPSW ???? ???????. ???? ?????.

?????

? ??, Token ???? ??? ?? ?? TokenType ???:

class Parser
{
    public function parse(Tokens $tokens): Node
    {
        // ...
    }
}

<code>                        +-------------+
                        | Binary Op + | 



<p>In PHP:</p>

```php
$ast = new BinaryOp(
    left:     new Integer(1),
    operator: '+',
    right:    new BinaryOp(
        left:     new Integer(1),
        operator: '/',
        right:    new Integer(5),
    )
);</code>

??? ??? ????.

class Evaluator
{
    public function evaluate(Node $node): int
    {
        // ...
    }
}

Tokenizer ???? ??? ?????.⁷

class Token
{
    public function __construct(
        public TokenType $type,
        public ?string $value = null
    ) {}
}

Tokens ???:

enum TokenType
{
    case Plus;
    case Minus;
    case Multiply;
    case Integer;
}

??

[
    new Token(TokenType::Integer, 50),
    new Token(TokenType::Plus),
    // ...
]

??? ??? ?? ??, ??? ?? ?? ? ??? ???? ?????. ?? ?? ??? ?? ??? "5??"? ?? ??? ?????.

???

class Tokenizer
{
    public function tokenize(string $expression): Tokens 
    {
        $offset = 0;
        $tokens = [];
        while (isset($expression[$offset])) {
            $char = $expression[$offset++];
            if (is_numeric($char)) {
                while (is_numeric($expression[$offset] ?? null)) {
                    $char .= $expression[$offset++];
                }
                $tokens[] = new Token(TokenType::Integer, $char);
                continue;
            }
            $token = match ($char) {
                '+' => new Token(TokenType::Plus),
                '-' => new Token(TokenType::Minus),
                '*' => new Token(TokenType::Multiply),
                ' ' => null,
                default => throw new RuntimeException(sprintf(
                    'Invalid operator: "%s"', $char
                )),
            };
            if ($token === null) {
                continue;
            }
            $tokens[] = $token;
        }
        return new Tokens($tokens);
    }
}

?? ????

? ??? ???? ???? ??? ???????. ?? ??? ????? ??? ? ????.

??? ????

1 * 3 4 ???? (1 * 3) 4 = 7??? ???, ?? ?? ???? ?? ?? ????? ?? 1 * (3 4) = 7?? ?????.⁸ Pratt ??? ?? ?????.

<code>              +-----------+  tokens  +--------+  ast  +-----------+ 
EXPRESSION ==>| Tokenizer |--------->| Parser |------>| Evaluator | => VALUE
              +-----------+          +--------+       +-----------+</code>

?? ??

• ??? ???: Robert Nystrom? ?(?? ? ?? ??)
• ??? ??? ?? ??: Robert Nystrom? ??? ???
• ?? ?? RPN ???: 2014 Igor Wiedler ??
• ?? ??
• PHPstan Phpdoc ??⁹

1. ??? ??? ??? ?????.
2. ? ????? ??? ?? ?? ??????.
3. PHP??? ???? ?? ?????.
4. ???? ??.
5. ??? ????.
6. ?????? ?? ??? ?????.
7. preg_ ??? ? ???? ? ????.
8. ?? ??? ???? ???? ?? ?????.
9. Doctrine? ?? ??? ?? ?? ??? ???????.

? ??? ? ?? ?? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!