gistfile1.php

<?php

interface LineNumber
{
    function getLineNumber($currentLineNumber);
}

class RelativeLineNumber implements LineNumber
{
    private $linesDelta;
    
    public function __construct($linesDelta)
    {
        $this->linesDelta = intval($linesDelta);
    }
    
    public function getLineNumber($currentLineNumber)
    {
        return $currentLineNumber + $this->linesDelta;
    }
}

class AbsoluteLineNumber implements LineNumber
{
    private $lineNumber;
    
    public function __construct($lineNumber)
    {
        $this->lineNumber = $lineNumber;
    }
    
    public function getLineNumber($currentLineNumber)
    {
        return $this->lineNumber;
    }
}

class LineMatch
{
    /** @var Expression */
    private $expression;

    public function __construct(Expression $expression)
    {
        $this->expression = $expression;
    }

    public function getRegex()
    {
        return (string) $this->expression;
    }
}

class Expression
{
    private $regex;

    private function __construct($regex)
    {
        $this->regex = $regex;
    }

    public static function regex($regex)
    {
        return new self($regex);
    }

    public static function exact($string)
    {
        return new self('{'.preg_quote($string).'}');
    }

    public static function glob($string)
    {
        return new self('{'.str_replace('\*', '.*?', preg_quote($string)).'}');
    }

    public function __toString()
    {
        return $this->regex;
    }
}

class Lines
{
    public static function down($lines)
    {
        return new RelativeLineNumber($lines);
    }
    
    public static function up($lines)
    {
        return new RelativeLineNumber(-$lines);
    }
    
    public static function exact($line)
    {
        return new AbsoluteLineNumber($line);
    }

    public static function match(Expression $expression)
    {
        return new LineMatch($expression);
    }
}

class LineNumberSearchStrategy implements SearchStrategy
{
    public function has(File $file, $pattern)
    {
        return count($file->readlines()) >= $pattern->getLineNumber($this->getCurrentLineNumber()) - 1;
    }

    public function findNext(File $file, $pattern)
    {
        return $pattern->getLineNumber($file->getCurrentLineNumber());
    }

    public function findPrev(File $file, $pattern)
    {
        return $pattern->getLineNumber($file->getCurrentLineNumber());
    }

    public function supports($pattern)
    {
        return is_object($pattern) && $pattern instanceof LineNumber;
    }
}

class LineSearchStrategy implements SearchStrategy
{
    public function has(File $file, $pattern)
    {
        try {
            $this->getLine($file->readlines(), $pattern->getRegex());

            return true;
        } catch (PatternNotFoundException $e) {
            return false;
        }
    }

    public function findNext(File $file, $pattern)
    {
        return $this->getLine(array_slice($file->readlines(), $file->getCurrentLineNumber()), $pattern->getRegex());
    }

    public function findPrev(File $file, $pattern)
    {
        return $this->getLine(array_reverse(array_slice($file->readlines(), 0, $file->getCurrentLineNumber())), $pattern->getRegex());
    }

    private function getLine($lines, $regex)
    {
        foreach ($lines as $number => $line) {
            if (preg_match($regex, $line)) {
                return $number;
            }
        }

        throw new PatternNotFoundException(...);
    }

    public function supports($pattern)
    {
        return is_object($pattern) && $pattern instanceof LineMatch;
    }
}