Using Laravel for Advanced String Manipulation in PHP/

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Parsing Directive Parameters

Parsing Directive Parameters

Learn how to look to the next non-whitespace character and jump to its location.

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Parsing Blade directive parameters will be very similar to how we parse the directives themselves. The main difference is that we need a simple way to look to the next non-whitespace character and jump to its location. We can also implement this using a cursor; it will simply break when it encounters a non-whitespace character. Once we have located the first instance of a non-whitespace character, we can check if it is the ( character. If it is, we can make use of our existing PairedBracketCursor cursor to scan to the end of the directive’s argument group:

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<?php
// ...
class NonWhitespaceCursor extends AbstractStringCursor
{
    public function accept(string $current,
                           ?string $prev = null,
                           ?string $next = null): ?bool
    {
        if (! ctype_space($current)) {
            return $this->break();
        }
        return $this->continue();
    }
}
class BladeDirectiveValidator
{
    // ...
    protected $nonWhitespaceCursor;
    protected $pairedBracketCursor;
    protected function parseArgs($offset)
    {
        $args = null;
        $this->hasAdvancedIterator = false;
        foreach ($this->string as $char) {
            if (! $this->hasAdvancedIterator) {
                $this->advance($offset);
                continue;
            }
            // Get the argument string.
            $result = $this->pairedBracketCursor->traverse();
            $args = new ParsedArguments();
            $this->fillStructureDetails($result, $args);
            $args->content = $result->content;
            $args->value = $result->value;
            break;
        }
        return $args;
    }
    protected function parseDirective($offset)
    {
        $directive = null;
        $this->hasAdvancedIterator = false;
        foreach ($this->string as $char) {
            if (!$this->hasAdvancedIterator) {
                $this->advance($offset);
                continue;
            }
            $result = $this->directiveCursor->traverse();
            $directive = new ParsedDirective();
            $this->fillStructureDetails($result, $directive);
            if (str($result->value)->startsWith('@')) {
                $directive->directiveName = str($result->value)
                                                ->substr(1)
                                                ->toString();
            } else {
                $directive->directiveName = $result->value;
            }
            if ($directive->endPosition + 1 < count($this->string)) {
                $this->string->setIteratorPosition(
                    $directive->endPosition + 1,
                    $this->string->index()[$directive->endPosition + 1]
                );
                $nextNonWhitespace = $this->nonWhitespaceCursor
                    ->traverse();
                if (str($nextNonWhitespace->value)->endsWith('(')) {
                    $directive->args = $this->parseArgs(
                        $nextNonWhitespace->endPosition
                    );
                }
            }
            break;
        }
        return $directive;
    }
    public function parse($value)
    {
        // ...
        foreach ($htmlRegions as $region) {
            $this->lineOffset = $region[2] - 1;
            $this->string = new Utf8StringIterator($region[1]);
            $this->locator = new CharacterPositionLocator($region[1]);
            $this->directiveCursor = new BladeDirectiveCursor(
                $this->string
            );
            $this->pairedBracketCursor = new PairedBracketCursor(
                $this->string,
                '(', ')'
            );
            $this->nonWhitespaceCursor = new NonWhitespaceCursor(
                $this->string
            );
        }
        return $this->structures;
    }
}

The additions in the code above will feel similar to ...