如何创建一个扩展来解析多行用于thephpleague/commonmark

Question

全,

我正在尝试创建一个扩展(我相信是为了扩展AbstractBlockParser )，它将找到一个开始标记，将后面的行移动到一个块中，然后在找到结束标记时停止(在最后一行)。

在查看所提供的示例时，很难确定它们是如何构建由多行组成的块的，例如使用代码围栏，而文档没有涵盖此场景。

列表解析器代码似乎显示ListItems被添加到ListBlock中，但是它如何知道何时停止呢？

示例Markdown

{{ Object ID
Any markdown goes here.
Some more
  * List 1
  * List 2
}}

其产出可能是：

<div class="object">
    <span>Object ID</span>
    <p>Any markdown goes here.
    Some more</p>
    <ul>
        <li>List 1</li>
        <li>List 2</li>
    </ul>
</div>

Answer 1

诀窍是，您的块应该有canContain()和matchesNextLine()方法(总是return true; )--这将确保后续的行总是作为子块添加。(看看FencedCode和ListBlock实现。)

下面是一些应该工作的代码：

ObjectBlock.php:

class ObjectBlock extends AbstractBlock
{
    private $objectId;

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

    public function getObjectId()
    {
        return $this->objectId;
    }

    public function canContain(AbstractBlock $block)
    {
        return true;
    }

    public function acceptsLines()
    {
        return false;
    }

    public function isCode()
    {
        return false;
    }

    public function matchesNextLine(Cursor $cursor)
    {
        return true;
    }
}

ObjectParser.php:

class ObjectParser extends AbstractBlockParser
{
    public function parse(ContextInterface $context, Cursor $cursor)
    {
        // Look for the starting syntax
        if ($cursor->match('/^{{ /')) {
            $id = $cursor->getRemainder();
            $cursor->advanceToEnd();

            $context->addBlock(new ObjectBlock($id));

            return true;
        // Look for the ending syntax
        } elseif ($cursor->match('/^}} +$/')) {
            // TODO: I don't know if this is the best approach, but it should work
            // Basically, we're going to locate a parent ObjectBlock in the AST...
            $container = $context->getContainer();
            while ($container) {
                if ($container instanceof ObjectBlock) {
                    $cursor->advanceToEnd();

                    // Found it!  Now we'll close everything up to (and including) it
                    $context->getBlockCloser()->setLastMatchedContainer($container->parent());
                    $context->getBlockCloser()->closeUnmatchedBlocks();
                    $context->setBlocksParsed(true);

                    return true;
                }

                $container = $container->parent();
            }
        }

        return false;
    }
}

ObjectRenderer:

class ObjectRenderer implements BlockRendererInterface
{
    public function render(AbstractBlock $block, ElementRendererInterface $htmlRenderer, $inTightList = false)
    {
        $span = sprintf('<span>%s</span>', $block->getObjectId());
        $contents = $htmlRenderer->renderBlocks($block->children());

        return new HtmlElement('div', ['class' => 'object'],
            $span . $contents
        );
    }
}

免责声明:虽然我是这个库的作者，但特定的逻辑(容器、提示和块关闭)大多是分叉式的，我只了解其中大约75%的内容--足以让我的叉子正常工作，并找到可行的方法:)