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Fix unbalanced markdown when an emphasis span is next to a whitespace-only one #274

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Fix unbalanced markdown when an emphasis span is next to a whitespace-only one #274

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a63c50a
EmphasisConverter: don't merge with a whitespace-only sibling
youdie006 Aug 6, 2026
e221e62
Add additional tests
colinodell Aug 10, 2026
3bd7094
Also suppress markers for falsy-content siblings (e.g. "0")
youdie006 Aug 11, 2026
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19 changes: 17 additions & 2 deletions src/Converter/EmphasisConverter.php
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Original file line number Diff line number Diff line change
Expand Up @@ -56,12 +56,27 @@ public function convert(ElementInterface $element): string
* the start or end $style, respectively. This prevents <em>foo</em><em>bar</em> from
* being converted to *foo**bar* which is incorrect. We want *foobar* instead.
*/
$preStyle = $this->getNormTag($element->getPreviousSibling()) === $tag ? '' : $style;
$postStyle = $this->getNormTag($element->getNextSibling()) === $tag ? '' : $style;
$preStyle = $this->isMergeableSibling($element->getPreviousSibling(), $tag) ? '' : $style;
$postStyle = $this->isMergeableSibling($element->getNextSibling(), $tag) ? '' : $style;

return $prefix . $preStyle . \trim($value) . $postStyle . $suffix;
}

/**
* A same-type sibling only emits emphasis markers when its trimmed content is
* truthy; a sibling whose trimmed value is falsy (whitespace-only, or "0")
* returns its bare value (see the early return in convert()) and emits none.
* Suppressing our marker is only correct in the former case, otherwise the
* output is left unbalanced (issue #252). The truthiness check mirrors
* convert()'s `! \trim($value)` guard so the two stay consistent.
*/
private function isMergeableSibling(?ElementInterface $sibling, string $tag): bool
{
return $sibling !== null
&& $this->getNormTag($sibling) === $tag
&& (bool) \trim($sibling->getValue());
}

/**
* @return string[]
*/
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10 changes: 10 additions & 0 deletions tests/HtmlConverterTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,16 @@ public function testConsecutiveSpans(): void
$this->assertHtmlGivesMarkdown('<em>Foo</em> <em>Bar</em>', '*Foo* *Bar*');
$this->assertHtmlGivesMarkdown('<strong>Foo</strong> <strong>Bar</strong>', '**Foo** **Bar**');
$this->assertHtmlGivesMarkdown('<strong>Foo</strong><b>Bar</b><em>Foo</em>', '**FooBar***Foo*');
// A whitespace-only neighbour of the same type emits no markers, so the
// adjacent span must keep its own instead of merging (issue #252).
$this->assertHtmlGivesMarkdown('<strong> </strong><strong>hello</strong>', ' **hello**');
$this->assertHtmlGivesMarkdown('<em> </em><em>hello</em>', ' *hello*');
$this->assertHtmlGivesMarkdown('<strong>hello</strong><strong> </strong>', '**hello** ');
$this->assertHtmlGivesMarkdown('<em>hello</em><em> </em>', '*hello* ');
// A same-type neighbour whose trimmed content is falsy (e.g. "0") also
// emits no markers, so the adjacent span must keep its own (issue #252).
$this->assertHtmlGivesMarkdown('<em>0</em><em>hello</em>', '0*hello*');
$this->assertHtmlGivesMarkdown('<em>hello</em><em>0</em>', '*hello*0');
}

public function testNesting(): void
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