From fa1a5a4b3f34b263685c089d03f643a1617aaa70 Mon Sep 17 00:00:00 2001
From: Stegmujo <johannesst@gmx.de>
Date: Wed, 5 Apr 2023 09:28:40 +0000
Subject: [PATCH] Fix style tag imbalance

* sometimes there have been more start-tags than end style tags

Bug: T315978
Change-Id: I6b20d45d7561b084376a54f4d6273a2ff5ed7bb4
---
 src/TexVC/Nodes/TexArray.php               | 19 +++++++++-----
 tests/phpunit/unit/TexVC/MMLRenderTest.php | 30 ++++++++++++++++++++++
 2 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/src/TexVC/Nodes/TexArray.php b/src/TexVC/Nodes/TexArray.php
index 12b6ae941..97070da16 100644
--- a/src/TexVC/Nodes/TexArray.php
+++ b/src/TexVC/Nodes/TexArray.php
@@ -157,7 +157,7 @@ class TexArray extends TexNode {
 	public function renderMML( $arguments = [], $state = [] ) {
 		// Everything here is for parsing displaystyle, probably refactored to TexVC grammar later
 		$fullRenderedArray = "";
-		$mmlStyle = null;
+		$mmlStyles = [];
 		$currentColor = null;
 
 		for ( $i = 0, $count = count( $this->args ); $i < $count; $i++ ) {
@@ -213,17 +213,23 @@ class TexArray extends TexNode {
 				continue;
 			}
 			$styleArguments = $this->checkForStyleArgs( $current );
-			// For cases with "displaystyle{someargs} otherargs"
 			if ( $styleArguments ) {
-				$mmlStyle = new MMLmstyle( "", $styleArguments );
 				$state["styleargs"] = $styleArguments;
-				$fullRenderedArray .= $mmlStyle->getStart();
 				if ( $next instanceof Curly ) {
+					// Wrap with style-tags when the next element is a Curly which determines start and end tag.
+					$mmlStyle = new MMLmstyle( "", $styleArguments );
+					$fullRenderedArray .= $mmlStyle->getStart();
 					$fullRenderedArray .= $this->createMMLwithContext( $currentColor, $next, $state, $arguments );
 					$fullRenderedArray .= $mmlStyle->getEnd();
 					$mmlStyle = null;
 					unset( $state["styleargs"] );
 					$i++;
+				} else {
+					// Start the style indicator in cases like \textstyle abc
+					$mmlStyle = new MMLmstyle( "", $styleArguments );
+					$fullRenderedArray .= $mmlStyle->getStart();
+					$mmlStyles[] = $mmlStyle->getEnd();
+
 				}
 			} else {
 				$fullRenderedArray .= $this->createMMLwithContext( $currentColor, $current, $state, $arguments );
@@ -239,8 +245,9 @@ class TexArray extends TexNode {
 				unset( $state["deriv"] );
 			}
 		}
-		if ( $mmlStyle ) {
-			$fullRenderedArray .= $mmlStyle->getEnd();
+
+		foreach ( array_reverse( $mmlStyles ) as $mmlStyleEnd ) {
+			$fullRenderedArray .= $mmlStyleEnd;
 		}
 
 		return $fullRenderedArray;
diff --git a/tests/phpunit/unit/TexVC/MMLRenderTest.php b/tests/phpunit/unit/TexVC/MMLRenderTest.php
index a455d15dc..84dbbc6c1 100644
--- a/tests/phpunit/unit/TexVC/MMLRenderTest.php
+++ b/tests/phpunit/unit/TexVC/MMLRenderTest.php
@@ -135,6 +135,36 @@ class MMLRenderTest extends MediaWikiUnitTestCase {
 		$this->assertStringContainsString( "#EF559F", $mathMLtexVC );
 	}
 
+	public function testStyle1() {
+		$input = "\\displaystyle \{U(\omega )\cdot \sigma _{H}(\omega )\} z";
+		$mathMLtexVC = $this->generateMML( $input );
+		$this->assertStringContainsString( "<mstyle displaystyle=\"true\" scriptlevel=\"0\">", $mathMLtexVC );
+		$this->assertStringContainsString( "<mi>z</mi>", $mathMLtexVC );
+		$this->assertStringContainsString( "</mstyle>", $mathMLtexVC, );
+	}
+
+	public function testStyle2() {
+		$input = "\\displaystyle abc \\textstyle def";
+		$mathMLtexVC = $this->generateMML( $input );
+		$this->assertStringContainsString( "<mstyle displaystyle=\"false\" scriptlevel=\"0\">", $mathMLtexVC );
+		$this->assertStringContainsString( "</mstyle>", $mathMLtexVC, );
+	}
+
+	public function testStyle3() {
+		$input = "\\scriptstyle{abc} def \\textstyle ghi";
+		$mathMLtexVC = $this->generateMML( $input );
+		$this->assertStringContainsString( "<mstyle displaystyle=\"false\" scriptlevel=\"1\">", $mathMLtexVC );
+		$this->assertStringContainsString( "</mstyle>", $mathMLtexVC, );
+	}
+
+	public function testStyle4() {
+		$input = "\\textstyle b > \\textstyle \\delta";
+		$mathMLtexVC = $this->generateMML( $input );
+		$count = 0;
+		str_replace( "<mstyle displaystyle", "", $mathMLtexVC, $count );
+		$this->assertEquals( 2, $count );
+	}
+
 	private function generateMML( $input, $chem = false ) {
 		$texVC = new TexVC();
 		$resultT = $texVC->check( $input, [