DiffFormatter: Don't mess with PHP output buffering

This is a line-by-line conversion to append to a string property rather
than print into a PHP output buffer.

The changes to the base class break subclasses such as MobileFrontend's
InlineDiffFormatter, which is updated in I81dd01cb.

Depends-On: I81dd01cbb9ce11b87115fb1fed511027aee436a1
Change-Id: Idf2a6c593b81a152edec923d4db6272ca1f3f545

3 files changed, 30 insertions, 18 deletions

diff --git a/includes/diff/DiffFormatter.php b/includes/diff/DiffFormatter.php
index 33ca931fdb58..23e39ea73bd3 100644
--- a/includes/diff/DiffFormatter.php
+++ b/includes/diff/DiffFormatter.php
@@ -49,6 +49,9 @@ abstract class DiffFormatter {
 	 */
 	protected $trailingContextLines = 0;
 
+	/** @var string The output buffer; holds the output while it is built. */
+	private $result = '';
+
 	/**
 	 * Format a diff.
 	 *
@@ -146,15 +149,24 @@ abstract class DiffFormatter {
 	}
 
 	protected function startDiff() {
-		ob_start();
+		$this->result = '';
+	}
+
+	/**
+	 * Writes a string to the output buffer.
+	 *
+	 * @param string $text
+	 */
+	protected function writeOutput( $text ) {
+		$this->result .= $text;
 	}
 
 	/**
 	 * @return string
 	 */
 	protected function endDiff() {
-		$val = ob_get_contents();
-		ob_end_clean();
+		$val = $this->result;
+		$this->result = '';
 
 		return $val;
 	}
@@ -185,7 +197,7 @@ abstract class DiffFormatter {
 	 * @param string $header
 	 */
 	protected function startBlock( $header ) {
-		echo $header . "\n";
+		$this->writeOutput( $header . "\n" );
 	}
 
 	/**
@@ -203,7 +215,7 @@ abstract class DiffFormatter {
 	 */
 	protected function lines( $lines, $prefix = ' ' ) {
 		foreach ( $lines as $line ) {
-			echo "$prefix $line\n";
+			$this->writeOutput( "$prefix $line\n" );
 		}
 	}
 
@@ -236,7 +248,7 @@ abstract class DiffFormatter {
 	 */
 	protected function changed( $orig, $closing ) {
 		$this->deleted( $orig );
-		echo "---\n";
+		$this->writeOutput( "---\n" );
 		$this->added( $closing );
 	}
 
diff --git a/includes/diff/TableDiffFormatter.php b/includes/diff/TableDiffFormatter.php
index be38e8759c3d..f1826edc5ec8 100644
--- a/includes/diff/TableDiffFormatter.php
+++ b/includes/diff/TableDiffFormatter.php
@@ -80,7 +80,7 @@ class TableDiffFormatter extends DiffFormatter {
 	 * @param string $header
 	 */
 	protected function startBlock( $header ) {
-		echo $header;
+		$this->writeOutput( $header );
 	}
 
 	protected function endBlock() {
@@ -157,9 +157,9 @@ class TableDiffFormatter extends DiffFormatter {
 	 */
 	protected function added( $lines ) {
 		foreach ( $lines as $line ) {
-			echo '<tr>' . $this->emptyLine() .
+			$this->writeOutput( '<tr>' . $this->emptyLine() .
 				$this->addedLine( '<ins class="diffchange">' .
-					htmlspecialchars( $line ) . '</ins>' ) . "</tr>\n";
+					htmlspecialchars( $line ) . '</ins>' ) . "</tr>\n" );
 		}
 	}
 
@@ -170,9 +170,9 @@ class TableDiffFormatter extends DiffFormatter {
 	 */
 	protected function deleted( $lines ) {
 		foreach ( $lines as $line ) {
-			echo '<tr>' . $this->deletedLine( '<del class="diffchange">' .
+			$this->writeOutput( '<tr>' . $this->deletedLine( '<del class="diffchange">' .
 					htmlspecialchars( $line ) . '</del>' ) .
-				$this->emptyLine() . "</tr>\n";
+				$this->emptyLine() . "</tr>\n" );
 		}
 	}
 
@@ -183,9 +183,9 @@ class TableDiffFormatter extends DiffFormatter {
 	 */
 	protected function context( $lines ) {
 		foreach ( $lines as $line ) {
-			echo '<tr>' .
+			$this->writeOutput( '<tr>' .
 				$this->contextLine( htmlspecialchars( $line ) ) .
-				$this->contextLine( htmlspecialchars( $line ) ) . "</tr>\n";
+				$this->contextLine( htmlspecialchars( $line ) ) . "</tr>\n" );
 		}
 	}
 
@@ -207,13 +207,13 @@ class TableDiffFormatter extends DiffFormatter {
 		$line = array_shift( $del );
 		while ( $line ) {
 			$aline = array_shift( $add );
-			echo '<tr>' . $this->deletedLine( $line ) .
-				$this->addedLine( $aline ) . "</tr>\n";
+			$this->writeOutput( '<tr>' . $this->deletedLine( $line ) .
+				$this->addedLine( $aline ) . "</tr>\n" );
 			$line = array_shift( $del );
 		}
 		foreach ( $add as $line ) { # If any leftovers
-			echo '<tr>' . $this->emptyLine() .
-				$this->addedLine( $line ) . "</tr>\n";
+			$this->writeOutput( '<tr>' . $this->emptyLine() .
+				$this->addedLine( $line ) . "</tr>\n" );
 		}
 	}
 
diff --git a/includes/diff/UnifiedDiffFormatter.php b/includes/diff/UnifiedDiffFormatter.php
index 5f3ad3d7bb8a..72f1a6603475 100644
--- a/includes/diff/UnifiedDiffFormatter.php
+++ b/includes/diff/UnifiedDiffFormatter.php
@@ -42,7 +42,7 @@ class UnifiedDiffFormatter extends DiffFormatter {
 	 */
 	protected function lines( $lines, $prefix = ' ' ) {
 		foreach ( $lines as $line ) {
-			echo "{$prefix}{$line}\n";
+			$this->writeOutput( "{$prefix}{$line}\n" );
 		}
 	}