Add clear to list classes

This is needed as a replacement for users of the holder interfaces to
remove all elements from one of the given list classes.

Bug: T128363

RELEASE-NOTES.md

@@ -1,8 +1,9 @@
 # Wikibase DataModel release notes
 
-## Version 5.1 (dev)
+## Version 5.1.0 (dev)
 
 * Deprecated `FingerprintHolder` and `StatementListHolder`
+* Added `clear` to `TermList`, `AliasGroupList` and `StatementList`
 
 ## Version 5.0.2 (2016-02-23)
 

src/Statement/StatementList.php

@@ -325,4 +325,13 @@ public function filter( StatementFilter $filter ) {
 		return $statementList;
 	}
 
+	/**
+	 * Removes all statements from this list.
+	 *
+	 * @since 5.1
+	 */
+	public function clear() {
+		$this->statements = array();
+	}
+
 }

src/Term/AliasGroupList.php

@@ -216,4 +216,13 @@ public function toTextArray() {
 		return $array;
 	}
 
+	/**
+	 * Removes all alias groups from this list.
+	 *
+	 * @since 5.1
+	 */
+	public function clear() {
+		$this->groups = array();
+	}
+
 }

src/Term/TermList.php

@@ -190,4 +190,13 @@ public function hasTerm( Term $term ) {
 			&& $this->terms[$term->getLanguageCode()]->equals( $term );
 	}
 
+	/**
+	 * Removes all terms from this list.
+	 *
+	 * @since 5.1
+	 */
+	public function clear() {
+		$this->terms = array();
+	}
+
 }

tests/unit/Statement/StatementListTest.php

@@ -650,4 +650,14 @@ public function testFilter() {
 		);
 	}
 
+	public function testClear() {
+		$statement1 = $this->getStatement( 1, null );
+		$statement2 = $this->getStatement( 2, null );
+		$statements = new StatementList( $statement1, $statement2 );
+
+		$statements->clear();
+
+		$this->assertEquals( new StatementList(), $statements );
+	}
+
 }

tests/unit/Term/AliasGroupListTest.php

@@ -384,4 +384,14 @@ public function testToTextArray() {
 		$this->assertEquals( $expected, $list->toTextArray() );
 	}
 
+	public function testClear() {
+		$list = new AliasGroupList();
+		$list->setAliasesForLanguage( 'en', array( 'foo', 'baz' ) );
+		$list->setAliasesForLanguage( 'de', array( 'bar' ) );
+
+		$list->clear();
+
+		$this->assertEquals( new AliasGroupList(), $list );
+	}
+
 }

tests/unit/Term/TermListTest.php

@@ -398,4 +398,14 @@ public function testGivenEmptyTerm_setTermRemovesExistingOne() {
 		);
 	}
 
+	public function testClear() {
+		$list = new TermList();
+		$list->setTextForLanguage( 'en', 'foo' );
+		$list->setTextForLanguage( 'de', 'bar' );
+
+		$list->clear();
+
+		$this->assertEquals( new TermList(), $list );
+	}
+
 }