Search backend:

* add "all:" prefix that searches all namespaces (port from LuceneSearch)
* added a simplistic replacePrefixes so that now image:something will
  always search the image namespace

includes/SearchEngine.php

@@ -176,6 +176,37 @@ class SearchEngine {
 	function setNamespaces( $namespaces ) {
 		$this->namespaces = $namespaces;
 	}
+	
+	/**
+	 * Parse some common prefixes: all (search everything)
+	 * or namespace names
+	 *
+	 * @param string $query
+	 */
+	function replacePrefixes( $query ){
+		global $wgContLang;
+				
+		if( strpos($query,':') === false )
+			return $query; // nothing to do
+			
+		$parsed = $query;
+		$allkeyword = wfMsg('searchall').":";
+		if( strncmp($query, $allkeyword, strlen($allkeyword)) == 0 ){
+			$this->namespaces = null;
+			$parsed = substr($query,strlen($allkeyword));
+		} else if( strpos($query,':') !== false ) {
+			$prefix = substr($query,0,strpos($query,':'));
+			$index = $wgContLang->getNsIndex($prefix);
+			if($index !== false){
+				$this->namespaces = array($index);
+				$parsed = substr($query,strlen($prefix)+1);
+			}
+		}
+		if(trim($parsed) == '')
+			return $query; // prefix was the whole query
+			
+		return $parsed;
+	}
 
 	/**
 	 * Make a list of searchable namespaces and their canonical names.

includes/SearchMySQL.php

@@ -115,6 +115,8 @@ class SearchMySQL extends SearchEngine {
 	 * @private
 	 */
 	function queryNamespaces() {
+		if( is_null($this->namespaces) )
+			return '';  # search all
 		$namespaces = implode( ',', $this->namespaces );
 		if ($namespaces == '') {
 			$namespaces = '0';

includes/SearchPostgres.php

@@ -174,11 +174,13 @@ class SearchPostgres extends SearchEngine {
 			$query .= ' AND page_is_redirect = 0';
 
 		## Namespaces - defaults to 0
-		if ( count($this->namespaces) < 1)
-			$query .= ' AND page_namespace = 0';
-		else {
-			$namespaces = implode( ',', $this->namespaces );
-			$query .= " AND page_namespace IN ($namespaces)";
+		if( !is_null($this->namespaces) ){ // null -> search all
+			if ( count($this->namespaces) < 1)
+				$query .= ' AND page_namespace = 0';
+			else {
+				$namespaces = implode( ',', $this->namespaces );
+				$query .= " AND page_namespace IN ($namespaces)";
+			}
 		}
 
 		$query .= " ORDER BY score DESC, page_id DESC";

includes/SpecialSearch.php

@@ -159,8 +159,10 @@ class SpecialSearch {
 		$search = SearchEngine::create();
 		$search->setLimitOffset( $this->limit, $this->offset );
 		$search->setNamespaces( $this->namespaces );
-		$search->showRedirects = $this->searchRedirects;
-		$titleMatches = $search->searchTitle( $term );
+		$search->showRedirects = $this->searchRedirects;		
+		$rewritten = $search->replacePrefixes($term);
+		
+		$titleMatches = $search->searchTitle( $rewritten );
 
 		// Sometimes the search engine knows there are too many hits
 		if ($titleMatches instanceof SearchResultTooMany) {
@@ -170,7 +172,7 @@ class SpecialSearch {
 			wfProfileOut( $fname );
 			return;
 		}
-		$textMatches = $search->searchText( $term );
+		$textMatches = $search->searchText( $rewritten );
 		
 		// did you mean...
 		if($textMatches && $textMatches->hasSuggestion()){

languages/messages/MessagesEn.php

@@ -1236,6 +1236,7 @@ Make sure that this change will maintain historical page continuity.
 'search-redirect'       => '(redirect $1)',
 'search-section'        => '(section $1)',
 'search-suggest'        => 'Did you mean: $1',
+'searchall'             => 'all',
 'showingresults'        => "Showing below up to {{PLURAL:$1|'''1''' result|'''$1''' results}} starting with #'''$2'''.",
 'showingresultsnum'     => "Showing below {{PLURAL:$3|'''1''' result|'''$3''' results}} starting with #'''$2'''.",
 'showingresultstotal'   => "Showing below results '''$1 - $2''' of '''$3'''",

maintenance/language/messages.inc

@@ -685,6 +685,7 @@ $wgMessageStructure = array(
 		'search-redirect',
 		'search-section',
 		'search-suggest',
+		'searchall',
 		'showingresults',
 		'showingresultsnum',
 		'showingresultstotal',