Make Ferret query functions sticky only if their values are not quoted

Summary:
Ref T13509. Currently, functions are "sticky", but this stickness is in the query execution layer.

Instead:

  - move stickiness to the query compiler; and
  - make it so that functions are not sticky if their arguments are quoted.

For example:

  - `title:x y` previously meant `title:x title:y` (and still does). The "title:" is sticky.
  - `title:"x" y` previously meant `title:x title:y`. It now means `title:x all:y`. The "title:" is not sticky because the argument is quoted.

Test Plan: Added unit tests, ran unit tests.

Maniphest Tasks: T13509

Differential Revision: https://secure.phabricator.com/D21108

src/applications/search/compiler/PhutilSearchQueryCompiler.php

@@ -262,6 +262,7 @@ final class PhutilSearchQueryCompiler
     }
 
     $results = array();
+    $last_function = null;
     foreach ($tokens as $token) {
       $value = implode('', $token['value']);
       $operator_string = implode('', $token['operator']);
@@ -339,7 +340,26 @@ final class PhutilSearchQueryCompiler
       );
 
       if ($enable_functions) {
-        $result['function'] = $token['function'];
+        // If a user provides a query like "title:a b c", we interpret all
+        // of the terms to be title terms: the "title:" function sticks
+        // until we encounter another function.
+
+        // If a user provides a query like "title:"a"" (with a quoted term),
+        // the function is not sticky.
+
+        if ($token['function'] !== null) {
+          $function = $token['function'];
+        } else {
+          $function = $last_function;
+        }
+
+        $result['function'] = $function;
+
+        if ($result['quoted']) {
+          $last_function = null;
+        } else {
+          $last_function = $function;
+        }
       }
 
       $results[] = $result;

src/applications/search/compiler/__tests__/PhutilSearchQueryCompilerTestCase.php

@@ -156,6 +156,21 @@ final class PhutilSearchQueryCompilerTestCase
 
       '~' => false,
       '-' => false,
+
+      // Functions like "title:" apply to following terms if their term is
+      // not specified with double quotes.
+      'title:x y' => array(
+        array('title', $op_and, 'x'),
+        array('title', $op_and, 'y'),
+      ),
+      'title: x y' => array(
+        array('title', $op_and, 'x'),
+        array('title', $op_and, 'y'),
+      ),
+      'title:"x" y' => array(
+        array('title', $op_and, 'x'),
+        array(null, $op_and, 'y'),
+      ),
     );
 
     $this->assertCompileFunctionQueries($function_tests);

src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php

@@ -1801,7 +1801,7 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
     $this->ferretEngine = $engine;
     $this->ferretTokens = $fulltext_tokens;
 
-    $current_function = $engine->getDefaultFunctionKey();
+    $default_function = $engine->getDefaultFunctionKey();
     $table_map = array();
     $idx = 1;
     foreach ($this->ferretTokens as $fulltext_token) {
@@ -1809,7 +1809,7 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
       $function = $raw_token->getFunction();
 
       if ($function === null) {
-        $function = $current_function;
+        $function = $default_function;
       }
 
       $raw_field = $engine->getFieldForFunction($function);
@@ -1821,8 +1821,6 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
           'key' => $raw_field,
         );
       }
-
-      $current_function = $function;
     }
 
     // Join the title field separately so we can rank results.