Add an "only()" edge logic constraint, meaning "only the other constraints, exactly"

Summary:
See PHI57. For example, a query for "ios, only()" finds tags tasked with iOS, exactly, and no other tags.

I called this "only()" instead of "exact()" because we use the term/function "Exact" elsewhere with a different meaning, e.g. in Differential.

Test Plan:
Basic query for a tag:

{F5168857}

Same query with "only", finds tasks tagged with only that tag:

{F5168858}

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D18543

src/__phutil_library_map__.php

@@ -3686,6 +3686,7 @@ phutil_register_library_map(array(
     'PhabricatorProjectLockTransaction' => 'applications/project/xaction/PhabricatorProjectLockTransaction.php',
     'PhabricatorProjectLogicalAncestorDatasource' => 'applications/project/typeahead/PhabricatorProjectLogicalAncestorDatasource.php',
     'PhabricatorProjectLogicalDatasource' => 'applications/project/typeahead/PhabricatorProjectLogicalDatasource.php',
+    'PhabricatorProjectLogicalOnlyDatasource' => 'applications/project/typeahead/PhabricatorProjectLogicalOnlyDatasource.php',
     'PhabricatorProjectLogicalOrNotDatasource' => 'applications/project/typeahead/PhabricatorProjectLogicalOrNotDatasource.php',
     'PhabricatorProjectLogicalUserDatasource' => 'applications/project/typeahead/PhabricatorProjectLogicalUserDatasource.php',
     'PhabricatorProjectLogicalViewerDatasource' => 'applications/project/typeahead/PhabricatorProjectLogicalViewerDatasource.php',
@@ -9179,6 +9180,7 @@ phutil_register_library_map(array(
     'PhabricatorProjectLockTransaction' => 'PhabricatorProjectTransactionType',
     'PhabricatorProjectLogicalAncestorDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'PhabricatorProjectLogicalDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
+    'PhabricatorProjectLogicalOnlyDatasource' => 'PhabricatorTypeaheadDatasource',
     'PhabricatorProjectLogicalOrNotDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'PhabricatorProjectLogicalUserDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'PhabricatorProjectLogicalViewerDatasource' => 'PhabricatorTypeaheadDatasource',

src/applications/project/typeahead/PhabricatorProjectLogicalDatasource.php

@@ -21,6 +21,7 @@ final class PhabricatorProjectLogicalDatasource
       new PhabricatorProjectLogicalAncestorDatasource(),
       new PhabricatorProjectLogicalOrNotDatasource(),
       new PhabricatorProjectLogicalViewerDatasource(),
+      new PhabricatorProjectLogicalOnlyDatasource(),
       new PhabricatorProjectLogicalUserDatasource(),
     );
   }

src/applications/project/typeahead/PhabricatorProjectLogicalOnlyDatasource.php

@@ -0,0 +1,76 @@
+<?php
+
+final class PhabricatorProjectLogicalOnlyDatasource
+  extends PhabricatorTypeaheadDatasource {
+
+  public function getBrowseTitle() {
+    return pht('Browse Only');
+  }
+
+  public function getPlaceholderText() {
+    return pht('Type only()...');
+  }
+
+  public function getDatasourceApplicationClass() {
+    return 'PhabricatorProjectApplication';
+  }
+
+  public function getDatasourceFunctions() {
+    return array(
+      'only' => array(
+        'name' => pht('Only Match Other Constraints'),
+        'summary' => pht(
+          'Find results with only the specified tags.'),
+        'description' => pht(
+          "This function is used with other tags, and causes the query to ".
+          "match only results with exactly those tags. For example, to find ".
+          "tasks tagged only iOS:".
+          "\n\n".
+          "> ios, only()".
+          "\n\n".
+          "This will omit results with any other project tag."),
+      ),
+    );
+  }
+
+  public function loadResults() {
+    $results = array(
+      $this->renderOnlyFunctionToken(),
+    );
+    return $this->filterResultsAgainstTokens($results);
+  }
+
+  protected function evaluateFunction($function, array $argv_list) {
+    $results = array();
+
+    $results[] = new PhabricatorQueryConstraint(
+      PhabricatorQueryConstraint::OPERATOR_ONLY,
+      null);
+
+    return $results;
+  }
+
+  public function renderFunctionTokens(
+    $function,
+    array $argv_list) {
+
+    $tokens = array();
+    foreach ($argv_list as $argv) {
+      $tokens[] = PhabricatorTypeaheadTokenView::newFromTypeaheadResult(
+        $this->renderOnlyFunctionToken());
+    }
+
+    return $tokens;
+  }
+
+  private function renderOnlyFunctionToken() {
+    return $this->newFunctionResult()
+      ->setName(pht('Only'))
+      ->setPHID('only()')
+      ->setIcon('fa-asterisk')
+      ->setUnique(true)
+      ->addAttribute(
+        pht('Select only results with exactly the other specified tags.'));
+  }
+
+}

src/applications/project/typeahead/PhabricatorProjectLogicalViewerDatasource.php

@@ -29,7 +29,7 @@ final class PhabricatorProjectLogicalViewerDatasource
           "\n\n".
           "This normally means //your// projects, but if you save a query ".
           "using this function and send it to someone else, it will mean ".
-          "//their// projects when they run it (they become the currnet ".
+          "//their// projects when they run it (they become the current ".
           "viewer). This can be useful for building dashboard panels."),
       ),
     );

src/infrastructure/query/constraint/PhabricatorQueryConstraint.php

@@ -8,6 +8,7 @@ final class PhabricatorQueryConstraint extends Phobject {
   const OPERATOR_NULL = 'null';
   const OPERATOR_ANCESTOR = 'ancestor';
   const OPERATOR_EMPTY = 'empty';
+  const OPERATOR_ONLY = 'only';
 
   private $operator;
   private $value;

src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php

@@ -2069,6 +2069,27 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
       $op_null = PhabricatorQueryConstraint::OPERATOR_NULL;
       $has_null = isset($constraints[$op_null]);
 
+      // If we're going to process an only() operator, build a list of the
+      // acceptable set of PHIDs first. We'll only match results which have
+      // no edges to any other PHIDs.
+      $all_phids = array();
+      if (isset($constraints[PhabricatorQueryConstraint::OPERATOR_ONLY])) {
+        foreach ($constraints as $operator => $list) {
+          switch ($operator) {
+            case PhabricatorQueryConstraint::OPERATOR_ANCESTOR:
+            case PhabricatorQueryConstraint::OPERATOR_AND:
+            case PhabricatorQueryConstraint::OPERATOR_OR:
+              foreach ($list as $constraint) {
+                $value = (array)$constraint->getValue();
+                foreach ($value as $v) {
+                  $all_phids[$v] = $v;
+                }
+              }
+              break;
+          }
+        }
+      }
+
       foreach ($constraints as $operator => $list) {
         $alias = $this->getEdgeLogicTableAlias($operator, $type);
 
@@ -2133,6 +2154,20 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
               $alias,
               $type);
             break;
+          case PhabricatorQueryConstraint::OPERATOR_ONLY:
+            $joins[] = qsprintf(
+              $conn,
+              'LEFT JOIN %T %T ON %Q = %T.src AND %T.type = %d
+                AND %T.dst NOT IN (%Ls)',
+              $edge_table,
+              $alias,
+              $phid_column,
+              $alias,
+              $alias,
+              $type,
+              $alias,
+              $all_phids);
+            break;
         }
       }
     }
@@ -2159,6 +2194,7 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
         $alias = $this->getEdgeLogicTableAlias($operator, $type);
         switch ($operator) {
           case PhabricatorQueryConstraint::OPERATOR_NOT:
+          case PhabricatorQueryConstraint::OPERATOR_ONLY:
             $full[] = qsprintf(
               $conn,
               '%T.dst IS NULL',
@@ -2258,6 +2294,7 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
             // discussion, see T12753.
             return true;
           case PhabricatorQueryConstraint::OPERATOR_NULL:
+          case PhabricatorQueryConstraint::OPERATOR_ONLY:
             return true;
         }
       }
@@ -2375,6 +2412,34 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
       }
     }
 
+    $op_and = PhabricatorQueryConstraint::OPERATOR_AND;
+    $op_or = PhabricatorQueryConstraint::OPERATOR_OR;
+    $op_ancestor = PhabricatorQueryConstraint::OPERATOR_ANCESTOR;
+
+    foreach ($this->edgeLogicConstraints as $type => $constraints) {
+      foreach ($constraints as $operator => $list) {
+        switch ($operator) {
+          case PhabricatorQueryConstraint::OPERATOR_ONLY:
+            if (count($list) > 1) {
+              throw new PhabricatorEmptyQueryException(
+                pht(
+                  'This query specifies only() more than once.'));
+            }
+
+            $have_and = idx($constraints, $op_and);
+            $have_or = idx($constraints, $op_or);
+            $have_ancestor = idx($constraints, $op_ancestor);
+            if (!$have_and && !$have_or && !$have_ancestor) {
+              throw new PhabricatorEmptyQueryException(
+                pht(
+                  'This query specifies only(), but no other constraints '.
+                  'which it can apply to.'));
+            }
+            break;
+        }
+      }
+    }
+
     $this->edgeLogicConstraintsAreValid = true;
 
     return $this;