Implement result modifiers in view query condition

8 files changed, 134 insertions, 4 deletions

diff --git a/odb/context.hxx b/odb/context.hxx
index 34f9692..d6e4713 100644
--- a/odb/context.hxx
+++ b/odb/context.hxx
@@ -199,6 +199,8 @@ view_relationship_map;
 //
 struct view_query
 {
+  view_query (): distinct (false), for_update (false) {}
+
   enum kind_type
   {
     runtime,
@@ -212,6 +214,11 @@ struct view_query
   cxx_tokens expr;
   tree scope;
   location_t loc;
+
+  // Result modifiers (only for condition).
+  //
+  bool distinct;   // SELECT DISTINCT
+  bool for_update; // SELECT FOR UPDATE
 };
 
 //
diff --git a/odb/pragma.cxx b/odb/pragma.cxx
index 7a3d6ec..618df67 100644
--- a/odb/pragma.cxx
+++ b/odb/pragma.cxx
@@ -176,8 +176,8 @@ parse_expression (cxx_lexer& l,
                   cxx_tokens& ts,
                   string const& prag)
 {
-  // Keep reading tokens until we see a matching ')' while keeping track
-  // of their balance.
+  // Keep reading tokens until we see a mis-matching ')' or ',' while
+  // keeping track of the '()' balance.
   //
   size_t balance (0);
 
@@ -201,6 +201,13 @@ parse_expression (cxx_lexer& l,
           balance--;
         break;
       }
+    case CPP_COMMA:
+      {
+        if (balance == 0)
+          done = true;
+        else
+          break;
+      }
     case CPP_STRING:
       {
         ct.literal = tl;
@@ -1584,6 +1591,55 @@ handle_pragma (cxx_lexer& l,
         return; // Diagnostics has already been issued.
     }
 
+    // Disallow query(, distinct).
+    //
+    if (tt == CPP_COMMA && vq.expr.empty ())
+    {
+      error (l) << "query expression expected in db pragma " << p << endl;
+      return;
+    }
+
+    // The query expression can be omitted with the modifier in its
+    // place. Handle this case.
+    //
+    if (vq.expr.size () == 1 && vq.expr.front ().type == CPP_NAME)
+    {
+      string const& n (vq.expr.front ().literal);
+
+      if (n == "distinct")
+        vq.distinct = true;
+      else if (n == "for_update")
+        vq.for_update = true;
+
+      if (vq.distinct || vq.for_update)
+        vq.expr.clear ();
+    }
+
+    if (tt == CPP_COMMA)
+    {
+      do
+      {
+        if (l.next (tl, &tn) != CPP_NAME)
+        {
+          error (l) << "result modifier expected in db pragma " << p << endl;
+          return;
+        }
+
+        if (tl == "distinct")
+          vq.distinct = true;
+        else if (tl == "for_update")
+          vq.for_update = true;
+        else
+        {
+          error (l) << "unknown result modifier '" << tl << "'" << endl;
+          return;
+        }
+
+        tt = l.next (tl, &tn);
+
+      } while (tt == CPP_COMMA);
+    }
+
     if (tt != CPP_CLOSE_PAREN)
     {
       error (l) << "')' expected at the end of db pragma " << p << endl;
diff --git a/odb/relational/mssql/source.cxx b/odb/relational/mssql/source.cxx
index ca36dfb..71bc40e 100644
--- a/odb/relational/mssql/source.cxx
+++ b/odb/relational/mssql/source.cxx
@@ -1179,6 +1179,17 @@ namespace relational
           }
         }
 
+        virtual string
+        from_trailer (type& c)
+        {
+          return c.get<view_query> ("query").for_update
+            ? " WITH (UPDLOCK)"
+            : "";
+        }
+
+        virtual string
+        select_trailer (type&) {return "";}
+
       private:
         // Go via the dynamic creation to get access to the constructor.
         //
diff --git a/odb/relational/oracle/source.cxx b/odb/relational/oracle/source.cxx
index ea4a14b..71b032e 100644
--- a/odb/relational/oracle/source.cxx
+++ b/odb/relational/oracle/source.cxx
@@ -619,6 +619,21 @@ namespace relational
 
           return r;
         }
+
+        virtual string
+        select_trailer (type& c)
+        {
+          view_query const& vq (c.get<view_query> ("query"));
+
+          if (vq.for_update && vq.distinct)
+          {
+            error (vq.loc)
+              << "Oracle does not support FOR UPDATE with DISTINCT" << endl;
+            throw operation_failed ();
+          }
+
+          return base::select_trailer (c);
+        }
       };
       entry<class_> class_entry_;
     }
diff --git a/odb/relational/processor.cxx b/odb/relational/processor.cxx
index 7658725..16904b6 100644
--- a/odb/relational/processor.cxx
+++ b/odb/relational/processor.cxx
@@ -1298,11 +1298,23 @@ namespace relational
               vq.kind = view_query::condition;
           }
           else
-            vq.kind = view_query::runtime;
+            vq.kind = (vq.distinct || vq.for_update)
+              ? view_query::condition // The query(distinct) case.
+              : view_query::runtime;
         }
         else
           vq.kind = has_o ? view_query::condition : view_query::runtime;
 
+        if ((vq.distinct || vq.for_update) && vq.kind != view_query::condition)
+        {
+          error (vq.loc)
+            << "result modifier specified for "
+            << (vq.kind == view_query::runtime ? "runtime" : "native")
+            << " query" << endl;
+
+          throw operation_failed ();
+        }
+
         // We cannot have an incomplete query if there are not objects
         // to derive the rest from.
         //
diff --git a/odb/relational/source.cxx b/odb/relational/source.cxx
index 39a210e..dc083bb 100644
--- a/odb/relational/source.cxx
+++ b/odb/relational/source.cxx
@@ -4770,6 +4770,8 @@ traverse_view (type& c)
           if (!i->alias.empty ())
             l += (need_alias_as ? " AS " : " ") + quote_id (i->alias);
 
+          l += from_trailer (c);
+
           from.push_back (l);
           continue;
         }
@@ -4829,6 +4831,8 @@ traverse_view (type& c)
         if (!alias.empty ())
           l += (need_alias_as ? " AS " : " ") + quote_id (alias);
 
+        l += from_trailer (c);
+
         from.push_back (l);
 
         if (poly_depth != 1)
@@ -5539,7 +5543,7 @@ traverse_view (type& c)
       string sep (versioned || query_optimize ? "\n" : " ");
 
       os << "query_base_type r (" << endl
-         << strlit ("SELECT" + sep);
+         << strlit ((vq.distinct ? "SELECT DISTINCT" : "SELECT") + sep);
 
       for (statement_columns::const_iterator i (sc.begin ()),
              e (sc.end ()); i != e;)
@@ -5632,6 +5636,13 @@ traverse_view (type& c)
            << "r += c.clause_prefix ();"
            << "r += c;"
            << "}";
+
+        string st (select_trailer (c));
+        if (!st.empty ())
+        {
+          os << "r += " << strlit (sep) << ";"
+             << "r += " << strlit (st) << ";";
+        }
       }
       else
       {
diff --git a/odb/relational/source.hxx b/odb/relational/source.hxx
index a725b6a..48d0e1d 100644
--- a/odb/relational/source.hxx
+++ b/odb/relational/source.hxx
@@ -6677,6 +6677,15 @@ namespace relational
            << "imb";
       }
 
+      virtual string
+      from_trailer (type&) { return "";}
+
+      virtual string
+      select_trailer (type& c)
+      {
+        return c.get<view_query> ("query").for_update ? "FOR UPDATE" : "";
+      }
+
       virtual void
       traverse_view (type& c);
 
diff --git a/odb/relational/sqlite/source.cxx b/odb/relational/sqlite/source.cxx
index 3dfaae2..0824eb2 100644
--- a/odb/relational/sqlite/source.cxx
+++ b/odb/relational/sqlite/source.cxx
@@ -246,6 +246,15 @@ namespace relational
         {
           os << im << "null = true;";
         }
+
+        virtual string
+        select_trailer (type&)
+        {
+          // SQLite has not support for FOR UPDATE and since this is an
+          // optimization, we simply ignore it.
+          //
+          return "";
+        }
       };
       entry<class_> class_entry_;
     }