From 071fe5eef8d88ac51d4ed6436aa2ffc95283ae5b Mon Sep 17 00:00:00 2001
From: Constantin Michael <constantin@codesynthesis.com>
Date: Thu, 8 Sep 2011 09:23:47 +0200
Subject: Implement SQLite style select statement interface

---
 odb/oracle/statement.cxx | 71 ++++++++++++++++++++++--------------------------
 odb/oracle/statement.hxx | 43 ++++++++++++++++++++++++-----
 2 files changed, 68 insertions(+), 46 deletions(-)

diff --git a/odb/oracle/statement.cxx b/odb/oracle/statement.cxx
index 9398820..f41c161 100644
--- a/odb/oracle/statement.cxx
+++ b/odb/oracle/statement.cxx
@@ -114,7 +114,7 @@ namespace odb
                       binding& cond,
                       binding& data)
         : statement (conn, s),
-          end_ (false),
+          done_ (false),
           rows_ (0)
     {
       bind_param (cond.bind, cond.count, 0);
@@ -124,7 +124,7 @@ namespace odb
     void select_statement::
     execute ()
     {
-      if (!end_)
+      if (!done_)
         free_result ();
 
       // @@ Retrieve a single row into the already bound output buffers
@@ -144,52 +144,45 @@ namespace odb
         translate_error (conn_.error_handle (), r);
     }
 
-    select_statement::result select_statement::
-    fetch ()
+    void select_statement::
+    free_result ()
     {
-      sword r (OCIStmtFetch2 (stmt_,
-                              conn_.error_handle (),
-                              1,
-                              OCI_FETCH_NEXT,
-                              0,
-                              OCI_DEFAULT));
-
-      switch (r)
+      if (!done_)
       {
-      case OCI_SUCCESS:
-        {
-          ++rows_;
-          return success;
-        }
-      case OCI_NO_DATA:
-        {
-          end_ = true;
-          return no_data;
-        }
-      default:
-        {
+        sword r (OCIStmtFetch2 (stmt_,
+                                conn_.error_handle (),
+                                0,
+                                OCI_FETCH_NEXT,
+                                0,
+                                OCI_DEFAULT));
+
+        if (r == OCI_ERROR || r == OCI_INVALID_HANDLE)
           translate_error (conn_.error_handle (), r);
-          return no_data; // Never reached.
-        }
+
+        done_ = true;
       }
-    }
 
+    }
 
-    void select_statement::
-    free_result ()
+    bool select_statement::
+    next ()
     {
-      end_ = true;
-      rows_ = 0;
+      if (!done_)
+      {
+        sword r (OCIStmtFetch2 (stmt_,
+                                conn_.error_handle (),
+                                1,
+                                OCI_FETCH_NEXT,
+                                0,
+                                OCI_DEFAULT));
 
-      sword r (OCIStmtFetch2 (stmt_,
-                              conn_.error_handle (),
-                              0,
-                              OCI_FETCH_NEXT,
-                              0,
-                              OCI_DEFAULT));
+        if (r == OCI_ERROR || r == OCI_INVALID_HANDLE)
+          translate_error (conn_.error_handle (), r);
+        else if (r == OCI_NO_DATA)
+          done_ = true;
+      }
 
-      if (r == OCI_ERROR || r == OCI_INVALID_HANDLE)
-        translate_error (conn_.error_handle (), r);
+      return !done_;
     }
 
     //
diff --git a/odb/oracle/statement.hxx b/odb/oracle/statement.hxx
index 8dfaa3f..6e183a8 100644
--- a/odb/oracle/statement.hxx
+++ b/odb/oracle/statement.hxx
@@ -74,26 +74,55 @@ namespace odb
       void
       execute ();
 
-      // Number of rows already fetched.
+      result
+      fetch ()
+      {
+        return next () ? load () : no_data;
+      }
+
+      // Never need to deal with truncation, so this is a dummy function.
       //
-      std::size_t
-      fetched () const
+      void
+      refetch ()
       {
-        return rows_;
       }
 
+      void
+      free_result ();
+
+      // More fine-grained Oracle-specific interface that splits fetch() into
+      // next() and load().
+      //
+    public:
+      // Return false if there is no more rows. You should call next() until it
+      // returns false or, alternatively, call free_result (). Otherwise, the
+      // statement will remain unfinished.
+      //
+      bool
+      next ();
+
       result
-      fetch ();
+      load ()
+      {
+        if (done_)
+          return no_data;
+
+        return success;
+      }
 
+      // Never need to deal with truncation, so this is a dummy function.
+      //
       void
-      free_result ();
+      reload ()
+      {
+      }
 
     private:
       select_statement (const select_statement&);
       select_statement& operator= (const select_statement&);
 
     private:
-      bool end_;
+      bool done_;
       std::size_t rows_;
     };
 
-- 
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