From 72f0237f3310a69fd566f1d2c25ca805f677199a Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 5 Jul 2011 18:39:09 +0200
Subject: Add support for multi-pass database schema generation

---
 odb/schema-catalog-impl.hxx |  3 ++-
 odb/schema-catalog.cxx      | 22 ++++++++++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/odb/schema-catalog-impl.hxx b/odb/schema-catalog-impl.hxx
index 782536a..51a4902 100644
--- a/odb/schema-catalog-impl.hxx
+++ b/odb/schema-catalog-impl.hxx
@@ -35,7 +35,8 @@ namespace odb
   //
   struct LIBODB_EXPORT schema_catalog_entry
   {
-    schema_catalog_entry (const char* name, void (*entry) (database&));
+    schema_catalog_entry (const char* name,
+                          bool (*entry) (database&, unsigned short pass));
   };
 }
 
diff --git a/odb/schema-catalog.cxx b/odb/schema-catalog.cxx
index 5332cce..2d8415f 100644
--- a/odb/schema-catalog.cxx
+++ b/odb/schema-catalog.cxx
@@ -14,7 +14,7 @@ using namespace std;
 
 namespace odb
 {
-  typedef void (*create_function) (database&);
+  typedef bool (*create_function) (database&, unsigned short pass);
   typedef vector<create_function> create_functions;
   struct schema_catalog_impl: map<string, create_functions> {};
 
@@ -33,9 +33,23 @@ namespace odb
 
     const create_functions& fs (i->second);
 
-    for (create_functions::const_iterator j (fs.begin ()), e (fs.end ());
-         j != e; ++j)
-      (*j) (db);
+    // Run the passes until we ran them all or all the functions
+    // return false, which means no more passes necessary.
+    //
+    for (unsigned short pass (0); pass < 3; ++pass)
+    {
+      bool done (true);
+
+      for (create_functions::const_iterator j (fs.begin ()), e (fs.end ());
+           j != e; ++j)
+      {
+        if ((*j) (db, pass))
+          done = false;
+      }
+
+      if (done)
+        break;
+    }
   }
 
   // schema_catalog_init
-- 
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