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Diffstat (limited to 'odb/mysql/polymorphic-object-result.txx')
-rw-r--r-- | odb/mysql/polymorphic-object-result.txx | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/odb/mysql/polymorphic-object-result.txx b/odb/mysql/polymorphic-object-result.txx new file mode 100644 index 0000000..2e27677 --- /dev/null +++ b/odb/mysql/polymorphic-object-result.txx @@ -0,0 +1,344 @@ +// file : odb/mysql/polymorphic-object-result.txx +// copyright : Copyright (c) 2009-2012 Code Synthesis Tools CC +// license : GNU GPL v2; see accompanying LICENSE file + +#include <cassert> + +#include <odb/callback.hxx> +#include <odb/cache-traits.hxx> +#include <odb/exceptions.hxx> // result_not_cached + +#include <odb/mysql/polymorphic-object-statements.hxx> + +namespace odb +{ + namespace mysql + { + template <typename T> + polymorphic_object_result_impl<T>:: + ~polymorphic_object_result_impl () + { + if (!this->end_) + statement_->free_result (); + } + + template <typename T> + polymorphic_object_result_impl<T>:: + polymorphic_object_result_impl (const query&, + details::shared_ptr<select_statement> st, + statements_type& sts) + : base_type (sts.connection ().database ()), + statement_ (st), + statements_ (sts), + count_ (0) + { + } + + template <typename T> + void polymorphic_object_result_impl<T>:: + load (object_type* pobj, bool f) + { + if (count_ > statement_->fetched ()) + fetch (); + else if (f && statement_->cached ()) + { + // We have to re-load the image in case it has been overwritten + // between the last time we fetched and this call to load(). + // + fetch (false); + } + + typename statements_type::root_statements_type& rsts ( + statements_.root_statements ()); + + // This is a top-level call so the statements cannot be locked. + // + assert (!rsts.locked ()); + typename statements_type::auto_lock l (rsts); + + odb::database& db (this->database ()); + typename object_traits::image_type& i (statements_.image ()); + typename root_traits::image_type& ri (rsts.image ()); + + id_type id (root_traits::id (ri)); + + // Determine this object's dynamic type. + // + typedef typename root_traits::info_type info_type; + discriminator_type d (root_traits::discriminator (ri)); + discriminator_type disc (d); + + // Use the polymorphic_info() helper to get concrete_info if + // object_type is concrete and NULL if it is abstract. + // + const info_type* spi (polymorphic_info (object_traits::info)); + const info_type& pi ( + spi != 0 && spi->discriminator == d + ? *spi + : root_traits::map->find (d)); + + typedef typename root_traits::pointer_type root_pointer_type; + typedef typename root_traits::pointer_traits root_pointer_traits; + + typename object_traits::pointer_cache_traits::insert_guard ig; + + if (pobj == 0) + { + // Need to create a new instance of the dynamic type. + // + root_pointer_type rp (pi.create ()); + pointer_type p ( + root_pointer_traits::template static_pointer_cast<object_type> (rp)); + + // Insert it as a root pointer (for non-unique pointers, rp should + // still be valid and for unique pointers this is a no-op). + // + ig.reset (object_traits::pointer_cache_traits::insert (db, id, rp)); + + pobj = &pointer_traits::get_ref (p); + current (p); + } + else + { + // We are loading into an existing instance. If the static and + // dynamic types differ, then make sure the instance is at least + // of the dynamic type. + // + if (&pi != &object_traits::info) + { + const info_type& dpi (root_traits::map->find (typeid (*pobj))); + + if (&dpi != &pi && dpi.derived (pi)) + throw object_not_persistent (); // @@ type_mismatch ? + } + } + + callback_event ce (callback_event::pre_load); + pi.dispatch (info_type::call_callback, db, pobj, &ce); + + object_traits::init (*pobj, i, &db); + + // Initialize the id image and binding and load the rest of the object + // (containers, dynamic part, etc). + // + typename object_traits::id_image_type& idi (statements_.id_image ()); + root_traits::init (idi, id); + + binding& idb (statements_.id_image_binding ()); + if (idi.version != statements_.id_image_version () || idb.version == 0) + { + object_traits::bind (idb.bind, idi); + statements_.id_image_version (idi.version); + idb.version++; + } + + object_traits::load_ (statements_, *pobj); + + // Load the dynamic part of the object unless static and dynamic + // types are the same. + // + if (&pi != &object_traits::info) + { + std::size_t d (object_traits::depth); + pi.dispatch (info_type::call_load, db, pobj, &d); + }; + + rsts.load_delayed (); + l.unlock (); + + ce = callback_event::post_load; + pi.dispatch (info_type::call_callback, db, pobj, &ce); + ig.release (); + } + + template <typename T> + typename polymorphic_object_result_impl<T>::id_type + polymorphic_object_result_impl<T>:: + load_id () + { + if (count_ > statement_->fetched ()) + fetch (); + else if (statement_->cached ()) + { + // We have to re-load the image in case it has been overwritten + // between the last time we fetched and this call to load_id(). + // + fetch (false); + } + + return root_traits::id (statements_.root_statements ().image ()); + } + + template <typename T> + typename polymorphic_object_result_impl<T>::discriminator_type + polymorphic_object_result_impl<T>:: + load_discriminator () + { + if (count_ > statement_->fetched ()) + fetch (); + else if (statement_->cached ()) + { + // We have to re-load the image in case it has been overwritten + // between the last time we fetched and this call to + // load_discriminator(). + // + fetch (false); + } + + return root_traits::discriminator ( + statements_.root_statements ().image ()); + } + + template <typename T> + void polymorphic_object_result_impl<T>:: + next () + { + this->current (pointer_type ()); + + // If we are cached, simply increment the position and + // postpone the actual row fetching until later. This way + // if the same object is loaded in between iteration, the + // image won't be messed up. + // + count_++; + + if (statement_->cached ()) + this->end_ = count_ > statement_->result_size (); + else + fetch (); + + if (this->end_) + statement_->free_result (); + } + + template <typename T, typename R> + struct polymorphic_image_rebind + { + // Derived type version. + // + typedef object_traits<T> traits; + + static bool + rebind (typename traits::statements_type& sts) + { + typename traits::image_type& im (sts.image ()); + + if (traits::check_version (sts.select_image_versions (), im)) + { + binding& b (sts.select_image_binding (traits::depth)); + traits::bind (b.bind, 0, 0, im, statement_select); + traits::update_version ( + sts.select_image_versions (), im, sts.select_image_bindings ()); + return true; + } + + return false; + } + }; + + template <typename R> + struct polymorphic_image_rebind<R, R> + { + // Root type version. + // + typedef object_traits<R> traits; + + static bool + rebind (typename traits::statements_type& sts) + { + typename traits::image_type& im (sts.image ()); + + if (im.version != sts.select_image_version ()) + { + binding& b (sts.select_image_binding ()); + traits::bind (b.bind, im, statement_select); + sts.select_image_version (im.version); + b.version++; + return true; + } + + return false; + } + }; + + template <typename T> + void polymorphic_object_result_impl<T>:: + fetch (bool next) + { + typedef polymorphic_image_rebind<object_type, root_type> image_rebind; + + // If the result is cached, the image can grow between calls + // to fetch() as a result of other statements execution. + // + if (statement_->cached ()) + image_rebind::rebind (statements_); + + while (!this->end_ && (!next || count_ > statement_->fetched ())) + { + select_statement::result r (statement_->fetch (next)); + + switch (r) + { + case select_statement::truncated: + { + // Don't re-fetch data we are skipping. + // + if (next && count_ != statement_->fetched ()) + continue; + + typename object_traits::image_type& im (statements_.image ()); + + if (object_traits::grow (im, + statements_.select_image_truncated ())) + im.version++; + + if (image_rebind::rebind (statements_)) + statement_->refetch (); + + // Fall throught. + } + case select_statement::success: + { + break; + } + case select_statement::no_data: + { + this->end_ = true; + break; + } + } + + // If we are refetching the current row, then we are done. + // + if (!next) + break; + } + } + + template <typename T> + void polymorphic_object_result_impl<T>:: + cache () + { + if (!statement_->cached ()) + { + statement_->cache (); + + if (count_ >= statement_->result_size ()) + { + statement_->free_result (); + this->end_ = true; + } + } + } + + template <typename T> + std::size_t polymorphic_object_result_impl<T>:: + size () + { + if (!statement_->cached ()) + throw result_not_cached (); + + return statement_->result_size (); + } + } +} |