gras: work on C++ API for properties interface

4 files changed, 169 insertions, 1 deletions

diff --git a/include/gras/CMakeLists.txt b/include/gras/CMakeLists.txt
index 301f96a..462b0ff 100644
--- a/include/gras/CMakeLists.txt
+++ b/include/gras/CMakeLists.txt
@@ -28,6 +28,8 @@ install(FILES
 
 install(FILES
 
+    detail/block.hpp
+    detail/property.hpp
     detail/sbuffer.hpp
     detail/work_buffer.hpp
 
diff --git a/include/gras/block.hpp b/include/gras/block.hpp
index 1c6516d..d33457b 100644
--- a/include/gras/block.hpp
+++ b/include/gras/block.hpp
@@ -9,6 +9,7 @@
 #include <gras/tags.hpp>
 #include <gras/work_buffer.hpp>
 #include <gras/buffer_queue.hpp>
+#include <gras/detail/property.hpp>
 #include <vector>
 #include <string>
 
@@ -105,7 +106,7 @@ struct GRAS_API OutputPortConfig
     size_t maximum_items;
 };
 
-struct GRAS_API Block : Element
+struct GRAS_API Block : Element, PropertyInterface
 {
 
     //! Contruct an empty/null block
@@ -214,6 +215,71 @@ struct GRAS_API Block : Element
     PMCC pop_input_msg(const size_t which_input);
 
     /*******************************************************************
+     * The property interface:
+     * Provides polymorphic, thread-safe access to block properties.
+     ******************************************************************/
+
+    /*!
+     * Register property get and set methods into the property interface.
+     * Call register_property() from the contructor of the block.
+     *
+     * Note: It is safe for the user to register a NULL function if the user
+     * wishes to not register a getter or setter for a particular property.
+     *
+     * Example register usage:
+     * this->register_property("foo", &MyBlock::get_foo, &MyBlock::set_foo);
+     *
+     * Example method declarations:
+     * int get_foo(void);
+     * void set_foo(const int &new_foo);
+     *
+     * \param key the string to identify this property
+     * \param get the class method to get the property
+     * \param set the class method to set the property
+     */
+    template <typename ClassType, typename ValueType>
+    void register_property(
+        const std::string &key,
+        ValueType(ClassType::*get)(void),
+        void(ClassType::*set)(const ValueType &)
+    );
+
+    /*!
+     * Set the value of a registered property.
+     *
+     * This call is synchronous and will not return until
+     * the block has actually called the registered set operation.
+     *
+     * Note: the user must be careful to only use a value
+     * that is of the exact type associated with this property.
+     * Otherwise, set_property with throw a type error.
+     *
+     * Example with template argument to be type explicit:
+     * my_block->set_property<size_t>("foo", 42);
+     *
+     * \param key the string to identify this property
+     * \param value the new value to set to this property
+     */
+    template <typename ValueType>
+    void set_property(const std::string &key, const ValueType &value);
+
+    /*!
+     * Get the value of a registered property.
+     *
+     * Note: the user must specify the correct value type
+     * that is of the exact type associated with this property.
+     * Otherwise, get_property with throw a type error.
+     *
+     * Example with template argument to be type explicit:
+     * const size_t foo = my_block->get_property<size_t>("foo");
+     *
+     * \param key the string to identify this property
+     * \return the value of this property
+     */
+    template <typename ValueType>
+    ValueType get_property(const std::string &key);
+
+    /*******************************************************************
      * Work related routines and fail states
      ******************************************************************/
 
@@ -396,4 +462,6 @@ struct GRAS_API Block : Element
 
 } //namespace gras
 
+#include <gras/detail/block.hpp>
+
 #endif /*INCLUDED_GRAS_BLOCK_HPP*/
diff --git a/include/gras/detail/block.hpp b/include/gras/detail/block.hpp
new file mode 100644
index 0000000..483b2bf
--- /dev/null
+++ b/include/gras/detail/block.hpp
@@ -0,0 +1,35 @@
+// Copyright (C) by Josh Blum. See LICENSE.txt for licensing information.
+
+#ifndef INCLUDED_GRAS_DETAIL_BLOCK_HPP
+#define INCLUDED_GRAS_DETAIL_BLOCK_HPP
+
+namespace gras
+{
+
+template <typename ClassType, typename ValueType>
+GRAS_FORCE_INLINE void Block::register_property(
+    const std::string &key,
+    ValueType(ClassType::*get)(void),
+    void(ClassType::*set)(const ValueType &)
+)
+{
+    boost::shared_ptr<PropertyRegistry> pr;
+    pr.reset(new PropertyRegistryImpl<ClassType, ValueType>(this, get, set));
+    this->property_interface_register(key, pr);
+}
+
+template <typename ValueType>
+GRAS_FORCE_INLINE void Block::set_property(const std::string &key, const ValueType &value)
+{
+    return this->property_interface_set(key, PMC_M(value));
+}
+
+template <typename ValueType>
+GRAS_FORCE_INLINE ValueType Block::get_property(const std::string &key)
+{
+    return this->property_interface_get(key).as<ValueType>();
+}
+
+} //namespace gras
+
+#endif /*INCLUDED_GRAS_DETAIL_BLOCK_HPP*/
diff --git a/include/gras/detail/property.hpp b/include/gras/detail/property.hpp
new file mode 100644
index 0000000..467fb70
--- /dev/null
+++ b/include/gras/detail/property.hpp
@@ -0,0 +1,63 @@
+// Copyright (C) by Josh Blum. See LICENSE.txt for licensing information.
+
+#ifndef INCLUDED_GRAS_DETAIL_PROPERTY_HPP
+#define INCLUDED_GRAS_DETAIL_PROPERTY_HPP
+
+#include <PMC/PMC.hpp>
+
+namespace gras
+{
+
+struct PropertyRegistry
+{
+    PropertyRegistry(void){}
+    ~PropertyRegistry(void){}
+    virtual void set(const PMCC &) = 0;
+    virtual PMCC get(void) = 0;
+};
+
+template <typename ClassType, typename ValueType>
+struct PropertyRegistryImpl : PropertyRegistry
+{
+    PropertyRegistryImpl(
+        ClassType *my_class,
+        ValueType(ClassType::*getter)(void),
+        void(ClassType::*setter)(const ValueType &)
+    ):
+        _my_class(my_class),
+        _getter(getter),
+        _setter(setter)
+    {}
+    ~PropertyRegistryImpl(void){}
+
+    void set(const PMCC &value)
+    {
+        return _setter(_my_class, value.as<ValueType>());
+    }
+
+    PMCC get(void)
+    {
+        return PMC_M(_getter(_my_class));
+    }
+
+    ClassType *_my_class;
+    ValueType(ClassType::*_getter)(void);
+    void(ClassType::*_setter)(const ValueType &);
+};
+
+struct PropertyInterface
+{
+    virtual void property_interface_register(
+        const std::string &key,
+        boost::shared_ptr<PropertyRegistry> pr
+    ) = 0;
+
+    virtual void property_interface_set(const std::string &key, const PMCC &value) = 0;
+
+    virtual PMCC property_interface_get(const std::string &key) = 0;
+
+};
+
+} //namespace gras
+
+#endif /*INCLUDED_GRAS_DETAIL_PROPERTY_HPP*/