DEV-31980: extract dispatch-by-string-name logic from LLAresListener to new

LLEventDispatcher and LLDispatchListener classes. See LLAresListener for
example usage.

1 files changed, 108 insertions, 0 deletions

diff --git a/indra/llcommon/lleventdispatcher.h b/indra/llcommon/lleventdispatcher.h
new file mode 100644
index 0000000000..d75055fd6f
--- /dev/null
+++ b/indra/llcommon/lleventdispatcher.h
@@ -0,0 +1,108 @@
+/**
+ * @file   lleventdispatcher.h
+ * @author Nat Goodspeed
+ * @date   2009-06-18
+ * @brief  Central mechanism for dispatching events by string name. This is
+ *         useful when you have a single LLEventPump listener on which you can
+ *         request different operations, vs. instantiating a different
+ *         LLEventPump for each such operation.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLEVENTDISPATCHER_H)
+#define LL_LLEVENTDISPATCHER_H
+
+#include <string>
+#include <map>
+#include <boost/function.hpp>
+#include <boost/bind.hpp>
+#include <typeinfo>
+#include "llevents.h"
+
+class LLSD;
+
+/**
+ * Given an LLSD map, examine a string-valued key and call a corresponding
+ * callable. This class is designed to be contained by an LLEventPump
+ * listener class that will register some of its own methods, though any
+ * callable can be used.
+ */
+class LLEventDispatcher
+{
+public:
+    LLEventDispatcher(const std::string& desc, const std::string& key);
+    virtual ~LLEventDispatcher();
+
+    /// Accept any C++ callable, typically a boost::bind() expression
+    typedef boost::function<void(const LLSD&)> Callable;
+
+    /// Register a @a callable by @a name. The optional @a required parameter
+    /// is used to validate the structure of each incoming event (see
+    /// llsd_matches()).
+    void add(const std::string& name, const Callable& callable, const LLSD& required=LLSD());
+
+    /// Special case: a subclass of this class can register a @a method
+    /// without explicitly specifying the <tt>boost::bind()</tt> expression.
+    /// The optional @a required parameter is used to validate the structure
+    /// of each incoming event (see llsd_matches()).
+    template <class CLASS>
+    void add(const std::string& name, void (CLASS::*method)(const LLSD&),
+             const LLSD& required=LLSD())
+    {
+        CLASS* downcast = dynamic_cast<CLASS*>(this);
+        if (! downcast)
+        {
+            addFail(name, typeid(CLASS).name());
+        }
+        else
+        {
+            add(name, boost::bind(method, downcast, _1), required);
+        }
+    }
+
+    /// Unregister a callable
+    bool remove(const std::string& name);
+
+    /// Call a registered callable with an explicitly-specified name. If no
+    /// such callable exists, die with LL_ERRS. If the @a event fails to match
+    /// the @a required prototype specified at add() time, die with LL_ERRS.
+    void operator()(const std::string& name, const LLSD& event) const;
+
+    /// Extract the @a key value from the incoming @a event, and call the
+    /// callable whose name is specified by that map @a key. If no such
+    /// callable exists, die with LL_ERRS. If the @a event fails to match the
+    /// @a required prototype specified at add() time, die with LL_ERRS.
+    void operator()(const LLSD& event) const;
+
+private:
+    void addFail(const std::string& name, const std::string& classname) const;
+    /// try to dispatch, return @c true if success
+    bool attemptCall(const std::string& name, const LLSD& event) const;
+
+    std::string mDesc, mKey;
+    typedef std::map<std::string, std::pair<Callable, LLSD> > DispatchMap;
+    DispatchMap mDispatch;
+};
+
+/**
+ * Bundle an LLEventPump and a listener with an LLEventDispatcher. A class
+ * that contains (or derives from) LLDispatchListener need only specify the
+ * LLEventPump name and dispatch key, and add() its methods. Incoming events
+ * will automatically be dispatched.
+ */
+class LLDispatchListener: public LLEventDispatcher
+{
+public:
+    LLDispatchListener(const std::string& pumpname, const std::string& key);
+
+private:
+    bool process(const LLSD& event);
+
+    LLEventStream mPump;
+    LLTempBoundListener mBoundListener;
+};
+
+#endif /* ! defined(LL_LLEVENTDISPATCHER_H) */