[[ Bug 20567 ]] Add 'the caller' LCB syntax

livecodeali · livecodeali · commit b2adedae6a06 · 2017-10-14T13:58:31.000+01:00
diff --git a/docs/lcb/notes/20567.md b/docs/lcb/notes/20567.md
@@ -0,0 +1,7 @@
+# LiveCode Builder Language
+
+## `the caller` syntax
+`the caller` syntax has been added to the engine module. It 
+returns the script object which called a the handler at the 
+beginning of the current chain of LiveCode Builder handler 
+execution.
diff --git a/engine/src/engine.lcb b/engine/src/engine.lcb
@@ -58,6 +58,8 @@ public foreign handler MCEngineExecSendWithArguments(in pIsFunction as CBool, in
 public foreign handler MCEngineExecPost(in pMessage as String) returns nothing binds to "<builtin>"
 public foreign handler MCEngineExecPostWithArguments(in pMessage as String, in pArguments as optional List) returns nothing binds to "<builtin>"
 
+public foreign handler MCEngineEvalCaller(out rObject as ScriptObject) returns nothing binds to "<builtin>"
+
 public foreign handler MCEngineEvalMessageWasHandled(out pHandled as CBool) returns nothing binds to "<builtin>"
 public foreign handler MCEngineEvalMessageWasNotHandled(out pHandled as CBool) returns nothing binds to "<builtin>"
 public foreign handler MCEngineExecExecuteScript(in pScript as String) returns any binds to "<builtin>"
@@ -397,6 +399,27 @@ begin
     MCEngineEvalMessageWasNotHandled(output)
 end syntax
 
+/**
+Summary: 	The caller's script object
+
+Example:
+	public handler NotifyMe() returns nothing
+		post "notify" to the caller
+	end handler
+
+Description:
+Returns the script object which called the handler at the beginning
+of the current chain of LiveCode Builder handler execution.
+
+Tags: Script Engine
+*/
+
+syntax Caller is expression
+    "the" "caller"
+begin
+    MCEngineEvalCaller(output)
+end syntax
+
 /**
 Summary: Executes some LiveCode script.
 Script:  The script to execute.
diff --git a/engine/src/module-engine.cpp b/engine/src/module-engine.cpp
@@ -602,6 +602,12 @@ extern "C" MC_DLLEXPORT_DEF void MCEngineEvalMessageWasNotHandled(bool& r_not_ha
     r_not_handled = !t_handled;
 }
 
+extern MCExecContext *MCECptr;
+extern "C" MC_DLLEXPORT_DEF void MCEngineEvalCaller(MCScriptObjectRef& r_script_object)
+{
+    if (!MCEngineScriptObjectCreate(MCECptr->GetObject(), 0, r_script_object))
+        return;
+}
 ////////////////////////////////////////////////////////////////////////////////
 
 static MCValueRef
diff --git a/tests/lcs/core/engine-lcb/_engine.lcb b/tests/lcs/core/engine-lcb/_engine.lcb
@@ -49,4 +49,7 @@ public handler TestExtensionLog_DeletedScriptObject()
 	log tScriptObject
 end handler
 
+public handler TestEngine_Caller(in pCallback as String)
+	send pCallback to the caller
+end handler
 end library
diff --git a/tests/lcs/core/engine-lcb/engine.livecodescript b/tests/lcs/core/engine-lcb/engine.livecodescript
@@ -136,3 +136,20 @@ on TestExtensionLogScriptObject
   TestDiagnostic sLastLog
   TestAssert "extension log deleted scriptobject", sLastLog is "<deleted script object>"
 end TestExtensionLogScriptObject
+
+local sCallbackTarget
+on CallerCallback
+	TestDiagnostic "called"
+	put the long id of the target into sCallbackTarget
+end CallerCallback
+
+on TestEngineCaller
+   local tButton
+   create button
+   put it into tButton
+   set the script of tButton to "on doTest;TestEngine_Caller" \
+      && quote & "CallerCallback" & quote & ";end doTest"
+    send "doTest" to tButton
+    TestAssert "library handler can get caller", \
+    	the long id of sCallbackTarget is the long id of tButton
+end TestEngineCaller
