From 0f8faf662b1416020d07306938d282ee1f6eee1b Mon Sep 17 00:00:00 2001
From: Miguel Sofer <miguel.sofer@gmail.com>
Date: Thu, 10 Dec 2009 18:23:28 +0000
Subject: reorganization and better comments in TclNRCoroutineObjCmd()

---
 generic/tclBasic.c | 95 ++++++++++++++++++++++++++----------------------------
 1 file changed, 46 insertions(+), 49 deletions(-)

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index aa1e26b..079d034 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -16,7 +16,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclBasic.c,v 1.426 2009/12/10 17:48:39 msofer Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.427 2009/12/10 18:23:28 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -8775,13 +8775,20 @@ TclNRCoroutineObjCmd(
 	return TCL_ERROR;
     }
 
-    corPtr = (CoroutineData *) ckalloc(sizeof(CoroutineData));
-    corPtr->eePtr = TclCreateExecEnv(interp, CORO_STACK_INITIAL_SIZE);
-    corPtr->callerEEPtr = iPtr->execEnvPtr;
-    corPtr->eePtr->corPtr = corPtr;
-    corPtr->stackLevel = NULL;
-    corPtr->callerBP = NULL;
+    /*
+     * We ARE creating the coroutine command: allocate the corresponding
+     * struct, add the callback in caller's env and record the caller's
+     * frames. 
+     */
     
+    corPtr = (CoroutineData *) ckalloc(sizeof(CoroutineData));
+    TclNRAddCallback(interp, NRCoroutineCallerCallback, corPtr, NULL, NULL,
+	    NULL);
+    SAVE_CONTEXT(corPtr->caller);
+
+    /*
+     * Create the coroutine command.
+     */
 
     Tcl_DStringInit(&ds);
     if (nsPtr != iPtr->globalNsPtr) {
@@ -8798,39 +8805,6 @@ TclNRCoroutineObjCmd(
     cmdPtr->refCount++;
 
     /*
-     * Be sure not to pass a canonical list for the command so that we insure
-     * the body is bytecompiled: we need a TEBC instance to handle [yield]
-     */
-
-    cmdObjPtr = Tcl_NewListObj(objc-2, &objv[2]);
-    TclGetString(cmdObjPtr);
-    TclFreeIntRep(cmdObjPtr);
-    cmdObjPtr->typePtr = NULL;
-
-    /*
-     * Set up the callback in caller execEnv and switch to the new execEnv.
-     * Switch now so that the CallFrame is allocated on the new execEnv's
-     * stack. Then push a CallFrame and CmdFrame.
-     */
-
-    TclNRAddCallback(interp, NRCoroutineCallerCallback, corPtr, NULL, NULL,
-	    NULL);
-    SAVE_CONTEXT(corPtr->caller);
-
-    iPtr->execEnvPtr = corPtr->eePtr;
-
-    /*
-     * Save the base context. The base cmdFramePtr is unknown at this time: it
-     * will be allocated in the Tcl stack. So signal TEBC that it has to
-     * initialize the base cmdFramePtr by setting it to NULL.
-     */
-
-    SAVE_CONTEXT(corPtr->base);
-    corPtr->base.cmdFramePtr = NULL;
-    corPtr->running = NULL_CONTEXT;
-
-    
-    /*
      * #280.
      * Provide the new coroutine with its own copy of the lineLABCPtr
      * hashtable for literal command arguments in bytecode. Note that that
@@ -8871,20 +8845,43 @@ TclNRCoroutineObjCmd(
     }
 
     /*
-     * Eval things in 'uplevel #0', except for the very first command lookup
-     * which should be looked up in caller's context.
-     *
-     * A better approach would use the lambda infrastructure, but it is a bit
-     * clumsy for now: we have the "lambda is a nameless proc" hack, we'd need
-     * the cleaner "proc is a named lambda" to do this properly.
+     * Save the base context. The base cmdFramePtr is unknown at this time: it
+     * will be allocated in the Tcl stack. So signal TEBC that it has to
+     * initialize the base cmdFramePtr by setting it to NULL.
      */
-
-    iPtr->lookupNsPtr = iPtr->framePtr->nsPtr;
+ 
+    SAVE_CONTEXT(corPtr->base);
+    corPtr->base.cmdFramePtr = NULL;
+    corPtr->running = NULL_CONTEXT;
+    corPtr->stackLevel = NULL;
     corPtr->auxNumLevels = iPtr->numLevels;
+    corPtr->callerBP = NULL;
+    
+    /*
+     * Create the command that will run at the bottom of the coroutine.
+     * Be sure not to pass a canonical list for the command so that we insure
+     * the body is bytecompiled: we need a TEBC instance to handle [yield]
+     */
+
+    cmdObjPtr = Tcl_NewListObj(objc-2, &objv[2]);
+    TclGetString(cmdObjPtr);
+    TclFreeIntRep(cmdObjPtr);
+    cmdObjPtr->typePtr = NULL;
+
+
+    /*
+     * Create the coro's execEnv and switch to it so that any CallFrames or
+     * callbacks refer to the new execEnv's stack. Add the exit callback, then
+     * the callback to eval the coro body.
+     */ 
+
+    corPtr->eePtr = TclCreateExecEnv(interp, CORO_STACK_INITIAL_SIZE);
+    corPtr->callerEEPtr = iPtr->execEnvPtr;
+    corPtr->eePtr->corPtr = corPtr;
+    iPtr->execEnvPtr = corPtr->eePtr;
 
     TclNRAddCallback(interp, NRCoroutineExitCallback, corPtr,
 	    NULL, NULL, NULL);
-
     iPtr->evalFlags |= TCL_EVAL_REDIRECT;
     TclNREvalObjEx(interp, cmdObjPtr, 0, NULL, 0);
 
-- 
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