Fix reporting out of nested custom C-shaped blocks

REPORT now reports to the nearest lexical element expecting an input
(which may not be the block holding the REPORT statement, this lets you
REPORT out of nested FOR loops).
STOP THIS BLOCK behaves as it used to.
If you’ve been using REPORT instead of STOP THIS BLOCK, you should
migrate.

1 files changed, 67 insertions, 103 deletions

diff --git a/threads.js b/threads.js
index 6a59f3c..dfa335e 100644
--- a/threads.js
+++ b/threads.js
@@ -83,7 +83,7 @@ ArgLabelMorph, localize, XML_Element, hex_sha512*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.threads = '2014-October-01';
+modules.threads = '2014-November-15';
 
 var ThreadManager;
 var Process;
@@ -586,7 +586,6 @@ Process.prototype.evaluateInput = function (input) {
                 ) || (input instanceof CSlotMorph && !input.isStatic)) {
                 // I know, this still needs yet to be done right....
                 ans = this.reify(ans, new List());
-                ans.isImplicitLambda = true;
             }
         }
     }
@@ -597,8 +596,6 @@ Process.prototype.evaluateInput = function (input) {
 Process.prototype.evaluateSequence = function (arr) {
     var pc = this.context.pc,
         outer = this.context.outerContext,
-        isLambda = this.context.isLambda,
-        isImplicitLambda = this.context.isImplicitLambda,
         isCustomBlock = this.context.isCustomBlock;
     if (pc === (arr.length - 1)) { // tail call elimination
         this.context = new Context(
@@ -607,8 +604,6 @@ Process.prototype.evaluateSequence = function (arr) {
             this.context.outerContext,
             this.context.receiver
         );
-        this.context.isLambda = isLambda;
-        this.context.isImplicitLambda = isImplicitLambda;
         this.context.isCustomBlock = isCustomBlock;
     } else {
         if (pc >= arr.length) {
@@ -626,8 +621,8 @@ Process.prototype.evaluateSequence = function (arr) {
 Caution: we cannot just revert to this version of the method, because to make
 tail call elimination work many tweaks had to be done to various primitives.
 For the most part these tweaks are about schlepping the outer context (for
-the variable bindings) and the isLambda flag along, and are indicated by a
-short comment in the code. But to really revert would take a good measure
+the variable bindings) and the isCustomBlock flag along, and are indicated
+by a short comment in the code. But to really revert would take a good measure
 of trial and error as well as debugging. In the developers file archive there
 is a version of threads.js dated 120119(2) which basically resembles the
 last version before introducing tail call optimization on 120123.
@@ -679,6 +674,11 @@ Process.prototype.doYield = function () {
     }
 };
 
+Process.prototype.exitReporter = function () {
+    // catch-tag for REPORT and STOP BLOCK primitives
+    this.popContext();
+};
+
 // Process Exception Handling
 
 Process.prototype.handleError = function (error, element) {
@@ -757,9 +757,15 @@ Process.prototype.reportJSFunction = function (parmNames, body) {
     );
 };
 
+/*
 Process.prototype.doRun = function (context, args, isCustomBlock) {
     return this.evaluate(context, args, true, isCustomBlock);
 };
+*/
+
+Process.prototype.doRun = function (context, args) {
+    return this.evaluate(context, args, true);
+};
 
 Process.prototype.evaluate = function (
     context,
@@ -783,6 +789,7 @@ Process.prototype.evaluate = function (
     var outer = new Context(null, null, context.outerContext),
         runnable,
         extra,
+        exit,
         parms = args.asArray(),
         i,
         value;
@@ -798,23 +805,17 @@ Process.prototype.evaluate = function (
     );
     extra = new Context(runnable, 'doYield');
 
-    /*
-        Note: if the context's expression is a ReporterBlockMorph,
-        the extra context gets popped off immediately without taking
-        effect (i.e. it doesn't yield within evaluating a stack of
-        nested reporters)
-    */
+        // Note: if the context's expression is a ReporterBlockMorph,
+        // the extra context gets popped off immediately without taking
+        // effect (i.e. it doesn't yield within evaluating a stack of
+        // nested reporters)
 
-    if (isCommand || (context.expression instanceof ReporterBlockMorph)) {
+    if (context.expression instanceof ReporterBlockMorph) {
         this.context.parentContext = extra;
     } else {
         this.context.parentContext = runnable;
     }
 
-    runnable.isLambda = true;
-    runnable.isImplicitLambda = context.isImplicitLambda;
-    runnable.isCustomBlock = false;
-
     // assign parameters if any were passed
     if (parms.length > 0) {
 
@@ -858,6 +859,18 @@ Process.prototype.evaluate = function (
 
     if (runnable.expression instanceof CommandBlockMorph) {
         runnable.expression = runnable.expression.blockSequence();
+
+        // insert a reporter exit tag for the
+        // CALL SCRIPT primitive variant
+        if (!isCommand) {
+            exit = new Context(
+                runnable.parentContext,
+                'exitReporter',
+                outer,
+                outer.receiver
+            );
+            runnable.parentContext = exit;
+        }
     }
 };
 
@@ -879,8 +892,6 @@ Process.prototype.fork = function (context, args) {
         stage = this.homeContext.receiver.parentThatIsA(StageMorph),
         proc = new Process();
 
-    runnable.isLambda = true;
-
     // assign parameters if any were passed
     if (parms.length > 0) {
 
@@ -933,68 +944,39 @@ Process.prototype.fork = function (context, args) {
     stage.threads.processes.push(proc);
 };
 
-Process.prototype.doReport = function (value, isCSlot) {
-    while (this.context && !this.context.isLambda) {
+Process.prototype.doReport = function (value) {
+    while (this.context && this.context.expression !== 'exitReporter') {
         if (this.context.expression === 'doStopWarping') {
             this.doStopWarping();
         } else {
             this.popContext();
         }
     }
-    if (this.context && this.context.isImplicitLambda) {
+    return value;
+};
+
+Process.prototype.doStopBlock = function () {
+    while (this.context && !this.context.isCustomBlock) {
         if (this.context.expression === 'doStopWarping') {
             this.doStopWarping();
         } else {
             this.popContext();
         }
-        return this.doReport(value, true);
-    }
-    if (this.context && this.context.isCustomBlock) {
-        // now I'm back at the custom block sequence.
-        // advance my pc to my expression's length
-        this.context.pc = this.context.expression.length - 1;
-    }
-    if (isCSlot) {
-        if (this.context &&
-                this.context.parentContext &&
-                this.context.parentContext.expression instanceof Array) {
-            this.popContext();
-        }
     }
-    return value;
-};
-
-Process.prototype.doStopBlock = function () {
-    this.doReport();
 };
 
-// Process evaluation variants, commented out for now (redundant)
-
-/*
-Process.prototype.doRunWithInputList = function (context, args) {
-    // provide an extra selector for the palette
-    return this.doRun(context, args);
-};
-
-Process.prototype.evaluateWithInputList = function (context, args) {
-    // provide an extra selector for the palette
-    return this.evaluate(context, args);
-};
-
-Process.prototype.forkWithInputList = function (context, args) {
-    // provide an extra selector for the palette
-    return this.fork(context, args);
-};
-*/
-
 // Process continuations primitives
 
-Process.prototype.doCallCC = function (aContext) {
-    this.evaluate(aContext, new List([this.context.continuation()]));
+Process.prototype.doCallCC = function (aContext, isReporter) {
+    this.evaluate(
+        aContext,
+        new List([this.context.continuation()]),
+        !isReporter
+    );
 };
 
 Process.prototype.reportCallCC = function (aContext) {
-    this.doCallCC(aContext);
+    this.doCallCC(aContext, true);
 };
 
 Process.prototype.runContinuation = function (aContext, args) {
@@ -1017,6 +999,7 @@ Process.prototype.evaluateCustomBlock = function () {
         args = new List(this.context.inputs),
         parms = args.asArray(),
         runnable,
+        exit,
         extra,
         i,
         value,
@@ -1024,7 +1007,7 @@ Process.prototype.evaluateCustomBlock = function () {
 
     if (!context) {return null; }
     outer = new Context();
-    outer.receiver = this.context.receiver; // || this.homeContext.receiver;
+    outer.receiver = this.context.receiver;
     outer.variables.parentFrame = outer.receiver ?
             outer.receiver.variables : null;
 
@@ -1032,16 +1015,12 @@ Process.prototype.evaluateCustomBlock = function () {
         this.context.parentContext,
         context.expression,
         outer,
-        outer.receiver,
-        true // is custom block
+        outer.receiver
     );
+    runnable.isCustomBlock = true;
     extra = new Context(runnable, 'doYield');
-
     this.context.parentContext = extra;
 
-    runnable.isLambda = true;
-    runnable.isCustomBlock = true;
-
     // passing parameters if any were passed
     if (parms.length > 0) {
 
@@ -1064,6 +1043,18 @@ Process.prototype.evaluateCustomBlock = function () {
 
     if (runnable.expression instanceof CommandBlockMorph) {
         runnable.expression = runnable.expression.blockSequence();
+
+        // insert a reporter exit tag for the
+        // CALL SCRIPT primitive variant
+        if (this.context.expression.definition.type !== 'command') {
+            exit = new Context(
+                runnable.parentContext,
+                'exitReporter',
+                outer,
+                outer.receiver
+            );
+            runnable.parentContext = exit;
+        }
     }
 };
 
@@ -1308,16 +1299,12 @@ Process.prototype.reportListContainsItem = function (list, element) {
 Process.prototype.doIf = function () {
     var args = this.context.inputs,
         outer = this.context.outerContext, // for tail call elimination
-        isLambda = this.context.isLambda,
-        isImplicitLambda = this.context.isImplicitLambda,
         isCustomBlock = this.context.isCustomBlock;
 
     this.popContext();
     if (args[0]) {
         if (args[1]) {
             this.pushContext(args[1].blockSequence(), outer);
-            this.context.isLambda = isLambda;
-            this.context.isImplicitLambda = isImplicitLambda;
             this.context.isCustomBlock = isCustomBlock;
         }
     }
@@ -1327,8 +1314,6 @@ Process.prototype.doIf = function () {
 Process.prototype.doIfElse = function () {
     var args = this.context.inputs,
         outer = this.context.outerContext, // for tail call elimination
-        isLambda = this.context.isLambda,
-        isImplicitLambda = this.context.isImplicitLambda,
         isCustomBlock = this.context.isCustomBlock;
 
     this.popContext();
@@ -1344,8 +1329,6 @@ Process.prototype.doIfElse = function () {
         }
     }
     if (this.context) {
-        this.context.isLambda = isLambda;
-        this.context.isImplicitLambda = isImplicitLambda;
         this.context.isCustomBlock = isCustomBlock;
     }
 
@@ -1420,8 +1403,6 @@ Process.prototype.doStopOthers = function (choice) {
 Process.prototype.doWarp = function (body) {
     // execute my contents block atomically (more or less)
     var outer = this.context.outerContext, // for tail call elimination
-        isLambda = this.context.isLambda,
-        isImplicitLambda = this.context.isImplicitLambda,
         isCustomBlock = this.context.isCustomBlock,
         stage;
 
@@ -1438,13 +1419,8 @@ Process.prototype.doWarp = function (body) {
                 stage.fps = 0; // variable frame rate
             }
         }
-
         this.pushContext('doYield');
-
-        this.context.isLambda = isLambda;
-        this.context.isImplicitLambda = isImplicitLambda;
         this.context.isCustomBlock = isCustomBlock;
-
         if (!this.isAtomic) {
             this.pushContext('doStopWarping');
         }
@@ -1523,28 +1499,19 @@ Process.prototype.doForever = function (body) {
 Process.prototype.doRepeat = function (counter, body) {
     var block = this.context.expression,
         outer = this.context.outerContext, // for tail call elimination
-        isLambda = this.context.isLambda,
-        isImplicitLambda = this.context.isImplicitLambda,
         isCustomBlock = this.context.isCustomBlock;
 
     if (counter < 1) { // was '=== 0', which caused infinite loops on non-ints
         return null;
     }
     this.popContext();
-
     this.pushContext(block, outer);
-
-    this.context.isLambda = isLambda;
-    this.context.isImplicitLambda = isImplicitLambda;
     this.context.isCustomBlock = isCustomBlock;
-
     this.context.addInput(counter - 1);
-
     this.pushContext('doYield');
     if (body) {
         this.pushContext(body.blockSequence());
     }
-
     this.pushContext();
 };
 
@@ -2775,8 +2742,6 @@ Process.prototype.reportFrameCount = function () {
     startValue        initial value for interpolated operations
     activeAudio     audio buffer for interpolated operations, don't persist
     activeNote      audio oscillator for interpolated ops, don't persist
-    isLambda        marker for return ops
-    isImplicitLambda    marker for return ops
     isCustomBlock   marker for return ops
     emptySlots        caches the number of empty slots for reification
 */
@@ -2801,22 +2766,18 @@ function Context(
     this.startTime = null;
     this.activeAudio = null;
     this.activeNote = null;
-    this.isLambda = false; // marks the end of a lambda
-    this.isImplicitLambda = false; // marks the end of a C-shaped slot
     this.isCustomBlock = false; // marks the end of a custom block's stack
     this.emptySlots = 0; // used for block reification
 }
 
 Context.prototype.toString = function () {
-    var pref = this.isLambda ? '\u03BB-' : '',
-        expr = this.expression;
-
+    var expr = this.expression;
     if (expr instanceof Array) {
         if (expr.length > 0) {
             expr = '[' + expr[0] + ']';
         }
     }
-    return pref + 'Context >> ' + expr + ' ' + this.variables;
+    return 'Context >> ' + expr + ' ' + this.variables;
 };
 
 Context.prototype.image = function () {
@@ -2872,6 +2833,9 @@ Context.prototype.continuation = function () {
     } else {
         return new Context(null, 'doStop');
     }
+    if (cont.expression === 'exitReporter') {
+        return cont.continuation();
+    }
     cont = cont.copyForContinuation();
     cont.isContinuation = true;
     return cont;