WIP tunnels -- a nightmare

hank/HankAST.hx

@@ -10,7 +10,12 @@ enum ExprType {
 
     EOutput(o: Output);
 
-    EDivert(target: String);
+    ETunnelDivert;
+    /**
+     A divert statement that may contain multiple targets strung together (tunneling). An empty
+     string means to return to the original position
+    **/
+    EDivert(targets: Array<String>);
     EKnot(name: String);
     EStitch(name: String);
     ENoOp;

hank/HankBuffer.hx

@@ -268,6 +268,12 @@ class HankBuffer {
         }
     }
 
+    public function takeToken() {
+        var value = takeUntil([" ", "\n", "\t"]);
+        skipWhitespace();
+        return value;
+    }
+
     /** Take data from the file until encountering one of the given terminator sequences. **/
     public function takeUntil(terminators: Array<String>, eofTerminates: Bool = false, dropTerminator = true): Option<BufferOutput> {
         return switch (peekUntil(terminators, eofTerminates)) {

hank/Parser.hx

@@ -13,6 +13,7 @@ import hank.HankBuffer;
 class Parser {
     static var symbols: Array<Map<String, HankBuffer -> HankBuffer.Position -> ExprType>> = [
         ['INCLUDE ' => include],
+        ['->->' => function(_, _) { return ETunnelDivert; }],
         ['->' => divert],
         ['===' => knot],
         ['==' => knot],
@@ -141,10 +142,23 @@ class Parser {
     }
 
     static function divert(buffer: HankBuffer, position: HankBuffer.Position) : ExprType {
-        buffer.drop('->');
-        buffer.skipWhitespace();
-        var tokens = lineTokens(buffer, 1, position, true, true);
-        return EDivert(tokens[0]);
+        var line = HankBuffer.Dummy(buffer.takeLine());
+
+        var targets = [];
+
+        do {
+            line.drop("->");
+            line.skipWhitespace();
+
+            switch (line.takeToken()) {
+                case Some(target):
+                    targets.push(target);
+                case None:
+                    targets.push('');
+            }
+        } while (!line.isEmpty());
+
+        return EDivert(targets);
     }
 
     static function output(buffer: HankBuffer, position: HankBuffer.Position) : ExprType {

hank/Story.hx

@@ -29,6 +29,10 @@ class Story {
     var hInterface: HInterface;
     var random: Random;
 
+    var tunnelBreadcrumbs: Array<Int> = [];
+    var tunnelTargets: Array<StoryNode> = [];
+    var tunnelReturns: Bool = false;
+
     var ast: HankAST;
     var exprIndex: Int;
 
@@ -126,9 +130,23 @@ class Story {
         if (exprIndex >= ast.length) {
             return Finished;
         }
+
+        // Diverts need to be handled here to support chaining tunnels
         return processExpr(ast[exprIndex].expr);
     }
 
+    private function makeNextDivert() {
+        if (tunnelTargets.length == 0) {
+            throw 'supposed to divert to the next in tunnel but there are none!';
+        }
+        var next = tunnelTargets.shift();
+        if (next.length > 0) {
+            divertTo(next);
+        } else {
+            exprIndex = tunnelBreadcrumbs.pop();
+        }
+    }
+
     private function processExpr(expr: ExprType): StoryFrame {
         switch (expr) {
             case EOutput(output):
@@ -144,11 +162,16 @@ class Story {
                 exprIndex += 1;
                 hInterface.runEmbeddedHaxe(h, nodeScopes);
                 return nextFrame();
-            case EDivert(target):
+            case ETunnelDivert:
+                makeNextDivert();
+            case EDivert(targets):
                 if (target.length == 0) {
                     exprIndex += 1;
                 } else {
-                    divertTo(target);
+                    tunnelBreadcrumbs.push(exprIndex);
+                    tunnelTargets = tunnelTargets.concat([for(target in targets) if (target.length > 0) resolveNodeInScope(targets)]);
+                    tunnelReturn = (targets[targets.length-1].length == 0);
+                    makeNextDivert();
                 }
                 return nextFrame();
 
@@ -265,14 +288,13 @@ class Story {
                 case None:
             }
         }
+        if (newScopes[0].astIndex == -1) {
+            throw 'Divert target not found: $label';
+        }
         return newScopes;
     }
 
-    public function divertTo(target: String) {
-        // Don't try to divert to a fallback target
-        if (target.length == 0) {
-            return;
-        }
+    public function divertTo(target: StoryNode) {
         switch (parent) {
             case Some(p):
                 // A divert from inside embedded hank, must leave the embedded context
@@ -285,15 +307,10 @@ class Story {
 
         // trace('diverting to $target');
 
-        var newScopes = resolveNodeInScope(target);
-        var targetIdx = newScopes[0].astIndex;
+        var targetIdx = target.astIndex;
 
-        if (targetIdx == -1) {
-            throw 'Divert target not found: $target';
-        }
         // update the expression index
         exprIndex = targetIdx; 
-        var target = newScopes[0];
         weaveDepth = 0;
 
         // Update the view count
@@ -306,7 +323,7 @@ class Story {
                 // If a knot directly starts with a stitch, run it
                 switch (ast[exprIndex].expr) {
                     case EStitch(label):
-                        var firstStitch = resolveNodeInScope(label, newScopes)[0];
+                        var firstStitch = resolveNodeInScope(label, target)[0];
                         viewCounts[firstStitch] += 1;
                         exprIndex += 1;
                     default:
@@ -317,7 +334,7 @@ class Story {
                 // if it's a stitch, increase its view count
                 viewCounts[target] += 1;
 
-                var enclosingKnot = newScopes[1];
+                var enclosingKnot = target[1];
                 // If we weren't in the stitch's containing section before, increase its viewcount
                 if (nodeScopes.indexOf(enclosingKnot) == -1) {
                     viewCounts[enclosingKnot] += 1;
@@ -333,7 +350,7 @@ class Story {
             default:
         }
         // Update nodeScopes to point to the new scope
-        nodeScopes = newScopes;
+        nodeScopes = target;
     }
 
     public function choose(choiceIndex: Int): String {