macro that allows collecting expressions throughout a file

kiss/src/kiss/Kiss.hx

@@ -39,7 +39,8 @@ typedef KissState = {
     fieldDict:Map<String, Field>,
     loadingDirectory:String,
     hscript:Bool,
-    macroVars:Map<String, Dynamic>
+    macroVars:Map<String, Dynamic>,
+    collectedBlocks:Map<String, Array<ReaderExp>>
 };
 
 class Kiss {
@@ -111,7 +112,8 @@ class Kiss {
             fieldDict: new Map(),
             loadingDirectory: "",
             hscript: false,
-            macroVars: new Map()
+            macroVars: new Map(),
+            collectedBlocks: new Map()
         };
 
         return k;
@@ -154,6 +156,7 @@ class Kiss {
         if (kissFile == null) {
             kissFile = classPath.withoutDirectory().withoutExtension().withExtension("kiss");
         }
+        //trace('kiss build $kissFile');
 
         return _try(() -> {
             if (k == null)

kiss/src/kiss/Macros.hx

@@ -839,6 +839,37 @@ class Macros {
             b.callSymbol("object", objectExps);
         }
 
+        // Macro for triggering collection of expressions throughout a Kiss file, to inject them later with collectedBlocks
+        macros["collectBlocks"] = (wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) -> {
+            wholeExp.checkNumArgs(1, 2, "(collectBlocks <block symbol> <?expression to inline instead of the blocks>)");
+            var blockName = try {
+                exps[0].symbolNameValue();
+            } catch (notSymbolError:String) {
+                throw CompileError.fromExp(wholeExp, notSymbolError);
+            }
+            k.collectedBlocks[blockName] = [];
+            // TODO some assertion that the coder hasn't defined over another macro (also should apply to defMacro)
+            macros[blockName] = (wholeExp:ReaderExp, innerExps:Array<ReaderExp>, k:KissState) -> {
+                k.collectedBlocks[blockName] = k.collectedBlocks[blockName].concat(innerExps);
+                if (exps.length > 1) exps[1] else null;
+            };
+            null;
+        };
+
+        macros["collectedBlocks"] = (wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) -> {
+            wholeExp.checkNumArgs(1, 1, "(collectedBlocks <block symbol>)");
+            var blockName = try {
+                exps[0].symbolNameValue();
+            } catch (notSymbolError:String) {
+                throw CompileError.fromExp(wholeExp, notSymbolError);
+            }
+            var b = wholeExp.expBuilder();
+            if (!k.collectedBlocks.exists(blockName)) {
+                throw CompileError.fromExp(wholeExp, 'no blocks for $blockName were collected. Try adding (collectBlocks ${blockName}) at the start of the file.');
+            }
+            b.begin(k.collectedBlocks[blockName]);
+        };
+
         macros["clamp"] = (wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) -> {
             wholeExp.checkNumArgs(2, 3, "(clamp <expr> <min or null> <?max or null>)");
             var b = wholeExp.expBuilder();