Lua: tuple returns as multiple results, hashtable natives printed in place

de.peeeq.wurstscript/parserspec/lua.parseq

@@ -20,11 +20,13 @@ LuaStatement =
       LuaDefinition
     | LuaChunkLocal(LuaDefinition definition) // a definition printed as a local of the main chunk
     | LuaAssignment(LuaExpr left, LuaExpr right)
+    | LuaMultipleAssignment(LuaExprlist targets, LuaExpr right) // the results of a call, one per target
     | LuaWhile(LuaExpr cond, LuaStatements body)
     | LuaFor(ref LuaVariable loopVar, LuaExpr from, LuaExpr to, LuaExprOpt step, LuaStatements body)
     | LuaIf(LuaExpr cond, LuaStatements thenStmts, LuaStatements elseStmts)
     | LuaBreak()
     | LuaReturn(LuaExprOpt retVal)
+    | LuaReturnValues(LuaExprlist values) // several results
     | LuaExpr
 
 LuaExprOpt = LuaExpr | LuaNoExpr()

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/WurstCompilerJassImpl.java

@@ -1027,8 +1027,8 @@ public LuaCompilationUnit transformProgToLua() {
 
         timeTaker.beginPhase("eliminate tuples");
         getImProg().flatten(imTranslator2);
+        // The tuples left are the multiple results of calls (LuaMultipleResults), whose shape the elimination checks.
         EliminateTuples.eliminateTuplesProg(getImProg(), imTranslator2);
-        imTranslator2.assertProperties(AssertProperty.NOTUPLES);
         timeTaker.endPhase();
 
         optimizer.removeGarbage();

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/intermediatelang/optimizer/ConstantAndCopyPropagation.java

@@ -6,6 +6,7 @@
 import de.peeeq.wurstscript.jassIm.*;
 import de.peeeq.wurstscript.translation.imtranslation.ImHelper;
 import de.peeeq.wurstscript.translation.imtranslation.ImTranslator;
+import de.peeeq.wurstscript.translation.imtranslation.LuaMultipleResults;
 import de.peeeq.wurstscript.types.TypesHelper;
 import io.vavr.Tuple2;
 import io.vavr.collection.HashMap;
@@ -37,26 +38,36 @@ public String getName() {
 
     static class Value {
         final @Nullable ImVar copyVar;
+        /** With a copyVar which holds a call's results (LuaMultipleResults): the component copied, otherwise -1. */
+        final int component;
         final @Nullable ImConst constantValue;
         final @Nullable ImTupleExpr constantTuple;
 
         public Value(ImVar copyVar) {
-            this.copyVar = copyVar;
+            this(copyVar, -1);
+        }
+
+        /** A copy of component {@code component} of the results local {@code results}. */
+        public Value(ImVar results, int component) {
+            this.copyVar = results;
+            this.component = component;
             this.constantValue = null;
             this.constantTuple = null;
-            if(copyVar.isGlobal()) {
+            if(results.isGlobal()) {
                 throw new IllegalArgumentException("copyVar must not be a Global.");
             }
         }
 
         public Value(ImConst constantValue) {
             this.copyVar = null;
+            this.component = -1;
             this.constantValue = constantValue;
             this.constantTuple = null;
         }
 
         public Value(ImTupleExpr tupleExpr) {
             this.copyVar = null;
+            this.component = -1;
             this.constantValue = null;
             this.constantTuple = tupleExpr;
 
@@ -93,7 +104,7 @@ public boolean equals(@Nullable Object obj) {
 
         public boolean equalValue(Value other) {
             if (copyVar != null && other.copyVar != null) {
-                return copyVar == other.copyVar;
+                return copyVar == other.copyVar && component == other.component;
             } else if (constantValue != null && other.constantValue != null) {
                 return constantValue.equalValue(other.constantValue);
             } else if (constantTuple != null && other.constantTuple != null) {
@@ -117,7 +128,7 @@ public boolean equalValue(Value other) {
         @Override
         public String toString() {
             if (copyVar != null) {
-                return "copy of " + copyVar;
+                return "copy of " + copyVar + (component < 0 ? "" : "." + component);
             } else if (constantValue != null) {
                 return "constant " + constantValue;
             } else {
@@ -180,6 +191,9 @@ public void visit(ImVarAccess va) {
                     if (val.constantValue != null) {
                         va.replaceBy(val.constantValue.copy());
                         totalPropagated++;
+                    } else if (val.component >= 0) {
+                        va.replaceBy(JassIm.ImTupleSelection(JassIm.ImVarAccess(val.copyVar), val.component));
+                        totalPropagated++;
                     } else if (val.copyVar != null) {
                         ImVar old = va.getVar();
                         ImVar target = val.copyVar;
@@ -328,6 +342,11 @@ private void analyzeComponent(List<Node> scc, Map<Node, Knowledge> knowledge) {
                                 }
                             } else if(right instanceof ImTupleExpr) {
                                 newValue = Value.tryValue(right);
+                            } else if (right instanceof ImTupleSelection selection
+                                && selection.getTupleExpr() instanceof ImVarAccess results
+                                && LuaMultipleResults.isResultsLocal(results.getVar())) {
+                                // a component of a call's results, which only another call writes
+                                newValue = new Value(results.getVar(), selection.getTupleIndex());
                             }
 
                             if (newValue == null) {

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/imoptimizer/ImInliner.java

@@ -435,7 +435,7 @@ private boolean isEffectFree(Element e) {
             ImFunction target = call.getFunc();
             if (!target.isNative() || localPlayerAnalysis().isLocalPlayerSource(target)
                 || !(SideEffectFreeNatives.isFunctionWithoutSideEffect(target.getName())
-                    || translator.isLuaKeyedMapRead(target))) {
+                    || translator.isLuaTableRead(target))) {
                 return false;
             }
         } else if (e instanceof ImExpr) {

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/imoptimizer/ImOptimizer.java

@@ -137,6 +137,11 @@ public void doNullsetting() {
     public boolean removeGarbage() {
         boolean wasFlat = trans.isUnitTestMode() && trans.isFlat();
         boolean changed = removeGarbageWithFacts();
+        // A Lua result which no call reads is not returned, and what computed it is then garbage of its own.
+        while (trans.luaMultipleResultsLowered() && LuaUnreadResults.drop(this, trans)) {
+            changed = true;
+            removeGarbageWithFacts();
+        }
         if (wasFlat && !trans.isFlat()) {
             throw new AssertionError("The garbage removal made a flat program not flat");
         }
@@ -438,7 +443,7 @@ private void collectTargetEffects(ImExpr target, SideEffectAnalyzer analyzer, Li
         }
     }
 
-    private List<ImExpr> collectSideEffects(ImExpr expr, SideEffectAnalyzer analyzer) {
+    List<ImExpr> collectSideEffects(ImExpr expr, SideEffectAnalyzer analyzer) {
         if (expr == null) {
             return Collections.emptyList();
         }
@@ -455,7 +460,7 @@ private List<ImExpr> collectSideEffects(ImExpr expr, SideEffectAnalyzer analyzer
         }
         if (analyzer.hasObservableSideEffects(expr, func -> func.isNative()
             && (SideEffectFreeNatives.isFunctionWithoutSideEffect(func.getName())
-                || trans.isLuaKeyedMapRead(func)))) {
+                || trans.isLuaTableRead(func)))) {
             return Collections.singletonList(expr);
         }
         return Collections.emptyList();