Fix comprehensions starting with multiple "if" clauses

This also significantly simplifies the $next$0() method – see the test case. CC ceylon/ceylon-spec#869
ceylon · Jan 19, 2014 · 024c4b8 · 024c4b8
1 parent 0006dd2
commit 024c4b8
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Showing 2 changed files with 45 additions and 35 deletions.
diff --git a/src/com/redhat/ceylon/compiler/java/codegen/ExpressionTransformer.java b/src/com/redhat/ceylon/compiler/java/codegen/ExpressionTransformer.java
@@ -4663,36 +4663,47 @@ public List<JCStatement> getResult() {
 
         private void transformIfClause(Tree.IfComprehensionClause clause) {
             List<JCStatement> body;
-            if (clause == comp.getInitialComprehensionClause()) {
-                //No previous context
-                ctxtName = naming.synthetic(Prefix.$next$, idx);
+            if (prevItemVar == null) {
+            	List<JCStatement> initBlock;
+            	if (clause == comp.getInitialComprehensionClause()) {
+            		//No previous context
+            		assert (ctxtName == null);
+            		ctxtName = naming.synthetic(Prefix.$next$, idx);
+            		//define a variable that records if the expression was already evaluated
+            		SyntheticName exhaustedName = ctxtName.suffixedBy(Suffix.$exhausted$);
+                    JCVariableDecl exhaustedDef = make().VarDef(make().Modifiers(Flags.PRIVATE),
+                            exhaustedName.asName(), makeJavaType(typeFact().getBooleanDeclaration().getType()), null);
+                    fields.add(exhaustedDef);
+                    JCStatement returnIfExhausted = make().If(exhaustedName.makeIdent(), make().Return(makeBoolean(false)), null);
+                    JCStatement setExhaustedTrue = make().Exec(make().Assign(exhaustedName.makeIdent(), makeBoolean(true)));
+                    initBlock =  List.<JCStatement>of(
+                    		//if we already evaluated the expression, return
+                    		returnIfExhausted,
+                            //record that we will have evaluated the expression
+                            setExhaustedTrue);
+            	} else {
+            		assert (ctxtName != null);
+            		JCStatement returnIfExhausted = make().If(
+            				//if the previous comprehension is false or was already evaluated...
+            				make().Unary(JCTree.NOT, make().Apply(null,
+            						ctxtName.makeIdentWithThis(), List.<JCExpression>nil())),
+            				//return false
+                    		make().Return(makeBoolean(false)), null);
+            		ctxtName = naming.synthetic(Prefix.$next$, idx);
+            		initBlock = List.<JCStatement>of(returnIfExhausted);
+            	}
 
-                SyntheticName exhaustedName = ctxtName.suffixedBy(Suffix.$exhausted$);
-                JCVariableDecl exhaustedDef = make().VarDef(make().Modifiers(Flags.PRIVATE),
-                        exhaustedName.asName(), makeJavaType(typeFact().getBooleanDeclaration().getType()), null);
-                fields.add(exhaustedDef);
-                JCStatement returnIfExhausted = make().If(exhaustedName.makeIdent(), make().Return(makeBoolean(false)), null);
-                SyntheticName resultName = naming.temp("result");
-                JCVariableDecl declareResult = make().VarDef(make().Modifiers(0),
-                        resultName.asName(), makeJavaType(typeFact().getBooleanDeclaration().getType()), makeBoolean(false));
-                JCStatement setResultTrue = make().Exec(make().Assign(resultName.makeIdent(), makeBoolean(true)));
-                JCStatement setExhaustedTrue = make().Exec(make().Assign(exhaustedName.makeIdent(), makeBoolean(true)));
-                JCStatement returnResult = make().Return(resultName.makeIdent());
+                JCStatement returnTrue = make().Return(makeBoolean(true));
+                JCStatement returnFalse = make().Return(makeBoolean(false));
 
                 body = new IfComprehensionCondList(clause.getConditionList().getConditions(),
+                    initBlock,
                     List.<JCStatement>of(
-                        //if we already evaluated the expression, return
-                        returnIfExhausted,
-                        //declare the result variable that's going to store the result of the conditions (init to false)
-                        declareResult),
-                    List.<JCStatement>of(
-                        //if the conditions apply: set the result variable to true
-                        setResultTrue),
+                        //if the conditions apply: return true
+                        returnTrue),
                     List.<JCStatement>of(
-                        //we evaluated the expression
-                        setExhaustedTrue,
-                        //and return the result
-                        returnResult)).getResult();
+                        //the conditions did not apply: return false
+                        returnFalse)).getResult();
             } else {
                 //Filter contexts need to check if the previous context applies and then check the condition
                 JCExpression condExpr = make().Apply(null,

diff --git a/test/src/com/redhat/ceylon/compiler/java/test/expression/comprehensions/if_exists.src b/test/src/com/redhat/ceylon/compiler/java/test/expression/comprehensions/if_exists.src
@@ -13,24 +13,23 @@ final class ifFor_ {
                     {
                     }
                     private boolean $next$0$exhausted$;
-                    private .java.lang.String x$2;
+                    private .java.lang.String x$1;
 
                     private final boolean $next$0() {
                         if ($next$0$exhausted$) return false;
-                        boolean $ceylontmp$result$0 = false;
-                        .ceylon.language.String x$1 = null;
-                        if ((x$1 = x) != null) {
-                            x$2 = x$1.toString();
-                            $ceylontmp$result$0 = true;
-                        }
                         $next$0$exhausted$ = true;
-                        return $ceylontmp$result$0;
+                        .ceylon.language.String x$0 = null;
+                        if ((x$0 = x) != null) {
+                            x$1 = x$0.toString();
+                            return true;
+                        }
+                        return false;
                     }
 
                     public final .java.lang.Object next() {
                         if (this.$next$0()) {
-                            final .java.lang.String x$2 = this.x$2;
-                            return .ceylon.language.String.instance(x$2);
+                            final .java.lang.String x$1 = this.x$1;
+                            return .ceylon.language.String.instance(x$1);
                         } else return .ceylon.language.finished_.get_();
                     }
                 };