Added operators on Strings

src/main/java/chocopy/pa3/CodeGenImpl.java

@@ -739,9 +739,25 @@ public class CodeGenImpl extends CodeGenBase
                 sp_off -= 2;
                 backend.emitADDI(SP, FP, -sp_off*wordSize, "restore sp");
                 }
+                if(operator.equals("!="))
+                {
+                incSp(2);
+                backend.emitSW(node.left.dispatch(this), FP, (1 - sp_off) *wordSize, "Push argument 0 from last.");
+                backend.emitSW(node.right.dispatch(this), FP, ( - sp_off) *wordSize, "Push argument 1 from last.");
+                backend.emitADDI(SP, FP, -sp_off * wordSize, "Set SP to last argument.");
+                backend.emitJAL(strneqlLabel, "Invoke method:strneql");
+                sp_off -= 2;
+                backend.emitADDI(SP, FP, -sp_off*wordSize, "restore sp");
+                }
                 else if(operator.equals("+"))
                 {
-                    
+                    incSp(2);
+                    backend.emitSW(node.left.dispatch(this), FP, (1 - sp_off) *wordSize, "Push argument 0 from last.");
+                    backend.emitSW(node.right.dispatch(this), FP, ( - sp_off) *wordSize, "Push argument 1 from last.");
+                    backend.emitADDI(SP, FP, -sp_off * wordSize, "Set SP to last argument.");
+                    backend.emitJAL(concatLabel, "Invoke method:concat");
+                    sp_off -= 2;
+                    backend.emitADDI(SP, FP, -sp_off*wordSize, "restore sp");
                 }
                 else
                     backend.emitJAL(errorNI, "Operator not implemented for String operands");