Refactor augmented assignment so we don't evaluate things twice

Evaluate everything immediately but store it as evaluatedCode for
later.

M2/Macaulay2/d/evaluate.d

@@ -1213,50 +1213,52 @@ augmentedAssignmentFun(x:augmentedAssignmentCode):Expr := (
     when lookup(x.oper.word, augmentedAssignmentOperatorTable)
     is null do buildErrorPacket("unknown augmented assignment operator")
     is s:Symbol do (
-	-- first check if user-defined method
-	-- TODO: when there isn't a user-defined method, we end up evaluating
-	-- the left-hand side twice.  is there any way to avoid this?
-	left := eval(x.lhs);
-	when left is e:Error do return Expr(e) else nothing;
-	meth := lookup(Class(left), Expr(SymbolClosure(globalFrame, x.oper)));
+	-- evaluate both sides first
+	left := evaluatedCode(eval(x.lhs), dummyPosition);
+	when left.expr is e:Error do return Expr(e) else nothing;
+	right := evaluatedCode(eval(x.rhs), dummyPosition);
+	when right.expr is e:Error do return Expr(e) else nothing;
+	-- check if user-defined method exists
+	meth := lookup(Class(left.expr),
+	    Expr(SymbolClosure(globalFrame, x.oper)));
 	if meth != nullE then (
-	    right := eval(x.rhs);
-	    when right is e:Error do return Expr(e)
-	    else (
-		r := applyEEE(meth, left, right);
-		when r
-		is s:SymbolClosure do (
-		    if s.symbol.word.name === "Default" then nothing
-		    else return r)
-		else return r));
+	    r := applyEEE(meth, left.expr, right.expr);
+	    when r
+	    is s:SymbolClosure do (
+		if s.symbol.word.name === "Default" then nothing
+		else return r)
+	    else return r);
 	-- if not, use default behavior
 	when x.lhs
 	is y:globalMemoryReferenceCode do (
-	    r := s.binary(x.lhs, x.rhs);
+	    r := s.binary(Code(left), Code(right));
 	    when r is e:Error do Expr(e)
 	    else globalAssignment(y.frameindex, x.info, r))
 	is y:localMemoryReferenceCode do (
-	    r := s.binary(x.lhs, x.rhs);
+	    r := s.binary(Code(left), Code(right));
 	    when r is e:Error do Expr(e)
 	    else localAssignment(y.nestingDepth, y.frameindex, r))
 	is y:threadMemoryReferenceCode do (
-	    r := s.binary(x.lhs, x.rhs);
+	    r := s.binary(Code(left), Code(right));
 	    when r is e:Error do Expr(e)
 	    else globalAssignment(y.frameindex, x.info, r))
 	is y:binaryCode do (
-	    r := Code(binaryCode(s.binary, y, x.rhs, dummyPosition));
+	    r := Code(binaryCode(s.binary, Code(left), Code(right),
+		    dummyPosition));
 	    if y.f == DotS.symbol.binary || y.f == SharpS.symbol.binary
 	    then AssignElemFun(y.lhs, y.rhs, r)
 	    else InstallValueFun(CodeSequence(Code(
 			globalSymbolClosureCode(x.info, dummyPosition)),
 		    y.lhs, y.rhs, r)))
 	is y:adjacentCode do (
-	    r := Code(binaryCode(s.binary, y, x.rhs, dummyPosition));
+	    r := Code(binaryCode(s.binary, Code(left), Code(right),
+		    dummyPosition));
 	    InstallValueFun(CodeSequence(Code(globalSymbolClosureCode(
 			    AdjacentS.symbol, dummyPosition)),
 		    y.lhs, y.rhs, r)))
 	is y:unaryCode do (
-	    r := Code(binaryCode(s.binary, y, x.rhs, dummyPosition));
+	    r := Code(binaryCode(s.binary, Code(left), Code(right),
+		    dummyPosition));
 	    UnaryInstallValueFun(
 		Code(globalSymbolClosureCode(x.info, dummyPosition)),
 		y.rhs, r))