Merge pull request #7579 from GuptaManan100/unary-ops

Avoiding addition of redundant unary operators

go/vt/sqlparser/ast_funcs.go

@@ -1338,3 +1338,19 @@ const (
 	// DoubleAt represnts @@
 	DoubleAt
 )
+
+// handleUnaryMinus handles the case when a unary minus operator is seen in the parser. It takes 1 argument which is the expr to which the unary minus has been added to.
+func handleUnaryMinus(expr Expr) Expr {
+	if num, ok := expr.(*Literal); ok && num.Type == IntVal {
+		// Handle double negative
+		if num.Val[0] == '-' {
+			num.Val = num.Val[1:]
+			return num
+		}
+		return NewIntLiteral(append([]byte("-"), num.Val...))
+	}
+	if unaryExpr, ok := expr.(*UnaryExpr); ok && unaryExpr.Operator == UMinusOp {
+		return unaryExpr.Expr
+	}
+	return &UnaryExpr{Operator: UMinusOp, Expr: expr}
+}

go/vt/sqlparser/parse_test.go

@@ -447,7 +447,8 @@ var (
 		input:  "select /* % no space */ 1 from t where a = b%c",
 		output: "select /* % no space */ 1 from t where a = b % c",
 	}, {
-		input: "select /* u+ */ 1 from t where a = +b",
+		input:  "select /* u+ */ 1 from t where a = +b",
+		output: "select /* u+ */ 1 from t where a = b",
 	}, {
 		input: "select /* u- */ 1 from t where a = -b",
 	}, {
@@ -607,7 +608,8 @@ var (
 		input:  "select /* binary unary */ a- -b from t",
 		output: "select /* binary unary */ a - -b from t",
 	}, {
-		input: "select /* - - */ - -b from t",
+		input:  "select /* - - */ - -b from t",
+		output: "select /* - - */ b from t",
 	}, {
 		input: "select /* binary binary */ binary  binary b from t",
 	}, {
@@ -904,6 +906,12 @@ var (
 		input: "set @variable = 42",
 	}, {
 		input: "set @period.variable = 42",
+	}, {
+		input:  "set S= +++-++-+(4+1)",
+		output: "set S = 4 + 1",
+	}, {
+		input:  "set S= +- - - - -(4+1)",
+		output: "set S = -(4 + 1)",
 	}, {
 		input:  "alter table a add foo int first v",
 		output: "alter table a add column foo int first v",