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Avoiding addition of redundant unary operators #7579

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merged 4 commits into from
Mar 3, 2021
Merged

Avoiding addition of redundant unary operators #7579

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1ae4f16
added a test and fixed the redundant unary operators
GuptaManan100 Mar 2, 2021
14341af
added another test case
GuptaManan100 Mar 2, 2021
e1af103
removed unary pluses where they are not required
GuptaManan100 Mar 2, 2021
67dca5c
Merge remote-tracking branch 'upstream/master' into unary-ops
GuptaManan100 Mar 3, 2021
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16 changes: 16 additions & 0 deletions go/vt/sqlparser/ast_funcs.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1642,3 +1642,19 @@ func (node *Default) Clone() Expr {
}
return &Default{ColName: node.ColName}
}

// 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}
}
12 changes: 10 additions & 2 deletions go/vt/sqlparser/parse_test.go
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Expand Up @@ -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",
}, {
Expand Down Expand Up @@ -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",
}, {
Expand Down Expand Up @@ -901,6 +903,12 @@ 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",
Expand Down
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