astutil: add Unparen utility, eliminating 7 copies.

Change-Id: I824328c275bd6198a57edd64bf72cb2cf0490a68
Reviewed-on: https://go-review.googlesource.com/2172
Reviewed-by: Chris Manghane <cmang@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

astutil/util.go

@@ -0,0 +1,14 @@
+package astutil
+
+import "go/ast"
+
+// Unparen returns e with any enclosing parentheses stripped.
+func Unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}

cmd/vet/bool.go

@@ -9,6 +9,8 @@ package main
 import (
 	"go/ast"
 	"go/token"
+
+	"golang.org/x/tools/astutil"
 )
 
 func init() {
@@ -162,7 +164,7 @@ func hasSideEffects(e ast.Expr) bool {
 // split returns []{d, c, b, a}.
 func (op boolOp) split(e ast.Expr) (exprs []ast.Expr) {
 	for {
-		e = unparen(e)
+		e = astutil.Unparen(e)
 		if b, ok := e.(*ast.BinaryExpr); ok && b.Op == op.tok {
 			exprs = append(exprs, op.split(b.Y)...)
 			e = b.X
@@ -173,13 +175,3 @@ func (op boolOp) split(e ast.Expr) (exprs []ast.Expr) {
 	}
 	return
 }
-
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			return e
-		}
-		e = p.X
-	}
-}

go/ssa/util.go

@@ -13,6 +13,7 @@ import (
 	"io"
 	"os"
 
+	"golang.org/x/tools/astutil"
 	"golang.org/x/tools/go/types"
 )
 
@@ -22,17 +23,7 @@ func unreachable() {
 
 //// AST utilities
 
-// unparen returns e with any enclosing parentheses stripped.
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			break
-		}
-		e = p.X
-	}
-	return e
-}
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
 
 // isBlankIdent returns true iff e is an Ident with name "_".
 // They have no associated types.Object, and thus no type.

go/types/builtins.go

@@ -10,6 +10,7 @@ import (
 	"go/ast"
 	"go/token"
 
+	"golang.org/x/tools/astutil"
 	"golang.org/x/tools/go/exact"
 )
 
@@ -608,15 +609,7 @@ func implicitArrayDeref(typ Type) Type {
 	return typ
 }
 
-// unparen removes any parentheses surrounding an expression and returns
-// the naked expression.
-//
-func unparen(x ast.Expr) ast.Expr {
-	if p, ok := x.(*ast.ParenExpr); ok {
-		return unparen(p.X)
-	}
-	return x
-}
+func unparen(x ast.Expr) ast.Expr { return astutil.Unparen(x) }
 
 func (check *Checker) complexArg(x *operand) bool {
 	t, _ := x.typ.Underlying().(*Basic)

oracle/oracle.go

@@ -482,17 +482,7 @@ func ptrAnalysis(o *Oracle) *pointer.Result {
 	return result
 }
 
-// unparen returns e with any enclosing parentheses stripped.
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			break
-		}
-		e = p.X
-	}
-	return e
-}
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
 
 // deref returns a pointer's element type; otherwise it returns typ.
 func deref(typ types.Type) types.Type {

refactor/eg/match.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"reflect"
 
+	"golang.org/x/tools/astutil"
 	"golang.org/x/tools/go/exact"
 	"golang.org/x/tools/go/loader"
 	"golang.org/x/tools/go/types"
@@ -216,18 +217,7 @@ func (tr *Transformer) matchWildcard(xobj *types.Var, y ast.Expr) bool {
 
 // -- utilities --------------------------------------------------------
 
-// unparen returns e with any enclosing parentheses stripped.
-// TODO(adonovan): move to astutil package.
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			break
-		}
-		e = p.X
-	}
-	return e
-}
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
 
 // isRef returns the object referred to by this (possibly qualified)
 // identifier, or nil if the node is not a referring identifier.

refactor/rename/util.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 	"unicode"
 
+	"golang.org/x/tools/astutil"
 	"golang.org/x/tools/go/types"
 )
 
@@ -100,14 +101,4 @@ func sameFile(x, y string) bool {
 	return false
 }
 
-// unparen returns e with any enclosing parentheses stripped.
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			break
-		}
-		e = p.X
-	}
-	return e
-}
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }

refactor/satisfy/find.go

@@ -49,6 +49,7 @@ import (
 	"go/ast"
 	"go/token"
 
+	"golang.org/x/tools/astutil"
 	"golang.org/x/tools/go/types"
 )
 
@@ -698,17 +699,7 @@ func deref(typ types.Type) types.Type {
 	return typ
 }
 
-// unparen returns e with any enclosing parentheses stripped.
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			break
-		}
-		e = p.X
-	}
-	return e
-}
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
 
 func isInterface(T types.Type) bool {
 	_, ok := T.Underlying().(*types.Interface)