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Copy pathutil.go
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Copy pathutil.go
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462 lines (436 loc) · 10.1 KB
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package astutil
import (
"fmt"
"go/ast"
"go/token"
"reflect"
"strings"
"golang.org/x/tools/go/ast/astutil"
)
func IsIdent(expr ast.Expr, ident string) bool {
id, ok := expr.(*ast.Ident)
return ok && id.Name == ident
}
// isBlank returns whether id is the blank identifier "_".
// If id == nil, the answer is false.
func IsBlank(id ast.Expr) bool {
ident, _ := id.(*ast.Ident)
return ident != nil && ident.Name == "_"
}
10000
// Deprecated: use code.IsIntegerLiteral instead.
func IsIntLiteral(expr ast.Expr, literal string) bool {
lit, ok := expr.(*ast.BasicLit)
return ok && lit.Kind == token.INT && lit.Value == literal
}
// Deprecated: use IsIntLiteral instead
func IsZero(expr ast.Expr) bool {
return IsIntLiteral(expr, "0")
}
func Preamble(f *ast.File) string {
cutoff := f.Package
if f.Doc != nil {
cutoff = f.Doc.Pos()
}
var out []string
for _, cmt := range f.Comments {
if cmt.Pos() >= cutoff {
break
}
out = append(out, cmt.Text())
}
return strings.Join(out, "\n")
}
func GroupSpecs(fset *token.FileSet, specs []ast.Spec) [][]ast.Spec {
if len(specs) == 0 {
return nil
}
groups := make([][]ast.Spec, 1)
groups[0] = append(groups[0], specs[0])
for _, spec := range specs[1:] {
g := groups[len(groups)-1]
if fset.PositionFor(spec.Pos(), false).Line-1 !=
fset.PositionFor(g[len(g)-1].End(), false).Line {
groups = append(groups, nil)
}
groups[len(groups)-1] = append(groups[len(groups)-1], spec)
}
return groups
}
// CopyExpr creates a deep copy of an expression.
// It doesn't support copying FuncLits and returns ok == false when encountering one.
func CopyExpr(node ast.Expr) (ast.Expr, bool) {
switch node := node.(type) {
case *ast.BasicLit:
cp := *node
return &cp, true
case *ast.BinaryExpr:
cp := *node
var ok1, ok2 bool
cp.X, ok1 = CopyExpr(cp.X)
cp.Y, ok2 = CopyExpr(cp.Y)
return &cp, ok1 && ok2
case *ast.CallExpr:
var ok bool
cp := *node
cp.Fun, ok = CopyExpr(cp.Fun)
if !ok {
return nil, false
}
cp.Args = make([]ast.Expr, len(node.Args))
for i, v := range node.Args {
cp.Args[i], ok = CopyExpr(v)
if !ok {
return nil, false
}
}
return &cp, true
case *ast.CompositeLit:
var ok bool
cp := *node
cp.Type, ok = CopyExpr(cp.Type)
if !ok {
return nil, false
}
cp.Elts = make([]ast.Expr, len(node.Elts))
for i, v := range node.Elts {
cp.Elts[i], ok = CopyExpr(v)
if !ok {
return nil, false
}
}
return &cp, true
case *ast.Ident:
cp := *node
return &cp, true
case *ast.IndexExpr:
var ok1, ok2 bool
cp := *node
cp.X, ok1 = CopyExpr(cp.X)
cp.Index, ok2 = CopyExpr(cp.Index)
return &cp, ok1 && ok2
case *ast.IndexListExpr:
var ok bool
cp := *node
cp.X, ok = CopyExpr(cp.X)
if !ok {
return nil, false
}
for i, v := range node.Indices {
cp.Indices[i], ok = CopyExpr(v)
if !ok {
return nil, false
}
}
return &cp, true
case *ast.KeyValueExpr:
var ok1, ok2 bool
cp := *node
cp.Key, ok1 = CopyExpr(cp.Key)
cp.Value, ok2 = CopyExpr(cp.Value)
return &cp, ok1 && ok2
case *ast.ParenExpr:
var ok bool
cp := *node
cp.X, ok = CopyExpr(cp.X)
return &cp, ok
case *ast.SelectorExpr:
var ok bool
cp := *node
cp.X, ok = CopyExpr(cp.X)
if !ok {
return nil, false
}
sel, ok := CopyExpr(cp.Sel)
if !ok {
// this is impossible
return nil, false
}
cp.Sel = sel.(*ast.Ident)
return &cp, true
case *ast.SliceExpr:
var ok1, ok2, ok3, ok4 bool
cp := *node
cp.X, ok1 = CopyExpr(cp.X)
cp.Low, ok2 = CopyExpr(cp.Low)
cp.High, ok3 = CopyExpr(cp.High)
cp.Max, ok4 = CopyExpr(cp.Max)
return &cp, ok1 && ok2 && ok3 && ok4
case *ast.StarExpr:
var ok bool
cp := *node
cp.X, ok = CopyExpr(cp.X)
return &cp, ok
case *ast.TypeAssertExpr:
var ok1, ok2 bool
cp := *node
cp.X, ok1 = CopyExpr(cp.X)
cp.Type, ok2 = CopyExpr(cp.Type)
return &cp, ok1 && ok2
case *ast.UnaryExpr:
var ok bool
cp := *node
cp.X, ok = CopyExpr(cp.X)
return &cp, ok
case *ast.MapType:
var ok1, ok2 bool
cp := *node
cp.Key, ok1 = CopyExpr(cp.Key)
cp.Value, ok2 = CopyExpr(cp.Value)
return &cp, ok1 && ok2
case *ast.ArrayType:
var ok1, ok2 bool
cp := *node
cp.Len, ok1 = CopyExpr(cp.Len)
cp.Elt, ok2 = CopyExpr(cp.Elt)
return &cp, ok1 && ok2
case *ast.Ellipsis:
var ok bool
cp := *node
cp.Elt, ok = CopyExpr(cp.Elt)
return &cp, ok
case *ast.InterfaceType:
cp := *node
return &cp, true
case *ast.StructType:
cp := *node
return &cp, true
case *ast.FuncLit, *ast.FuncType:
// TODO(dh): implement copying of function literals and types.
return nil, false
case *ast.ChanType:
var ok bool
cp := *node
cp.Value, ok = CopyExpr(cp.Value)
return &cp, ok
case nil:
return nil, true
default:
panic(fmt.Sprintf("unreachable: %T", node))
}
}
func Equal(a, b ast.Node) bool {
if a == b {
return true
}
if a == nil || b == nil {
return false
}
if reflect.TypeOf(a) != reflect.TypeOf(b) {
return false
}
switch a := a.(type) {
case *ast.BasicLit:
b := b.(*ast.BasicLit)
return a.Kind == b.Kind && a.Value == b.Value
case *ast.BinaryExpr:
b := b.(*ast.BinaryExpr)
return Equal(a.X, b.X) && a.Op == b.Op && Equal(a.Y, b.Y)
case *ast.CallExpr:
b := b.(*ast.CallExpr)
if len(a.Args) != len(b.Args) {
return false
}
for i, arg := range a.Args {
if !Equal(arg, b.Args[i]) {
return false
}
}
return Equal(a.Fun, b.Fun) &&
(a.Ellipsis == token.NoPos && b.Ellipsis == token.NoPos || a.Ellipsis != token.NoPos && b.Ellipsis != token.NoPos)
case *ast.CompositeLit:
b := b.(*ast.CompositeLit)
if len(a.Elts) != len(b.Elts) {
return false
}
for i, elt := range b.Elts {
if !Equal(elt, b.Elts[i]) {
return false
}
}
return Equal(a.Type, b.Type) && a.Incomplete == b.Incomplete
case *ast.Ident:
b := b.(*ast.Ident)
return a.Name == b.Name
case *ast.IndexExpr:
b := b.(*ast.IndexExpr)
return Equal(a.X, b.X) && Equal(a.Index, b.Index)
case *ast.IndexListExpr:
b := b.(*ast.IndexListExpr)
if len(a.Indices) != len(b.Indices) {
return false
}
for i, v := range a.Indices {
if !Equal(v, b.Indices[i]) {
return false
}
}
return Equal(a.X, b.X)
case *ast.KeyValueExpr:
b := b.(*ast.KeyValueExpr)
return Equal(a.Key, b.Key) && Equal(a.Value, b.Value)
case *ast.ParenExpr:
b := b.(*ast.ParenExpr)
return Equal(a.X, b.X)
case *ast.SelectorExpr:
b := b.(*ast.SelectorExpr)
return Equal(a.X, b.X) && Equal(a.Sel, b.Sel)
case *ast.SliceExpr:
b := b.(*ast.SliceExpr)
return Equal(a.X, b.X) && Equal(a.Low, b.Low) && Equal(a.High, b.High) && Equal(a.Max, b.Max) && a.Slice3 == b.Slice3
case *ast.StarExpr:
b := b.(*ast.StarExpr)
return Equal(a.X, b.X)
case *ast.TypeAssertExpr:
b := b.(*ast.TypeAssertExpr)
return Equal(a.X, b.X) && Equal(a.Type, b.Type)
case *ast.UnaryExpr:
b := b.(*ast.UnaryExpr)
return a.Op == b.Op && Equal(a.X, b.X)
case *ast.MapType:
b := b.(*ast.MapType)
return Equal(a.Key, b.Key) && Equal(a.Value, b.Value)
case *ast.ArrayType:
b := b.(*ast.ArrayType)
return Equal(a.Len, b.Len) && Equal(a.Elt, b.Elt)
case *ast.Ellipsis:
b := b.(*ast.Ellipsis)
return Equal(a.Elt, b.Elt)
case *ast.InterfaceType:
b := b.(*ast.InterfaceType)
return a.Incomplete == b.Incomplete && Equal(a.Methods, b.Methods)
case *ast.StructType:
b := b.(*ast.StructType)
return a.Incomplete == b.Incomplete && Equal(a.Fields, b.Fields)
case *ast.FuncLit:
// TODO(dh): support function literals
return false
case *ast.ChanType:
b := b.(*ast.ChanType)
return a.Dir == b.Dir && (a.Arrow == token.NoPos && b.Arrow == token.NoPos || a.Arrow != token.NoPos && b.Arrow != token.NoPos)
case *ast.FieldList:
b := b.(*ast.FieldList)
if len(a.List) != len(b.List) {
return false
}
for i, fieldA := range a.List {
if !Equal(fieldA, b.List[i]) {
return false
}
}
return true
case *ast.Field:
b := b.(*ast.Field)
if len(a.Names) != len(b.Names) {
return false
}
for j, name := range a.Names {
if !Equal(name, b.Names[j]) {
return false
}
}
if !Equal(a.Type, b.Type) || !Equal(a.Tag, b.Tag) {
return false
}
return true
default:
panic(fmt.Sprintf("unreachable: %T", a))
}
}
func NegateDeMorgan(expr ast.Expr, recursive bool) ast.Expr {
switch expr := expr.(type) {
case *ast.BinaryExpr:
var out ast.BinaryExpr
switch expr.Op {
case token.EQL:
out.X = expr.X
out.Op = token.NEQ
out.Y = expr.Y
case token.LSS:
out.X = expr.X
out.Op = token.GEQ
out.Y = expr.Y
case token.GTR:
out.X = expr.X
out.Op = token.LEQ
out.Y = expr.Y
case token.NEQ:
out.X = expr.X
out.Op = token.EQL
out.Y = expr.Y
case token.LEQ:
out.X = expr.X
out.Op = token.GTR
out.Y = expr.Y
case token.GEQ:
out.X = expr.X
out.Op = token.LSS
out.Y = expr.Y
case token.LAND:
out.X = NegateDeMorgan(expr.X, recursive)
out.Op = token.LOR
out.Y = NegateDeMorgan(expr.Y, recursive)
case token.LOR:
out.X = NegateDeMorgan(expr.X, recursive)
out.Op = token.LAND
out.Y = NegateDeMorgan(expr.Y, recursive)
}
return &out
case *ast.ParenExpr:
if recursive {
return &ast.ParenExpr{
X: NegateDeMorgan(expr.X, recursive),
}
} else {
return &ast.UnaryExpr{
Op: token.NOT,
X: expr,
}
}
case *ast.UnaryExpr:
if expr.Op == token.NOT {
return expr.X
} else {
return &ast.UnaryExpr{
Op: token.NOT,
X: expr,
}
}
default:
return &ast.UnaryExpr{
Op: token.NOT,
X: expr,
}
}
}
func SimplifyParentheses(node ast.Expr) ast.Expr {
var changed bool
// XXX accept list of ops to operate on
// XXX copy AST node, don't modify in place
post := func(c *astutil.Cursor) bool {
out := c.Node()
if paren, ok := c.Node().(*ast.ParenExpr); ok {
out = paren.X
}
if binop, ok := out.(*ast.BinaryExpr); ok {
if right, ok := binop.Y.(*ast.BinaryExpr); ok && binop.Op == right.Op {
// XXX also check that Op is associative
root := binop
pivot := root.Y.(*ast.BinaryExpr)
root.Y = pivot.X
pivot.X = root
root = pivot
out = root
}
}
if out != c.Node() {
changed = true
c.Replace(out)
}
return true
}
for changed = true; changed; {
changed = false
node = astutil.Apply(node, nil, post).(ast.Expr)
}
return node
}