/
compile.go
1062 lines (914 loc) · 23.2 KB
/
compile.go
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// Copyright 2020 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package compile
import (
"strings"
"cuelang.org/go/cue/ast"
"cuelang.org/go/cue/errors"
"cuelang.org/go/cue/literal"
"cuelang.org/go/cue/token"
"cuelang.org/go/internal"
"cuelang.org/go/internal/astinternal"
"cuelang.org/go/internal/core/adt"
)
// A Scope represents a nested scope of Vertices.
type Scope interface {
Parent() Scope
Vertex() *adt.Vertex
}
// Config configures a compilation.
type Config struct {
// Scope specifies a node in which to look up unresolved references. This
// is useful for evaluating expressions within an already evaluated
// configuration.
Scope Scope
// Imports allows unresolved identifiers to resolve to imports.
//
// Under normal circumstances, identifiers bind to import specifications,
// which get resolved to an ImportReference. Use this option to
// automatically resolve identifiers to imports.
Imports func(x *ast.Ident) (pkgPath string)
// pkgPath is used to qualify the scope of hidden fields. The default
// scope is "_".
pkgPath string
}
// Files compiles the given files as a single instance. It disregards
// the package names and it is the responsibility of the user to verify that
// the packages names are consistent. The pkgID must be a unique identifier
// for a package in a module, for instance as obtained from build.Instance.ID.
//
// Files may return a completed parse even if it has errors.
func Files(cfg *Config, r adt.Runtime, pkgID string, files ...*ast.File) (*adt.Vertex, errors.Error) {
c := newCompiler(cfg, pkgID, r)
v := c.compileFiles(files)
if c.errs != nil {
return v, c.errs
}
return v, nil
}
// Expr compiles the given expression into a conjunct. The pkgID must be a
// unique identifier for a package in a module, for instance as obtained from
// build.Instance.ID.
func Expr(cfg *Config, r adt.Runtime, pkgPath string, x ast.Expr) (adt.Conjunct, errors.Error) {
c := newCompiler(cfg, pkgPath, r)
v := c.compileExpr(x)
if c.errs != nil {
return v, c.errs
}
return v, nil
}
func newCompiler(cfg *Config, pkgPath string, r adt.Runtime) *compiler {
c := &compiler{
index: r,
}
if cfg != nil {
c.Config = *cfg
}
if pkgPath == "" {
pkgPath = "_"
}
c.Config.pkgPath = pkgPath
return c
}
type compiler struct {
Config
upCountOffset int32 // 1 for files; 0 for expressions
index adt.StringIndexer
stack []frame
inSelector int
fileScope map[adt.Feature]bool
num literal.NumInfo
errs errors.Error
}
func (c *compiler) reset() {
c.fileScope = nil
c.stack = c.stack[:0]
c.errs = nil
}
func (c *compiler) errf(n ast.Node, format string, args ...interface{}) *adt.Bottom {
err := &compilerError{
n: n,
path: c.path(),
Message: errors.NewMessage(format, args),
}
c.errs = errors.Append(c.errs, err)
return &adt.Bottom{Err: err}
}
func (c *compiler) path() []string {
a := []string{}
for _, f := range c.stack {
if f.label != nil {
a = append(a, f.label.labelString())
}
}
return a
}
type frame struct {
label labeler // path name leading to this frame.
scope ast.Node // *ast.File or *ast.Struct
field *ast.Field
// scope map[ast.Node]bool
upCount int32 // 1 for field, 0 for embedding.
aliases map[string]aliasEntry
}
type aliasEntry struct {
label labeler
srcExpr ast.Expr
expr adt.Expr
source ast.Node
used bool
}
func (c *compiler) insertAlias(id *ast.Ident, a aliasEntry) *adt.Bottom {
k := len(c.stack) - 1
m := c.stack[k].aliases
if m == nil {
m = map[string]aliasEntry{}
c.stack[k].aliases = m
}
if id == nil || !ast.IsValidIdent(id.Name) {
return c.errf(a.source, "invalid identifier name")
}
if e, ok := m[id.Name]; ok {
return c.errf(a.source,
"alias %q already declared; previous declaration at %s",
id.Name, e.source.Pos())
}
m[id.Name] = a
return nil
}
func (c *compiler) updateAlias(id *ast.Ident, expr adt.Expr) {
k := len(c.stack) - 1
m := c.stack[k].aliases
x := m[id.Name]
x.expr = expr
x.label = nil
x.srcExpr = nil
m[id.Name] = x
}
// lookupAlias looks up an alias with the given name at the k'th stack position.
func (c *compiler) lookupAlias(k int, id *ast.Ident) aliasEntry {
m := c.stack[k].aliases
name := id.Name
entry, ok := m[name]
if !ok {
err := c.errf(id, "could not find LetClause associated with identifier %q", name)
return aliasEntry{expr: err}
}
switch {
case entry.label != nil:
if entry.srcExpr == nil {
entry.expr = c.errf(id, "cyclic references in let clause or alias")
break
}
src := entry.srcExpr
entry.srcExpr = nil // mark to allow detecting cycles
m[name] = entry
entry.expr = c.labeledExprAt(k, nil, entry.label, src)
entry.label = nil
}
entry.used = true
m[name] = entry
return entry
}
func (c *compiler) pushScope(n labeler, upCount int32, id ast.Node) *frame {
c.stack = append(c.stack, frame{
label: n,
scope: id,
upCount: upCount,
})
return &c.stack[len(c.stack)-1]
}
func (c *compiler) popScope() {
k := len(c.stack) - 1
f := c.stack[k]
for k, v := range f.aliases {
if !v.used {
c.errf(v.source, "unreferenced alias or let clause %s", k)
}
}
c.stack = c.stack[:k]
}
func (c *compiler) compileFiles(a []*ast.File) *adt.Vertex { // Or value?
c.fileScope = map[adt.Feature]bool{}
c.upCountOffset = 1
// TODO(resolve): this is also done in the runtime package, do we need both?
// Populate file scope to handle unresolved references.
// Excluded from cross-file resolution are:
// - import specs
// - aliases
// - anything in an anonymous file
//
for _, f := range a {
if p := internal.GetPackageInfo(f); p.IsAnonymous() {
continue
}
for _, d := range f.Decls {
if f, ok := d.(*ast.Field); ok {
if id, ok := f.Label.(*ast.Ident); ok {
c.fileScope[c.label(id)] = true
}
}
}
}
// TODO: set doc.
res := &adt.Vertex{}
// env := &adt.Environment{Vertex: nil} // runtime: c.runtime
env := &adt.Environment{}
top := env
for p := c.Config.Scope; p != nil; p = p.Parent() {
top.Vertex = p.Vertex()
top.Up = &adt.Environment{}
top = top.Up
}
for _, file := range a {
c.pushScope(nil, 0, file) // File scope
v := &adt.StructLit{Src: file}
c.addDecls(v, file.Decls)
res.Conjuncts = append(res.Conjuncts, adt.MakeRootConjunct(env, v))
c.popScope()
}
return res
}
func (c *compiler) compileExpr(x ast.Expr) adt.Conjunct {
expr := c.expr(x)
env := &adt.Environment{}
top := env
for p := c.Config.Scope; p != nil; p = p.Parent() {
top.Vertex = p.Vertex()
top.Up = &adt.Environment{}
top = top.Up
}
return adt.MakeRootConjunct(env, expr)
}
// resolve assumes that all existing resolutions are legal. Validation should
// be done in a separate step if required.
//
// TODO: collect validation pass to verify that all resolutions are
// legal?
func (c *compiler) resolve(n *ast.Ident) adt.Expr {
// X in import "path/X"
// X in import X "path"
if imp, ok := n.Node.(*ast.ImportSpec); ok {
return &adt.ImportReference{
Src: n,
ImportPath: c.label(imp.Path),
Label: c.label(n),
}
}
label := c.label(n)
if label == adt.InvalidLabel { // `_`
return &adt.Top{Src: n}
}
// Unresolved field.
if n.Node == nil {
upCount := int32(0)
for _, c := range c.stack {
upCount += c.upCount
}
if c.fileScope[label] {
return &adt.FieldReference{
Src: n,
UpCount: upCount,
Label: label,
}
}
upCount += c.upCountOffset
for p := c.Scope; p != nil; p = p.Parent() {
for _, a := range p.Vertex().Arcs {
if a.Label == label {
return &adt.FieldReference{
Src: n,
UpCount: upCount,
Label: label,
}
}
}
upCount++
}
if c.Config.Imports != nil {
if pkgPath := c.Config.Imports(n); pkgPath != "" {
return &adt.ImportReference{
Src: n,
ImportPath: adt.MakeStringLabel(c.index, pkgPath),
Label: c.label(n),
}
}
}
if p := predeclared(n); p != nil {
return p
}
return c.errf(n, "reference %q not found", n.Name)
}
// X in [X=x]: y Scope: Field Node: Expr (x)
// X in X=[x]: y Scope: Field Node: Field
// X in x: X=y Scope: Field Node: Alias
if f, ok := n.Scope.(*ast.Field); ok {
upCount := int32(0)
k := len(c.stack) - 1
for ; k >= 0; k-- {
if c.stack[k].field == f {
break
}
upCount += c.stack[k].upCount
}
label := &adt.LabelReference{
Src: n,
UpCount: upCount,
}
switch f := n.Node.(type) {
case *ast.Field:
_ = c.lookupAlias(k, f.Label.(*ast.Alias).Ident) // mark as used
return &adt.DynamicReference{
Src: n,
UpCount: upCount,
Label: label,
}
case *ast.Alias:
_ = c.lookupAlias(k, f.Ident) // mark as used
return &adt.ValueReference{
Src: n,
UpCount: upCount,
Label: c.label(f.Ident),
}
}
return label
}
upCount := int32(0)
k := len(c.stack) - 1
for ; k >= 0; k-- {
if c.stack[k].scope == n.Scope {
break
}
upCount += c.stack[k].upCount
}
if k < 0 {
// This is a programmatic error and should never happen if the users
// just builds with the cue command or if astutil.Resolve is used
// correctly.
c.errf(n, "reference %q set to unknown node in AST; "+
"this can result from incorrect API usage or a compiler bug",
n.Name)
}
if n.Scope == nil {
// Package.
// Should have been handled above.
return c.errf(n, "unresolved identifier %v", n.Name)
}
switch f := n.Node.(type) {
// Local expressions
case *ast.LetClause:
entry := c.lookupAlias(k, n)
// let x = y
return &adt.LetReference{
Src: n,
UpCount: upCount,
Label: label,
X: entry.expr,
}
// TODO: handle new-style aliases
case *ast.Field:
// X=x: y
// X=(x): y
// X="\(x)": y
a, ok := f.Label.(*ast.Alias)
if !ok {
return c.errf(n, "illegal reference %s", n.Name)
}
aliasInfo := c.lookupAlias(k, a.Ident) // marks alias as used.
lab, ok := a.Expr.(ast.Label)
if !ok {
return c.errf(a.Expr, "invalid label expression")
}
name, _, err := ast.LabelName(lab)
switch {
case errors.Is(err, ast.ErrIsExpression):
if aliasInfo.expr == nil {
panic("unreachable")
}
return &adt.DynamicReference{
Src: n,
UpCount: upCount,
Label: aliasInfo.expr,
}
case err != nil:
return c.errf(n, "invalid label: %v", err)
case name != "":
label = c.label(lab)
default:
return c.errf(n, "unsupported field alias %q", name)
}
}
return &adt.FieldReference{
Src: n,
UpCount: upCount,
Label: label,
}
}
func (c *compiler) addDecls(st *adt.StructLit, a []ast.Decl) {
for _, d := range a {
c.markAlias(d)
}
for _, d := range a {
c.addLetDecl(d)
}
for _, d := range a {
if x := c.decl(d); x != nil {
st.Decls = append(st.Decls, x)
}
}
}
func (c *compiler) markAlias(d ast.Decl) {
switch x := d.(type) {
case *ast.Field:
lab := x.Label
if a, ok := lab.(*ast.Alias); ok {
if _, ok = a.Expr.(ast.Label); !ok {
c.errf(a, "alias expression is not a valid label")
}
e := aliasEntry{source: a}
c.insertAlias(a.Ident, e)
}
case *ast.LetClause:
a := aliasEntry{
label: (*letScope)(x),
srcExpr: x.Expr,
source: x,
}
c.insertAlias(x.Ident, a)
case *ast.Alias:
c.errf(x, "old-style alias no longer supported: use let clause; use cue fix to update.")
}
}
func (c *compiler) decl(d ast.Decl) adt.Decl {
switch x := d.(type) {
case *ast.BadDecl:
return c.errf(d, "")
case *ast.Field:
lab := x.Label
if a, ok := lab.(*ast.Alias); ok {
if lab, ok = a.Expr.(ast.Label); !ok {
return c.errf(a, "alias expression is not a valid label")
}
switch lab.(type) {
case *ast.Ident, *ast.BasicLit, *ast.ListLit:
// Even though we won't need the alias, we still register it
// for duplicate and failed reference detection.
default:
c.updateAlias(a.Ident, c.expr(a.Expr))
}
}
v := x.Value
var value adt.Expr
if a, ok := v.(*ast.Alias); ok {
c.pushScope(nil, 0, a)
c.insertAlias(a.Ident, aliasEntry{source: a})
value = c.labeledExpr(x, (*fieldLabel)(x), a.Expr)
c.popScope()
} else {
value = c.labeledExpr(x, (*fieldLabel)(x), v)
}
switch l := lab.(type) {
case *ast.Ident, *ast.BasicLit:
label := c.label(lab)
if label == adt.InvalidLabel {
return c.errf(x, "cannot use _ as label")
}
// TODO(legacy): remove: old-school definitions
if x.Token == token.ISA && !label.IsDef() {
name, isIdent, err := ast.LabelName(lab)
if err == nil && isIdent {
idx := c.index.StringToIndex(name)
label, _ = adt.MakeLabel(x, idx, adt.DefinitionLabel)
}
}
if x.Optional == token.NoPos {
return &adt.Field{
Src: x,
Label: label,
Value: value,
}
} else {
return &adt.OptionalField{
Src: x,
Label: label,
Value: value,
}
}
case *ast.ListLit:
if len(l.Elts) != 1 {
// error
return c.errf(x, "list label must have one element")
}
var label adt.Feature
elem := l.Elts[0]
// TODO: record alias for error handling? In principle it is okay
// to have duplicates, but we do want it to be used.
if a, ok := elem.(*ast.Alias); ok {
label = c.label(a.Ident)
elem = a.Expr
}
return &adt.BulkOptionalField{
Src: x,
Filter: c.expr(elem),
Value: value,
Label: label,
}
case *ast.ParenExpr:
if x.Token == token.ISA {
c.errf(x, "definitions not supported for dynamic fields")
}
return &adt.DynamicField{
Src: x,
Key: c.expr(l),
Value: value,
}
case *ast.Interpolation:
if x.Token == token.ISA {
c.errf(x, "definitions not supported for interpolations")
}
return &adt.DynamicField{
Src: x,
Key: c.expr(l),
Value: value,
}
}
// Handled in addLetDecl.
case *ast.LetClause:
// case: *ast.Alias: // TODO(value alias)
case *ast.CommentGroup:
// Nothing to do for a free-floating comment group.
case *ast.Attribute:
// Nothing to do for now for an attribute declaration.
case *ast.Ellipsis:
return &adt.Ellipsis{
Src: x,
Value: c.expr(x.Type),
}
case *ast.Comprehension:
return c.comprehension(x)
case *ast.EmbedDecl: // Deprecated
return c.expr(x.Expr)
case ast.Expr:
return c.expr(x)
}
return nil
}
func (c *compiler) addLetDecl(d ast.Decl) {
switch x := d.(type) {
// An alias reference will have an expression that is looked up in the
// environment cash.
case *ast.LetClause:
// Cache the parsed expression. Creating a unique expression for each
// reference allows the computation to be shared given that we don't
// have fields for expressions. This, in turn, prevents exponential
// blowup in x2: x1+x1, x3: x2+x2, ... patterns.
expr := c.labeledExpr(nil, (*letScope)(x), x.Expr)
c.updateAlias(x.Ident, expr)
case *ast.Alias:
c.errf(x, "old-style alias no longer supported: use let clause; use cue fix to update.")
}
}
func (c *compiler) elem(n ast.Expr) adt.Elem {
switch x := n.(type) {
case *ast.Ellipsis:
return &adt.Ellipsis{
Src: x,
Value: c.expr(x.Type),
}
case *ast.Comprehension:
return c.comprehension(x)
case ast.Expr:
return c.expr(x)
}
return nil
}
func (c *compiler) comprehension(x *ast.Comprehension) adt.Elem {
var cur adt.Yielder
var first adt.Yielder
var prev, next *adt.Yielder
for _, v := range x.Clauses {
switch x := v.(type) {
case *ast.ForClause:
var key adt.Feature
if x.Key != nil {
key = c.label(x.Key)
}
y := &adt.ForClause{
Syntax: x,
Key: key,
Value: c.label(x.Value),
Src: c.expr(x.Source),
}
cur = y
c.pushScope((*forScope)(x), 1, v)
defer c.popScope()
next = &y.Dst
case *ast.IfClause:
y := &adt.IfClause{
Src: x,
Condition: c.expr(x.Condition),
}
cur = y
next = &y.Dst
case *ast.LetClause:
y := &adt.LetClause{
Src: x,
Label: c.label(x.Ident),
Expr: c.expr(x.Expr),
}
cur = y
c.pushScope((*letScope)(x), 1, v)
defer c.popScope()
next = &y.Dst
}
if prev != nil {
*prev = cur
} else {
first = cur
if _, ok := cur.(*adt.LetClause); ok {
return c.errf(x,
"first comprehension clause must be 'if' or 'for'")
}
}
prev = next
}
// TODO: make x.Value an *ast.StructLit and this is redundant.
if y, ok := x.Value.(*ast.StructLit); !ok {
return c.errf(x.Value,
"comprehension value must be struct, found %T", y)
}
y := c.expr(x.Value)
st, ok := y.(*adt.StructLit)
if !ok {
// Error must have been generated.
return y
}
if prev != nil {
*prev = &adt.ValueClause{StructLit: st}
} else {
return c.errf(x, "comprehension value without clauses")
}
return &adt.Comprehension{
Clauses: first,
Value: st,
}
}
func (c *compiler) labeledExpr(f *ast.Field, lab labeler, expr ast.Expr) adt.Expr {
k := len(c.stack) - 1
return c.labeledExprAt(k, f, lab, expr)
}
func (c *compiler) labeledExprAt(k int, f *ast.Field, lab labeler, expr ast.Expr) adt.Expr {
if c.stack[k].field != nil {
panic("expected nil field")
}
saved := c.stack[k]
c.stack[k].label = lab
c.stack[k].field = f
value := c.expr(expr)
c.stack[k] = saved
return value
}
func (c *compiler) expr(expr ast.Expr) adt.Expr {
switch n := expr.(type) {
case nil:
return nil
case *ast.Ident:
return c.resolve(n)
case *ast.StructLit:
c.pushScope(nil, 1, n)
v := &adt.StructLit{Src: n}
c.addDecls(v, n.Elts)
c.popScope()
return v
case *ast.ListLit:
c.pushScope(nil, 1, n)
v := &adt.ListLit{Src: n}
elts, ellipsis := internal.ListEllipsis(n)
for _, d := range elts {
elem := c.elem(d)
switch x := elem.(type) {
case nil:
case adt.Elem:
v.Elems = append(v.Elems, x)
default:
c.errf(d, "type %T not allowed in ListLit", d)
}
}
if ellipsis != nil {
d := &adt.Ellipsis{
Src: ellipsis,
Value: c.expr(ellipsis.Type),
}
v.Elems = append(v.Elems, d)
}
c.popScope()
return v
case *ast.SelectorExpr:
c.inSelector++
ret := &adt.SelectorExpr{
Src: n,
X: c.expr(n.X),
Sel: c.label(n.Sel)}
c.inSelector--
return ret
case *ast.IndexExpr:
return &adt.IndexExpr{
Src: n,
X: c.expr(n.X),
Index: c.expr(n.Index),
}
case *ast.SliceExpr:
slice := &adt.SliceExpr{Src: n, X: c.expr(n.X)}
if n.Low != nil {
slice.Lo = c.expr(n.Low)
}
if n.High != nil {
slice.Hi = c.expr(n.High)
}
return slice
case *ast.BottomLit:
return &adt.Bottom{
Src: n,
Code: adt.UserError,
Err: errors.Newf(n.Pos(), "explicit error (_|_ literal) in source"),
}
case *ast.BadExpr:
return c.errf(n, "invalid expression")
case *ast.BasicLit:
return c.parse(n)
case *ast.Interpolation:
if len(n.Elts) == 0 {
return c.errf(n, "invalid interpolation")
}
first, ok1 := n.Elts[0].(*ast.BasicLit)
last, ok2 := n.Elts[len(n.Elts)-1].(*ast.BasicLit)
if !ok1 || !ok2 {
return c.errf(n, "invalid interpolation")
}
if len(n.Elts) == 1 {
return c.expr(n.Elts[0])
}
lit := &adt.Interpolation{Src: n}
info, prefixLen, _, err := literal.ParseQuotes(first.Value, last.Value)
if err != nil {
return c.errf(n, "invalid interpolation: %v", err)
}
if info.IsDouble() {
lit.K = adt.StringKind
} else {
lit.K = adt.BytesKind
}
prefix := ""
for i := 0; i < len(n.Elts); i += 2 {
l, ok := n.Elts[i].(*ast.BasicLit)
if !ok {
return c.errf(n, "invalid interpolation")
}
s := l.Value
if !strings.HasPrefix(s, prefix) {
return c.errf(l, "invalid interpolation: unmatched ')'")
}
s = l.Value[prefixLen:]
x := parseString(c, l, info, s)
lit.Parts = append(lit.Parts, x)
if i+1 < len(n.Elts) {
lit.Parts = append(lit.Parts, c.expr(n.Elts[i+1]))
}
prefix = ")"
prefixLen = 1
}
return lit
case *ast.ParenExpr:
return c.expr(n.X)
case *ast.CallExpr:
call := &adt.CallExpr{Src: n, Fun: c.expr(n.Fun)}
for _, a := range n.Args {
call.Args = append(call.Args, c.expr(a))
}
return call
case *ast.UnaryExpr:
switch n.Op {
case token.NOT, token.ADD, token.SUB:
return &adt.UnaryExpr{
Src: n,
Op: adt.OpFromToken(n.Op),
X: c.expr(n.X),
}
case token.GEQ, token.GTR, token.LSS, token.LEQ,
token.NEQ, token.MAT, token.NMAT:
return &adt.BoundExpr{
Src: n,
Op: adt.OpFromToken(n.Op),
Expr: c.expr(n.X),
}
case token.MUL:
return c.errf(n, "preference mark not allowed at this position")
default:
return c.errf(n, "unsupported unary operator %q", n.Op)
}
case *ast.BinaryExpr:
switch n.Op {
case token.OR:
d := &adt.DisjunctionExpr{Src: n}
c.addDisjunctionElem(d, n.X, false)
c.addDisjunctionElem(d, n.Y, false)
return d
default:
op := adt.OpFromToken(n.Op)
x := c.expr(n.X)
y := c.expr(n.Y)
if op != adt.AndOp {
c.assertConcreteIsPossible(n.X, op, x)
c.assertConcreteIsPossible(n.Y, op, y)
}
// return updateBin(c,
return &adt.BinaryExpr{Src: n, Op: op, X: x, Y: y} // )
}
default:
return c.errf(n, "%s values not allowed in this position", ast.Name(n))
}
}
func (c *compiler) assertConcreteIsPossible(src ast.Node, op adt.Op, x adt.Expr) bool {
if !adt.AssertConcreteIsPossible(op, x) {
str := astinternal.DebugStr(src)
c.errf(src, "invalid operand %s ('%s' requires concrete value)", str, op)
}
return false
}
func (c *compiler) addDisjunctionElem(d *adt.DisjunctionExpr, n ast.Expr, mark bool) {
switch x := n.(type) {
case *ast.BinaryExpr:
if x.Op == token.OR {
c.addDisjunctionElem(d, x.X, mark)
c.addDisjunctionElem(d, x.Y, mark)
return
}
case *ast.UnaryExpr:
if x.Op == token.MUL {
d.HasDefaults = true
c.addDisjunctionElem(d, x.X, true)