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// Copyright 2021 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 cue
import (
"cuelang.org/go/internal/core/adt"
)
// This file contains query-related code.
// getScopePrefix finds the Vertex that exists in v for the longest prefix of p.
//
// It is used to make the parent scopes visible when resolving expressions.
func getScopePrefix(v Value, p Path) Value {
for _, sel := range p.Selectors() {
w := v.LookupPath(MakePath(sel))
if !w.Exists() {
break
}
v = w
}
return v
}
// LookupPath reports the value for path p relative to v.
//
// Use [AnyString] and [AnyIndex] to find the value of undefined element types
// for structs and lists respectively, for example for the patterns in
// `{[string]: int}` and `[...string]`.
func (v Value) LookupPath(p Path) Value {
if v.v == nil {
return Value{}
}
n := v.v
parent := v.parent_
ctx := v.ctx()
outer:
for _, sel := range p.path {
f := sel.sel.feature(v.idx)
deref := n.DerefValue()
for _, a := range deref.Arcs {
if a.Label == f {
if a.IsConstraint() && !sel.sel.isConstraint() {
break
}
parent = linkParent(parent, n, a)
n = a
continue outer
}
}
if sel.sel.isConstraint() {
x := &adt.Vertex{
Parent: n,
Label: sel.sel.feature(ctx),
}
deref.MatchAndInsert(ctx, x)
if x.HasConjuncts() {
x.Finalize(ctx)
parent = linkParent(parent, n, x)
n = x
continue
}
}
var x *adt.Bottom
if err, ok := sel.sel.(pathError); ok {
x = &adt.Bottom{Err: err.Error}
} else {
x = mkErr(n, adt.EvalError, "field not found: %v", sel.sel)
if n.Accept(ctx, f) {
x.Code = adt.IncompleteError
}
x.NotExists = true
}
v := makeValue(v.idx, n, parent)
return newErrValue(v, x)
}
return makeValue(v.idx, n, parent)
}
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