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cue: support optional field lookup in LookupPath
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This is done by allowing Selectors to be converted
to an optional form (if they aren't already).

It also supports the use of the Selectors AnyIndex and
AnyString for getting `T` for  `[string]: T` and `[...T]`.

This also allows deprecating Elem and Template, which
will be done in a separate CL.

Change-Id: I6074382f12259c3dd87557471d80f82720a84779
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9347
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
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mpvl committed Apr 8, 2021
1 parent e70a1db commit 957003c
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Showing 5 changed files with 194 additions and 12 deletions.
48 changes: 42 additions & 6 deletions cue/path.go
Original file line number Diff line number Diff line change
Expand Up @@ -70,11 +70,18 @@ var (
anyLabel = Selector{sel: anySelector(adt.AnyRegular)}
)

// Optional converts sel into an optional equivalent.
// foo -> foo?
func (sel Selector) Optional() Selector {
return wrapOptional(sel)
}

type selector interface {
String() string

feature(ctx adt.Runtime) adt.Feature
kind() adt.FeatureType
optional() bool
}

// A Path is series of selectors to query a CUE value.
Expand Down Expand Up @@ -144,6 +151,17 @@ func (p Path) String() string {
return b.String()
}

// Optional returns the optional form of a Path. For instance,
// foo.bar --> foo?.bar?
//
func (p Path) Optional() Path {
q := make([]Selector, 0, len(p.path))
for _, s := range p.path {
q = appendSelector(q, wrapOptional(s))
}
return Path{path: q}
}

func toSelectors(expr ast.Expr) []Selector {
switch x := expr.(type) {
case *ast.Ident:
Expand Down Expand Up @@ -293,6 +311,7 @@ type scopedSelector struct {
func (s scopedSelector) String() string {
return s.name
}
func (scopedSelector) optional() bool { return false }

func (s scopedSelector) kind() adt.FeatureType {
switch {
Expand Down Expand Up @@ -331,6 +350,8 @@ func (d definitionSelector) String() string {
return string(d)
}

func (d definitionSelector) optional() bool { return false }

func (d definitionSelector) kind() adt.FeatureType {
return adt.DefinitionLabel
}
Expand All @@ -354,6 +375,7 @@ func (s stringSelector) String() string {
return str
}

func (s stringSelector) optional() bool { return false }
func (s stringSelector) kind() adt.FeatureType { return adt.StringLabel }

func (s stringSelector) feature(r adt.Runtime) adt.Feature {
Expand All @@ -376,6 +398,7 @@ func (s indexSelector) String() string {
}

func (s indexSelector) kind() adt.FeatureType { return adt.IntLabel }
func (s indexSelector) optional() bool { return false }

func (s indexSelector) feature(r adt.Runtime) adt.Feature {
return adt.Feature(s)
Expand All @@ -385,6 +408,7 @@ func (s indexSelector) feature(r adt.Runtime) adt.Feature {
type anySelector adt.Feature

func (s anySelector) String() string { return "_" }
func (s anySelector) optional() bool { return true }
func (s anySelector) kind() adt.FeatureType { return adt.Feature(s).Typ() }

func (s anySelector) feature(r adt.Runtime) adt.Feature {
Expand All @@ -398,16 +422,27 @@ func (s anySelector) feature(r adt.Runtime) adt.Feature {
// func ImportPath(s string) Selector {
// return importSelector(s)
// }
type optionalSelector struct {
selector
}

// type importSelector string
func wrapOptional(sel Selector) Selector {
if !sel.sel.optional() {
sel = Selector{optionalSelector{sel.sel}}
}
return sel
}

// func (s importSelector) String() string {
// return literal.String.Quote(string(s))
// func isOptional(sel selector) bool {
// _, ok := sel.(optionalSelector)
// return ok
// }

// func (s importSelector) feature(r adt.Runtime) adt.Feature {
// return adt.InvalidLabel
// }
func (s optionalSelector) optional() bool { return true }

func (s optionalSelector) String() string {
return s.selector.String() + "?"
}

// TODO: allow looking up in parent scopes?

Expand All @@ -429,6 +464,7 @@ type pathError struct {
}

func (p pathError) String() string { return p.Error.Error() }
func (p pathError) optional() bool { return false }
func (p pathError) kind() adt.FeatureType { return 0 }
func (p pathError) feature(r adt.Runtime) adt.Feature {
return adt.InvalidLabel
Expand Down
18 changes: 17 additions & 1 deletion cue/query.go
Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,12 @@ func resolveExpr(ctx *context, v *adt.Vertex, x ast.Expr) adt.Value {

// LookupPath reports the value for path p relative to v.
func (v Value) LookupPath(p Path) Value {
if v.v == nil {
return Value{}
}
n := v.v
ctx := v.ctx().opCtx

outer:
for _, sel := range p.path {
f := sel.sel.feature(v.idx.Runtime)
Expand All @@ -65,7 +70,18 @@ outer:
continue outer
}
}
// TODO: if optional, look up template for name.
if sel.sel.optional() {
x := &adt.Vertex{
Parent: v.v,
Label: sel.sel.feature(ctx),
}
n.MatchAndInsert(ctx, x)
if len(x.Conjuncts) > 0 {
x.Finalize(ctx)
n = x
continue
}
}

var x *adt.Bottom
if err, ok := sel.sel.(pathError); ok {
Expand Down
125 changes: 125 additions & 0 deletions cue/query_test.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,125 @@
// 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_test

import (
"bytes"
"testing"

"cuelang.org/go/cue"
"cuelang.org/go/internal/diff"
)

func TestLookupPath(t *testing.T) {
r := &cue.Runtime{}

testCases := []struct {
in string
path cue.Path
out string `test:"update"` // :nerdSnipe:
notExist bool `test:"update"` // :nerdSnipe:
}{{
in: `
[Name=string]: { a: Name }
`,
path: cue.MakePath(cue.Str("a")),
notExist: true,
}, {
in: `
#V: {
x: int
}
#X: {
[string]: int64
} & #V
v: #X
`,
path: cue.ParsePath("v.x"),
out: `int64`,
}, {
in: `
a: [...int]
`,
path: cue.MakePath(cue.Str("a"), cue.AnyIndex),
out: `int`,
}, {
in: `
[Name=string]: { a: Name }
`,
path: cue.MakePath(cue.AnyString, cue.Str("a")),
out: `string`,
}, {
in: `
[Name=string]: { a: Name }
`,
path: cue.MakePath(cue.Str("b").Optional(), cue.Str("a")),
out: `"b"`,
}, {
in: `
[Name=string]: { a: Name }
`,
path: cue.MakePath(cue.AnyString),
out: `{a: string}`,
}, {
in: `
a: [Foo=string]: [Bar=string]: { b: Foo+Bar }
`,
path: cue.MakePath(cue.Str("a"), cue.Str("b"), cue.Str("c")).Optional(),
out: `{b: "bc"}`,
}, {
in: `
a: [Foo=string]: b: [Bar=string]: { c: Foo }
a: foo: b: [Bar=string]: { d: Bar }
`,
path: cue.MakePath(cue.Str("a"), cue.Str("foo"), cue.Str("b"), cue.AnyString),
out: `{c: "foo", d: string}`,
}, {
in: `
[Name=string]: { a: Name }
`,
path: cue.MakePath(cue.Str("a")),
notExist: true,
}}
for _, tc := range testCases {
t.Run(tc.path.String(), func(t *testing.T) {
v := compileT(t, r, tc.in)

v = v.LookupPath(tc.path)

if exists := v.Exists(); exists != !tc.notExist {
t.Fatalf("exists: got %v; want: %v", exists, !tc.notExist)
} else if !exists {
return
}

w := compileT(t, r, tc.out)

if k, d := diff.Diff(v, w); k != diff.Identity {
b := &bytes.Buffer{}
diff.Print(b, d)
t.Error(b)
}
})
}
}

func compileT(t *testing.T, r *cue.Runtime, s string) cue.Value {
t.Helper()
inst, err := r.Compile("", s)
if err != nil {
t.Fatal(err)
}
return inst.Value()
}
1 change: 1 addition & 0 deletions internal/core/adt/feature.go
Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,7 @@ func (f Feature) ToValue(ctx *OpContext) Value {
if !f.IsRegular() {
panic("not a regular label")
}
// TODO: Handle special regular values: invalid and AnyRegular.
if f.IsInt() {
return ctx.NewInt64(int64(f.Index()))
}
Expand Down
14 changes: 9 additions & 5 deletions internal/core/adt/optional.go
Original file line number Diff line number Diff line change
Expand Up @@ -36,18 +36,22 @@ outer:
}
}

if !arc.Label.IsRegular() {
f := arc.Label
if !f.IsRegular() {
return
}
if int64(f.Index()) == MaxIndex {
f = 0
}

var label Value
if o.types&HasComplexPattern != 0 && arc.Label.IsString() {
label = arc.Label.ToValue(c)
if o.types&HasComplexPattern != 0 && f.IsString() {
label = f.ToValue(c)
}

if len(o.Bulk) > 0 {
bulkEnv := *env
bulkEnv.DynamicLabel = arc.Label
bulkEnv.DynamicLabel = f
bulkEnv.Deref = nil
bulkEnv.Cycles = nil

Expand All @@ -56,7 +60,7 @@ outer:
// if matched && f.additional {
// continue
// }
if matchBulk(c, env, b, arc.Label, label) {
if matchBulk(c, env, b, f, label) {
matched = true
info := closeInfo.SpawnSpan(b.Value, ConstraintSpan)
arc.AddConjunct(MakeConjunct(&bulkEnv, b, info))
Expand Down

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