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selector: simplify the public interface of the package
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Those extra interfaces are not necessary.
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@MichaelMure
MichaelMure committed Aug 31, 2024
1 parent 5b26d85 commit b0c96b2
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Showing 2 changed files with 26 additions and 54 deletions.
76 changes: 25 additions & 51 deletions capability/policy/selector/selector.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ import (

// Selector describes a UCAN policy selector, as specified here:
// https://github.com/ucan-wg/delegation/blob/4094d5878b58f5d35055a3b93fccda0b8329ebae/README.md#selectors
type Selector []Segment
type Selector []segment

func (s Selector) String() string {
var str string
Expand All @@ -23,23 +23,6 @@ func (s Selector) String() string {
return str
}

type Segment interface {
// Identity flags that this selector is the identity selector.
Identity() bool
// Optional flags that this selector is optional.
Optional() bool
// Iterator flags that this selector is an iterator segment.
Iterator() bool
// Slice flags that this segemnt targets a range of a slice.
Slice() []int
// Field is the name of a field in a struct/map.
Field() string
// Index is an index of a slice.
Index() int
// String returns the segment's string representation.
String() string
}

var Identity = segment{".", true, false, false, nil, "", 0}

var (
Expand All @@ -58,37 +41,44 @@ type segment struct {
index int
}

// String returns the segment's string representation.
func (s segment) String() string {
return s.str
}

// Identity flags that this selector is the identity selector.
func (s segment) Identity() bool {
return s.identity
}

// Optional flags that this selector is optional.
func (s segment) Optional() bool {
return s.optional
}

// Iterator flags that this selector is an iterator segment.
func (s segment) Iterator() bool {
return s.iterator
}

// Slice flags that this segment targets a range of a slice.
func (s segment) Slice() []int {
return s.slice
}

// Field is the name of a field in a struct/map.
func (s segment) Field() string {
return s.field
}

// Index is an index of a slice.
func (s segment) Index() int {
return s.index
}

func Parse(str string) (Selector, error) {
if string(str[0]) != "." {
return nil, NewParseError("selector must start with identity segment '.'", str, 0, string(str[0]))
return nil, newParseError("selector must start with identity segment '.'", str, 0, string(str[0]))
}

col := 0
Expand All @@ -102,7 +92,7 @@ func Parse(str string) (Selector, error) {
switch seg {
case ".":
if len(sel) > 0 && sel[len(sel)-1].Identity() {
return nil, NewParseError("selector contains unsupported recursive descent segment: '..'", str, col, tok)
return nil, newParseError("selector contains unsupported recursive descent segment: '..'", str, col, tok)
}
sel = append(sel, Identity)
case "[]":
Expand All @@ -114,7 +104,7 @@ func Parse(str string) (Selector, error) {
if indexRegex.MatchString(lookup) { // index
idx, err := strconv.Atoi(lookup)
if err != nil {
return nil, NewParseError("invalid index", str, col, tok)
return nil, newParseError("invalid index", str, col, tok)
}
sel = append(sel, segment{str: tok, optional: opt, index: idx})
} else if strings.HasPrefix(lookup, "\"") && strings.HasSuffix(lookup, "\"") { // explicit field
Expand All @@ -127,25 +117,25 @@ func Parse(str string) (Selector, error) {
} else {
i, err := strconv.Atoi(splt[0])
if err != nil {
return nil, NewParseError("invalid slice index", str, col, tok)
return nil, newParseError("invalid slice index", str, col, tok)
}
rng = append(rng, i)
}
if splt[1] != "" {
i, err := strconv.Atoi(splt[1])
if err != nil {
return nil, NewParseError("invalid slice index", str, col, tok)
return nil, newParseError("invalid slice index", str, col, tok)
}
rng = append(rng, i)
}
sel = append(sel, segment{str: tok, optional: opt, slice: rng})
} else {
return nil, NewParseError(fmt.Sprintf("invalid segment: %s", seg), str, col, tok)
return nil, newParseError(fmt.Sprintf("invalid segment: %s", seg), str, col, tok)
}
} else if fieldRegex.MatchString(seg) {
sel = append(sel, segment{str: tok, optional: opt, field: seg[1:]})
} else {
return nil, NewParseError(fmt.Sprintf("invalid segment: %s", seg), str, col, tok)
return nil, newParseError(fmt.Sprintf("invalid segment: %s", seg), str, col, tok)
}
}
col += len(tok)
Expand Down Expand Up @@ -193,15 +183,6 @@ func tokenize(str string) []string {
return toks
}

type ParseError interface {
error
Name() string
Message() string
Source() string
Column() int
Token() string
}

type parseerr struct {
msg string
src string
Expand Down Expand Up @@ -233,7 +214,7 @@ func (p parseerr) Token() string {
return p.tok
}

func NewParseError(message string, source string, column int, token string) error {
func newParseError(message string, source string, column int, token string) error {
return parseerr{message, source, column, token}
}

Expand Down Expand Up @@ -312,7 +293,7 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
} else if seg.Optional() {
cur = nil
} else {
return nil, nil, NewResolutionError(fmt.Sprintf("can not iterate over kind: %s", kindString(cur)), at)
return nil, nil, newResolutionError(fmt.Sprintf("can not iterate over kind: %s", kindString(cur)), at)
}

} else if seg.Field() != "" {
Expand All @@ -324,7 +305,7 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
if seg.Optional() {
cur = nil
} else {
return nil, nil, NewResolutionError(fmt.Sprintf("object has no field named: %s", seg.Field()), at)
return nil, nil, newResolutionError(fmt.Sprintf("object has no field named: %s", seg.Field()), at)
}
} else {
return nil, nil, err
Expand All @@ -334,17 +315,17 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
} else if seg.Optional() {
cur = nil
} else {
return nil, nil, NewResolutionError(fmt.Sprintf("can not access field: %s on kind: %s", seg.Field(), kindString(cur)), at)
return nil, nil, newResolutionError(fmt.Sprintf("can not access field: %s on kind: %s", seg.Field(), kindString(cur)), at)
}
} else if seg.Slice() != nil {
if cur != nil && cur.Kind() == datamodel.Kind_List {
return nil, nil, NewResolutionError("list slice selection not yet implemented", at)
return nil, nil, newResolutionError("list slice selection not yet implemented", at)
} else if cur != nil && cur.Kind() == datamodel.Kind_Bytes {
return nil, nil, NewResolutionError("bytes slice selection not yet implemented", at)
return nil, nil, newResolutionError("bytes slice selection not yet implemented", at)
} else if seg.Optional() {
cur = nil
} else {
return nil, nil, NewResolutionError(fmt.Sprintf("can not index: %s on kind: %s", seg.Field(), kindString(cur)), at)
return nil, nil, newResolutionError(fmt.Sprintf("can not index: %s on kind: %s", seg.Field(), kindString(cur)), at)
}
} else {
at = append(at, fmt.Sprintf("%d", seg.Index()))
Expand All @@ -355,7 +336,7 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
if seg.Optional() {
cur = nil
} else {
return nil, nil, NewResolutionError(fmt.Sprintf("index out of bounds: %d", seg.Index()), at)
return nil, nil, newResolutionError(fmt.Sprintf("index out of bounds: %d", seg.Index()), at)
}
} else {
return nil, nil, err
Expand All @@ -365,7 +346,7 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
} else if seg.Optional() {
cur = nil
} else {
return nil, nil, NewResolutionError(fmt.Sprintf("can not access field: %s on kind: %s", seg.Field(), kindString(cur)), at)
return nil, nil, newResolutionError(fmt.Sprintf("can not access field: %s on kind: %s", seg.Field(), kindString(cur)), at)
}
}
}
Expand Down Expand Up @@ -393,13 +374,6 @@ func isMissing(err error) bool {
return false
}

type ResolutionError interface {
error
Name() string
Message() string
At() []string
}

type resolutionerr struct {
msg string
at []string
Expand All @@ -421,6 +395,6 @@ func (r resolutionerr) Error() string {
return r.Message()
}

func NewResolutionError(message string, at []string) error {
func newResolutionError(message string, at []string) error {
return resolutionerr{message, at}
}
4 changes: 1 addition & 3 deletions capability/policy/selector/selector_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -377,9 +377,7 @@ func TestSelect(t *testing.T) {

fmt.Println(err)

if _, ok := err.(ResolutionError); !ok {
t.Fatalf("error was not a resolution error")
}
require.ErrorAs(t, err, &resolutionerr{}, "error was not a resolution error")
})

t.Run("optional not exists", func(t *testing.T) {
Expand Down

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