Yonah
87f59d0cf9
This can be used with both system and member identifiers. Signed-off-by: Yonah <contrib@gensokyo.uk>
100 lines
2.6 KiB
Go
100 lines
2.6 KiB
Go
// Package ident is the reference implementation of system and member
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// identifiers.
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package ident
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import (
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"encoding"
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"errors"
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"fmt"
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"strconv"
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"unsafe"
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)
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var (
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// ErrNewline is returned for identifiers found to contain newline characters.
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ErrNewline = errors.New("identifier contains newline characters")
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// ErrSeparator is returned for representations of [F] missing its separator
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// byte in its expected index.
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ErrSeparator = errors.New("identifier has incorrect separator byte")
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)
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// UnexpectedSizeError describes a malformed string representation of an
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// identifier, with unexpected length.
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type UnexpectedSizeError struct {
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Data []byte
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Want int
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}
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func (e *UnexpectedSizeError) Error() string {
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return "got " + strconv.Itoa(len(e.Data)) + " bytes for " +
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"a " + strconv.Itoa(e.Want) + "-byte identifier"
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}
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// MS is a system or member identifier.
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type MS interface {
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encoding.TextMarshaler
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encoding.TextUnmarshaler
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fmt.Stringer
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// EncodedSize returns the number of bytes appended by Encode.
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EncodedSize() int
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// Encode appends the canonical string representation of MS to dst and
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// returns the extended buffer.
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Encode(dst []byte) []byte
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// ident is a no-op function but serves to distinguish types that are
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// identifiers from ordinary types with custom marshaler/unmarshaler
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// behaviour: a type is an identifier part if it has an ident method.
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ident()
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}
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// F represents a full system or member identifier.
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type F[V any, T interface {
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MS
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*V
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}] struct {
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// Underlying system or member.
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I T
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// Split from instance suffix after [Separator] byte.
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Remote Remote
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}
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// Separator is the byte separating representation of [MS] from [Remote].
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const Separator = ':'
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// Encode appends the canonical string representation of full to dst and returns
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// the extended buffer.
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func (full *F[V, T]) Encode(dst []byte) []byte {
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dst = full.I.Encode(dst)
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dst = append(dst, Separator)
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dst = full.Remote.Encode(dst)
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return dst
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}
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// String returns the canonical string representation of full.
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func (full *F[V, T]) String() string {
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s := full.Encode(nil)
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return unsafe.String(unsafe.SliceData(s), len(s))
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}
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// MarshalText returns the result of Encode.
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func (full *F[V, T]) MarshalText() (data []byte, err error) {
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return full.Encode(nil), nil
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}
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// UnmarshalText strictly decodes data into full.
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func (full *F[V, T]) UnmarshalText(data []byte) (err error) {
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sz := full.I.EncodedSize()
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if len(data) < sz+1 || data[sz] != Separator {
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return ErrSeparator
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}
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if full.I == nil {
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full.I = new(V)
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}
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if err = full.I.UnmarshalText(data[:sz]); err != nil {
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return
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}
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return full.Remote.UnmarshalText(data[sz+1:])
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}
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