README
¶
list
Treats a delimited string as a list, without ever allocating a []string. Generic free functions (Head, Tail, First, Last, Split, SplitTail, At, PushHead, PushTail, RemoveLast, Index, LastIndex, IsEmpty) operate on any ~string | []byte value plus a delimiter byte. Named wrapper types (Comma, Dot, Slash, Semicolon, Space) bind a delimiter so you can call the same operations as methods. Part of rosetta.
What matters here
- This is string slicing, not slice building — there is no
[]stringin sight.Head/Tailwalk the string to the next delimiter and return substrings; iterating a list is aHead/Tailloop, not afor rangeover a slice. This avoids allocation for the common "peel off the first path segment" case (e.g. routing on a/-delimited path). If you actually want a[]string, usestrings.Splitinstead. - The delimiter is a single
byte, not a string. Multi-character delimiters aren't supported by design; the named types (Comma=,,Dot=.,Slash=/, …) each pin one byte via aDelimiter…constant. Tail/SplitTail/PushHead/PushTailreturn the list's own typeT, whileHead/First/Last/Atreturn a plainstring. The "remaining list" stays in the list type so you can keep chaining; an extracted single item drops tostring. Mind the return types when composing them.- The named types are immutable value types.
PushHead/PushTail/RemoveLastreturn a new list rather than mutating the receiver — assign the result.
Documentation
¶
Overview ¶
Package list treats a delimited string as a list, without splitting it into a slice.
Head, Tail, Split, At, Last, PushHead, PushTail, and the rest read and rewrite a string in place around a single-byte delimiter, so walking a dotted path or a comma-separated field costs no allocations for the intermediate pieces. The named types — Dot, Comma, Slash, Semicolon, Space, Equal — bind a delimiter to a string so the same operations read as methods, and the List interface lets code accept any of them.
The delimiter is a byte, not a rune. A multi-byte delimiter cannot be expressed here, and the functions are written for the ASCII punctuation that path and header syntaxes actually use.
Index ¶
- Constants
- func At[T Stringlike](value T, delimiter byte, index int) string
- func First[T Stringlike](value T, delimiter byte) string
- func First2(l List) (string, string)
- func First3(l List) (string, string, string)
- func First4(l List) (string, string, string, string)
- func Head[T Stringlike](value T, delimiter byte) string
- func Index[T Stringlike](value T, delimiter byte) int
- func IsEmpty[T Stringlike](value T) bool
- func IsEmptyTail[T Stringlike](value T, delimiter byte) bool
- func Last[T Stringlike](value T, delimiter byte) string
- func Last2(l List) (string, string)
- func Last3(l List) (string, string, string)
- func Last4(l List) (string, string, string, string)
- func LastIndex[T Stringlike](value T, delimiter byte) int
- func PushHead[T Stringlike](value T, headValue string, delimiter byte) T
- func PushTail[T Stringlike](value T, tailValue string, delimiter byte) T
- func RemoveLast[T Stringlike](value T, delimiter byte) T
- func Second(l List) string
- func Split[T Stringlike](value T, delimiter byte) (string, T)
- func SplitTail[T Stringlike](value T, delimiter byte) (T, string)
- func Tail[T Stringlike](value T, delimiter byte) T
- func Third(l List) string
- type Comma
- func (list Comma) At(index int) string
- func (list Comma) Bytes() []byte
- func (list Comma) First() string
- func (list Comma) Head() string
- func (list Comma) IsEmpty() bool
- func (list Comma) IsEmptyTail() bool
- func (list Comma) Last() string
- func (list Comma) PushHead(value string) List
- func (list Comma) PushTail(value string) List
- func (list Comma) RemoveLast() List
- func (list Comma) Split() (string, List)
- func (list Comma) SplitTail() (List, string)
- func (list Comma) String() string
- func (list Comma) Tail() List
- type Dot
- func (list Dot) At(index int) string
- func (list Dot) Bytes() []byte
- func (list Dot) First() string
- func (list Dot) Head() string
- func (list Dot) IsEmpty() bool
- func (list Dot) IsEmptyTail() bool
- func (list Dot) Last() string
- func (list Dot) PushHead(value string) List
- func (list Dot) PushTail(value string) List
- func (list Dot) RemoveLast() List
- func (list Dot) Split() (string, List)
- func (list Dot) SplitTail() (List, string)
- func (list Dot) String() string
- func (list Dot) Tail() List
- type Equal
- func (list Equal) At(index int) string
- func (list Equal) Bytes() []byte
- func (list Equal) First() string
- func (list Equal) Head() string
- func (list Equal) IsEmpty() bool
- func (list Equal) IsEmptyTail() bool
- func (list Equal) Last() string
- func (list Equal) PushHead(value string) List
- func (list Equal) PushTail(value string) List
- func (list Equal) RemoveLast() List
- func (list Equal) Split() (string, List)
- func (list Equal) SplitTail() (List, string)
- func (list Equal) String() string
- func (list Equal) Tail() List
- type List
- type Semicolon
- func (list Semicolon) At(index int) string
- func (list Semicolon) Bytes() []byte
- func (list Semicolon) First() string
- func (list Semicolon) Head() string
- func (list Semicolon) IsEmpty() bool
- func (list Semicolon) IsEmptyTail() bool
- func (list Semicolon) Last() string
- func (list Semicolon) PushHead(value string) List
- func (list Semicolon) PushTail(value string) List
- func (list Semicolon) RemoveLast() List
- func (list Semicolon) Split() (string, List)
- func (list Semicolon) SplitTail() (List, string)
- func (list Semicolon) String() string
- func (list Semicolon) Tail() List
- type Slash
- func (list Slash) At(index int) string
- func (list Slash) Bytes() []byte
- func (list Slash) First() string
- func (list Slash) Head() string
- func (list Slash) IsEmpty() bool
- func (list Slash) IsEmptyTail() bool
- func (list Slash) Last() string
- func (list Slash) PushHead(value string) List
- func (list Slash) PushTail(value string) List
- func (list Slash) RemoveLast() List
- func (list Slash) Split() (string, List)
- func (list Slash) SplitTail() (List, string)
- func (list Slash) String() string
- func (list Slash) Tail() List
- type Space
- func (list Space) At(index int) string
- func (list Space) Bytes() []byte
- func (list Space) First() string
- func (list Space) Head() string
- func (list Space) IsEmpty() bool
- func (list Space) IsEmptyTail() bool
- func (list Space) Last() string
- func (list Space) PushHead(value string) List
- func (list Space) PushTail(value string) List
- func (list Space) RemoveLast() List
- func (list Space) Split() (string, List)
- func (list Space) SplitTail() (List, string)
- func (list Space) String() string
- func (list Space) Tail() List
- type Stringlike
Constants ¶
const DelimiterComma = ','
DelimiterComma is the delimiter used by the Comma list type.
const DelimiterDot = '.'
DelimiterDot is the delimiter used by the Dot list type.
const DelimiterEqual = '='
DelimiterEqual is the delimiter used by the Equal list type.
const DelimiterSemicolon = ';'
DelimiterSemicolon is the delimiter used by the Semicolon list type.
const DelimiterSlash = '/'
DelimiterSlash is the delimiter used by the Slash list type.
const DelimiterSpace = ' '
DelimiterSpace is the delimiter used by the Space list type.
Variables ¶
This section is empty.
Functions ¶
func At ¶
func At[T Stringlike](value T, delimiter byte, index int) string
At returns the list value at a particular index
func First ¶ added in v0.7.0
func First[T Stringlike](value T, delimiter byte) string
First returns the FIRST item in a list (alias for Head)
func Head ¶
func Head[T Stringlike](value T, delimiter byte) string
Head returns the FIRST item in a list
func Index ¶ added in v0.3.0
func Index[T Stringlike](value T, delimiter byte) int
Index finds the first occurrence of the delimiter (-1 if not found)
func IsEmpty ¶ added in v0.3.0
func IsEmpty[T Stringlike](value T) bool
IsEmpty returns TRUE if the list is empty.
func IsEmptyTail ¶ added in v0.3.0
func IsEmptyTail[T Stringlike](value T, delimiter byte) bool
IsEmptyTail returns TRUE if this list only has one element
func Last ¶
func Last[T Stringlike](value T, delimiter byte) string
Last returns the LAST item in a T-based-list
func Last2 ¶ added in v0.18.3
Last2 returns the final two items in the list (last, then second-to-last).
func LastIndex ¶ added in v0.3.0
func LastIndex[T Stringlike](value T, delimiter byte) int
LastIndex finds the last occurrence of the delimiter (-1 if not found)
func PushHead ¶
func PushHead[T Stringlike](value T, headValue string, delimiter byte) T
PushHead adds a new item to the beginning of the list
func PushTail ¶
func PushTail[T Stringlike](value T, tailValue string, delimiter byte) T
PushTail adds a new item to the end of the list
func RemoveLast ¶
func RemoveLast[T Stringlike](value T, delimiter byte) T
RemoveLast returns the full list, with the last element removed.
func Split ¶
func Split[T Stringlike](value T, delimiter byte) (string, T)
Split returns the FIRST element, and the REST element in one function call
func SplitTail ¶
func SplitTail[T Stringlike](value T, delimiter byte) (T, string)
SplitTail behaves like split, but splits the beginning of the list from the last item in the list. So, the list "a,b,c" => "a,b", "c" A list with no delimiter at all keeps the whole value as the leading list and returns an empty last item ("photo" => "photo", ""), which is what callers splitting a filename from its extension rely on. Note this is NOT the RemoveLast/Last decomposition, which would give "", "photo".
func Tail ¶
func Tail[T Stringlike](value T, delimiter byte) T
Tail returns any values in the list AFTER the first item
Types ¶
type Comma ¶ added in v0.3.0
type Comma string
Comma is a List backed by a comma-delimited string.
func (Comma) IsEmptyTail ¶ added in v0.3.0
IsEmptyTail returns TRUE if the list has no items after the head.
func (Comma) PushHead ¶ added in v0.3.0
PushHead returns a new list with the value prepended as the new head.
func (Comma) PushTail ¶ added in v0.3.0
PushTail returns a new list with the value appended as the new tail.
func (Comma) RemoveLast ¶ added in v0.3.0
RemoveLast returns a new list with the final item removed.
func (Comma) SplitTail ¶ added in v0.3.0
SplitTail returns a list of the leading items and the final item.
type Dot ¶ added in v0.3.0
type Dot string
Dot is a List backed by a dot-delimited string.
func (Dot) IsEmptyTail ¶ added in v0.3.0
IsEmptyTail returns TRUE if the list has no items after the head.
func (Dot) PushHead ¶ added in v0.3.0
PushHead returns a new list with the value prepended as the new head.
func (Dot) PushTail ¶ added in v0.3.0
PushTail returns a new list with the value appended as the new tail.
func (Dot) RemoveLast ¶ added in v0.3.0
RemoveLast returns a new list with the final item removed.
func (Dot) SplitTail ¶ added in v0.3.0
SplitTail returns a list of the leading items and the final item.
type Equal ¶ added in v0.3.0
type Equal string
Equal is a List backed by an equals-delimited string.
func (Equal) IsEmptyTail ¶ added in v0.3.0
IsEmptyTail returns TRUE if the list has no items after the head.
func (Equal) PushHead ¶ added in v0.3.0
PushHead returns a new list with the value prepended as the new head.
func (Equal) PushTail ¶ added in v0.3.0
PushTail returns a new list with the value appended as the new tail.
func (Equal) RemoveLast ¶ added in v0.3.0
RemoveLast returns a new list with the final item removed.
func (Equal) SplitTail ¶ added in v0.3.0
SplitTail returns a list of the leading items and the final item.
type List ¶ added in v0.6.0
type List interface {
// IsEmpty returns TRUE if the list contains no items
IsEmpty() bool
// IsEmptyTail returns TRUE if the list contains at most one item, so its tail is empty
IsEmptyTail() bool
// Head returns the first item in the list
Head() string
// Tail returns a list containing every item except the first
Tail() List
// First returns the first item in the list
First() string
// Last returns the last item in the list
Last() string
// RemoveLast returns a list containing every item except the last
RemoveLast() List
// Split returns the first item in the list, along with a list of the remaining items
Split() (string, List)
// SplitTail returns a list of every item except the last, along with the last item
SplitTail() (List, string)
// At returns the item at the specified index, or an empty string if the index is out of bounds
At(index int) string
// PushHead returns a new list with the value prepended to the front
PushHead(value string) List
// PushTail returns a new list with the value appended to the end
PushTail(value string) List
// String returns the delimited string representation of the list
String() string
// Bytes returns the delimited byte-slice representation of the list
Bytes() []byte
}
List interface wraps all of the list manipulation methods implemented by standard lists in this library.
func BySemicolon ¶ added in v0.7.0
BySemicolon returns a List that joins/splits its items on semicolons.
type Semicolon ¶ added in v0.7.0
type Semicolon string
Semicolon is a List backed by a semicolon-delimited string.
func (Semicolon) At ¶ added in v0.7.0
At returns the item at the given index, or "" if out of range.
func (Semicolon) Bytes ¶ added in v0.8.1
Bytes returns the list as its underlying delimited byte slice.
func (Semicolon) IsEmptyTail ¶ added in v0.7.0
IsEmptyTail returns TRUE if the list has no items after the head.
func (Semicolon) PushHead ¶ added in v0.7.0
PushHead returns a new list with the value prepended as the new head.
func (Semicolon) PushTail ¶ added in v0.7.0
PushTail returns a new list with the value appended as the new tail.
func (Semicolon) RemoveLast ¶ added in v0.7.0
RemoveLast returns a new list with the final item removed.
func (Semicolon) Split ¶ added in v0.7.0
Split returns the head item and a list of the remaining items.
func (Semicolon) SplitTail ¶ added in v0.7.0
SplitTail returns a list of the leading items and the final item.
type Slash ¶ added in v0.3.0
type Slash string
Slash is a List backed by a slash-delimited string.
func (Slash) IsEmptyTail ¶ added in v0.3.0
IsEmptyTail returns TRUE if the list has no items after the head.
func (Slash) PushHead ¶ added in v0.3.0
PushHead returns a new list with the value prepended as the new head.
func (Slash) PushTail ¶ added in v0.3.0
PushTail returns a new list with the value appended as the new tail.
func (Slash) RemoveLast ¶ added in v0.3.0
RemoveLast returns a new list with the final item removed.
func (Slash) SplitTail ¶ added in v0.3.0
SplitTail returns a list of the leading items and the final item.
type Space ¶ added in v0.3.0
type Space string
Space is a List backed by a space-delimited string.
func (Space) IsEmptyTail ¶ added in v0.3.0
IsEmptyTail returns TRUE if the list has no items after the head.
func (Space) PushHead ¶ added in v0.3.0
PushHead returns a new list with the value prepended as the new head.
func (Space) PushTail ¶ added in v0.3.0
PushTail returns a new list with the value appended as the new tail.
func (Space) RemoveLast ¶ added in v0.3.0
RemoveLast returns a new list with the final item removed.
func (Space) SplitTail ¶ added in v0.3.0
SplitTail returns a list of the leading items and the final item.
type Stringlike ¶ added in v0.3.0
Stringlike constrains the underlying string-like types a list may be built from.
Source Files