go-strutil

A small, focused collection of string manipulation helpers for Go, modeled loosely on Laravel's Illuminate\Support\Str facade but translated to idiomatic, rune-safe Go. All functions are top-level, pure, and handle empty input gracefully. The only non-stdlib dependency is golang.org/x/text for Unicode normalization inside Slugify.

Status: pre-1.0 (v0.1.x). API surface is stable enough for production use but may evolve in minor versions. Breaking changes will be called out loudly in CHANGELOG.md.

API reference: https://pkg.go.dev/github.com/hollis-labs/go-strutil

Installation

go get github.com/hollis-labs/go-strutil

import "github.com/hollis-labs/go-strutil"

slug := strutil.Slugify("Café du Monde") // "cafe-du-monde"

See examples/ for runnable demonstrations of each function group.

Function reference

Slug and normalization

Function	Signature	Description	Example
Slugify	Slugify(s string) string	URL-safe kebab-case slug; transliterates accents via NFKD.	Slugify("Café du Monde") → "cafe-du-monde"
SlugifyN	SlugifyN(s string, maxRunes int) string	Slugify capped at maxRunes runes; trims trailing hyphens left by the cut.	SlugifyN("hello world foo bar", 12) → "hello-world"
DefaultMaxSlugLength	const DefaultMaxSlugLength = 80	Sensible default cap: fits VARCHAR(100), keeps URLs readable.	SlugifyN(title, strutil.DefaultMaxSlugLength)

Case conversion

Function	Signature	Description	Example
SnakeCase	SnakeCase(s string) string	Any case style → snake_case.	SnakeCase("helloWorld") → "hello_world"
KebabCase	KebabCase(s string) string	Any case style → kebab-case (preserves multi-byte characters).	KebabCase("HelloWorld") → "hello-world"
CamelCase	CamelCase(s string) string	Any case style → camelCase.	CamelCase("hello_world") → "helloWorld"
StudlyCase	StudlyCase(s string) string	Any case style → StudlyCase (PascalCase).	StudlyCase("hello-world") → "HelloWorld"
Title	Title(s string) string	Title Case — capitalizes each whitespace-separated word; underscores are not separators.	Title("hello world") → "Hello World"
UcFirst	UcFirst(s string) string	Uppercases the first rune only.	UcFirst("hello") → "Hello"
LcFirst	LcFirst(s string) string	Lowercases the first rune only.	LcFirst("Hello") → "hello"

Truncation

Function	Signature	Description	Example
Truncate	Truncate(s string, length int, suffix string) string	Cap to length runes, append suffix if cut.	Truncate("hello world", 5, "...") → "hello..."
Words	Words(s string, count int, suffix string) string	Cap to count whitespace-separated words.	Words("the quick brown fox", 2, "...") → "the quick..."
Limit	Limit(s string, length int) string	Hard rune cap with no suffix.	Limit("hello world", 5) → "hello"

Manipulation

Function	Signature	Description	Example
Squish	Squish(s string) string	Collapse whitespace runs to single spaces and trim.	Squish(" a b ") → "a b"
Finish	Finish(s, suffix string) string	Ensure s ends with suffix.	Finish("dir", "/") → "dir/"
Start	Start(s, prefix string) string	Ensure s starts with prefix.	Start("path", "/") → "/path"
After	After(s, search string) string	Substring after first occurrence of search.	After("one.two.three", ".") → "two.three"
Before	Before(s, search string) string	Substring before first occurrence of search.	Before("one.two.three", ".") → "one"
Between	Between(s, start, end string) string	Substring between first start and first subsequent end.	Between("[hello]", "[", "]") → "hello"

Inspection

Function	Signature	Description	Example
ContainsAll	ContainsAll(s string, subs []string) bool	True iff every substring is present.	ContainsAll("hello world", []string{"hello","world"}) → true
ContainsAny	ContainsAny(s string, subs []string) bool	True iff at least one substring is present.	ContainsAny("hello world", []string{"mars","world"}) → true

Random

Function	Signature	Description	Example
Random	Random(length int) string	Cryptographically secure random alphanumeric string using crypto/rand.	Random(8) → "xK2mP9qR"

Design notes

• Rune-safe. Truncate, Limit, and case conversions iterate runes, not bytes, so multi-byte UTF-8 strings are handled correctly.
• Acronym splitting. splitWords (internal) breaks XMLParser into ["XML", "Parser"] — a run of uppercase letters followed by a lowercase letter splits before the last upper. Trailing acronyms stay intact: parseXML → ["parse", "XML"].
• No package state. Every function is pure; there are no init-time side effects and no global configuration.
• No panics on bad input (except Random if the OS CSPRNG is broken, which is already unrecoverable). Empty inputs yield empty outputs.
• Slugify vs KebabCase. Slugify transliterates accents and strips non-ASCII; KebabCase preserves multi-byte characters and only changes casing/separators.

Development

go test ./... -v                                       # run tests
go test ./... -cover                                   # coverage (currently >96%)
go test ./... -run '^$' -fuzz='^FuzzSlugify$' -fuzztime=10s   # fuzz Slugify invariants
go test ./... -run '^$' -fuzz='^FuzzSlugifyN$' -fuzztime=10s  # fuzz SlugifyN invariants
go vet ./...                                           # static checks
gofmt -l .                                             # formatting check (should print nothing)

Fuzz invariants

FuzzSlugify and FuzzSlugifyN verify the structural contract every slug must meet for any input: ASCII-only [a-z0-9-], no leading/trailing hyphen, no consecutive hyphens, Slugify is idempotent, and SlugifyN always respects its rune cap.

Out of scope (for now)

The following Laravel Str helpers were intentionally deferred and may land in later releases or separate modules:

• Plural / Singular — needs an inflection dictionary.
• Markdown / Html stripping — large scope.
• Mask / Censor / Redact.
• Ulid / Uuid — belong in their own module.
• Is (glob-style match).
• Fluent Stringable wrapper — not idiomatic Go.

License

MIT — see LICENSE.