Matthew Stobbs
79c235de31
Started doing all comparisons in Runes string cound emojis as 4 runes instead of just the 1 it is
141 lines
3.2 KiB
Go
141 lines
3.2 KiB
Go
package tind
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import (
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"crypto/rand"
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"errors"
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"log"
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)
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// Config is a configuration for generating and working with TinD id's of
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// possibly varying sizes and runesets
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type Config struct {
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size int
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runes []rune
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runesize int
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mod byte
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}
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const (
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defaultRunes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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defaultSize = 4
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)
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// NewTinDConfig starts off a factory pattern to build a TinD
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// with either the default values, or setting custom values
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// using the `With` functions
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// Example:
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//
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// Get a default TinD id
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// `id := New().Get()`
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//
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// Get a TinD with 8 bytes but the default runeset
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// `id := New().WithSize(8).Get()`
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//
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// Get a TinD of default size with a special runeset
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// `id := New().WithRuneset("😃😡🕰️🧰BGD").Get()`
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//
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// You can always define the configuration and create new TinD's
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// using it.
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// Example:
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//
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// myNumberOnlyConfig := New().WithSize(8).WithRuneset("0123456789")
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func NewTinDConfig() *Config {
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return &Config{
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size: defaultSize,
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runes: []rune(defaultRunes),
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runesize: len(defaultRunes),
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mod: byte(len(defaultRunes) - 1),
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}
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}
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// WithRuneset requires a string as input, where each character must be unique.
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// The string can be comprised of any unique unicode character.
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// Will filter out duplicate runes before storing it
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//
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// This does slow down initialization, but the final product still runs fast to
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// generate ids
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func (c *Config) WithRuneset(r []rune) *Config {
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c.runes = ensureUniqueRunes(r)
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c.runesize = len(c.runes)
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c.mod = byte(c.runesize - 1)
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return c
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}
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func ensureUniqueRunes(r []rune) []rune {
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unq := make(map[rune]int)
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var index int
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// loop through the runes to find duplicates
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for _, v := range r {
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// if the current rune hasn't been seen yet, assign it
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if _, ok := unq[v]; !ok {
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unq[v] = index
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index++
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}
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}
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rr := make([]rune, len(unq))
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for k, n := range unq {
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rr[n] = k
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}
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return rr
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}
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// WithSize sets the number of bytes in the TinD ID
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func (c *Config) WithSize(s int) *Config {
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c.size = s
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return c
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}
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// Zero returns a zero value TinD ID of the configured size
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func (c *Config) Zero() TinD {
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t := TinD{
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bytes: make([]byte, c.size),
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config: c,
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}
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t.String() // set the string so it's faster to recall
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return t
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}
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// Gen generates a TinD with the given configuration
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func (c *Config) Gen() TinD {
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bytes := make([]byte, c.size)
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runes := make([]rune, c.size)
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_, err := rand.Read(bytes)
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if err != nil {
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log.Fatalln(err)
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}
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// Make sure each byte fits the rune so it can be encoded and decoded
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for i := 0; i < c.size; i++ {
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bytes[i] = bytes[i] & c.mod
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runes[i] = c.runes[bytes[i]]
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}
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t := TinD{
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bytes: bytes,
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runes: runes,
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config: c,
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}
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return t
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}
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// FromString takes a string representation of a TinD id and returns
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// the actual TinD as bytes
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func (c *Config) FromString(in string) (TinD, error) {
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// Make sure the number of characters matches what's needed
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if len(in) != c.size {
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return c.Zero(), errors.New("given id isn't the same size as the configuration")
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}
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t := TinD{
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bytes: make([]byte, c.size),
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config: c,
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}
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r := []rune(in)
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for i := 0; i < c.size; i++ {
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for j := 0; j < c.runesize; j++ {
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if r[i] == c.runes[j] {
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t.bytes[i] = byte(j)
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break
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}
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}
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}
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return TinD(t), nil
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}
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