status-go/vendor/github.com/golang-migrate/migrate/v4/source/migration.go

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package source
import (
"sort"
)
// Direction is either up or down.
type Direction string
const (
Down Direction = "down"
Up Direction = "up"
)
// Migration is a helper struct for source drivers that need to
// build the full directory tree in memory.
// Migration is fully independent from migrate.Migration.
type Migration struct {
// Version is the version of this migration.
Version uint
// Identifier can be any string that helps identifying
// this migration in the source.
Identifier string
// Direction is either Up or Down.
Direction Direction
// Raw holds the raw location path to this migration in source.
// ReadUp and ReadDown will use this.
Raw string
}
// Migrations wraps Migration and has an internal index
// to keep track of Migration order.
type Migrations struct {
index uintSlice
migrations map[uint]map[Direction]*Migration
}
func NewMigrations() *Migrations {
return &Migrations{
index: make(uintSlice, 0),
migrations: make(map[uint]map[Direction]*Migration),
}
}
func (i *Migrations) Append(m *Migration) (ok bool) {
if m == nil {
return false
}
if i.migrations[m.Version] == nil {
i.migrations[m.Version] = make(map[Direction]*Migration)
}
// reject duplicate versions
if _, dup := i.migrations[m.Version][m.Direction]; dup {
return false
}
i.migrations[m.Version][m.Direction] = m
i.buildIndex()
return true
}
func (i *Migrations) buildIndex() {
i.index = make(uintSlice, 0)
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for version := range i.migrations {
i.index = append(i.index, version)
}
sort.Sort(i.index)
}
func (i *Migrations) First() (version uint, ok bool) {
if len(i.index) == 0 {
return 0, false
}
return i.index[0], true
}
func (i *Migrations) Prev(version uint) (prevVersion uint, ok bool) {
pos := i.findPos(version)
if pos >= 1 && len(i.index) > pos-1 {
return i.index[pos-1], true
}
return 0, false
}
func (i *Migrations) Next(version uint) (nextVersion uint, ok bool) {
pos := i.findPos(version)
if pos >= 0 && len(i.index) > pos+1 {
return i.index[pos+1], true
}
return 0, false
}
func (i *Migrations) Up(version uint) (m *Migration, ok bool) {
if _, ok := i.migrations[version]; ok {
if mx, ok := i.migrations[version][Up]; ok {
return mx, true
}
}
return nil, false
}
func (i *Migrations) Down(version uint) (m *Migration, ok bool) {
if _, ok := i.migrations[version]; ok {
if mx, ok := i.migrations[version][Down]; ok {
return mx, true
}
}
return nil, false
}
func (i *Migrations) findPos(version uint) int {
if len(i.index) > 0 {
ix := i.index.Search(version)
if ix < len(i.index) && i.index[ix] == version {
return ix
}
}
return -1
}
type uintSlice []uint
func (s uintSlice) Len() int {
return len(s)
}
func (s uintSlice) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
func (s uintSlice) Less(i, j int) bool {
return s[i] < s[j]
}
func (s uintSlice) Search(x uint) int {
return sort.Search(len(s), func(i int) bool { return s[i] >= x })
}