110 lines
1.9 KiB
Go
110 lines
1.9 KiB
Go
package xdb
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import (
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"fmt"
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"strings"
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"sync"
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)
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// region manager with:
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// 1, content cache.
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// 2, util functions
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// global cache map
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var rcLock sync.Mutex
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var regionCache = map[string]*Region{}
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type Region struct {
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Str string // region string
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fields []string // region fields
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}
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var EmptyRegion = CacheRegion("")
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// Create or get the region from the global cache.
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// And it is a thread-safe implementation.
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func CacheRegion(str string) *Region {
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// check the cache and return it directly
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// if there is a cache available
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rcLock.Lock()
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defer rcLock.Unlock()
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region, ok := regionCache[str]
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if ok {
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return region
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}
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// cache the new region
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region = &Region{
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Str: str,
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fields: nil,
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}
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regionCache[str] = region
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return region
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}
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// Create a new region without checking cache info
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func NewRegion(str string) *Region {
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return &Region{
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Str: str,
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fields: nil,
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}
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}
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func (r *Region) Fields() []string {
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if r.fields == nil {
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r.fields = strings.Split(r.Str, "|")
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}
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return r.fields
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}
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func (r *Region) Join(sep string) string {
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if sep == "|" {
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return r.Str
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}
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return strings.Join(r.Fields(), sep)
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}
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func (r *Region) Filtering(fields []int) (*Region, error) {
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if len(fields) == 0 {
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return r, nil
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}
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fs := r.Fields()
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var sb []string
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for _, idx := range fields {
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if idx < 0 {
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return r, fmt.Errorf("negative filter index %d", idx)
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}
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if idx >= len(fs) {
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return r, fmt.Errorf("field index %d exceeded the max length of %d", idx, len(fs))
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}
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sb = append(sb, fs[idx])
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}
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new := CacheRegion(strings.Join(sb, "|"))
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if new.fields == nil {
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new.fields = sb
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}
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return new, nil
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}
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// Equal check ptr (share the same region cache) or the Str is the same.
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func (r *Region) Equal(dst *Region) bool {
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return (r == dst || r.Str == dst.Str)
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}
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func (r *Region) IsEmpty() bool {
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return r.Str == ""
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}
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func (r *Region) String() string {
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return r.Str
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}
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