mirror of
https://github.com/go-gitea/gitea.git
synced 2025-11-02 20:44:13 +01:00
a380cfd8e0
* update bleve to master b17287a86f6cac923a5d886e10618df994eeb54b6724eac2e3b8dde89cfbe3a2 * remove unused pkg from dep file * change bleve from master to recent revision
97 lines
2.5 KiB
Go
97 lines
2.5 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package numeric
|
|
|
|
import "fmt"
|
|
|
|
const ShiftStartInt64 byte = 0x20
|
|
|
|
// PrefixCoded is a byte array encoding of
|
|
// 64-bit numeric values shifted by 0-63 bits
|
|
type PrefixCoded []byte
|
|
|
|
func NewPrefixCodedInt64(in int64, shift uint) (PrefixCoded, error) {
|
|
if shift > 63 {
|
|
return nil, fmt.Errorf("cannot shift %d, must be between 0 and 63", shift)
|
|
}
|
|
|
|
nChars := ((63 - shift) / 7) + 1
|
|
rv := make(PrefixCoded, nChars+1)
|
|
rv[0] = ShiftStartInt64 + byte(shift)
|
|
|
|
sortableBits := int64(uint64(in) ^ 0x8000000000000000)
|
|
sortableBits = int64(uint64(sortableBits) >> shift)
|
|
for nChars > 0 {
|
|
// Store 7 bits per byte for compatibility
|
|
// with UTF-8 encoding of terms
|
|
rv[nChars] = byte(sortableBits & 0x7f)
|
|
nChars--
|
|
sortableBits = int64(uint64(sortableBits) >> 7)
|
|
}
|
|
return rv, nil
|
|
}
|
|
|
|
func MustNewPrefixCodedInt64(in int64, shift uint) PrefixCoded {
|
|
rv, err := NewPrefixCodedInt64(in, shift)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
return rv
|
|
}
|
|
|
|
// Shift returns the number of bits shifted
|
|
// returns 0 if in uninitialized state
|
|
func (p PrefixCoded) Shift() (uint, error) {
|
|
if len(p) > 0 {
|
|
shift := p[0] - ShiftStartInt64
|
|
if shift < 0 || shift < 63 {
|
|
return uint(shift), nil
|
|
}
|
|
}
|
|
return 0, fmt.Errorf("invalid prefix coded value")
|
|
}
|
|
|
|
func (p PrefixCoded) Int64() (int64, error) {
|
|
shift, err := p.Shift()
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
var sortableBits int64
|
|
for _, inbyte := range p[1:] {
|
|
sortableBits <<= 7
|
|
sortableBits |= int64(inbyte)
|
|
}
|
|
return int64(uint64((sortableBits << shift)) ^ 0x8000000000000000), nil
|
|
}
|
|
|
|
func ValidPrefixCodedTerm(p string) (bool, int) {
|
|
return ValidPrefixCodedTermBytes([]byte(p))
|
|
}
|
|
|
|
func ValidPrefixCodedTermBytes(p []byte) (bool, int) {
|
|
if len(p) > 0 {
|
|
if p[0] < ShiftStartInt64 || p[0] > ShiftStartInt64+63 {
|
|
return false, 0
|
|
}
|
|
shift := p[0] - ShiftStartInt64
|
|
nChars := ((63 - int(shift)) / 7) + 1
|
|
if len(p) != nChars+1 {
|
|
return false, 0
|
|
}
|
|
return true, int(shift)
|
|
}
|
|
return false, 0
|
|
}
|