mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-11-24 11:31:54 +01:00
316 lines
7.2 KiB
Go
316 lines
7.2 KiB
Go
// Copyright (c) 2017 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 vellum
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"fmt"
|
|
"strconv"
|
|
)
|
|
|
|
func init() {
|
|
registerDecoder(versionV1, func(data []byte) decoder {
|
|
return newDecoderV1(data)
|
|
})
|
|
}
|
|
|
|
type decoderV1 struct {
|
|
data []byte
|
|
root uint64
|
|
len uint64
|
|
}
|
|
|
|
func newDecoderV1(data []byte) *decoderV1 {
|
|
return &decoderV1{
|
|
data: data,
|
|
}
|
|
}
|
|
|
|
func (d *decoderV1) getRoot() int {
|
|
if len(d.data) < footerSizeV1 {
|
|
return noneAddr
|
|
}
|
|
footer := d.data[len(d.data)-footerSizeV1:]
|
|
root := binary.LittleEndian.Uint64(footer[8:])
|
|
return int(root)
|
|
}
|
|
|
|
func (d *decoderV1) getLen() int {
|
|
if len(d.data) < footerSizeV1 {
|
|
return 0
|
|
}
|
|
footer := d.data[len(d.data)-footerSizeV1:]
|
|
dlen := binary.LittleEndian.Uint64(footer)
|
|
return int(dlen)
|
|
}
|
|
|
|
func (d *decoderV1) stateAt(addr int, prealloc fstState) (fstState, error) {
|
|
state, ok := prealloc.(*fstStateV1)
|
|
if ok && state != nil {
|
|
*state = fstStateV1{} // clear the struct
|
|
} else {
|
|
state = &fstStateV1{}
|
|
}
|
|
err := state.at(d.data, addr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return state, nil
|
|
}
|
|
|
|
type fstStateV1 struct {
|
|
data []byte
|
|
top int
|
|
bottom int
|
|
numTrans int
|
|
|
|
// single trans only
|
|
singleTransChar byte
|
|
singleTransNext bool
|
|
singleTransAddr uint64
|
|
singleTransOut uint64
|
|
|
|
// shared
|
|
transSize int
|
|
outSize int
|
|
|
|
// multiple trans only
|
|
final bool
|
|
transTop int
|
|
transBottom int
|
|
destTop int
|
|
destBottom int
|
|
outTop int
|
|
outBottom int
|
|
outFinal int
|
|
}
|
|
|
|
func (f *fstStateV1) isEncodedSingle() bool {
|
|
if f.data[f.top]>>7 > 0 {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (f *fstStateV1) at(data []byte, addr int) error {
|
|
f.data = data
|
|
if addr == emptyAddr {
|
|
return f.atZero()
|
|
} else if addr == noneAddr {
|
|
return f.atNone()
|
|
}
|
|
if addr > len(data) || addr < 16 {
|
|
return fmt.Errorf("invalid address %d/%d", addr, len(data))
|
|
}
|
|
f.top = addr
|
|
f.bottom = addr
|
|
if f.isEncodedSingle() {
|
|
return f.atSingle(data, addr)
|
|
}
|
|
return f.atMulti(data, addr)
|
|
}
|
|
|
|
func (f *fstStateV1) atZero() error {
|
|
f.top = 0
|
|
f.bottom = 1
|
|
f.numTrans = 0
|
|
f.final = true
|
|
f.outFinal = 0
|
|
return nil
|
|
}
|
|
|
|
func (f *fstStateV1) atNone() error {
|
|
f.top = 0
|
|
f.bottom = 1
|
|
f.numTrans = 0
|
|
f.final = false
|
|
f.outFinal = 0
|
|
return nil
|
|
}
|
|
|
|
func (f *fstStateV1) atSingle(data []byte, addr int) error {
|
|
// handle single transition case
|
|
f.numTrans = 1
|
|
f.singleTransNext = data[f.top]&transitionNext > 0
|
|
f.singleTransChar = data[f.top] & maxCommon
|
|
if f.singleTransChar == 0 {
|
|
f.bottom-- // extra byte for uncommon
|
|
f.singleTransChar = data[f.bottom]
|
|
} else {
|
|
f.singleTransChar = decodeCommon(f.singleTransChar)
|
|
}
|
|
if f.singleTransNext {
|
|
// now we know the bottom, can compute next addr
|
|
f.singleTransAddr = uint64(f.bottom - 1)
|
|
f.singleTransOut = 0
|
|
} else {
|
|
f.bottom-- // extra byte with pack sizes
|
|
f.transSize, f.outSize = decodePackSize(data[f.bottom])
|
|
f.bottom -= f.transSize // exactly one trans
|
|
f.singleTransAddr = readPackedUint(data[f.bottom : f.bottom+f.transSize])
|
|
if f.outSize > 0 {
|
|
f.bottom -= f.outSize // exactly one out (could be length 0 though)
|
|
f.singleTransOut = readPackedUint(data[f.bottom : f.bottom+f.outSize])
|
|
} else {
|
|
f.singleTransOut = 0
|
|
}
|
|
// need to wait till we know bottom
|
|
if f.singleTransAddr != 0 {
|
|
f.singleTransAddr = uint64(f.bottom) - f.singleTransAddr
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (f *fstStateV1) atMulti(data []byte, addr int) error {
|
|
// handle multiple transitions case
|
|
f.final = data[f.top]&stateFinal > 0
|
|
f.numTrans = int(data[f.top] & maxNumTrans)
|
|
if f.numTrans == 0 {
|
|
f.bottom-- // extra byte for number of trans
|
|
f.numTrans = int(data[f.bottom])
|
|
if f.numTrans == 1 {
|
|
// can't really be 1 here, this is special case that means 256
|
|
f.numTrans = 256
|
|
}
|
|
}
|
|
f.bottom-- // extra byte with pack sizes
|
|
f.transSize, f.outSize = decodePackSize(data[f.bottom])
|
|
|
|
f.transTop = f.bottom
|
|
f.bottom -= f.numTrans // one byte for each transition
|
|
f.transBottom = f.bottom
|
|
|
|
f.destTop = f.bottom
|
|
f.bottom -= f.numTrans * f.transSize
|
|
f.destBottom = f.bottom
|
|
|
|
if f.outSize > 0 {
|
|
f.outTop = f.bottom
|
|
f.bottom -= f.numTrans * f.outSize
|
|
f.outBottom = f.bottom
|
|
if f.final {
|
|
f.bottom -= f.outSize
|
|
f.outFinal = f.bottom
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (f *fstStateV1) Address() int {
|
|
return f.top
|
|
}
|
|
|
|
func (f *fstStateV1) Final() bool {
|
|
return f.final
|
|
}
|
|
|
|
func (f *fstStateV1) FinalOutput() uint64 {
|
|
if f.numTrans > 0 && f.final && f.outSize > 0 {
|
|
return readPackedUint(f.data[f.outFinal : f.outFinal+f.outSize])
|
|
}
|
|
return 0
|
|
}
|
|
|
|
func (f *fstStateV1) NumTransitions() int {
|
|
return f.numTrans
|
|
}
|
|
|
|
func (f *fstStateV1) TransitionAt(i int) byte {
|
|
if f.isEncodedSingle() {
|
|
return f.singleTransChar
|
|
}
|
|
transitionKeys := f.data[f.transBottom:f.transTop]
|
|
return transitionKeys[f.numTrans-i-1]
|
|
}
|
|
|
|
func (f *fstStateV1) TransitionFor(b byte) (int, int, uint64) {
|
|
if f.isEncodedSingle() {
|
|
if f.singleTransChar == b {
|
|
return 0, int(f.singleTransAddr), f.singleTransOut
|
|
}
|
|
return -1, noneAddr, 0
|
|
}
|
|
transitionKeys := f.data[f.transBottom:f.transTop]
|
|
pos := bytes.IndexByte(transitionKeys, b)
|
|
if pos < 0 {
|
|
return -1, noneAddr, 0
|
|
}
|
|
transDests := f.data[f.destBottom:f.destTop]
|
|
dest := int(readPackedUint(transDests[pos*f.transSize : pos*f.transSize+f.transSize]))
|
|
if dest > 0 {
|
|
// convert delta
|
|
dest = f.bottom - dest
|
|
}
|
|
transVals := f.data[f.outBottom:f.outTop]
|
|
var out uint64
|
|
if f.outSize > 0 {
|
|
out = readPackedUint(transVals[pos*f.outSize : pos*f.outSize+f.outSize])
|
|
}
|
|
return f.numTrans - pos - 1, dest, out
|
|
}
|
|
|
|
func (f *fstStateV1) String() string {
|
|
rv := ""
|
|
rv += fmt.Sprintf("State: %d (%#x)", f.top, f.top)
|
|
if f.final {
|
|
rv += " final"
|
|
fout := f.FinalOutput()
|
|
if fout != 0 {
|
|
rv += fmt.Sprintf(" (%d)", fout)
|
|
}
|
|
}
|
|
rv += "\n"
|
|
rv += fmt.Sprintf("Data: % x\n", f.data[f.bottom:f.top+1])
|
|
|
|
for i := 0; i < f.numTrans; i++ {
|
|
transChar := f.TransitionAt(i)
|
|
_, transDest, transOut := f.TransitionFor(transChar)
|
|
rv += fmt.Sprintf(" - %d (%#x) '%s' ---> %d (%#x) with output: %d", transChar, transChar, string(transChar), transDest, transDest, transOut)
|
|
rv += "\n"
|
|
}
|
|
if f.numTrans == 0 {
|
|
rv += "\n"
|
|
}
|
|
return rv
|
|
}
|
|
|
|
func (f *fstStateV1) DotString(num int) string {
|
|
rv := ""
|
|
label := fmt.Sprintf("%d", num)
|
|
final := ""
|
|
if f.final {
|
|
final = ",peripheries=2"
|
|
}
|
|
rv += fmt.Sprintf(" %d [label=\"%s\"%s];\n", f.top, label, final)
|
|
|
|
for i := 0; i < f.numTrans; i++ {
|
|
transChar := f.TransitionAt(i)
|
|
_, transDest, transOut := f.TransitionFor(transChar)
|
|
out := ""
|
|
if transOut != 0 {
|
|
out = fmt.Sprintf("/%d", transOut)
|
|
}
|
|
rv += fmt.Sprintf(" %d -> %d [label=\"%s%s\"];\n", f.top, transDest, escapeInput(transChar), out)
|
|
}
|
|
|
|
return rv
|
|
}
|
|
|
|
func escapeInput(b byte) string {
|
|
x := strconv.AppendQuoteRune(nil, rune(b))
|
|
return string(x[1:(len(x) - 1)])
|
|
}
|