waveterm/pkg/util/logview/logview.go

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// Copyright 2024, Command Line Inc.
// SPDX-License-Identifier: Apache-2.0
package logview
import (
"fmt"
"io"
"os"
"regexp"
)
const BufSize = 256 * 1024
const MaxLineSize = 1024
type LinePtr struct {
Offset int64
RealLineNum int64
LineNum int64
}
type LogView struct {
File *os.File
MultiBuf *MultiBufferByteGetter
MatchRe *regexp.Regexp
}
func MakeLogView(file *os.File) *LogView {
return &LogView{
File: file,
MultiBuf: MakeMultiBufferByteGetter(file, BufSize),
}
}
func (lv *LogView) Close() {
lv.File.Close()
}
func (lv *LogView) ReadLineData(linePtr *LinePtr) ([]byte, error) {
return lv.readLineAt(linePtr.Offset)
}
func (lv *LogView) readLineAt(offset int64) ([]byte, error) {
var rtn []byte
for {
if len(rtn) > MaxLineSize {
break
}
b, err := lv.MultiBuf.GetByte(offset)
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
if b == '\n' {
break
}
rtn = append(rtn, b)
offset++
}
return rtn, nil
}
func (lv *LogView) FirstLinePtr() (*LinePtr, error) {
linePtr := &LinePtr{Offset: 0, RealLineNum: 1, LineNum: 1}
if lv.isLineMatch(0) {
return linePtr, nil
}
return lv.NextLinePtr(linePtr)
}
func (lv *LogView) isLineMatch(offset int64) bool {
if lv.MatchRe == nil {
return true
}
lineData, err := lv.readLineAt(offset)
if err != nil {
return false
}
return lv.MatchRe.Match(lineData)
}
func (lv *LogView) NextLinePtr(linePtr *LinePtr) (*LinePtr, error) {
if linePtr == nil {
return nil, fmt.Errorf("linePtr is nil")
}
numLines := int64(0)
offset := linePtr.Offset
for {
var err error
nextOffset, err := lv.MultiBuf.NextLine(offset)
if err == io.EOF {
return nil, nil
}
if err != nil {
return nil, err
}
numLines++
if lv.isLineMatch(nextOffset) {
return &LinePtr{Offset: nextOffset, RealLineNum: linePtr.RealLineNum + numLines, LineNum: linePtr.LineNum + 1}, nil
}
offset = nextOffset
}
}
func (lv *LogView) PrevLinePtr(linePtr *LinePtr) (*LinePtr, error) {
if linePtr == nil {
return nil, fmt.Errorf("linePtr is nil")
}
numLines := int64(0)
offset := linePtr.Offset
for {
var err error
prevOffset, err := lv.MultiBuf.PrevLine(offset)
if err == ErrBOF {
return nil, nil
}
if err != nil {
return nil, err
}
numLines++
if lv.isLineMatch(prevOffset) {
return &LinePtr{Offset: prevOffset, RealLineNum: linePtr.RealLineNum - numLines, LineNum: linePtr.LineNum - 1}, nil
}
offset = prevOffset
}
}
func (lv *LogView) Move(linePtr *LinePtr, offset int) (int, *LinePtr, error) {
var n int
if offset > 0 {
for {
nextLinePtr, err := lv.NextLinePtr(linePtr)
if err == io.EOF {
break
}
if err != nil {
return 0, nil, err
}
linePtr = nextLinePtr
n++
if n == offset {
break
}
}
return n, linePtr, nil
}
if offset < 0 {
for {
prevLinePtr, err := lv.PrevLinePtr(linePtr)
if err == ErrBOF {
break
}
if err != nil {
return 0, nil, err
}
linePtr = prevLinePtr
n--
if n == offset {
break
}
}
return n, linePtr, nil
}
return 0, linePtr, nil
}
func (lv *LogView) LastLinePtr(linePtr *LinePtr) (*LinePtr, error) {
if linePtr == nil {
var err error
linePtr, err = lv.FirstLinePtr()
if err != nil {
return nil, err
}
}
if linePtr == nil {
return nil, nil
}
for {
nextLinePtr, err := lv.NextLinePtr(linePtr)
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
if nextLinePtr == nil {
break
}
linePtr = nextLinePtr
}
return linePtr, nil
}
func (lv *LogView) ReadWindow(linePtr *LinePtr, winSize int) ([][]byte, error) {
if linePtr == nil {
return nil, nil
}
var rtn [][]byte
for len(rtn) < winSize {
lineData, err := lv.readLineAt(linePtr.Offset)
if err != nil {
return nil, err
}
rtn = append(rtn, lineData)
nextLinePtr, err := lv.NextLinePtr(linePtr)
if err != nil {
return nil, err
}
if nextLinePtr == nil {
break
}
linePtr = nextLinePtr
}
return rtn, nil
}