69 lines
1.5 KiB
Go
69 lines
1.5 KiB
Go
package fsutils
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import (
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"bytes"
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"fmt"
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"sync"
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)
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type fileLinesCache [][]byte
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type LineCache struct {
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files sync.Map
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fileCache *FileCache
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}
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func NewLineCache(fc *FileCache) *LineCache {
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return &LineCache{
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fileCache: fc,
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}
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}
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// GetLine returns the index1-th (1-based index) line from the file on filePath
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func (lc *LineCache) GetLine(filePath string, index1 int) (string, error) {
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if index1 == 0 { // some linters, e.g. gosec can do it: it really means first line
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index1 = 1
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}
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const index1To0Offset = -1
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rawLine, err := lc.getRawLine(filePath, index1+index1To0Offset)
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if err != nil {
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return "", err
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}
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return string(bytes.Trim(rawLine, "\r")), nil
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}
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func (lc *LineCache) getRawLine(filePath string, index0 int) ([]byte, error) {
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fc, err := lc.getFileCache(filePath)
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if err != nil {
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return nil, fmt.Errorf("failed to get file %s lines cache: %w", filePath, err)
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}
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if index0 < 0 {
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return nil, fmt.Errorf("invalid file line index0 < 0: %d", index0)
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}
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if index0 >= len(fc) {
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return nil, fmt.Errorf("invalid file line index0 (%d) >= len(fc) (%d)", index0, len(fc))
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}
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return fc[index0], nil
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}
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func (lc *LineCache) getFileCache(filePath string) (fileLinesCache, error) {
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loadedFc, ok := lc.files.Load(filePath)
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if ok {
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return loadedFc.(fileLinesCache), nil
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}
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fileBytes, err := lc.fileCache.GetFileBytes(filePath)
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if err != nil {
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return nil, fmt.Errorf("can't get file %s bytes from cache: %w", filePath, err)
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}
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fc := bytes.Split(fileBytes, []byte("\n"))
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lc.files.Store(filePath, fileLinesCache(fc))
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return fc, nil
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}
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