this repo has no description
Improve clarity of LineReaderAt implementation
Try to avoid confusion about whether variables refer to byte or line
counts/positions. It still isn't perfect, but I'm not sure how to
further clarify without being overly verbose.
+36
-31
+36
-31
gitdiff/io.go
+36
-31
gitdiff/io.go
···
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}
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func (r *lineReaderAt) ReadLinesAt(lines [][]byte, offset int64) (n int, err error) {
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-
// TODO(bkeyes): revisit variable names
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// - it's generally not clear when something is bytes vs lines
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// - offset is a good example of this
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-
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if offset < 0 {
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return 0, errors.New("ReadLinesAt: negative offset")
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}
···
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return 0, nil
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}
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-
endLine := offset + int64(len(lines))
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count := len(lines)
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startLine := offset
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endLine := startLine + int64(count)
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+
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if endLine > int64(len(r.index)) && !r.eof {
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if err := r.indexTo(endLine); err != nil {
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return 0, err
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}
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}
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if offset > int64(len(r.index)) {
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if startLine > int64(len(r.index)) {
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return 0, io.EOF
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}
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size, readOffset := lookupLines(r.index, offset, int64(len(lines)))
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-
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b := make([]byte, size)
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if _, err := r.r.ReadAt(b, readOffset); err != nil {
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if err == io.EOF {
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err = errors.New("ReadLinesAt: corrupt line index or changed source data")
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}
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buf, byteOffset, err := r.readBytes(startLine, int64(count))
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if err != nil {
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return 0, err
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}
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for n = 0; n < len(lines) && offset+int64(n) < int64(len(r.index)); n++ {
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i := offset + int64(n)
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start, end := readOffset, r.index[i]
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if i > 0 {
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start = r.index[i-1]
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for n = 0; n < count && startLine+int64(n) < int64(len(r.index)); n++ {
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lineno := startLine + int64(n)
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start, end := int64(0), r.index[lineno]-byteOffset
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if lineno > 0 {
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start = r.index[lineno-1] - byteOffset
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}
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lines[n] = b[start-readOffset : end-readOffset]
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lines[n] = buf[start:end]
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}
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if n < len(lines) || b[size-1] != '\n' {
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if n < count || buf[len(buf)-1] != '\n' {
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return n, io.EOF
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}
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return n, nil
···
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return nil
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}
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// lookupLines gets the byte offset and size of a range of lines from an index
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// where the value at n is the offset of the first byte after line number n.
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func lookupLines(index []int64, start, n int64) (size int64, offset int64) {
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if start > int64(len(index)) {
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offset = index[len(index)-1]
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} else if start > 0 {
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offset = index[start-1]
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// readBytes reads the bytes of the n lines starting at line and returns the
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// bytes and the offset of the first byte in the underlying source.
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func (r *lineReaderAt) readBytes(line, n int64) (b []byte, offset int64, err error) {
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indexLen := int64(len(r.index))
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+
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var size int64
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if line > indexLen {
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offset = r.index[indexLen-1]
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} else if line > 0 {
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offset = r.index[line-1]
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}
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if n > 0 {
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if start+n > int64(len(index)) {
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size = index[len(index)-1] - offset
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if line+n > indexLen {
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size = r.index[indexLen-1] - offset
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} else {
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size = index[start+n-1] - offset
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size = r.index[line+n-1] - offset
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}
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}
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-
return
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+
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b = make([]byte, size)
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if _, err := r.r.ReadAt(b, offset); err != nil {
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if err == io.EOF {
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err = errors.New("ReadLinesAt: corrupt line index or changed source data")
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}
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return nil, 0, err
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}
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return b, offset, nil
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}
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func isLen(r io.ReaderAt, n int64) (bool, error) {