oppi.li
+36
-31
gitdiff/io.go
+36
-31
gitdiff/io.go
···
31
31
}
32
32
33
33
func (r *lineReaderAt) ReadLinesAt(lines [][]byte, offset int64) (n int, err error) {
34
-
// TODO(bkeyes): revisit variable names
35
-
// - it's generally not clear when something is bytes vs lines
36
-
// - offset is a good example of this
37
-
38
34
if offset < 0 {
39
35
return 0, errors.New("ReadLinesAt: negative offset")
40
36
}
···
42
38
return 0, nil
43
39
}
44
40
45
-
endLine := offset + int64(len(lines))
41
+
count := len(lines)
42
+
startLine := offset
43
+
endLine := startLine + int64(count)
44
+
46
45
if endLine > int64(len(r.index)) && !r.eof {
47
46
if err := r.indexTo(endLine); err != nil {
48
47
return 0, err
49
48
}
50
49
}
51
-
if offset > int64(len(r.index)) {
50
+
if startLine > int64(len(r.index)) {
52
51
return 0, io.EOF
53
52
}
54
53
55
-
size, readOffset := lookupLines(r.index, offset, int64(len(lines)))
56
-
57
-
b := make([]byte, size)
58
-
if _, err := r.r.ReadAt(b, readOffset); err != nil {
59
-
if err == io.EOF {
60
-
err = errors.New("ReadLinesAt: corrupt line index or changed source data")
61
-
}
54
+
buf, byteOffset, err := r.readBytes(startLine, int64(count))
55
+
if err != nil {
62
56
return 0, err
63
57
}
64
58
65
-
for n = 0; n < len(lines) && offset+int64(n) < int64(len(r.index)); n++ {
66
-
i := offset + int64(n)
67
-
start, end := readOffset, r.index[i]
68
-
if i > 0 {
69
-
start = r.index[i-1]
59
+
for n = 0; n < count && startLine+int64(n) < int64(len(r.index)); n++ {
60
+
lineno := startLine + int64(n)
61
+
start, end := int64(0), r.index[lineno]-byteOffset
62
+
if lineno > 0 {
63
+
start = r.index[lineno-1] - byteOffset
70
64
}
71
-
lines[n] = b[start-readOffset : end-readOffset]
65
+
lines[n] = buf[start:end]
72
66
}
73
67
74
-
if n < len(lines) || b[size-1] != '\n' {
68
+
if n < count || buf[len(buf)-1] != '\n' {
75
69
return n, io.EOF
76
70
}
77
71
return n, nil
···
110
104
return nil
111
105
}
112
106
113
-
// lookupLines gets the byte offset and size of a range of lines from an index
114
-
// where the value at n is the offset of the first byte after line number n.
115
-
func lookupLines(index []int64, start, n int64) (size int64, offset int64) {
116
-
if start > int64(len(index)) {
117
-
offset = index[len(index)-1]
118
-
} else if start > 0 {
119
-
offset = index[start-1]
107
+
// readBytes reads the bytes of the n lines starting at line and returns the
108
+
// bytes and the offset of the first byte in the underlying source.
109
+
func (r *lineReaderAt) readBytes(line, n int64) (b []byte, offset int64, err error) {
110
+
indexLen := int64(len(r.index))
111
+
112
+
var size int64
113
+
if line > indexLen {
114
+
offset = r.index[indexLen-1]
115
+
} else if line > 0 {
116
+
offset = r.index[line-1]
120
117
}
121
118
if n > 0 {
122
-
if start+n > int64(len(index)) {
123
-
size = index[len(index)-1] - offset
119
+
if line+n > indexLen {
120
+
size = r.index[indexLen-1] - offset
124
121
} else {
125
-
size = index[start+n-1] - offset
122
+
size = r.index[line+n-1] - offset
126
123
}
127
124
}
128
-
return
125
+
126
+
b = make([]byte, size)
127
+
if _, err := r.r.ReadAt(b, offset); err != nil {
128
+
if err == io.EOF {
129
+
err = errors.New("ReadLinesAt: corrupt line index or changed source data")
130
+
}
131
+
return nil, 0, err
132
+
}
133
+
return b, offset, nil
129
134
}
130
135
131
136
func isLen(r io.ReaderAt, n int64) (bool, error) {