// TODO(knorton): This is still being tested. This is a grep that supports context lines. Unlike the version
// in codesearch, this one does not operate on chunks. The downside is that we have to have the whole file
// in memory to do the grep. Fortunately, we limit the size of files that get indexed anyway. 10M files tend
// to not be source code.
func (g *grepper) grep2(
r io.Reader,
re *regexp.Regexp,
nctx int,
fn func(line []byte, lineno int, before [][]byte, after [][]byte) (bool, error)) error {
buf, err := g.fillFrom(r)
if err != nil {
return err
}
lineno := 0
for {
if len(buf) == 0 {
return nil
}
m := re.Match(buf, true, true)
if m < 0 {
return nil
}
// start of matched line.
str := bytes.LastIndex(buf[:m], nl) + 1
//end of previous line
endl := str - 1
if endl < 0 {
endl = 0
}
//end of current line
end := m + 1
if end > len(buf) {
end = len(buf)
}
lineno += countLines(buf[:str])
more, err := fn(
bytes.TrimRight(buf[str:end], "\n"),
lineno+1,
lastNLines(buf[:endl], nctx),
firstNLines(buf[end:], nctx))
if err != nil {
return err
}
if !more {
return nil
}
lineno++
buf = buf[end:]
}
}
// This nonsense is adapted from https://code.google.com/p/codesearch/source/browse/regexp/match.go#399
// and I assume it is a mess to make it faster, but I would like to try a much simpler cleaner version.
func (g *grepper) grep(r io.Reader, re *regexp.Regexp, fn func(line []byte, lineno int) (bool, error)) error {
if g.buf == nil {
g.buf = make([]byte, 1<<20)
}
var (
buf = g.buf[:0]
lineno = 1
beginText = true
endText = false
)
for {
n, err := io.ReadFull(r, buf[len(buf):cap(buf)])
buf = buf[:len(buf)+n]
end := len(buf)
if err == nil {
end = bytes.LastIndex(buf, nl) + 1
} else {
endText = true
}
chunkStart := 0
for chunkStart < end {
m1 := re.Match(buf[chunkStart:end], beginText, endText) + chunkStart
beginText = false
if m1 < chunkStart {
break
}
lineStart := bytes.LastIndex(buf[chunkStart:m1], nl) + 1 + chunkStart
lineEnd := m1 + 1
if lineEnd > end {
lineEnd = end
}
lineno += countLines(buf[chunkStart:lineStart])
line := buf[lineStart:lineEnd]
more, err := fn(line, lineno)
if err != nil {
return err
}
if !more {
return nil
}
lineno++
chunkStart = lineEnd
}
if err == nil {
lineno += countLines(buf[chunkStart:end])
}
n = copy(buf, buf[end:])
buf = buf[:n]
if len(buf) == 0 && err != nil {
if err != io.EOF && err != io.ErrUnexpectedEOF {
return err
}
return nil
}
}
return nil
}
