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|
package gitdiff
import (
"fmt"
"io"
"strconv"
"strings"
)
// ParseTextFragments parses text fragments until the next file header or the
// end of the stream and attaches them to the given file. It returns the number
// of fragments that were added.
func (p *parser) ParseTextFragments(f *File) (n int, err error) {
for {
frag, err := p.ParseTextFragmentHeader()
if err != nil {
return n, err
}
if frag == nil {
return n, nil
}
if f.IsNew && frag.OldLines > 0 {
return n, p.Errorf(-1, "new file depends on old contents")
}
if f.IsDelete && frag.NewLines > 0 {
return n, p.Errorf(-1, "deleted file still has contents")
}
if err := p.ParseTextChunk(frag); err != nil {
return n, err
}
f.TextFragments = append(f.TextFragments, frag)
n++
}
}
func (p *parser) ParseTextFragmentHeader() (*TextFragment, error) {
const (
startMark = "@@ -"
endMark = " @@"
)
if !strings.HasPrefix(p.Line(0), startMark) {
return nil, nil
}
parts := strings.SplitAfterN(p.Line(0), endMark, 2)
if len(parts) < 2 {
return nil, p.Errorf(0, "invalid fragment header")
}
f := &TextFragment{}
f.Comment = strings.TrimSpace(parts[1])
header := parts[0][len(startMark) : len(parts[0])-len(endMark)]
ranges := strings.Split(header, " +")
if len(ranges) != 2 {
return nil, p.Errorf(0, "invalid fragment header")
}
var err error
if f.OldPosition, f.OldLines, err = parseRange(ranges[0]); err != nil {
return nil, p.Errorf(0, "invalid fragment header: %v", err)
}
if f.NewPosition, f.NewLines, err = parseRange(ranges[1]); err != nil {
return nil, p.Errorf(0, "invalid fragment header: %v", err)
}
if err := p.Next(); err != nil && err != io.EOF {
return nil, err
}
return f, nil
}
func (p *parser) ParseTextChunk(frag *TextFragment) error {
if p.Line(0) == "" {
return p.Errorf(0, "no content following fragment header")
}
oldLines, newLines := frag.OldLines, frag.NewLines
for oldLines > 0 || newLines > 0 {
line := p.Line(0)
op, data := line[0], line[1:]
switch op {
case '\n':
data = "\n"
fallthrough // newer GNU diff versions create empty context lines
case ' ':
oldLines--
newLines--
if frag.LinesAdded == 0 && frag.LinesDeleted == 0 {
frag.LeadingContext++
} else {
frag.TrailingContext++
}
frag.Lines = append(frag.Lines, Line{OpContext, data})
case '-':
oldLines--
frag.LinesDeleted++
frag.TrailingContext = 0
frag.Lines = append(frag.Lines, Line{OpDelete, data})
case '+':
newLines--
frag.LinesAdded++
frag.TrailingContext = 0
frag.Lines = append(frag.Lines, Line{OpAdd, data})
case '\\':
// this may appear in middle of fragment if it's for a deleted line
if isNoNewlineMarker(line) {
removeLastNewline(frag)
break
}
fallthrough
default:
// TODO(bkeyes): if this is because we hit the next header, it
// would be helpful to return the miscounts line error. We could
// either test for the common headers ("@@ -", "diff --git") or
// assume any invalid op ends the fragment; git returns the same
// generic error in all cases so either is compatible
return p.Errorf(0, "invalid line operation: %q", op)
}
if err := p.Next(); err != nil {
if err == io.EOF {
break
}
return err
}
}
if oldLines != 0 || newLines != 0 {
hdr := max(frag.OldLines-oldLines, frag.NewLines-newLines) + 1
return p.Errorf(-hdr, "fragment header miscounts lines: %+d old, %+d new", -oldLines, -newLines)
}
if frag.LinesAdded == 0 && frag.LinesDeleted == 0 {
return p.Errorf(0, "fragment contains no changes")
}
// check for a final "no newline" marker since it is not included in the
// counters used to stop the loop above
if isNoNewlineMarker(p.Line(0)) {
removeLastNewline(frag)
if err := p.Next(); err != nil && err != io.EOF {
return err
}
}
return nil
}
func isNoNewlineMarker(s string) bool {
// test for "\ No newline at end of file" by prefix because the text
// changes by locale (git claims all versions are at least 12 chars)
return len(s) >= 12 && s[:2] == "\\ "
}
func removeLastNewline(frag *TextFragment) {
if len(frag.Lines) > 0 {
last := &frag.Lines[len(frag.Lines)-1]
last.Line = strings.TrimSuffix(last.Line, "\n")
}
}
func parseRange(s string) (start int64, end int64, err error) {
parts := strings.SplitN(s, ",", 2)
if start, err = strconv.ParseInt(parts[0], 10, 64); err != nil {
nerr := err.(*strconv.NumError)
return 0, 0, fmt.Errorf("bad start of range: %s: %v", parts[0], nerr.Err)
}
if len(parts) > 1 {
if end, err = strconv.ParseInt(parts[1], 10, 64); err != nil {
nerr := err.(*strconv.NumError)
return 0, 0, fmt.Errorf("bad end of range: %s: %v", parts[1], nerr.Err)
}
} else {
end = 1
}
return
}
func max(a, b int64) int64 {
if a > b {
return a
}
return b
}
|
