Method ParseTraditionalFileHeader

pkg/gitdiff/file_header.go:110–167

()

}

func (p *parser) ParseTraditionalFileHeader() (*File, error) {
	const shortestValidFragHeader = "@@ -1 +1 @@\n"
	const (
		oldPrefix = "--- "
		newPrefix = "+++ "
	)

	oldLine, newLine := p.Line(0), p.Line(1)

	if !strings.HasPrefix(oldLine, oldPrefix) || !strings.HasPrefix(newLine, newPrefix) {
		return nil, nil
	}
	// heuristic: only a file header if followed by a (probable) fragment header
	if len(p.Line(2)) < len(shortestValidFragHeader) || !strings.HasPrefix(p.Line(2), "@@ -") {
		return nil, nil
	}

	// advance past the first two lines so parser is after the header
	// no EOF check needed because we know there are >=3 valid lines
	if err := p.Next(); err != nil {
		return nil, err
	}
	if err := p.Next(); err != nil {
		return nil, err
	}

	oldName, _, err := parseName(oldLine[len(oldPrefix):], '\t', 0)
	if err != nil {
		return nil, p.Errorf(0, "file header: %v", err)
	}

	newName, _, err := parseName(newLine[len(newPrefix):], '\t', 0)
	if err != nil {
		return nil, p.Errorf(1, "file header: %v", err)
	}

	f := &File{}
	switch {
	case oldName == devNull || hasEpochTimestamp(oldLine):
		f.IsNew = true
		f.NewName = newName
	case newName == devNull || hasEpochTimestamp(newLine):
		f.IsDelete = true
		f.OldName = oldName
	default:
		// if old name is a prefix of new name, use that instead
		// this avoids picking variants like "file.bak" or "file~"
		if strings.HasPrefix(newName, oldName) {
			f.OldName = oldName
			f.NewName = oldName
		} else {
			f.OldName = newName
			f.NewName = newName
		}
	}

	return f, nil
}