WriteUnifiedDiff compares two sequences of lines and generates the delta as a unified diff. Unified diffs are a compact way of showing line changes and a few lines of context. The number of context lines is set by 'n' which defaults to three. By default, the diff control lines (those with ---, ++
(writer io.Writer, diff UnifiedDiff)
| 894 | // 'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'. |
| 895 | // The modification times are normally expressed in the ISO 8601 format. |
| 896 | func WriteUnifiedDiff(writer io.Writer, diff UnifiedDiff) error { |
| 897 | //buf := bufio.NewWriter(writer) |
| 898 | //defer buf.Flush() |
| 899 | var bld strings.Builder |
| 900 | bld.Reset() |
| 901 | wf := func(format string, args ...interface{}) error { |
| 902 | _, err := fmt.Fprintf(&bld, format, args...) |
| 903 | return err |
| 904 | } |
| 905 | ws := func(s []byte) error { |
| 906 | _, err := bld.Write(s) |
| 907 | return err |
| 908 | } |
| 909 | |
| 910 | if len(diff.Eol) == 0 { |
| 911 | diff.Eol = []byte("\n") |
| 912 | } |
| 913 | |
| 914 | started := false |
| 915 | m := NewMatcher(diff.A, diff.B) |
| 916 | for _, g := range m.GetGroupedOpCodes(diff.Context) { |
| 917 | if !started { |
| 918 | started = true |
| 919 | fromDate := "" |
| 920 | if len(diff.FromDate) > 0 { |
| 921 | fromDate = "\t" + diff.FromDate |
| 922 | } |
| 923 | toDate := "" |
| 924 | if len(diff.ToDate) > 0 { |
| 925 | toDate = "\t" + diff.ToDate |
| 926 | } |
| 927 | if diff.FromFile != "" || diff.ToFile != "" { |
| 928 | err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol) |
| 929 | if err != nil { |
| 930 | return err |
| 931 | } |
| 932 | err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol) |
| 933 | if err != nil { |
| 934 | return err |
| 935 | } |
| 936 | } |
| 937 | } |
| 938 | first, last := g[0], g[len(g)-1] |
| 939 | range1 := formatRangeUnified(first.I1, last.I2) |
| 940 | range2 := formatRangeUnified(first.J1, last.J2) |
| 941 | if err := wf("@@ -%s +%s @@%s", range1, range2, diff.Eol); err != nil { |
| 942 | return err |
| 943 | } |
| 944 | for _, c := range g { |
| 945 | i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2 |
| 946 | if c.Tag == 'e' { |
| 947 | for _, line := range diff.A[i1:i2] { |
| 948 | if err := ws(SPACE); err != nil { |
| 949 | return err |
| 950 | } |
| 951 | if err := ws(line); err != nil { |
| 952 | return err |
| 953 | } |
no test coverage detected