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Skip file headers if FromFile/ToFile are empty
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@shazow
shazow committed Dec 8, 2015
1 parent e8554b8 commit 509b2ff
Showing 1 changed file with 13 additions and 9 deletions.
22 changes: 13 additions & 9 deletions difflib/difflib.go
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Original file line number Diff line number Diff line change
Expand Up @@ -585,13 +585,15 @@ func WriteUnifiedDiff(writer io.Writer, diff UnifiedDiff) error {
if len(diff.ToDate) > 0 {
toDate = "\t" + diff.ToDate
}
err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol)
if err != nil {
return err
}
err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol)
if err != nil {
return err
if diff.FromFile != "" || diff.ToFile != "" {
err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol)
if err != nil {
return err
}
err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol)
if err != nil {
return err
}
}
}
first, last := g[0], g[len(g)-1]
Expand Down Expand Up @@ -710,8 +712,10 @@ func WriteContextDiff(writer io.Writer, diff ContextDiff) error {
if len(diff.ToDate) > 0 {
toDate = "\t" + diff.ToDate
}
wf("*** %s%s%s", diff.FromFile, fromDate, diff.Eol)
wf("--- %s%s%s", diff.ToFile, toDate, diff.Eol)
if diff.FromFile != "" || diff.ToFile != "" {
wf("*** %s%s%s", diff.FromFile, fromDate, diff.Eol)
wf("--- %s%s%s", diff.ToFile, toDate, diff.Eol)
}
}

first, last := g[0], g[len(g)-1]
Expand Down

2 comments on commit 509b2ff

@gonzalop
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This commit breaks compatibility to other tools that deal with unified diffs. The format of a unified diff always has the file headers ->
http://www.gnu.org/software/diffutils/manual/html_node/Detailed-Unified.html#Detailed-Unified

@pmezard
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You are correct and I was reluctant to introduce the change though I see the point of it. But what is done is done and I would rather not change it again (and avoid future changes in this code), since working around it is not too hard.

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