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perf(encode): skip OmitEmpty slice allocation when no fields omitted #49

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Merged
xe-nvdk merged 1 commit into from
Mar 3, 2026
Merged

perf(encode): skip OmitEmpty slice allocation when no fields omitted #49

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14 changes: 13 additions & 1 deletion types.go
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Original file line number Diff line number Diff line change
Expand Up @@ -159,8 +159,20 @@ func (fs *fields) OmitEmpty(e *Encoder, strct reflect.Value) []*field {
return fs.List
}

fields := make([]*field, 0, len(fs.List))
// First pass: count surviving fields. If all survive, return the
// original slice without allocating a filtered copy.
n := 0
for _, f := range fs.List {
if !f.Omit(e, strct) {
n++
}
}
if n == len(fs.List) {
return fs.List
}

// Second pass: build the filtered slice only when necessary.
fields := make([]*field, 0, n)
for _, f := range fs.List {
if !f.Omit(e, strct) {
fields = append(fields, f)
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