feat: add the 'omitnil' struct field's option

CHANGELOG.md

@@ -4,6 +4,9 @@ All notable changes to this project are documented in this file.
 
 **THIS LIBRARY IS STILL IN ALPHA AND THERE ARE NO GUARANTEES REGARDING API STABILITY YET**
 
+## [v0.7.0] - 2020-02-17
+- Add the `omitnil` field tag's option, which specifies that a field with a nil pointer should be omitted from the encoding. This option has precedence over the `omitempty` option. See this issue for more informations about the original proposal: golang.org/issue/22480.
+
 ## [v0.6.0] - 2020-02-14
 - Add support for the `sync.Map` type. The marshaling behavior for this type is similar to the one of the Go `map`.
 
@@ -16,7 +19,7 @@ This includes the following changes, but not limited to:
 - Improve the marshaling performances of many types.
 - Add support for marshaling `json.RawMessage` values.
 - Add new options `DenyList`, `NoNumberValidation`, `NoCompact`, and rename some others.
-- Replace the `Marshaler` and `MarshalerCtx` interfaces by `AppendMarshaler` and `AppendMarshalerCtx` to follow the new *append* model.
+- Replace the `Marshaler` and `MarshalerCtx` interfaces by `AppendMarshaler` and `AppendMarshalerCtx` to follow the new *append* model. See this issue on GitHub for more details: golang.org/issue/34701.
 - Remove the `IntegerBase` option, which didn't worked properly with the `string` JSON tag.
 
 > Some of the improvements have been inspired by the **github.com/segmentio/encoding** project.
@@ -53,6 +56,7 @@ This includes the following changes, but not limited to:
 ## [v0.1.0] - 2019-08-30
 Initial realease.
 
+[v0.7.0]: https://github.com/wI2L/jettison/compare/v0.6.0...v0.7.0
 [v0.6.0]: https://github.com/wI2L/jettison/compare/v0.5.0...v0.6.0
 [v0.5.0]: https://github.com/wI2L/jettison/compare/v0.4.1...v0.5.0
 [v0.4.1]: https://github.com/wI2L/jettison/compare/v0.4.0...v0.4.1

README.md

@@ -17,7 +17,7 @@
 
 Jettison uses the new [Go modules](https://github.com/golang/go/wiki/Modules). Releases are tagged according to the _SemVer_ format, prefixed with a `v`, starting from *0.2.0*. You can get the latest release using the following command.
 
-```sh
+```console
 $ go get github.com/wI2L/jettison
 ```
 
@@ -53,6 +53,8 @@ All notable differences with the standard library behavior are listed below. Ple
 
 - The `sync.Map` type is handled natively. The marshaling behavior is similar to the one of a standard Go `map`. The option `UnsortedMap` can also be used in cunjunction with this type to disable the default keys sort.
 
+- The `omitnil` field tag's option can be used to specify that a field with a nil pointer should be omitted from the encoding. This option has precedence over the `omitempty` option.
+
 ##### Bugs
 
 - Nil map keys values implementing the `encoding.TextMarshaler` interface are encoded as empty strings, while the `encoding/json` package currently panic because of that. See this [issue](https://github.com/golang/go/issues/33675) for more details.<sup>[1]</sup>
@@ -128,47 +130,47 @@ OS:  macOS Mojave (10.14.6)
 CPU: 2.6 GHz Intel Core i7
 Mem: 16GB
 Go:  go version go1.13.7 darwin/amd64
-Tag: v0.5.0
+Tag: v0.7.0
 ```
 
 <details><summary>Stats</summary><br><pre>
 name                    time/op
-Simple/standard-8          666ns ± 4%
-Simple/jsoniter-8          770ns ± 1%
-Simple/segmentj-8          376ns ± 0%
-Simple/jettison-8          485ns ± 1%
+Simple/standard-8          662ns ± 1%
+Simple/jsoniter-8          775ns ± 1%
+Simple/segmentj-8          380ns ± 1%
+Simple/jettison-8          472ns ± 1%
 Complex/standard-8        13.8µs ± 1%
-Complex/jsoniter-8        14.1µs ± 2%
-Complex/segmentj-8        9.77µs ± 2%
-Complex/jettison-8        6.84µs ± 1%
-CodeMarshal/standard-8    7.27ms ± 1%
-CodeMarshal/jsoniter-8    8.28ms ± 1%
-CodeMarshal/segmentj-8    5.55ms ± 0%
-CodeMarshal/jettison-8    5.99ms ± 1%
-Map/standard-8            2.19µs ± 0%
-Map/jsoniter-8            1.84µs ± 1%
+Complex/jsoniter-8        14.1µs ± 1%
+Complex/segmentj-8        9.72µs ± 1%
+Complex/jettison-8        6.86µs ± 1%
+CodeMarshal/standard-8    7.25ms ± 0%
+CodeMarshal/jsoniter-8    8.27ms ± 1%
+CodeMarshal/segmentj-8    5.54ms ± 0%
+CodeMarshal/jettison-8    6.02ms ± 0%
+Map/standard-8            2.19µs ± 1%
+Map/jsoniter-8            1.83µs ± 1%
 Map/segmentj-8            1.92µs ± 0%
-Map/jettison-8             917ns ± 1%
-Map/jettison-nosort-8      607ns ± 2%
+Map/jettison-8             904ns ± 1%
+Map/jettison-nosort-8      600ns ± 1%
 
 name                    speed
-Simple/standard-8        203MB/s ± 4%
-Simple/jsoniter-8        175MB/s ± 1%
-Simple/segmentj-8        359MB/s ± 0%
-Simple/jettison-8        278MB/s ± 1%
+Simple/standard-8        204MB/s ± 1%
+Simple/jsoniter-8        174MB/s ± 1%
+Simple/segmentj-8        355MB/s ± 2%
+Simple/jettison-8        286MB/s ± 1%
 Complex/standard-8      61.8MB/s ± 1%
-Complex/jsoniter-8      58.1MB/s ± 2%
-Complex/segmentj-8      88.1MB/s ± 2%
-Complex/jettison-8       124MB/s ± 2%
-CodeMarshal/standard-8   267MB/s ± 1%
-CodeMarshal/jsoniter-8   234MB/s ± 1%
-CodeMarshal/segmentj-8   349MB/s ± 0%
-CodeMarshal/jettison-8   324MB/s ± 1%
-Map/standard-8          38.9MB/s ± 0%
-Map/jsoniter-8          46.2MB/s ± 1%
-Map/segmentj-8          44.2MB/s ± 1%
-Map/jettison-8          92.7MB/s ± 1%
-Map/jettison-nosort-8    140MB/s ± 2%
+Complex/jsoniter-8      58.1MB/s ± 1%
+Complex/segmentj-8      88.5MB/s ± 1%
+Complex/jettison-8       124MB/s ± 1%
+CodeMarshal/standard-8   268MB/s ± 0%
+CodeMarshal/jsoniter-8   235MB/s ± 1%
+CodeMarshal/segmentj-8   350MB/s ± 0%
+CodeMarshal/jettison-8   322MB/s ± 0%
+Map/standard-8          38.9MB/s ± 1%
+Map/jsoniter-8          46.4MB/s ± 1%
+Map/segmentj-8          44.3MB/s ± 0%
+Map/jettison-8          94.0MB/s ± 1%
+Map/jettison-nosort-8    142MB/s ± 1%
 
 name                    alloc/op
 Simple/standard-8           144B ± 0%
@@ -179,12 +181,12 @@ Complex/standard-8        4.76kB ± 0%
 Complex/jsoniter-8        4.65kB ± 0%
 Complex/segmentj-8        3.25kB ± 0%
 Complex/jettison-8        1.38kB ± 0%
-CodeMarshal/standard-8    1.96MB ± 1%
-CodeMarshal/jsoniter-8    1.99MB ± 5%
-CodeMarshal/segmentj-8    1.98MB ± 2%
-CodeMarshal/jettison-8    1.98MB ± 2%
+CodeMarshal/standard-8    1.95MB ± 1%
+CodeMarshal/jsoniter-8    1.99MB ± 2%
+CodeMarshal/segmentj-8    1.97MB ± 2%
+CodeMarshal/jettison-8    1.97MB ± 2%
 Map/standard-8              848B ± 0%
-Map/jsoniter-8              924B ± 0%
+Map/jsoniter-8              925B ± 0%
 Map/segmentj-8              592B ± 0%
 Map/jettison-8             96.0B ± 0%
 Map/jettison-nosort-8       160B ± 0%

encode.go

@@ -208,7 +208,7 @@ fieldLoop:
 		// Find the nested struct field by following
 		// the offset sequence, indirecting encountered
 		// pointers as needed.
-		for _, s := range f.embedSeqs {
+		for _, s := range f.embedSeq {
 			v = unsafe.Pointer(uintptr(v) + s.offset)
 			if s.indir {
 				if v = *(*unsafe.Pointer)(v); v == nil {
@@ -219,8 +219,13 @@ fieldLoop:
 				}
 			}
 		}
+		// Ignore the field if it is a nil pointer and has
+		// the omitnil option in his tag.
+		if f.omitNil && *(*unsafe.Pointer)(v) == nil {
+			continue
+		}
 		// Ignore the field if it represents the zero-value
-		// of its type and has the omitempty option in its tag.
+		// of its type and has the omitempty option in his tag.
 		// Empty func is non-nil only if the field has the
 		// omitempty option in its tag.
 		if f.omitEmpty && f.empty(v) {