diff options
Diffstat (limited to 'vendor/github.com/pelletier/go-toml/v2/README.md')
| -rw-r--r-- | vendor/github.com/pelletier/go-toml/v2/README.md | 556 |
1 files changed, 556 insertions, 0 deletions
diff --git a/vendor/github.com/pelletier/go-toml/v2/README.md b/vendor/github.com/pelletier/go-toml/v2/README.md new file mode 100644 index 00000000..ca5b5ced --- /dev/null +++ b/vendor/github.com/pelletier/go-toml/v2/README.md @@ -0,0 +1,556 @@ +# go-toml v2 + +Go library for the [TOML](https://toml.io/en/) format. + +This library supports [TOML v1.0.0](https://toml.io/en/v1.0.0). + +## Development status + +This is the upcoming major version of go-toml. It is currently in active +development. As of release v2.0.0-beta.1, the library has reached feature parity +with v1, and fixes a lot known bugs and performance issues along the way. + +If you do not need the advanced document editing features of v1, you are +encouraged to try out this version. + +[👉 Roadmap for v2](https://github.com/pelletier/go-toml/discussions/506) + +[🐞 Bug Reports](https://github.com/pelletier/go-toml/issues) + +[💬 Anything else](https://github.com/pelletier/go-toml/discussions) + +## Documentation + +Full API, examples, and implementation notes are available in the Go +documentation. + +[](https://pkg.go.dev/github.com/pelletier/go-toml/v2) + +## Import + +```go +import "github.com/pelletier/go-toml/v2" +``` + +See [Modules](#Modules). + +## Features + +### Stdlib behavior + +As much as possible, this library is designed to behave similarly as the +standard library's `encoding/json`. + +### Performance + +While go-toml favors usability, it is written with performance in mind. Most +operations should not be shockingly slow. See [benchmarks](#benchmarks). + +### Strict mode + +`Decoder` can be set to "strict mode", which makes it error when some parts of +the TOML document was not prevent in the target structure. This is a great way +to check for typos. [See example in the documentation][strict]. + +[strict]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#example-Decoder.DisallowUnknownFields + +### Contextualized errors + +When most decoding errors occur, go-toml returns [`DecodeError`][decode-err]), +which contains a human readable contextualized version of the error. For +example: + +``` +2| key1 = "value1" +3| key2 = "missing2" + | ~~~~ missing field +4| key3 = "missing3" +5| key4 = "value4" +``` + +[decode-err]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#DecodeError + +### Local date and time support + +TOML supports native [local date/times][ldt]. It allows to represent a given +date, time, or date-time without relation to a timezone or offset. To support +this use-case, go-toml provides [`LocalDate`][tld], [`LocalTime`][tlt], and +[`LocalDateTime`][tldt]. Those types can be transformed to and from `time.Time`, +making them convenient yet unambiguous structures for their respective TOML +representation. + +[ldt]: https://toml.io/en/v1.0.0#local-date-time +[tld]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#LocalDate +[tlt]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#LocalTime +[tldt]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#LocalDateTime + +## Getting started + +Given the following struct, let's see how to read it and write it as TOML: + +```go +type MyConfig struct { + Version int + Name string + Tags []string +} +``` + +### Unmarshaling + +[`Unmarshal`][unmarshal] reads a TOML document and fills a Go structure with its +content. For example: + +```go +doc := ` +version = 2 +name = "go-toml" +tags = ["go", "toml"] +` + +var cfg MyConfig +err := toml.Unmarshal([]byte(doc), &cfg) +if err != nil { + panic(err) +} +fmt.Println("version:", cfg.Version) +fmt.Println("name:", cfg.Name) +fmt.Println("tags:", cfg.Tags) + +// Output: +// version: 2 +// name: go-toml +// tags: [go toml] +``` + +[unmarshal]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Unmarshal + +### Marshaling + +[`Marshal`][marshal] is the opposite of Unmarshal: it represents a Go structure +as a TOML document: + +```go +cfg := MyConfig{ + Version: 2, + Name: "go-toml", + Tags: []string{"go", "toml"}, +} + +b, err := toml.Marshal(cfg) +if err != nil { + panic(err) +} +fmt.Println(string(b)) + +// Output: +// Version = 2 +// Name = 'go-toml' +// Tags = ['go', 'toml'] +``` + +[marshal]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Marshal + +## Benchmarks + +Execution time speedup compared to other Go TOML libraries: + +<table> + <thead> + <tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr> + </thead> + <tbody> + <tr><td>Marshal/HugoFrontMatter-2</td><td>1.9x</td><td>1.9x</td></tr> + <tr><td>Marshal/ReferenceFile/map-2</td><td>1.7x</td><td>1.8x</td></tr> + <tr><td>Marshal/ReferenceFile/struct-2</td><td>2.2x</td><td>2.5x</td></tr> + <tr><td>Unmarshal/HugoFrontMatter-2</td><td>2.9x</td><td>2.9x</td></tr> + <tr><td>Unmarshal/ReferenceFile/map-2</td><td>2.6x</td><td>2.9x</td></tr> + <tr><td>Unmarshal/ReferenceFile/struct-2</td><td>4.4x</td><td>5.3x</td></tr> + </tbody> +</table> +<details><summary>See more</summary> +<p>The table above has the results of the most common use-cases. The table below +contains the results of all benchmarks, including unrealistic ones. It is +provided for completeness.</p> + +<table> + <thead> + <tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr> + </thead> + <tbody> + <tr><td>Marshal/SimpleDocument/map-2</td><td>1.8x</td><td>2.9x</td></tr> + <tr><td>Marshal/SimpleDocument/struct-2</td><td>2.7x</td><td>4.2x</td></tr> + <tr><td>Unmarshal/SimpleDocument/map-2</td><td>4.5x</td><td>3.1x</td></tr> + <tr><td>Unmarshal/SimpleDocument/struct-2</td><td>6.2x</td><td>3.9x</td></tr> + <tr><td>UnmarshalDataset/example-2</td><td>3.1x</td><td>3.5x</td></tr> + <tr><td>UnmarshalDataset/code-2</td><td>2.3x</td><td>3.1x</td></tr> + <tr><td>UnmarshalDataset/twitter-2</td><td>2.5x</td><td>2.6x</td></tr> + <tr><td>UnmarshalDataset/citm_catalog-2</td><td>2.1x</td><td>2.2x</td></tr> + <tr><td>UnmarshalDataset/canada-2</td><td>1.6x</td><td>1.3x</td></tr> + <tr><td>UnmarshalDataset/config-2</td><td>4.3x</td><td>3.2x</td></tr> + <tr><td>[Geo mean]</td><td>2.7x</td><td>2.8x</td></tr> + </tbody> +</table> +<p>This table can be generated with <code>./ci.sh benchmark -a -html</code>.</p> +</details> + +## Modules + +go-toml uses Go's standard modules system. + +Installation instructions: + +- Go ≥ 1.16: Nothing to do. Use the import in your code. The `go` command deals + with it automatically. +- Go ≥ 1.13: `GO111MODULE=on go get github.com/pelletier/go-toml/v2`. + +In case of trouble: [Go Modules FAQ][mod-faq]. + +[mod-faq]: https://github.com/golang/go/wiki/Modules#why-does-installing-a-tool-via-go-get-fail-with-error-cannot-find-main-module + +## Tools + +Go-toml provides three handy command line tools: + + * `tomljson`: Reads a TOML file and outputs its JSON representation. + + ``` + $ go install github.com/pelletier/go-toml/v2/cmd/tomljson@latest + $ tomljson --help + ``` + + * `jsontoml`: Reads a JSON file and outputs a TOML representation. + + ``` + $ go install github.com/pelletier/go-toml/v2/cmd/jsontoml@latest + $ jsontoml --help + ``` + + * `tomll`: Lints and reformats a TOML file. + + ``` + $ go install github.com/pelletier/go-toml/v2/cmd/tomll@latest + $ tomll --help + ``` + +### Docker image + +Those tools are also available as a [Docker image][docker]. For example, to use +`tomljson`: + +``` +docker run -i ghcr.io/pelletier/go-toml:v2 tomljson < example.toml +``` + +Multiple versions are availble on [ghcr.io][docker]. + +[docker]: https://github.com/pelletier/go-toml/pkgs/container/go-toml + +## Migrating from v1 + +This section describes the differences between v1 and v2, with some pointers on +how to get the original behavior when possible. + +### Decoding / Unmarshal + +#### Automatic field name guessing + +When unmarshaling to a struct, if a key in the TOML document does not exactly +match the name of a struct field or any of the `toml`-tagged field, v1 tries +multiple variations of the key ([code][v1-keys]). + +V2 instead does a case-insensitive matching, like `encoding/json`. + +This could impact you if you are relying on casing to differentiate two fields, +and one of them is a not using the `toml` struct tag. The recommended solution +is to be specific about tag names for those fields using the `toml` struct tag. + +[v1-keys]: https://github.com/pelletier/go-toml/blob/a2e52561804c6cd9392ebf0048ca64fe4af67a43/marshal.go#L775-L781 + +#### Ignore preexisting value in interface + +When decoding into a non-nil `interface{}`, go-toml v1 uses the type of the +element in the interface to decode the object. For example: + +```go +type inner struct { + B interface{} +} +type doc struct { + A interface{} +} + +d := doc{ + A: inner{ + B: "Before", + }, +} + +data := ` +[A] +B = "After" +` + +toml.Unmarshal([]byte(data), &d) +fmt.Printf("toml v1: %#v\n", d) + +// toml v1: main.doc{A:main.inner{B:"After"}} +``` + +In this case, field `A` is of type `interface{}`, containing a `inner` struct. +V1 sees that type and uses it when decoding the object. + +When decoding an object into an `interface{}`, V2 instead disregards whatever +value the `interface{}` may contain and replaces it with a +`map[string]interface{}`. With the same data structure as above, here is what +the result looks like: + +```go +toml.Unmarshal([]byte(data), &d) +fmt.Printf("toml v2: %#v\n", d) + +// toml v2: main.doc{A:map[string]interface {}{"B":"After"}} +``` + +This is to match `encoding/json`'s behavior. There is no way to make the v2 +decoder behave like v1. + +#### Values out of array bounds ignored + +When decoding into an array, v1 returns an error when the number of elements +contained in the doc is superior to the capacity of the array. For example: + +```go +type doc struct { + A [2]string +} +d := doc{} +err := toml.Unmarshal([]byte(`A = ["one", "two", "many"]`), &d) +fmt.Println(err) + +// (1, 1): unmarshal: TOML array length (3) exceeds destination array length (2) +``` + +In the same situation, v2 ignores the last value: + +```go +err := toml.Unmarshal([]byte(`A = ["one", "two", "many"]`), &d) +fmt.Println("err:", err, "d:", d) +// err: <nil> d: {[one two]} +``` + +This is to match `encoding/json`'s behavior. There is no way to make the v2 +decoder behave like v1. + +#### Support for `toml.Unmarshaler` has been dropped + +This method was not widely used, poorly defined, and added a lot of complexity. +A similar effect can be achieved by implementing the `encoding.TextUnmarshaler` +interface and use strings. + +#### Support for `default` struct tag has been dropped + +This feature adds complexity and a poorly defined API for an effect that can be +accomplished outside of the library. + +It does not seem like other format parsers in Go support that feature (the +project referenced in the original ticket #202 has not been updated since 2017). +Given that go-toml v2 should not touch values not in the document, the same +effect can be achieved by pre-filling the struct with defaults (libraries like +[go-defaults][go-defaults] can help). Also, string representation is not well +defined for all types: it creates issues like #278. + +The recommended replacement is pre-filling the struct before unmarshaling. + +[go-defaults]: https://github.com/mcuadros/go-defaults + +#### `toml.Tree` replacement + +This structure was the initial attempt at providing a document model for +go-toml. It allows manipulating the structure of any document, encoding and +decoding from their TOML representation. While a more robust feature was +initially planned in go-toml v2, this has been ultimately [removed from +scope][nodoc] of this library, with no plan to add it back at the moment. The +closest equivalent at the moment would be to unmarshal into an `interface{}` and +use type assertions and/or reflection to manipulate the arbitrary +structure. However this would fall short of providing all of the TOML features +such as adding comments and be specific about whitespace. + + +#### `toml.Position` are not retrievable anymore + +The API for retrieving the position (line, column) of a specific TOML element do +not exist anymore. This was done to minimize the amount of concepts introduced +by the library (query path), and avoid the performance hit related to storing +positions in the absence of a document model, for a feature that seemed to have +little use. Errors however have gained more detailed position +information. Position retrieval seems better fitted for a document model, which +has been [removed from the scope][nodoc] of go-toml v2 at the moment. + +### Encoding / Marshal + +#### Default struct fields order + +V1 emits struct fields order alphabetically by default. V2 struct fields are +emitted in order they are defined. For example: + +```go +type S struct { + B string + A string +} + +data := S{ + B: "B", + A: "A", +} + +b, _ := tomlv1.Marshal(data) +fmt.Println("v1:\n" + string(b)) + +b, _ = tomlv2.Marshal(data) +fmt.Println("v2:\n" + string(b)) + +// Output: +// v1: +// A = "A" +// B = "B" + +// v2: +// B = 'B' +// A = 'A' +``` + +There is no way to make v2 encoder behave like v1. A workaround could be to +manually sort the fields alphabetically in the struct definition, or generate +struct types using `reflect.StructOf`. + +#### No indentation by default + +V1 automatically indents content of tables by default. V2 does not. However the +same behavior can be obtained using [`Encoder.SetIndentTables`][sit]. For example: + +```go +data := map[string]interface{}{ + "table": map[string]string{ + "key": "value", + }, +} + +b, _ := tomlv1.Marshal(data) +fmt.Println("v1:\n" + string(b)) + +b, _ = tomlv2.Marshal(data) +fmt.Println("v2:\n" + string(b)) + +buf := bytes.Buffer{} +enc := tomlv2.NewEncoder(&buf) +enc.SetIndentTables(true) +enc.Encode(data) +fmt.Println("v2 Encoder:\n" + string(buf.Bytes())) + +// Output: +// v1: +// +// [table] +// key = "value" +// +// v2: +// [table] +// key = 'value' +// +// +// v2 Encoder: +// [table] +// key = 'value' +``` + +[sit]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Encoder.SetIndentTables + +#### Keys and strings are single quoted + +V1 always uses double quotes (`"`) around strings and keys that cannot be +represented bare (unquoted). V2 uses single quotes instead by default (`'`), +unless a character cannot be represented, then falls back to double quotes. As a +result of this change, `Encoder.QuoteMapKeys` has been removed, as it is not +useful anymore. + +There is no way to make v2 encoder behave like v1. + +#### `TextMarshaler` emits as a string, not TOML + +Types that implement [`encoding.TextMarshaler`][tm] can emit arbitrary TOML in +v1. The encoder would append the result to the output directly. In v2 the result +is wrapped in a string. As a result, this interface cannot be implemented by the +root object. + +There is no way to make v2 encoder behave like v1. + +[tm]: https://golang.org/pkg/encoding/#TextMarshaler + +#### `Encoder.CompactComments` has been removed + +Emitting compact comments is now the default behavior of go-toml. This option +is not necessary anymore. + +#### Struct tags have been merged + +V1 used to provide multiple struct tags: `comment`, `commented`, `multiline`, +`toml`, and `omitempty`. To behave more like the standard library, v2 has merged +`toml`, `multiline`, and `omitempty`. For example: + +```go +type doc struct { + // v1 + F string `toml:"field" multiline:"true" omitempty:"true"` + // v2 + F string `toml:"field,multiline,omitempty"` +} +``` + +Has a result, the `Encoder.SetTag*` methods have been removed, as there is just +one tag now. + + +#### `commented` tag has been removed + +There is no replacement for the `commented` tag. This feature would be better +suited in a proper document model for go-toml v2, which has been [cut from +scope][nodoc] at the moment. + +#### `Encoder.ArraysWithOneElementPerLine` has been renamed + +The new name is `Encoder.SetArraysMultiline`. The behavior should be the same. + +#### `Encoder.Indentation` has been renamed + +The new name is `Encoder.SetIndentSymbol`. The behavior should be the same. + + +#### Embedded structs behave like stdlib + +V1 defaults to merging embedded struct fields into the embedding struct. This +behavior was unexpected because it does not follow the standard library. To +avoid breaking backward compatibility, the `Encoder.PromoteAnonymous` method was +added to make the encoder behave correctly. Given backward compatibility is not +a problem anymore, v2 does the right thing by default: it follows the behavior +of `encoding/json`. `Encoder.PromoteAnonymous` has been removed. + +[nodoc]: https://github.com/pelletier/go-toml/discussions/506#discussioncomment-1526038 + +### `query` + +go-toml v1 provided the [`go-toml/query`][query] package. It allowed to run +JSONPath-style queries on TOML files. This feature is not available in v2. For a +replacement, check out [dasel][dasel]. + +This package has been removed because it was essentially not supported anymore +(last commit May 2020), increased the complexity of the code base, and more +complete solutions exist out there. + +[query]: https://github.com/pelletier/go-toml/tree/f99d6bbca119636aeafcf351ee52b3d202782627/query +[dasel]: https://github.com/TomWright/dasel + +## License + +The MIT License (MIT). Read [LICENSE](LICENSE). |