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vmux: Split each muxer into its own file
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sam boyer
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May 17, 2023
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,30 @@ | ||
| package vmux | ||
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| import "github.com/grafana/thema" | ||
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| // ByteMux is a version multiplexer that maps a []byte containing data at any | ||
| // schematized version to a []byte containing data at a particular schematized version. | ||
| type ByteMux func(b []byte) ([]byte, thema.TranslationLacunas, error) | ||
|
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| // NewByteMux creates a [ByteMux] func from the provided [thema.Schema]. | ||
| // | ||
| // When the returned mux func is called, it will: | ||
| // | ||
| // - Decode the input []byte using the provided [Codec], then | ||
| // - Pass the result to [thema.Schema.Validate], then | ||
| // - Call [thema.Instance.Translate] on the result, to the version of the provided [thema.Schema], then | ||
| // - Encode the resulting [thema.Instance] to a []byte, then | ||
| // - Return the resulting []byte, [thema.TranslationLacunas], and error | ||
| // | ||
| // The returned error may be from any of the above steps. | ||
| func NewByteMux(sch thema.Schema, codec Codec) ByteMux { | ||
| f := NewUntypedMux(sch, codec) | ||
| return func(b []byte) ([]byte, thema.TranslationLacunas, error) { | ||
| ti, lac, err := f(b) | ||
| if err != nil { | ||
| return nil, lac, err | ||
| } | ||
| ob, err := codec.Encode(ti.Underlying()) | ||
| return ob, lac, err | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,62 @@ | ||
| package vmux | ||
|
|
||
| import ( | ||
| "fmt" | ||
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| "github.com/grafana/thema" | ||
| ) | ||
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| // TypedMux is a version multiplexer that maps a []byte containing data at any | ||
| // schematized version to a [thema.TypedInstance] at a particular schematized version. | ||
| type TypedMux[T thema.Assignee] func(b []byte) (*thema.TypedInstance[T], thema.TranslationLacunas, error) | ||
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| // NewTypedMux creates a [TypedMux] func from the provided [thema.TypedSchema]. | ||
| // | ||
| // When the returned mux func is called, it will: | ||
| // | ||
| // - Decode the input []byte using the provided [Decoder], then | ||
| // - Pass the result to [thema.TypedSchema.ValidateTyped], then | ||
| // - Call [thema.Instance.Translate] on the result, to the version of the provided [thema.TypedSchema], then | ||
| // - Return the resulting [thema.TypedInstance], [thema.TranslationLacunas], and error | ||
| // | ||
| // The returned error may be from any of the above steps. | ||
| func NewTypedMux[T thema.Assignee](sch thema.TypedSchema[T], dec Decoder) TypedMux[T] { | ||
| ctx := sch.Lineage().Underlying().Context() | ||
| // Prepare no-match error string once for reuse | ||
| vstring := allvstr(sch) | ||
|
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| return func(b []byte) (*thema.TypedInstance[T], thema.TranslationLacunas, error) { | ||
| v, err := dec.Decode(ctx, b) | ||
| if err != nil { | ||
| // TODO wrap error for use with errors.Is | ||
| return nil, nil, err | ||
| } | ||
|
|
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| // Try the given schema first, on the premise that in general it's the | ||
| // most likely one for an application to encounter | ||
| tinst, err := sch.ValidateTyped(v) | ||
| if err == nil { | ||
| return tinst, nil, nil | ||
| } | ||
|
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| // Walk in reverse order on the premise that, in general, newer versions are more | ||
| // likely to be provided than older versions | ||
| isch := latest(sch.Lineage()) | ||
| for ; isch != nil; isch = isch.Predecessor() { | ||
| if isch.Version() == sch.Version() { | ||
| continue | ||
| } | ||
|
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| if inst, ierr := isch.Validate(v); ierr == nil { | ||
| trinst, lac := inst.Translate(sch.Version()) | ||
| tinst, err := thema.BindInstanceType(trinst, sch) | ||
| if err != nil { | ||
| panic(fmt.Errorf("unreachable, instance type should always be bindable: %w", err)) | ||
| } | ||
| return tinst, lac, nil | ||
| } | ||
| } | ||
|
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| return nil, nil, fmt.Errorf("data invalid against all versions (%s), error against %s: %w", vstring, sch.Version(), err) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,58 @@ | ||
| package vmux | ||
|
|
||
| import ( | ||
| "fmt" | ||
|
|
||
| "github.com/grafana/thema" | ||
| ) | ||
|
|
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| // UntypedMux is a version multiplexer that maps a []byte containing data at any | ||
| // schematized version to a [thema.Instance] at a particular schematized version. | ||
| type UntypedMux func(b []byte) (*thema.Instance, thema.TranslationLacunas, error) | ||
|
|
||
| // NewUntypedMux creates an [UntypedMux] from the provided [thema.Schema]. | ||
| // | ||
| // When the returned mux func is called, it will: | ||
| // | ||
| // - Decode the input []byte using the provided [Decoder], then | ||
| // - Pass the result to [thema.Schema.Validate], then | ||
| // - Call [thema.Instance.Translate] on the result, to the version of the provided [thema.Schema], then | ||
| // - Return the resulting [thema.Instance], [thema.TranslationLacunas], and error | ||
| // | ||
| // The returned error may be from any of the above steps. | ||
| func NewUntypedMux(sch thema.Schema, dec Decoder) UntypedMux { | ||
| ctx := sch.Lineage().Underlying().Context() | ||
| // Prepare no-match error string once for reuse | ||
| vstring := allvstr(sch) | ||
|
|
||
| return func(b []byte) (*thema.Instance, thema.TranslationLacunas, error) { | ||
| v, err := dec.Decode(ctx, b) | ||
| if err != nil { | ||
| // TODO wrap error for use with errors.Is | ||
| return nil, nil, err | ||
| } | ||
|
|
||
| // Try the given schema first, on the premise that in general it's the | ||
| // most likely one for an application to encounter | ||
| tinst, err := sch.Validate(v) | ||
| if err == nil { | ||
| return tinst, nil, nil | ||
| } | ||
|
|
||
| // Walk in reverse order on the premise that, in general, newer versions are more | ||
| // likely to be provided than older versions | ||
| isch := latest(sch.Lineage()) | ||
| for ; isch != nil; isch = isch.Predecessor() { | ||
| if isch.Version() == sch.Version() { | ||
| continue | ||
| } | ||
|
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| if inst, ierr := isch.Validate(v); ierr == nil { | ||
| trinst, lac := inst.Translate(sch.Version()) | ||
| return trinst, lac, nil | ||
| } | ||
| } | ||
|
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| return nil, nil, fmt.Errorf("data invalid against all versions (%s), error against %s: %w", vstring, sch.Version(), err) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,31 @@ | ||
| package vmux | ||
|
|
||
| import "github.com/grafana/thema" | ||
|
|
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| // ValueMux is a version multiplexer that maps a []byte containing data at any | ||
| // schematized version to a Go var of a type that a particular schematized | ||
| // version is [thema.AssignableTo]. | ||
| type ValueMux[T thema.Assignee] func(b []byte) (T, thema.TranslationLacunas, error) | ||
|
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| // NewValueMux creates a [ValueMux] func from the provided [thema.TypedSchema]. | ||
| // | ||
| // When the returned mux func is called, it will: | ||
| // | ||
| // - Decode the input []byte using the provided [Decoder], then | ||
| // - Pass the result to [thema.TypedSchema.ValidateTyped], then | ||
| // - Call [thema.Instance.Translate] on the result, to the version of the provided [thema.TypedSchema], then | ||
| // - Populate an instance of T by calling [thema.TypedInstance.Value] on the result, then | ||
| // - Return the resulting T, [thema.TranslationLacunas], and error | ||
| // | ||
| // The returned error may be from any of the above steps. | ||
| func NewValueMux[T thema.Assignee](sch thema.TypedSchema[T], dec Decoder) ValueMux[T] { | ||
| f := NewTypedMux[T](sch, dec) | ||
| return func(b []byte) (T, thema.TranslationLacunas, error) { | ||
| ti, lac, err := f(b) | ||
| if err != nil { | ||
| return sch.NewT(), lac, err | ||
| } | ||
| t, err := ti.Value() | ||
| return t, lac, err | ||
| } | ||
| } |