59 lines
1.6 KiB
Go
59 lines
1.6 KiB
Go
package registry
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import (
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"fmt"
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"reflect"
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"git.maximhutz.com/max/lambda/pkg/codec"
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)
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// A Codec is a type-erased codec that serializes and deserializes expressions
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// as Expr values, regardless of the underlying representation type.
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type Codec interface {
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codec.Codec[Expr]
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// InType returns the name of the representation this codec handles.
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InType() string
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}
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// A registeredCodec adapts a typed codec.Codec[T] into the type-erased Codec
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// interface. It wraps decoded values into Expr on decode, and extracts the
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// underlying T from an Expr on encode.
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type registeredCodec[T any] struct {
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codec codec.Codec[T]
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inType string
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}
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func (c registeredCodec[T]) Decode(s string) (Expr, error) {
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t, err := c.codec.Decode(s)
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if err != nil {
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return nil, err
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}
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return NewExpr(c.inType, t), nil
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}
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func (c registeredCodec[T]) Encode(r Expr) (string, error) {
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t, ok := r.Data().(T)
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if !ok {
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dataType := reflect.TypeOf(r.Data())
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allowedType := reflect.TypeFor[T]()
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return "", fmt.Errorf("Codec for '%s' cannot parse '%s'", allowedType, dataType)
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}
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return c.codec.Encode(t)
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}
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func (c registeredCodec[T]) InType() string { return c.inType }
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// RegisterCodec registers a typed codec under the given representation name.
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// Returns an error if a codec for that representation is already registered.
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func RegisterCodec[T any](registry *Registry, m codec.Codec[T], inType string) error {
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if _, ok := registry.codecs[inType]; ok {
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return fmt.Errorf("Codec for '%s' already registered", inType)
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}
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registry.codecs[inType] = registeredCodec[T]{m, inType}
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return nil
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}
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