package convert import ( "errors" "github.com/zclconf/go-cty/cty" ) // This file contains the public interface of this package, which is intended // to be a small, convenient interface designed for easy integration into // a hypothetical language type checker and interpreter. // Conversion is a named function type representing a conversion from a // value of one type to a value of another type. // // The source type for a conversion is always the source type given to // the function that returned the Conversion, but there is no way to recover // that from a Conversion value itself. If a Conversion is given a value // that is not of its expected type (with the exception of DynamicPseudoType, // which is always supported) then the function may panic or produce undefined // results. type Conversion func(in cty.Value) (out cty.Value, err error) // GetConversion returns a Conversion between the given in and out Types if // a safe one is available, or returns nil otherwise. func GetConversion(in cty.Type, out cty.Type) Conversion { return retConversion(getConversion(in, out, false)) } // GetConversionUnsafe returns a Conversion between the given in and out Types // if either a safe or unsafe one is available, or returns nil otherwise. func GetConversionUnsafe(in cty.Type, out cty.Type) Conversion { return retConversion(getConversion(in, out, true)) } // Convert returns the result of converting the given value to the given type // if an safe or unsafe conversion is available, or returns an error if such a // conversion is impossible. // // This is a convenience wrapper around calling GetConversionUnsafe and then // immediately passing the given value to the resulting function. func Convert(in cty.Value, want cty.Type) (cty.Value, error) { if in.Type().Equals(want) { return in, nil } conv := GetConversionUnsafe(in.Type(), want) if conv == nil { return cty.NilVal, errors.New(MismatchMessage(in.Type(), want)) } return conv(in) } // Unify attempts to find the most general type that can be converted from // all of the given types. If this is possible, that type is returned along // with a slice of necessary conversions for some of the given types. // // If no common supertype can be found, this function returns cty.NilType and // a nil slice. // // If a common supertype *can* be found, the returned slice will always be // non-nil and will contain a non-nil conversion for each given type that // needs to be converted, with indices corresponding to the input slice. // Any given type that does *not* need conversion (because it is already of // the appropriate type) will have a nil Conversion. // // cty.DynamicPseudoType is, as usual, a special case. If the given type list // contains a mixture of dynamic and non-dynamic types, the dynamic types are // disregarded for type selection and a conversion is returned for them that // will attempt a late conversion of the given value to the target type, // failing with a conversion error if the eventual concrete type is not // compatible. If *all* given types are DynamicPseudoType, or in the // degenerate case of an empty slice of types, the returned type is itself // cty.DynamicPseudoType and no conversions are attempted. func Unify(types []cty.Type) (cty.Type, []Conversion) { return unify(types, false) } // UnifyUnsafe is the same as Unify except that it may return unsafe // conversions in situations where a safe conversion isn't also available. func UnifyUnsafe(types []cty.Type) (cty.Type, []Conversion) { return unify(types, true) }