route/vendor/github.com/hashicorp/hil/convert.go

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2017-12-02 23:34:35 +00:00
package hil
import (
"fmt"
"reflect"
"github.com/hashicorp/hil/ast"
"github.com/mitchellh/mapstructure"
)
// UnknownValue is a sentinel value that can be used to denote
// that a value of a variable (or map element, list element, etc.)
// is unknown. This will always have the type ast.TypeUnknown.
const UnknownValue = "74D93920-ED26-11E3-AC10-0800200C9A66"
var hilMapstructureDecodeHookSlice []interface{}
var hilMapstructureDecodeHookStringSlice []string
var hilMapstructureDecodeHookMap map[string]interface{}
// hilMapstructureWeakDecode behaves in the same way as mapstructure.WeakDecode
// but has a DecodeHook which defeats the backward compatibility mode of mapstructure
// which WeakDecodes []interface{}{} into an empty map[string]interface{}. This
// allows us to use WeakDecode (desirable), but not fail on empty lists.
func hilMapstructureWeakDecode(m interface{}, rawVal interface{}) error {
config := &mapstructure.DecoderConfig{
DecodeHook: func(source reflect.Type, target reflect.Type, val interface{}) (interface{}, error) {
sliceType := reflect.TypeOf(hilMapstructureDecodeHookSlice)
stringSliceType := reflect.TypeOf(hilMapstructureDecodeHookStringSlice)
mapType := reflect.TypeOf(hilMapstructureDecodeHookMap)
if (source == sliceType || source == stringSliceType) && target == mapType {
return nil, fmt.Errorf("Cannot convert %s into a %s", source, target)
}
return val, nil
},
WeaklyTypedInput: true,
Result: rawVal,
}
decoder, err := mapstructure.NewDecoder(config)
if err != nil {
return err
}
return decoder.Decode(m)
}
func InterfaceToVariable(input interface{}) (ast.Variable, error) {
if inputVariable, ok := input.(ast.Variable); ok {
return inputVariable, nil
}
var stringVal string
if err := hilMapstructureWeakDecode(input, &stringVal); err == nil {
// Special case the unknown value to turn into "unknown"
if stringVal == UnknownValue {
return ast.Variable{Value: UnknownValue, Type: ast.TypeUnknown}, nil
}
// Otherwise return the string value
return ast.Variable{
Type: ast.TypeString,
Value: stringVal,
}, nil
}
var mapVal map[string]interface{}
if err := hilMapstructureWeakDecode(input, &mapVal); err == nil {
elements := make(map[string]ast.Variable)
for i, element := range mapVal {
varElement, err := InterfaceToVariable(element)
if err != nil {
return ast.Variable{}, err
}
elements[i] = varElement
}
return ast.Variable{
Type: ast.TypeMap,
Value: elements,
}, nil
}
var sliceVal []interface{}
if err := hilMapstructureWeakDecode(input, &sliceVal); err == nil {
elements := make([]ast.Variable, len(sliceVal))
for i, element := range sliceVal {
varElement, err := InterfaceToVariable(element)
if err != nil {
return ast.Variable{}, err
}
elements[i] = varElement
}
return ast.Variable{
Type: ast.TypeList,
Value: elements,
}, nil
}
return ast.Variable{}, fmt.Errorf("value for conversion must be a string, interface{} or map[string]interface: got %T", input)
}
func VariableToInterface(input ast.Variable) (interface{}, error) {
if input.Type == ast.TypeString {
if inputStr, ok := input.Value.(string); ok {
return inputStr, nil
} else {
return nil, fmt.Errorf("ast.Variable with type string has value which is not a string")
}
}
if input.Type == ast.TypeList {
inputList, ok := input.Value.([]ast.Variable)
if !ok {
return nil, fmt.Errorf("ast.Variable with type list has value which is not a []ast.Variable")
}
result := make([]interface{}, 0)
if len(inputList) == 0 {
return result, nil
}
for _, element := range inputList {
if convertedElement, err := VariableToInterface(element); err == nil {
result = append(result, convertedElement)
} else {
return nil, err
}
}
return result, nil
}
if input.Type == ast.TypeMap {
inputMap, ok := input.Value.(map[string]ast.Variable)
if !ok {
return nil, fmt.Errorf("ast.Variable with type map has value which is not a map[string]ast.Variable")
}
result := make(map[string]interface{}, 0)
if len(inputMap) == 0 {
return result, nil
}
for key, value := range inputMap {
if convertedValue, err := VariableToInterface(value); err == nil {
result[key] = convertedValue
} else {
return nil, err
}
}
return result, nil
}
return nil, fmt.Errorf("unknown input type: %s", input.Type)
}