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package toolbox
import (
"fmt"
"reflect"
"strings"
)
//GetFunction returns function for provided owner and name, or error
func GetFunction(owner interface{}, name string) (interface{}, error) {
if owner == nil {
return nil, fmt.Errorf("failed to lookup %v on %T, owner was nil", name, owner)
}
var ownerType = reflect.TypeOf(owner)
var method, has = ownerType.MethodByName(name)
if !has {
var available = make([]string, 0)
for i := 0; i < ownerType.NumMethod(); i++ {
available = append(available, ownerType.Method(i).Name)
}
return nil, fmt.Errorf("failed to lookup %T.%v, available:[%v]", owner, name, strings.Join(available, ","))
}
return reflect.ValueOf(owner).MethodByName(method.Name).Interface(), nil
}
//CallFunction calls passed in function with provided parameters,it returns a function result.
func CallFunction(function interface{}, parameters ...interface{}) []interface{} {
AssertKind(function, reflect.Func, "function")
var functionParameters = make([]reflect.Value, 0)
ProcessSlice(parameters, func(item interface{}) bool {
functionParameters = append(functionParameters, reflect.ValueOf(item))
return true
})
functionValue := reflect.ValueOf(function)
var resultValues = functionValue.Call(functionParameters)
var result = make([]interface{}, len(resultValues))
for i, resultValue := range resultValues {
result[i] = resultValue.Interface()
}
return result
}
//AsCompatibleFunctionParameters takes incompatible function parameters and converts then into provided function signature compatible
func AsCompatibleFunctionParameters(function interface{}, parameters []interface{}) ([]interface{}, error) {
return AsFunctionParameters(function, parameters, map[string]interface{}{})
}
//AsFunctionParameters takes incompatible function parameters and converts then into provided function signature compatible
func AsFunctionParameters(function interface{}, parameters []interface{}, parametersKV map[string]interface{}) ([]interface{}, error) {
AssertKind(function, reflect.Func, "function")
functionValue := reflect.ValueOf(function)
funcSignature := GetFuncSignature(function)
actualMethodSignatureLength := len(funcSignature)
converter := Converter{}
if actualMethodSignatureLength != len(parameters) {
return nil, fmt.Errorf("invalid number of parameters wanted: [%T], had: %v", function, len(parameters))
}
var functionParameters = make([]interface{}, 0)
for i, parameterValue := range parameters {
isStruct := IsStruct(funcSignature[i])
if isStruct && parameterValue == nil {
parameterValue = make(map[string]interface{})
}
reflectValue := reflect.ValueOf(parameterValue)
if !isStruct {
if parameterValue == nil {
return nil, fmt.Errorf("parameter[%v] was empty", i)
}
if reflectValue.Kind() == reflect.Slice && funcSignature[i].Kind() != reflectValue.Kind() {
return nil, fmt.Errorf("incompatible types expected: %v, but had %v", funcSignature[i].Kind(), reflectValue.Kind())
} else if !reflectValue.IsValid() {
if funcSignature[i].Kind() == reflect.Slice {
parameterValue = reflect.New(funcSignature[i]).Interface()
reflectValue = reflect.ValueOf(parameterValue)
}
}
}
if reflectValue.Type() != funcSignature[i] {
newValuePointer := reflect.New(funcSignature[i])
var err error
if IsStruct(funcSignature[i]) && !(IsStruct(parameterValue) || IsMap(parameterValue)) {
err = converter.AssignConverted(newValuePointer.Interface(), parametersKV)
} else {
err = converter.AssignConverted(newValuePointer.Interface(), parameterValue)
}
if err != nil {
return nil, fmt.Errorf("failed to assign convert %v to %v due to %v", parametersKV, newValuePointer.Interface(), err)
}
reflectValue = newValuePointer.Elem()
}
if functionValue.Type().IsVariadic() && funcSignature[i].Kind() == reflect.Slice && i+1 == len(funcSignature) {
ProcessSlice(reflectValue.Interface(), func(item interface{}) bool {
functionParameters = append(functionParameters, item)
return true
})
} else {
functionParameters = append(functionParameters, reflectValue.Interface())
}
}
return functionParameters, nil
}
//BuildFunctionParameters builds function parameters provided in the parameterValues.
// Parameters value will be converted if needed to expected by the function signature type. It returns function parameters , or error
func BuildFunctionParameters(function interface{}, parameters []string, parameterValues map[string]interface{}) ([]interface{}, error) {
var functionParameters = make([]interface{}, 0)
for _, name := range parameters {
functionParameters = append(functionParameters, parameterValues[name])
}
return AsFunctionParameters(function, functionParameters, parameterValues)
}
//GetFuncSignature returns a function signature
func GetFuncSignature(function interface{}) []reflect.Type {
AssertKind(function, reflect.Func, "function")
functionValue := reflect.ValueOf(function)
var result = make([]reflect.Type, 0)
functionType := functionValue.Type()
for i := 0; i < functionType.NumIn(); i++ {
result = append(result, functionType.In(i))
}
return result
}
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