150 lines
3.2 KiB
Go
150 lines
3.2 KiB
Go
package dynfunc
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import (
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"fmt"
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"reflect"
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"strings"
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"git.xdrm.io/go/aicra/api"
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"git.xdrm.io/go/aicra/internal/config"
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)
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type spec struct {
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Input map[string]reflect.Type
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Output map[string]reflect.Type
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// HasContext defines whether the given handler has api.Ctx as first argument
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HasContext bool
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}
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// builds a spec from the configuration service
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func makeSpec(service config.Service) *spec {
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s := &spec{
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Input: make(map[string]reflect.Type),
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Output: make(map[string]reflect.Type),
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}
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for _, param := range service.Input {
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if len(param.Rename) < 1 {
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continue
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}
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// make a pointer if optional
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if param.Optional {
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s.Input[param.Rename] = reflect.PtrTo(param.ExtractType)
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continue
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}
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s.Input[param.Rename] = param.ExtractType
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}
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for _, param := range service.Output {
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if len(param.Rename) < 1 {
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continue
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}
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s.Output[param.Rename] = param.ExtractType
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}
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return s
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}
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// checks for HandlerFn input arguments
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func (s *spec) checkInput(impl reflect.Type, index int) error {
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var requiredInput, structIndex = index, index
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if len(s.Input) > 0 { // arguments struct
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requiredInput++
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}
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// missing arguments
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if impl.NumIn() > requiredInput {
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return errUnexpectedInput
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}
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// none required
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if len(s.Input) == 0 {
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return nil
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}
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// too much arguments
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if impl.NumIn() != requiredInput {
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return errMissingHandlerArgumentParam
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}
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// arg must be a struct
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structArg := impl.In(structIndex)
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if structArg.Kind() != reflect.Struct {
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return errMissingParamArgument
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}
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// check for invalid param
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for name, ptype := range s.Input {
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if name[0] == strings.ToLower(name)[0] {
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return fmt.Errorf("%s: %w", name, errUnexportedName)
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}
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field, exists := structArg.FieldByName(name)
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if !exists {
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return fmt.Errorf("%s: %w", name, errMissingParamFromConfig)
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}
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if !ptype.AssignableTo(field.Type) {
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return fmt.Errorf("%s: %w (%s instead of %s)", name, errWrongParamTypeFromConfig, field.Type, ptype)
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}
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}
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return nil
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}
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// checks for HandlerFn output arguments
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func (s spec) checkOutput(impl reflect.Type) error {
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if impl.NumOut() < 1 {
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return errMissingHandlerOutput
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}
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// last output must be api.Err
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errOutput := impl.Out(impl.NumOut() - 1)
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if !errOutput.AssignableTo(reflect.TypeOf(api.ErrUnknown)) {
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return errMissingHandlerErrorOutput
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}
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// no output -> ok
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if len(s.Output) == 0 {
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return nil
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}
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if impl.NumOut() != 2 {
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return errMissingParamOutput
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}
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// fail if first output is not a pointer to struct
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structOutputPtr := impl.Out(0)
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if structOutputPtr.Kind() != reflect.Ptr {
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return errMissingParamOutput
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}
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structOutput := structOutputPtr.Elem()
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if structOutput.Kind() != reflect.Struct {
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return errMissingParamOutput
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}
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// fail on invalid output
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for name, ptype := range s.Output {
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if name[0] == strings.ToLower(name)[0] {
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return fmt.Errorf("%s: %w", name, errUnexportedName)
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}
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field, exists := structOutput.FieldByName(name)
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if !exists {
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return fmt.Errorf("%s: %w", name, errMissingOutputFromConfig)
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}
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// ignore types evalutating to nil
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if ptype == nil {
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continue
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}
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if !field.Type.ConvertibleTo(ptype) {
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return fmt.Errorf("%s: %w (%s instead of %s)", name, errWrongParamTypeFromConfig, field.Type, ptype)
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}
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}
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return nil
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}
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