Flow/go/src/flow/registry/entry.go

package registry

import (
	"fmt"
	"reflect"
)

// Description of an entry
type Description struct {
	Name string   `json:"name"`
	Tags []string `json:"categories"`

	Inputs     []string       `json:"inputs"`
	InputDesc  map[int]string `json:"inputsDesc"`
	Output     string         `json:"output"`
	OutputDesc string         `json:"outputDesc"`

	Extra map[string]interface{} `json:"extra"`
}

// Entry contains a function description params etc
type Entry struct {
	registry    *R
	fn          interface{}
	Inputs      []reflect.Type
	Output      reflect.Type
	Description *Description
	err         error
}

// NewEntry creates and describes a New Entry
func NewEntry(r *R, fn interface{}) *Entry {
	e := &Entry{registry: r, fn: fn}

	fntyp := reflect.TypeOf(e.fn)
	if fntyp.Kind() != reflect.Func {
		e.err = ErrNotAFunc
		return e
	}
	if fntyp.NumOut() == 0 {
		e.err = ErrOutput
		return e
	}

	fnTyp := reflect.TypeOf(e.fn)
	Inputs := []string{}
	nInputs := fnTyp.NumIn()
	for i := 0; i < nInputs; i++ {
		e.Inputs = append(e.Inputs, fnTyp.In(i))
		Inputs = append(Inputs, fmt.Sprint(fnTyp.In(i)))
	}
	Output := fmt.Sprint(fnTyp.Out(0))
	e.Output = fnTyp.Out(0)

	e.Description = &Description{
		Tags:      []string{"generic"},
		Inputs:    Inputs,
		Output:    Output,
		InputDesc: map[int]string{},
		Extra:     map[string]interface{}{},
	}
	return e
}

// Err returns error of the entry if any
func (e *Entry) Err() error {
	return e.err
}

//Tags of the entry
func (e *Entry) Tags(cat ...string) *Entry {
	if e.err != nil {
		return e
	}
	e.Description.Tags = cat
	return e
}

// DescInput description for Input
func (e *Entry) DescInput(i int, desc string) *Entry {
	if e.err != nil {
		return e
	}
	e.Description.InputDesc[i] = desc
	return e
}

// DescOutput description for Input
func (e *Entry) DescOutput(desc string) *Entry {
	if e.err != nil {
		return e
	}
	e.Description.OutputDesc = desc
	return e
}

// Extra information on entry
func (e *Entry) Extra(name string, extra interface{}) *Entry {
	if e.err != nil {
		return e
	}
	e.Description.Extra[name] = extra
	return e
}

//Batch helper to batch set properties
type Batch []*Entry

//Tags set categories of the group
func (eg Batch) Tags(cat ...string) Batch {
	for _, e := range eg {
		e.Tags(cat...)
	}
	return eg
}

// Extra set extras of the group
func (eg Batch) Extra(name string, value interface{}) Batch {
	for _, e := range eg {
		e.Extra(name, value)
	}
	return eg
}