plugin.go

package partial

import (
	"errors"
	"plugin"
	"strings"
)

var (
	ErrOpened       = errors.New("plugin already opened")
	ErrIncompatible = errors.New("plugin incompatible")
	ErrBadSetup     = errors.New("plugin has invalid setup")
)

var plugins map[string]*Plugin

// NewPlugin returns pointer to a new Plugin.
func NewPlugin(name string) *Plugin {
	return &Plugin{Name: name}
}

// Plugins return a slice of registered plugin names.
func Plugins() []string {
	pls := make([]string, len(plugins))
	var i int
	for name := range plugins {
		pls[i] = name
		i++
	}
	return pls
}

// GetPlugin gets plugin with specific name.
func GetPlugin(name string) *Plugin {
	return plugins[name]
}

// Plugin holds information on a plugin.
type Plugin struct {
	Name    string   `json:"name"`
	Valid   bool     `json:"valid"`
	Partial *Partial `json:"-"`
	plugin  *plugin.Plugin
}

// Register registers the plugin.
func (p *Plugin) Register() bool {
	if _, ok := plugins[p.Name]; !ok {
		plugins[p.Name] = p
		return true
	} else {
		return false
	}
}

// Open opens the plugin.
func (p *Plugin) Open() error {
	if p.plugin == nil {
		return ErrOpened
	}

	if pl, err := plugin.Open("plugins/" + p.Name); err != nil {
		if strings.Contains(err.Error(), "plugin was built with a different version of package") {
			return ErrIncompatible
		} else {
			return err
		}
	} else {
		p.plugin = pl
	}