5d664855de
This adds the requirement that all function implementations provider a String() string method so that these can be used as vertices in the pgraph library. If we eventually move to generics for the pgraph DAG, then this might not matter, but it's not bad that these have names either.
94 lines
2.6 KiB
Go
94 lines
2.6 KiB
Go
// Mgmt
|
|
// Copyright (C) 2013-2022+ James Shubin and the project contributors
|
|
// Written by James Shubin <james@shubin.ca> and the project contributors
|
|
//
|
|
// This program is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// This program is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package structs
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"github.com/purpleidea/mgmt/lang/interfaces"
|
|
"github.com/purpleidea/mgmt/lang/types"
|
|
)
|
|
|
|
const (
|
|
// ConstFuncName is the unique name identifier for this function.
|
|
ConstFuncName = "const"
|
|
)
|
|
|
|
// ConstFunc is a function that returns the constant value passed to Value.
|
|
type ConstFunc struct {
|
|
Value types.Value
|
|
|
|
init *interfaces.Init
|
|
closeChan chan struct{}
|
|
}
|
|
|
|
// String returns a simple name for this function. This is needed so this struct
|
|
// can satisfy the pgraph.Vertex interface.
|
|
func (obj *ConstFunc) String() string {
|
|
return ConstFuncName
|
|
}
|
|
|
|
// Validate makes sure we've built our struct properly.
|
|
func (obj *ConstFunc) Validate() error {
|
|
if obj.Value == nil {
|
|
return fmt.Errorf("must specify `Value` input")
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Info returns some static info about itself.
|
|
func (obj *ConstFunc) Info() *interfaces.Info {
|
|
var typ *types.Type
|
|
if obj.Value != nil { // don't panic if called speculatively
|
|
if t := obj.Value.Type(); t != nil {
|
|
typ = types.NewType(fmt.Sprintf("func() %s", t.String()))
|
|
}
|
|
}
|
|
return &interfaces.Info{
|
|
Pure: true,
|
|
Memo: false, // TODO: ???
|
|
Sig: typ,
|
|
Err: obj.Validate(), // XXX: implement this and check .Err in engine!
|
|
}
|
|
}
|
|
|
|
// Init runs some startup code for this const.
|
|
func (obj *ConstFunc) Init(init *interfaces.Init) error {
|
|
obj.init = init
|
|
obj.closeChan = make(chan struct{})
|
|
return nil
|
|
}
|
|
|
|
// Stream returns the single value that this const has, and then closes.
|
|
func (obj *ConstFunc) Stream() error {
|
|
select {
|
|
case obj.init.Output <- obj.Value:
|
|
// pass
|
|
case <-obj.closeChan:
|
|
return nil
|
|
}
|
|
close(obj.init.Output) // signal that we're done sending
|
|
return nil
|
|
}
|
|
|
|
// Close runs some shutdown code for this const and turns off the stream.
|
|
func (obj *ConstFunc) Close() error {
|
|
close(obj.closeChan)
|
|
return nil
|
|
}
|