129 lines
3.9 KiB
Go
129 lines
3.9 KiB
Go
// Mgmt
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// Copyright (C) James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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package structs
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import (
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"context"
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"fmt"
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"github.com/purpleidea/mgmt/lang/interfaces"
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"github.com/purpleidea/mgmt/lang/types"
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)
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const (
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// ConstFuncName is the unique name identifier for this function.
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ConstFuncName = "const"
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)
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// ConstFunc is a function that returns the constant value passed to Value.
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type ConstFunc struct {
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Value types.Value
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NameHint string
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init *interfaces.Init
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}
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// String returns a simple name for this function. This is needed so this struct
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// can satisfy the pgraph.Vertex interface.
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func (obj *ConstFunc) String() string {
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if obj.NameHint != "" {
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return obj.NameHint
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}
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if obj.Value != nil && obj.Value.Type() != nil {
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return fmt.Sprintf("%s: %s(%s)", ConstFuncName, obj.Value.Type().String(), obj.Value.String())
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}
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return ConstFuncName
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}
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// Validate makes sure we've built our struct properly.
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func (obj *ConstFunc) Validate() error {
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if obj.Value == nil {
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return fmt.Errorf("must specify `Value` input")
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}
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return nil
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}
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// Info returns some static info about itself.
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func (obj *ConstFunc) Info() *interfaces.Info {
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var typ *types.Type
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if obj.Value != nil { // don't panic if called speculatively
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if t := obj.Value.Type(); t != nil {
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typ = types.NewType(fmt.Sprintf("func() %s", t.String()))
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}
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}
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return &interfaces.Info{
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Pure: true,
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Memo: false, // TODO: ???
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Sig: typ,
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Err: obj.Validate(), // XXX: implement this and check .Err in engine!
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}
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}
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// Init runs some startup code for this const.
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func (obj *ConstFunc) Init(init *interfaces.Init) error {
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obj.init = init
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return nil
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}
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// Stream returns the single value that this const has, and then closes.
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func (obj *ConstFunc) Stream(ctx context.Context) error {
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value, err := obj.Call(ctx, nil)
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if err != nil {
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return err
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}
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select {
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case obj.init.Output <- value:
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// pass
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case <-ctx.Done():
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return nil
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}
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close(obj.init.Output) // signal that we're done sending
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return nil
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}
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// Call this function with the input args and return the value if it is possible
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// to do so at this time.
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func (obj *ConstFunc) Call(ctx context.Context, args []types.Value) (types.Value, error) {
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if obj.Info() == nil {
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return nil, fmt.Errorf("info is empty")
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}
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if obj.Info().Sig == nil {
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return nil, fmt.Errorf("sig is empty")
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}
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if i, j := len(args), len(obj.Info().Sig.Ord); i != j {
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return nil, fmt.Errorf("arg length doesn't match, got %d, exp: %d", i, j)
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}
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if obj.Value == nil {
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return nil, fmt.Errorf("no value available from const")
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}
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return obj.Value, nil
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}
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