Files
mgmt/lang/core/len_func.go
James Shubin 415e22abe2 lang: core, funcs, types: Add ctx to simple func
Plumb through the standard context.Context so that a function can be
cancelled if someone requests this. It makes it less awkward to write
simple functions that might depend on io or network access.
2024-05-09 19:25:46 -04:00

78 lines
2.5 KiB
Go

// Mgmt
// Copyright (C) 2013-2024+ 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 <https://www.gnu.org/licenses/>.
//
// Additional permission under GNU GPL version 3 section 7
//
// If you modify this program, or any covered work, by linking or combining it
// with embedded mcl code and modules (and that the embedded mcl code and
// modules which link with this program, contain a copy of their source code in
// the authoritative form) containing parts covered by the terms of any other
// license, the licensors of this program grant you additional permission to
// convey the resulting work. Furthermore, the licensors of this program grant
// the original author, James Shubin, additional permission to update this
// additional permission if he deems it necessary to achieve the goals of this
// additional permission.
package core
import (
"context"
"fmt"
"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
"github.com/purpleidea/mgmt/lang/types"
)
func init() {
simplepoly.Register("len", []*types.FuncValue{
{
T: types.NewType("func(str) int"),
V: Len,
},
{
T: types.NewType("func([]variant) int"),
V: Len,
},
{
T: types.NewType("func(map{variant: variant}) int"),
V: Len,
},
// TODO: should we add support for struct or func lengths?
})
}
// Len returns the number of elements in a list or the number of key pairs in a
// map. It can operate on either of these types.
func Len(ctx context.Context, input []types.Value) (types.Value, error) {
var length int
switch k := input[0].Type().Kind; k {
case types.KindStr:
length = len(input[0].Str())
case types.KindList:
length = len(input[0].List())
case types.KindMap:
length = len(input[0].Map())
default:
return nil, fmt.Errorf("unsupported kind: %+v", k)
}
return &types.IntValue{
V: int64(length),
}, nil
}