274 lines
8.5 KiB
Go
274 lines
8.5 KiB
Go
// Mgmt
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// Copyright (C) 2013-2024+ 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 coremap
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import (
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"context"
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"fmt"
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"github.com/purpleidea/mgmt/lang/funcs"
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"github.com/purpleidea/mgmt/lang/funcs/wrapped"
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"github.com/purpleidea/mgmt/lang/interfaces"
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"github.com/purpleidea/mgmt/lang/types"
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"github.com/purpleidea/mgmt/util/errwrap"
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)
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const (
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// MapLookupFuncName is the name this function is registered as.
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MapLookupFuncName = "lookup" // map.lookup
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// arg names...
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mapLookupArgNameMap = "map"
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mapLookupArgNameKey = "key"
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mapLookupArgNameDef = "default"
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)
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func init() {
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funcs.ModuleRegister(ModuleName, MapLookupFuncName, func() interfaces.Func { return &MapLookupFunc{} }) // must register the func and name
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}
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var _ interfaces.BuildableFunc = &MapLookupFunc{} // ensure it meets this expectation
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// MapLookupFunc is a key map lookup function. It can take either two or three
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// arguments. The first argument is the map to lookup a value by key in. The
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// second is the key to use. If you specify a third argument, then this value
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// will be returned if the map key is not present. If the third argument is
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// omitted, then this function errors if the map key is not present.
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type MapLookupFunc struct {
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*wrapped.Func // *wrapped.Func as a type alias to pull in the base impl.
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Type *types.Type // Kind == Map, that is used as the map we lookup
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hasDefault *bool // does this function take a third arg?
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init *interfaces.Init
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last types.Value // last value received to use for diff
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result types.Value // last calculated output
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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 *MapLookupFunc) String() string {
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return MapLookupFuncName
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}
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// ArgGen returns the Nth arg name for this function.
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func (obj *MapLookupFunc) ArgGen(index int) (string, error) {
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seq := []string{mapLookupArgNameMap, mapLookupArgNameKey, mapLookupArgNameDef}
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if l := len(seq); index >= l {
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return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
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}
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return seq[index], nil
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}
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// helper
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func (obj *MapLookupFunc) sig() *types.Type {
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// func(map map{?1: ?2}, key ?1) ?2
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// OR
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// func(map map{?1: ?2}, key ?1, default ?2) ?2
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if obj.hasDefault == nil { // not yet known
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return nil
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}
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k := "?1"
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v := "?2"
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m := fmt.Sprintf("map{%s: %s}", k, v)
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if obj.Type != nil { // don't panic if called speculatively
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k = obj.Type.Key.String()
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v = obj.Type.Val.String()
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m = obj.Type.String()
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}
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if *obj.hasDefault {
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return types.NewType(fmt.Sprintf(
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"func(%s %s, %s %s, %s %s) %s",
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mapLookupArgNameMap, m,
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mapLookupArgNameKey, k,
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mapLookupArgNameDef, v,
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v,
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))
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}
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return types.NewType(fmt.Sprintf(
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"func(%s %s, %s %s) %s",
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mapLookupArgNameMap, m,
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mapLookupArgNameKey, k,
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v,
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))
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}
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// FuncInfer takes partial type and value information from the call site of this
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// function so that it can build an appropriate type signature for it. The type
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// signature may include unification variables.
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func (obj *MapLookupFunc) FuncInfer(partialType *types.Type, partialValues []types.Value) (*types.Type, []*interfaces.UnificationInvariant, error) {
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if l := len(partialValues); l != 2 && l != 3 {
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return nil, nil, fmt.Errorf("function must have either 2 or 3 args")
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}
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b := false
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//if len(partialValues) == 2 {
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// b = false
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//}
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if len(partialValues) == 3 {
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b = true
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}
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obj.hasDefault = &b // store for later
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return obj.sig(), []*interfaces.UnificationInvariant{}, nil
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}
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// Build is run to turn the polymorphic, undetermined function, into the
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// specific statically typed version. It is usually run after Unify completes,
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// and must be run before Info() and any of the other Func interface methods are
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// used. This function is idempotent, as long as the arg isn't changed between
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// runs.
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func (obj *MapLookupFunc) Build(typ *types.Type) (*types.Type, error) {
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// typ is the KindFunc signature we're trying to build...
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if typ.Kind != types.KindFunc {
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return nil, fmt.Errorf("input type must be of kind func")
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}
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if obj.hasDefault == nil {
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return nil, fmt.Errorf("the maplookup function needs exactly two or three args")
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}
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if *obj.hasDefault && len(typ.Ord) != 3 {
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return nil, fmt.Errorf("the maplookup function needs exactly three args")
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}
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if !*obj.hasDefault && len(typ.Ord) != 2 {
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return nil, fmt.Errorf("the maplookup function needs exactly two args")
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}
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if typ.Out == nil {
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return nil, fmt.Errorf("return type of function must be specified")
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}
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if typ.Map == nil {
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return nil, fmt.Errorf("invalid input type")
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}
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tMap, exists := typ.Map[typ.Ord[0]]
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if !exists || tMap == nil {
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return nil, fmt.Errorf("first arg must be specified")
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}
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tKey, exists := typ.Map[typ.Ord[1]]
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if !exists || tKey == nil {
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return nil, fmt.Errorf("second arg must be specified")
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}
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if err := tMap.Key.Cmp(tKey); err != nil {
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return nil, errwrap.Wrapf(err, "key must match map key type")
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}
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if err := tMap.Val.Cmp(typ.Out); err != nil {
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return nil, errwrap.Wrapf(err, "return type must match map val type")
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}
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if *obj.hasDefault {
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tDef, exists := typ.Map[typ.Ord[2]]
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if !exists || tDef == nil {
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return nil, fmt.Errorf("third arg must be specified")
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}
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if err := tMap.Val.Cmp(tDef); err != nil {
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return nil, errwrap.Wrapf(err, "default must match map val type")
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}
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}
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obj.Func = &wrapped.Func{
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Name: obj.String(),
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Type: typ, // .Copy(),
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}
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obj.Type = tMap // map type
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fn := &types.FuncValue{
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T: typ,
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V: obj.Function, // implementation
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}
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obj.Fn = fn // inside wrapper.Func
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//return obj.Fn.T, nil
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return obj.sig(), nil
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}
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// Copy is implemented so that the obj.hasDefault value is not lost if we copy
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// this function. That value is learned during FuncInfer, and previously would
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// have been lost by the time we used it in Build.
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func (obj *MapLookupFunc) Copy() interfaces.Func {
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return &MapLookupFunc{
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Type: obj.Type, // don't copy because we use this after unification
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hasDefault: obj.hasDefault,
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init: obj.init, // likely gets overwritten anyways
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}
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}
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// Function is the actual implementation here. This is used in lieu of the
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// Stream function which we'd have these contents within.
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func (obj *MapLookupFunc) Function(ctx context.Context, input []types.Value) (types.Value, error) {
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m := (input[0]).(*types.MapValue)
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key := input[1]
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//zero := m.Type().Val.New() // the zero value
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val, exists := m.Lookup(key)
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if exists {
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return val, nil
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}
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if len(input) == 3 { // default value since lookup is missing
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return input[2], nil
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}
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return nil, fmt.Errorf("map key not present, got: %v", key)
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}
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// Validate tells us if the input struct takes a valid form.
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func (obj *MapLookupFunc) Validate() error {
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if obj.Type == nil { // build must be run first
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return fmt.Errorf("type is still unspecified")
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}
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if obj.Type.Kind != types.KindMap {
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return fmt.Errorf("type must be a kind of map")
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}
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if obj.hasDefault == nil {
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return fmt.Errorf("function not built correctly")
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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. Build must be called before this
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// will return correct data.
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func (obj *MapLookupFunc) Info() *interfaces.Info {
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return &interfaces.Info{
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Pure: true,
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Memo: false,
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Sig: obj.sig(), // helper
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Err: obj.Validate(),
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}
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}
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