lang: funcs: Move standalone functions into core

Everything should be all together.

lang/core/lookup_default.go

@@ -0,0 +1,163 @@
+// 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"
+	"github.com/purpleidea/mgmt/lang/interfaces"
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+const (
+	// LookupDefaultFuncName is the name this function is registered as.
+	// This starts with an underscore so that it cannot be used from the
+	// lexer.
+	LookupDefaultFuncName = funcs.LookupDefaultFuncName
+
+	// arg names...
+	lookupDefaultArgNameListOrMap  = "listormap"
+	lookupDefaultArgNameIndexOrKey = "indexorkey"
+	lookupDefaultArgNameDefault    = "default"
+)
+
+func init() {
+	funcs.Register(LookupDefaultFuncName, func() interfaces.Func { return &LookupDefaultFunc{} }) // must register the func and name
+}
+
+var _ interfaces.BuildableFunc = &LookupDefaultFunc{} // ensure it meets this expectation
+
+// LookupDefaultFunc is a list index or map key lookup function. It does both
+// because the current syntax in the parser is identical, so it's convenient to
+// mix the two together. This calls out to some of the code in the
+// ListLookupDefaultFunc and MapLookupDefaultFunc implementations. If the index
+// or key for this input doesn't exist, then it will return the default value
+// you specified for this function.
+// TODO: Eventually we will deprecate this function when the function engine can
+// support passing a value for erroring functions. (Bad index could be an err!)
+type LookupDefaultFunc struct {
+	Type *types.Type // Kind == List OR Map, that is used as the list/map we lookup in
+
+	//init *interfaces.Init
+	fn interfaces.BuildableFunc // handle to ListLookupDefaultFunc or MapLookupDefaultFunc
+}
+
+// String returns a simple name for this function. This is needed so this struct
+// can satisfy the pgraph.Vertex interface.
+func (obj *LookupDefaultFunc) String() string {
+	return LookupDefaultFuncName
+}
+
+// ArgGen returns the Nth arg name for this function.
+func (obj *LookupDefaultFunc) ArgGen(index int) (string, error) {
+	seq := []string{lookupDefaultArgNameListOrMap, lookupDefaultArgNameIndexOrKey, lookupDefaultArgNameDefault}
+	if l := len(seq); index >= l {
+		return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
+	}
+	return seq[index], nil
+}
+
+// Build is run to turn the polymorphic, undetermined function, into the
+// specific statically typed version. It is usually run after Unify completes,
+// and must be run before Info() and any of the other Func interface methods are
+// used. This function is idempotent, as long as the arg isn't changed between
+// runs.
+func (obj *LookupDefaultFunc) Build(typ *types.Type) (*types.Type, error) {
+	// typ is the KindFunc signature we're trying to build...
+	if typ.Kind != types.KindFunc {
+		return nil, fmt.Errorf("input type must be of kind func")
+	}
+
+	if len(typ.Ord) < 1 {
+		return nil, fmt.Errorf("the lookup function needs at least one arg") // actually 2 or 3
+	}
+	tListOrMap, exists := typ.Map[typ.Ord[0]]
+	if !exists || tListOrMap == nil {
+		return nil, fmt.Errorf("first arg must be specified")
+	}
+	if tListOrMap == nil {
+		return nil, fmt.Errorf("first arg must have a type")
+	}
+
+	if tListOrMap.Kind == types.KindList {
+		obj.fn = &ListLookupDefaultFunc{} // set it
+		return obj.fn.Build(typ)
+	}
+	if tListOrMap.Kind == types.KindMap {
+		obj.fn = &MapLookupDefaultFunc{} // set it
+		return obj.fn.Build(typ)
+	}
+
+	return nil, fmt.Errorf("we must lookup from either a list or a map")
+}
+
+// Validate tells us if the input struct takes a valid form.
+func (obj *LookupDefaultFunc) Validate() error {
+	if obj.fn == nil { // build must be run first
+		return fmt.Errorf("type is still unspecified")
+	}
+	return obj.fn.Validate()
+}
+
+// Info returns some static info about itself. Build must be called before this
+// will return correct data.
+func (obj *LookupDefaultFunc) Info() *interfaces.Info {
+	// func(list []?1, index int, default ?1) ?1
+	// OR
+	// func(map map{?1: ?2}, key ?1, default ?2) ?2
+	if obj.fn == nil {
+		return &interfaces.Info{
+			Pure: true,
+			Memo: false,
+			Sig:  types.NewType("func(?1, ?2, ?3) ?3"), // func kind
+			Err:  obj.Validate(),
+		}
+	}
+	return obj.fn.Info()
+}
+
+// Init runs some startup code for this function.
+func (obj *LookupDefaultFunc) Init(init *interfaces.Init) error {
+	if obj.fn == nil {
+		return fmt.Errorf("function not built correctly")
+	}
+	//obj.init = init
+	return obj.fn.Init(init)
+}
+
+// Stream returns the changing values that this func has over time.
+func (obj *LookupDefaultFunc) Stream(ctx context.Context) error {
+	if obj.fn == nil {
+		return fmt.Errorf("function not built correctly")
+	}
+	return obj.fn.Stream(ctx)
+}