lang: core: Add list and map packages

Put the common functionality for those types in there.

lang/core/core.go

@@ -44,6 +44,8 @@ import (
 	_ "github.com/purpleidea/mgmt/lang/core/example/nested"
 	_ "github.com/purpleidea/mgmt/lang/core/fmt"
 	_ "github.com/purpleidea/mgmt/lang/core/iter"
+	_ "github.com/purpleidea/mgmt/lang/core/list"
+	_ "github.com/purpleidea/mgmt/lang/core/map"
 	_ "github.com/purpleidea/mgmt/lang/core/math"
 	_ "github.com/purpleidea/mgmt/lang/core/net"
 	_ "github.com/purpleidea/mgmt/lang/core/os"

lang/core/list/list.go

@@ -0,0 +1,35 @@
+// 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 corelist
+
+const (
+	// ModuleName is the prefix given to all the functions in this module.
+	ModuleName = "list"
+)

lang/core/list/list_lookup_func.go

@@ -0,0 +1,306 @@
+// 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 corelist
+
+import (
+	"context"
+	"fmt"
+	"math"
+
+	"github.com/purpleidea/mgmt/lang/funcs"
+	"github.com/purpleidea/mgmt/lang/interfaces"
+	"github.com/purpleidea/mgmt/lang/types"
+	"github.com/purpleidea/mgmt/util/errwrap"
+)
+
+const (
+	// ListLookupFuncName is the name this function is registered as.
+	ListLookupFuncName = "lookup" // list.lookup
+
+	// arg names...
+	listLookupArgNameList    = "list"
+	listLookupArgNameIndex   = "index"
+	listLookupArgNameDefault = "default"
+)
+
+func init() {
+	funcs.ModuleRegister(ModuleName, ListLookupFuncName, func() interfaces.Func { return &ListLookupFunc{} }) // must register the func and name
+}
+
+var _ interfaces.BuildableFunc = &ListLookupFunc{} // ensure it meets this expectation
+
+// ListLookupFunc is a list index lookup function. It can take either two or
+// three arguments. The first argument is the list to lookup a value in. The
+// second is the integer index. If you specify a third argument, then this value
+// will be returned if the list index is not present. If the third argument is
+// omitted, then this function errors if the list index is not present. Passing
+// a negative index will always result in an error.
+type ListLookupFunc struct {
+	Type *types.Type // Kind == List, that is used as the list we lookup in
+
+	hasDefault *bool // does this function take a third arg?
+
+	init *interfaces.Init
+	last types.Value // last value received to use for diff
+
+	result types.Value // last calculated output
+}
+
+// String returns a simple name for this function. This is needed so this struct
+// can satisfy the pgraph.Vertex interface.
+func (obj *ListLookupFunc) String() string {
+	return ListLookupFuncName
+}
+
+// ArgGen returns the Nth arg name for this function.
+func (obj *ListLookupFunc) ArgGen(index int) (string, error) {
+	seq := []string{listLookupArgNameList, listLookupArgNameIndex, listLookupArgNameDefault}
+	if l := len(seq); index >= l {
+		return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
+	}
+	return seq[index], nil
+}
+
+// helper
+func (obj *ListLookupFunc) sig() *types.Type {
+	// func(list []?1, index int) ?1
+	// OR
+	// func(list []?1, index int, default ?1) ?1
+
+	if obj.hasDefault == nil { // not yet known
+		return nil
+	}
+
+	v := "?1"
+	if obj.Type != nil { // don't panic if called speculatively
+		v = obj.Type.Val.String()
+	}
+
+	if *obj.hasDefault {
+		return types.NewType(fmt.Sprintf(
+			"func(%s []%s, %s int, %s %s) %s",
+			listLookupArgNameList, v,
+			listLookupArgNameIndex,
+			listLookupArgNameDefault, v,
+			v,
+		))
+	}
+
+	return types.NewType(fmt.Sprintf(
+		"func(%s []%s, %s int) %s",
+		listLookupArgNameList, v,
+		listLookupArgNameIndex,
+		v,
+	))
+}
+
+// FuncInfer takes partial type and value information from the call site of this
+// function so that it can build an appropriate type signature for it. The type
+// signature may include unification variables.
+func (obj *ListLookupFunc) FuncInfer(partialType *types.Type, partialValues []types.Value) (*types.Type, []*interfaces.UnificationInvariant, error) {
+	if l := len(partialValues); l != 2 && l != 3 {
+		return nil, nil, fmt.Errorf("function must have either 2 or 3 args")
+	}
+
+	b := false
+	//if len(partialValues) == 2 {
+	//	b = false
+	//}
+	if len(partialValues) == 3 {
+		b = true
+	}
+	obj.hasDefault = &b // store for later
+
+	return obj.sig(), []*interfaces.UnificationInvariant{}, 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 *ListLookupFunc) 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 obj.hasDefault == nil {
+		return nil, fmt.Errorf("the listlookup function needs exactly two or three args")
+	}
+	if *obj.hasDefault && len(typ.Ord) != 3 {
+		return nil, fmt.Errorf("the listlookup function needs exactly three args")
+	}
+	if !*obj.hasDefault && len(typ.Ord) != 2 {
+		return nil, fmt.Errorf("the listlookup function needs exactly two args")
+	}
+
+	if typ.Out == nil {
+		return nil, fmt.Errorf("return type of function must be specified")
+	}
+	if typ.Map == nil {
+		return nil, fmt.Errorf("invalid input type")
+	}
+
+	tList, exists := typ.Map[typ.Ord[0]]
+	if !exists || tList == nil {
+		return nil, fmt.Errorf("first arg must be specified")
+	}
+
+	tIndex, exists := typ.Map[typ.Ord[1]]
+	if !exists || tIndex == nil {
+		return nil, fmt.Errorf("second arg must be specified")
+	}
+
+	if tIndex != nil && tIndex.Kind != types.KindInt {
+		return nil, fmt.Errorf("index must be int kind")
+	}
+
+	if err := tList.Val.Cmp(typ.Out); err != nil {
+		return nil, errwrap.Wrapf(err, "return type must match list val type")
+	}
+
+	if *obj.hasDefault {
+		tDefault, exists := typ.Map[typ.Ord[2]]
+		if !exists || tDefault == nil {
+			return nil, fmt.Errorf("third arg must be specified")
+		}
+		if err := tList.Val.Cmp(tDefault); err != nil {
+			return nil, errwrap.Wrapf(err, "default must match list val type")
+		}
+	}
+
+	obj.Type = tList // list type
+	return obj.sig(), nil
+}
+
+// Copy is implemented so that the obj.hasDefault value is not lost if we copy
+// this function. That value is learned during FuncInfer, and previously would
+// have been lost by the time we used it in Build.
+func (obj *ListLookupFunc) Copy() interfaces.Func {
+	return &ListLookupFunc{
+		Type:       obj.Type, // don't copy because we use this after unification
+		hasDefault: obj.hasDefault,
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
+// Validate tells us if the input struct takes a valid form.
+func (obj *ListLookupFunc) Validate() error {
+	if obj.Type == nil { // build must be run first
+		return fmt.Errorf("type is still unspecified")
+	}
+	if obj.Type.Kind != types.KindList {
+		return fmt.Errorf("type must be a kind of list")
+	}
+	if obj.hasDefault == nil {
+		return fmt.Errorf("function not built correctly")
+	}
+	return nil
+}
+
+// Info returns some static info about itself. Build must be called before this
+// will return correct data.
+func (obj *ListLookupFunc) Info() *interfaces.Info {
+	return &interfaces.Info{
+		Pure: true,
+		Memo: false,
+		Sig:  obj.sig(), // helper
+		Err:  obj.Validate(),
+	}
+}
+
+// Init runs some startup code for this function.
+func (obj *ListLookupFunc) Init(init *interfaces.Init) error {
+	obj.init = init
+	return nil
+}
+
+// Stream returns the changing values that this func has over time.
+func (obj *ListLookupFunc) Stream(ctx context.Context) error {
+	defer close(obj.init.Output) // the sender closes
+	for {
+		select {
+		case input, ok := <-obj.init.Input:
+			if !ok {
+				return nil // can't output any more
+			}
+			//if err := input.Type().Cmp(obj.Info().Sig.Input); err != nil {
+			//	return errwrap.Wrapf(err, "wrong function input")
+			//}
+
+			if obj.last != nil && input.Cmp(obj.last) == nil {
+				continue // value didn't change, skip it
+			}
+			obj.last = input // store for next
+
+			l := (input.Struct()[listLookupArgNameList]).(*types.ListValue)
+			index := input.Struct()[listLookupArgNameIndex].Int()
+			//zero := l.Type().New() // the zero value
+
+			// TODO: should we handle overflow by returning zero?
+			if index > math.MaxInt { // max int size varies by arch
+				return fmt.Errorf("list index overflow, got: %d, max is: %d", index, math.MaxInt)
+			}
+			if index < 0 {
+				return fmt.Errorf("list index was negative, got: %d", index)
+			}
+
+			// negative index values are "not found" here!
+			var result types.Value
+			val, exists := l.Lookup(int(index))
+			if exists {
+				result = val
+			} else if *obj.hasDefault {
+				result = input.Struct()[listLookupArgNameDefault]
+			} else {
+				return fmt.Errorf("list index not present, got: %d, len is: %d", index, len(l.List()))
+			}
+
+			// if previous input was `2 + 4`, but now it
+			// changed to `1 + 5`, the result is still the
+			// same, so we can skip sending an update...
+			if obj.result != nil && result.Cmp(obj.result) == nil {
+				continue // result didn't change
+			}
+			obj.result = result // store new result
+
+		case <-ctx.Done():
+			return nil
+		}
+
+		select {
+		case obj.init.Output <- obj.result: // send
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}

lang/core/map/map.go

@@ -0,0 +1,35 @@
+// 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 coremap
+
+const (
+	// ModuleName is the prefix given to all the functions in this module.
+	ModuleName = "map"
+)

lang/core/map/map_lookup_func.go

@@ -0,0 +1,299 @@
+// 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 coremap
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/purpleidea/mgmt/lang/funcs"
+	"github.com/purpleidea/mgmt/lang/interfaces"
+	"github.com/purpleidea/mgmt/lang/types"
+	"github.com/purpleidea/mgmt/util/errwrap"
+)
+
+const (
+	// MapLookupFuncName is the name this function is registered as.
+	MapLookupFuncName = "lookup" // map.lookup
+
+	// arg names...
+	mapLookupArgNameMap = "map"
+	mapLookupArgNameKey = "key"
+	mapLookupArgNameDef = "default"
+)
+
+func init() {
+	funcs.ModuleRegister(ModuleName, MapLookupFuncName, func() interfaces.Func { return &MapLookupFunc{} }) // must register the func and name
+}
+
+var _ interfaces.BuildableFunc = &MapLookupFunc{} // ensure it meets this expectation
+
+// MapLookupFunc is a key map lookup function. It can take either two or three
+// arguments. The first argument is the map to lookup a value by key in. The
+// second is the key to use. If you specify a third argument, then this value
+// will be returned if the map key is not present. If the third argument is
+// omitted, then this function errors if the map key is not present.
+type MapLookupFunc struct {
+	Type *types.Type // Kind == Map, that is used as the map we lookup
+
+	hasDefault *bool // does this function take a third arg?
+
+	init *interfaces.Init
+	last types.Value // last value received to use for diff
+
+	result types.Value // last calculated output
+}
+
+// String returns a simple name for this function. This is needed so this struct
+// can satisfy the pgraph.Vertex interface.
+func (obj *MapLookupFunc) String() string {
+	return MapLookupFuncName
+}
+
+// ArgGen returns the Nth arg name for this function.
+func (obj *MapLookupFunc) ArgGen(index int) (string, error) {
+	seq := []string{mapLookupArgNameMap, mapLookupArgNameKey, mapLookupArgNameDef}
+	if l := len(seq); index >= l {
+		return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
+	}
+	return seq[index], nil
+}
+
+// helper
+func (obj *MapLookupFunc) sig() *types.Type {
+	// func(map map{?1: ?2}, key ?1) ?2
+	// OR
+	// func(map map{?1: ?2}, key ?1, default ?2) ?2
+
+	if obj.hasDefault == nil { // not yet known
+		return nil
+	}
+
+	k := "?1"
+	v := "?2"
+	m := fmt.Sprintf("map{%s: %s}", k, v)
+	if obj.Type != nil { // don't panic if called speculatively
+		k = obj.Type.Key.String()
+		v = obj.Type.Val.String()
+		m = obj.Type.String()
+	}
+
+	if *obj.hasDefault {
+		return types.NewType(fmt.Sprintf(
+			"func(%s %s, %s %s, %s %s) %s",
+			mapLookupArgNameMap, m,
+			mapLookupArgNameKey, k,
+			mapLookupArgNameDef, v,
+			v,
+		))
+	}
+
+	return types.NewType(fmt.Sprintf(
+		"func(%s %s, %s %s) %s",
+		mapLookupArgNameMap, m,
+		mapLookupArgNameKey, k,
+		v,
+	))
+}
+
+// FuncInfer takes partial type and value information from the call site of this
+// function so that it can build an appropriate type signature for it. The type
+// signature may include unification variables.
+func (obj *MapLookupFunc) FuncInfer(partialType *types.Type, partialValues []types.Value) (*types.Type, []*interfaces.UnificationInvariant, error) {
+	if l := len(partialValues); l != 2 && l != 3 {
+		return nil, nil, fmt.Errorf("function must have either 2 or 3 args")
+	}
+
+	b := false
+	//if len(partialValues) == 2 {
+	//	b = false
+	//}
+	if len(partialValues) == 3 {
+		b = true
+	}
+	obj.hasDefault = &b // store for later
+
+	return obj.sig(), []*interfaces.UnificationInvariant{}, 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 *MapLookupFunc) 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 obj.hasDefault == nil {
+		return nil, fmt.Errorf("the maplookup function needs exactly two or three args")
+	}
+	if *obj.hasDefault && len(typ.Ord) != 3 {
+		return nil, fmt.Errorf("the maplookup function needs exactly three args")
+	}
+	if !*obj.hasDefault && len(typ.Ord) != 2 {
+		return nil, fmt.Errorf("the maplookup function needs exactly two args")
+	}
+
+	if typ.Out == nil {
+		return nil, fmt.Errorf("return type of function must be specified")
+	}
+	if typ.Map == nil {
+		return nil, fmt.Errorf("invalid input type")
+	}
+
+	tMap, exists := typ.Map[typ.Ord[0]]
+	if !exists || tMap == nil {
+		return nil, fmt.Errorf("first arg must be specified")
+	}
+
+	tKey, exists := typ.Map[typ.Ord[1]]
+	if !exists || tKey == nil {
+		return nil, fmt.Errorf("second arg must be specified")
+	}
+
+	if err := tMap.Key.Cmp(tKey); err != nil {
+		return nil, errwrap.Wrapf(err, "key must match map key type")
+	}
+
+	if err := tMap.Val.Cmp(typ.Out); err != nil {
+		return nil, errwrap.Wrapf(err, "return type must match map val type")
+	}
+
+	if *obj.hasDefault {
+		tDef, exists := typ.Map[typ.Ord[2]]
+		if !exists || tDef == nil {
+			return nil, fmt.Errorf("third arg must be specified")
+		}
+		if err := tMap.Val.Cmp(tDef); err != nil {
+			return nil, errwrap.Wrapf(err, "default must match map val type")
+		}
+	}
+
+	obj.Type = tMap // map type
+	return obj.sig(), nil
+}
+
+// Copy is implemented so that the obj.hasDefault value is not lost if we copy
+// this function. That value is learned during FuncInfer, and previously would
+// have been lost by the time we used it in Build.
+func (obj *MapLookupFunc) Copy() interfaces.Func {
+	return &MapLookupFunc{
+		Type:       obj.Type, // don't copy because we use this after unification
+		hasDefault: obj.hasDefault,
+
+		init: obj.init, // likely gets overwritten anyways
+	}
+}
+
+// Validate tells us if the input struct takes a valid form.
+func (obj *MapLookupFunc) Validate() error {
+	if obj.Type == nil { // build must be run first
+		return fmt.Errorf("type is still unspecified")
+	}
+	if obj.Type.Kind != types.KindMap {
+		return fmt.Errorf("type must be a kind of map")
+	}
+	if obj.hasDefault == nil {
+		return fmt.Errorf("function not built correctly")
+	}
+	return nil
+}
+
+// Info returns some static info about itself. Build must be called before this
+// will return correct data.
+func (obj *MapLookupFunc) Info() *interfaces.Info {
+	return &interfaces.Info{
+		Pure: true,
+		Memo: false,
+		Sig:  obj.sig(), // helper
+		Err:  obj.Validate(),
+	}
+}
+
+// Init runs some startup code for this function.
+func (obj *MapLookupFunc) Init(init *interfaces.Init) error {
+	obj.init = init
+	return nil
+}
+
+// Stream returns the changing values that this func has over time.
+func (obj *MapLookupFunc) Stream(ctx context.Context) error {
+	defer close(obj.init.Output) // the sender closes
+	for {
+		select {
+		case input, ok := <-obj.init.Input:
+			if !ok {
+				return nil // can't output any more
+			}
+			//if err := input.Type().Cmp(obj.Info().Sig.Input); err != nil {
+			//	return errwrap.Wrapf(err, "wrong function input")
+			//}
+
+			if obj.last != nil && input.Cmp(obj.last) == nil {
+				continue // value didn't change, skip it
+			}
+			obj.last = input // store for next
+
+			m := (input.Struct()[mapLookupArgNameMap]).(*types.MapValue)
+			key := input.Struct()[mapLookupArgNameKey]
+			//zero := m.Type().New() // the zero value
+
+			var result types.Value
+			val, exists := m.Lookup(key)
+			if exists {
+				result = val
+			} else if *obj.hasDefault {
+				result = input.Struct()[mapLookupArgNameDef]
+			} else {
+				return fmt.Errorf("map key not present, got: %v", key)
+			}
+
+			// if previous input was `2 + 4`, but now it
+			// changed to `1 + 5`, the result is still the
+			// same, so we can skip sending an update...
+			if obj.result != nil && result.Cmp(obj.result) == nil {
+				continue // result didn't change
+			}
+			obj.result = result // store new result
+
+		case <-ctx.Done():
+			return nil
+		}
+
+		select {
+		case obj.init.Output <- obj.result: // send
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}