policy: IPLD encode/decode

Still WIP

capability/policy/ipld.go

@@ -0,0 +1,252 @@
+package policy
+
+import (
+	"fmt"
+
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/must"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+
+	"github.com/ucan-wg/go-ucan/v1/capability/policy/selector"
+)
+
+func PolicyFromIPLD(node datamodel.Node) (Policy, error) {
+	return statementsFromIPLD("/", node)
+}
+
+func statementFromIPLD(path string, node datamodel.Node) (Statement, error) {
+	// sanity checks
+	if node.Kind() != datamodel.Kind_List {
+		return nil, ErrNotATuple(path)
+	}
+	if node.Length() != 2 && node.Length() != 3 {
+		return nil, ErrUnrecognizedShape(path)
+	}
+
+	// extract operator
+	opNode, _ := node.LookupByIndex(0)
+	if opNode.Kind() != datamodel.Kind_String {
+		return nil, ErrNotAString(path)
+	}
+	op := must.String(opNode)
+
+	arg2AsSelector := func() (selector.Selector, error) {
+		nd, _ := node.LookupByIndex(1)
+		if nd.Kind() != datamodel.Kind_String {
+			return nil, ErrNotAString(path + "1/")
+		}
+		sel, err := selector.Parse(must.String(nd))
+		if err != nil {
+			return nil, ErrInvalidSelector(path+"1/", err)
+		}
+		return sel, nil
+	}
+
+	switch node.Length() {
+	case 2:
+		switch op {
+		case KindNot:
+			arg2, _ := node.LookupByIndex(1)
+			statement, err := statementFromIPLD(path+"1/", arg2)
+			if err != nil {
+				return nil, err
+			}
+			return Not(statement), nil
+
+		case KindAnd, KindOr:
+			arg2, _ := node.LookupByIndex(1)
+			statement, err := statementsFromIPLD(path+"1/", arg2)
+			if err != nil {
+				return nil, err
+			}
+			return connective{kind: op, statements: statement}, nil
+
+		default:
+			return nil, ErrUnrecognizedOperator(path, op)
+		}
+	case 3:
+		switch op {
+		case KindEqual, KindLessThan, KindLessThanOrEqual, KindGreaterThan, KindGreaterThanOrEqual:
+			sel, err := arg2AsSelector()
+			if err != nil {
+				return nil, err
+			}
+			arg3, _ := node.LookupByIndex(2)
+			return equality{kind: op, selector: sel, value: arg3}, nil
+
+		case KindLike:
+			sel, err := arg2AsSelector()
+			if err != nil {
+				return nil, err
+			}
+			pattern, _ := node.LookupByIndex(2)
+			if pattern.Kind() != datamodel.Kind_String {
+				return nil, ErrNotAString(path + "2/")
+			}
+			res, err := Like(sel, must.String(pattern))
+			if err != nil {
+				return nil, ErrInvalidPattern(path+"2/", err)
+			}
+			return res, nil
+
+		case KindAll, KindAny:
+			sel, err := arg2AsSelector()
+			if err != nil {
+				return nil, err
+			}
+			statementsNodes, _ := node.LookupByIndex(2)
+			statements, err := statementsFromIPLD(path+"1/", statementsNodes)
+			return quantifier{kind: op, selector: sel, statements: statements}, nil
+
+		default:
+			return nil, ErrUnrecognizedOperator(path, op)
+		}
+
+	default:
+		return nil, ErrUnrecognizedShape(path)
+	}
+}
+
+func statementsFromIPLD(path string, node datamodel.Node) ([]Statement, error) {
+	// sanity checks
+	if node.Kind() != datamodel.Kind_List {
+		return nil, ErrNotATuple(path)
+	}
+	if node.Length() == 0 {
+		return nil, ErrEmptyList(path)
+	}
+
+	res := make([]Statement, node.Length())
+
+	for i := int64(0); i < node.Length(); i++ {
+		nd, _ := node.LookupByIndex(i)
+		statement, err := statementFromIPLD(fmt.Sprintf("%s%d/", path, i), nd)
+		if err != nil {
+			return nil, err
+		}
+		res[i] = statement
+	}
+
+	return res, nil
+}
+
+func (p Policy) ToIPLD() (datamodel.Node, error) {
+	return statementsToIPLD(p)
+}
+
+func statementsToIPLD(statements []Statement) (datamodel.Node, error) {
+	list := basicnode.Prototype.List.NewBuilder()
+	// can't error, we have the right builder.
+	listBuilder, _ := list.BeginList(int64(len(statements)))
+	for _, argStatement := range statements {
+		node, err := statementToIPLD(argStatement)
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignNode(node)
+		if err != nil {
+			return nil, err
+		}
+	}
+	err := listBuilder.Finish()
+	if err != nil {
+		return nil, err
+	}
+	return list.Build(), nil
+}
+
+func statementToIPLD(statement Statement) (datamodel.Node, error) {
+	list := basicnode.Prototype.List.NewBuilder()
+
+	length := int64(3)
+	switch statement.(type) {
+	case negation, connective:
+		length = 2
+	}
+
+	// can't error, we have the right builder.
+	listBuilder, _ := list.BeginList(length)
+
+	switch statement := statement.(type) {
+	case equality:
+		err := listBuilder.AssembleValue().AssignString(statement.kind)
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignString(statement.selector.String())
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignNode(statement.value)
+		if err != nil {
+			return nil, err
+		}
+
+	case negation:
+		err := listBuilder.AssembleValue().AssignString(statement.Kind())
+		if err != nil {
+			return nil, err
+		}
+		node, err := statementToIPLD(statement.statement)
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignNode(node)
+		if err != nil {
+			return nil, err
+		}
+
+	case connective:
+		err := listBuilder.AssembleValue().AssignString(statement.kind)
+		if err != nil {
+			return nil, err
+		}
+		args, err := statementsToIPLD(statement.statements)
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignNode(args)
+		if err != nil {
+			return nil, err
+		}
+
+	case wildcard:
+		err := listBuilder.AssembleValue().AssignString(statement.Kind())
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignString(statement.selector.String())
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignString(statement.pattern)
+		if err != nil {
+			return nil, err
+		}
+
+	case quantifier:
+		err := listBuilder.AssembleValue().AssignString(statement.kind)
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignString(statement.selector.String())
+		if err != nil {
+			return nil, err
+		}
+		args, err := statementsToIPLD(statement.statements)
+		if err != nil {
+			return nil, err
+		}
+		err = listBuilder.AssembleValue().AssignNode(args)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	err := listBuilder.Finish()
+	if err != nil {
+		return nil, err
+	}
+
+	return list.Build(), nil
+}

capability/policy/ipld_errors.go

@@ -0,0 +1,47 @@
+package policy
+
+import "fmt"
+
+type errWithPath struct {
+	path string
+	msg  string
+}
+
+func (e errWithPath) Error() string {
+	return fmt.Sprintf("IPLD path '%s': %s", e.path, e.msg)
+}
+
+func ErrInvalidSelector(path string, err error) error {
+	return errWithPath{path: path, msg: fmt.Sprintf("invalid selector: %s", err)}
+}
+
+func ErrInvalidPattern(path string, err error) error {
+	return errWithPath{path: path, msg: fmt.Sprintf("invalid pattern: %s", err)}
+}
+
+func ErrNotAString(path string) error {
+	return errWithPath{path: path, msg: ""}
+}
+
+func ErrUnrecognizedOperator(path string, op string) error {
+	return errWithPath{path: path, msg: fmt.Sprintf("unrecognized operator '%s'", safeStr(op))}
+}
+
+func ErrUnrecognizedShape(path string) error {
+	return errWithPath{path: path, msg: "unrecognized shape"}
+}
+
+func ErrNotATuple(path string) error {
+	return errWithPath{path: path, msg: "not a tuple"}
+}
+
+func ErrEmptyList(path string) error {
+	return errWithPath{path: path, msg: "empty list"}
+}
+
+func safeStr(str string) string {
+	if len(str) > 10 {
+		return str[:10]
+	}
+	return str
+}

capability/policy/ipld_test.go

@@ -0,0 +1,48 @@
+package policy
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/codec/dagjson"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIpldRoundTrip(t *testing.T) {
+	const illustrativeExample = `[
+    ["==", ".status", "draft"],
+    ["all", ".reviewer", [["like", ".email", "*@example.com"]]],
+    ["any", ".tags", 
+      ["or", [
+        ["==", ".", "news"], 
+        ["==", ".", "press"]]
+      ]]
+]`
+
+	for _, tc := range []struct {
+		name, dagjson string
+	}{
+		{"illustrativeExample", illustrativeExample},
+	} {
+		// strip all spaces and carriage return
+		asDagJson := strings.Join(strings.Fields(tc.dagjson), "")
+
+		nodes, err := ipld.Decode([]byte(asDagJson), dagjson.Decode)
+		require.NoError(t, err)
+
+		pol, err := PolicyFromIPLD(nodes)
+		require.NoError(t, err)
+
+		fmt.Println(pol)
+
+		wroteIpld, err := pol.ToIPLD()
+		require.NoError(t, err)
+
+		wroteAsDagJson, err := ipld.Encode(wroteIpld, dagjson.Encode)
+		require.NoError(t, err)
+
+		require.Equal(t, asDagJson, string(wroteAsDagJson))
+	}
+}

capability/policy/match_test.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/gobwas/glob"
 	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
 	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
@@ -294,8 +293,7 @@ func TestMatch(t *testing.T) {
 	})
 
 	t.Run("wildcard", func(t *testing.T) {
-		glb, err := glob.Compile(`Alice\*, Bob*, Carol.`)
-		require.NoError(t, err)
+		pattern := `Alice\*, Bob*, Carol.`
 
 		for _, s := range []string{
 			"Alice*, Bob, Carol.",
@@ -310,7 +308,10 @@ func TestMatch(t *testing.T) {
 					nb.AssignString(s)
 					nd := nb.Build()
 
-					pol := Policy{Like(selector.MustParse("."), glb)}
+					statement, err := Like(selector.MustParse("."), pattern)
+					require.NoError(t, err)
+
+					pol := Policy{statement}
 					ok := Match(pol, nd)
 					require.True(t, ok)
 				})
@@ -331,7 +332,10 @@ func TestMatch(t *testing.T) {
 					nb.AssignString(s)
 					nd := nb.Build()
 
-					pol := Policy{Like(selector.MustParse("."), glb)}
+					statement, err := Like(selector.MustParse("."), pattern)
+					require.NoError(t, err)
+
+					pol := Policy{statement}
 					ok := Match(pol, nd)
 					require.False(t, ok)
 				})