feat(ipldbridge): define bridge interface

Define an interface for interacting with go-ipld-prime and write semi-functional implementation

go.mod

@@ -8,10 +8,13 @@ require (
 	github.com/ipfs/go-cid v0.0.1
 	github.com/ipfs/go-ipfs-blocksutil v0.0.1
 	github.com/ipfs/go-log v0.0.1
+	github.com/ipld/go-ipld-prime v0.0.0-20190306022502-066284669cf6
 	github.com/jbenet/go-random v0.0.0-20190219211222-123a90aedc0c
 	github.com/libp2p/go-libp2p-host v0.0.1
 	github.com/libp2p/go-libp2p-net v0.0.1
 	github.com/libp2p/go-libp2p-peer v0.0.1
 	github.com/libp2p/go-libp2p-peerstore v0.0.1
 	github.com/libp2p/go-libp2p-protocol v0.0.1
+	github.com/multiformats/go-multihash v0.0.1
+	github.com/polydawn/refmt v0.0.0-20190221155625-df39d6c2d992 // indirect
 )

go.sum

@@ -45,6 +45,10 @@ github.com/ipfs/go-ipfs-util v0.0.1 h1:Wz9bL2wB2YBJqggkA4dD7oSmqB4cAnpNbGrlHJulv
 github.com/ipfs/go-ipfs-util v0.0.1/go.mod h1:spsl5z8KUnrve+73pOhSVZND1SIxPW5RyBCNzQxlJBc=
 github.com/ipfs/go-log v0.0.1 h1:9XTUN/rW64BCG1YhPK9Hoy3q8nr4gOmHHBpgFdfw6Lc=
 github.com/ipfs/go-log v0.0.1/go.mod h1:kL1d2/hzSpI0thNYjiKfjanbVNU+IIGA/WnNESY9leM=
+github.com/ipld/go-ipld-prime v0.0.0-20190227132703-aaea73ad73c5 h1:Fm+tk5iaitTL/3L1nRlwibgLFtI5Eld4nIrjX4ajcKY=
+github.com/ipld/go-ipld-prime v0.0.0-20190227132703-aaea73ad73c5/go.mod h1:hSGXgXt4BSdqvjA3Kkxhzcg4Rsk9yvIeEuEVCPCi7/A=
+github.com/ipld/go-ipld-prime v0.0.0-20190306022502-066284669cf6 h1:FJW7rDl8g/580E6ZuR5rXzDT/9SsJvCuAEQCq8cbdPQ=
+github.com/ipld/go-ipld-prime v0.0.0-20190306022502-066284669cf6/go.mod h1:hSGXgXt4BSdqvjA3Kkxhzcg4Rsk9yvIeEuEVCPCi7/A=
 github.com/jbenet/go-random v0.0.0-20190219211222-123a90aedc0c h1:uUx61FiAa1GI6ZmVd2wf2vULeQZIKG66eybjNXKYCz4=
 github.com/jbenet/go-random v0.0.0-20190219211222-123a90aedc0c/go.mod h1:sdx1xVM9UuLw1tXnhJWN3piypTUO3vCIHYmG15KE/dU=
 github.com/jbenet/goprocess v0.0.0-20160826012719-b497e2f366b8 h1:bspPhN+oKYFk5fcGNuQzp6IGzYQSenLEgH3s6jkXrWw=
@@ -103,6 +107,8 @@ github.com/opentracing/opentracing-go v1.0.2 h1:3jA2P6O1F9UOrWVpwrIo17pu01KWvNWg
 github.com/opentracing/opentracing-go v1.0.2/go.mod h1:UkNAQd3GIcIGf0SeVgPpRdFStlNbqXla1AfSYxPUl2o=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/polydawn/refmt v0.0.0-20190221155625-df39d6c2d992 h1:bzMe+2coZJYHnhGgVlcQKuRy4FSny4ds8dLQjw5P1XE=
+github.com/polydawn/refmt v0.0.0-20190221155625-df39d6c2d992/go.mod h1:uIp+gprXxxrWSjjklXD+mN4wed/tMfjMMmN/9+JsA9o=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/syndtr/goleveldb v1.0.0/go.mod h1:ZVVdQEZoIme9iO1Ch2Jdy24qqXrMMOU6lpPAyBWyWuQ=

ipldbridge/ipld_impl.go

+package ipldbridge
+
+import (
+	"bytes"
+	"context"
+	"errors"
+
+	ipld "github.com/ipld/go-ipld-prime"
+	ipldfree "github.com/ipld/go-ipld-prime/impl/free"
+	ipldrepose "github.com/ipld/go-ipld-prime/repose"
+	ipldtraversal "github.com/ipld/go-ipld-prime/traversal"
+	ipldselector "github.com/ipld/go-ipld-prime/traversal/selector"
+	ipldtypesystem "github.com/ipld/go-ipld-prime/typed/system"
+)
+
+// not sure how these will come into being or from where
+var cidRootedSelectorType ipldtypesystem.Type
+var universe ipldtypesystem.Universe
+
+// TraversalConfig is an alias from ipld, in case it's renamed/moved.
+type TraversalConfig = ipldtraversal.TraversalConfig
+
+type ipldBridge struct {
+	nodeBuilderChooser NodeBuilderChooser
+	multicodecTable    MulticodecDecodeTable
+}
+
+// NewIPLDBridge returns an IPLD Bridge.
+func NewIPLDBridge(nodeBuilderChooser NodeBuilderChooser,
+	multicodecTable MulticodecDecodeTable) IPLDBridge {
+	return &ipldBridge{nodeBuilderChooser, multicodecTable}
+}
+
+func (rb *ipldBridge) ComposeLinkLoader(
+	actualLoader RawLoader) LinkLoader {
+	return ipldrepose.ComposeLinkLoader(actualLoader, rb.nodeBuilderChooser, rb.multicodecTable)
+}
+
+func (rb *ipldBridge) Traverse(ctx context.Context, loader LinkLoader, root ipld.Node, s Selector, fn AdvVisitFn) error {
+	config := &TraversalConfig{Ctx: ctx, LinkLoader: loader}
+	return TraversalProgress{TraversalConfig: config}.TraverseInformatively(root, s, fn)
+}
+
+func (rb *ipldBridge) ValidateSelectorSpec(cidRootedSelector ipld.Node) []error {
+	return ipldtypesystem.Validate(universe, cidRootedSelectorType, cidRootedSelector)
+}
+
+func (rb *ipldBridge) EncodeNode(node ipld.Node) ([]byte, error) {
+	var buffer bytes.Buffer
+	err := ipldrepose.EncoderDagCbor(node, &buffer)
+	if err != nil {
+		return nil, err
+	}
+	return buffer.Bytes(), nil
+}
+
+func (rb *ipldBridge) DecodeNode(encoded []byte) (ipld.Node, error) {
+	reader := bytes.NewReader(encoded)
+	return ipldrepose.DecoderDagCbor(ipldfree.NodeBuilder(), reader)
+}
+
+func (rb *ipldBridge) DecodeSelectorSpec(cidRootedSelector ipld.Node) (ipld.Node, Selector, error) {
+
+	errs := rb.ValidateSelectorSpec(cidRootedSelector)
+	if len(errs) != 0 {
+		return nil, nil, errors.New("Node does not validate as selector spec")
+	}
+
+	root, err := cidRootedSelector.TraverseField("root")
+	if err != nil {
+		return nil, nil, err
+	}
+	rootCid, err := root.AsLink()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	node, err := ipldfree.NodeBuilder().CreateLink(rootCid)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	selector, err := ipldselector.ReifySelector(cidRootedSelector)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return node, selector, nil
+}

ipldbridge/ipldbridge.go

+package ipldbridge
+
+import (
+	"context"
+
+	ipld "github.com/ipld/go-ipld-prime"
+	ipldrepose "github.com/ipld/go-ipld-prime/repose"
+	ipldtraversal "github.com/ipld/go-ipld-prime/traversal"
+	ipldselector "github.com/ipld/go-ipld-prime/traversal/selector"
+)
+
+// MulticodecDecodeTable is an alias from ipld, in case it's renamed/moved.
+type MulticodecDecodeTable = ipldrepose.MulticodecDecodeTable
+
+// NodeBuilderChooser is an an alias from ipld, in case it's renamed/moved.
+type NodeBuilderChooser = ipldrepose.NodeBuilderChooser
+
+// LinkLoader is alias from ipld, in case it.s renamed/moved.
+type LinkLoader = ipldtraversal.LinkLoader
+
+// RawLoader is an alias from ipld, in case it's renamed/moved.
+type RawLoader = ipldrepose.ActualLoader
+
+// AdvVisitFn is an alias from ipld, in case it's renamed/moved.
+type AdvVisitFn = ipldtraversal.AdvVisitFn
+
+// Selector is an alias from ipld, in case it's renamed/moved.
+type Selector = ipldselector.Selector
+
+// LinkContext is an alias from ipld, in case it's renamed/moved.
+type LinkContext = ipldtraversal.LinkContext
+
+// TraversalProgress is an alias from ipld, in case it's renamed/moved.
+type TraversalProgress = ipldtraversal.TraversalProgress
+
+// TraversalReason is an alias from ipld, in case it's renamed/moved.
+type TraversalReason = ipldtraversal.TraversalReason
+
+// IPLDBridge is an interface for making calls to IPLD, which can be
+// replaced with alternative implementations
+type IPLDBridge interface {
+	ComposeLinkLoader(actualLoader RawLoader) LinkLoader
+	ValidateSelectorSpec(cidRootedSelector ipld.Node) []error
+	EncodeNode(ipld.Node) ([]byte, error)
+	DecodeNode([]byte) (ipld.Node, error)
+	DecodeSelectorSpec(cidRootedSelector ipld.Node) (ipld.Node, Selector, error)
+	Traverse(ctx context.Context, loader LinkLoader, root ipld.Node, s Selector, fn AdvVisitFn) error
+}