Feat: Separate "path" from "path/resolver"

Currently the "path" module does two very different things:

* Defines how ipfs paths look like and provides tools to parse/split etc.
* Provides a resolver to resolve paths.

This moves the resolver stuff to `path/resolver` and leaves the
path utilities in `path`.

The result is that now the IPFS `path` package just defines what a path
looks like and becomes a module that can be exported/re-used without problems.
Currently there are circular dependency cycles (resolve_test -> merkledag/utils,
merkledag->path), which the prevent the export of merkledag itself.

License: MIT
Signed-off-by: Hector Sanjuan <hector@protocol.ai>


This commit was moved from ipfs/kubo@93d1a69

gateway/core/corehttp/gateway_handler.go

@@ -19,6 +19,7 @@ import (
 	dag "github.com/ipfs/go-ipfs/merkledag"
 	dagutils "github.com/ipfs/go-ipfs/merkledag/utils"
 	path "github.com/ipfs/go-ipfs/path"
+	resolver "github.com/ipfs/go-ipfs/path/resolver"
 	ft "github.com/ipfs/go-ipfs/unixfs"
 	uio "github.com/ipfs/go-ipfs/unixfs/io"
 
@@ -445,7 +446,7 @@ func (i *gatewayHandler) putHandler(w http.ResponseWriter, r *http.Request) {
 	var newcid *cid.Cid
 	rnode, err := core.Resolve(ctx, i.node.Namesys, i.node.Resolver, rootPath)
 	switch ev := err.(type) {
-	case path.ErrNoLink:
+	case resolver.ErrNoLink:
 		// ev.Node < node where resolve failed
 		// ev.Name < new link
 		// but we need to patch from the root
@@ -599,7 +600,7 @@ func (i *gatewayHandler) addUserHeaders(w http.ResponseWriter) {
 }
 
 func webError(w http.ResponseWriter, message string, err error, defaultCode int) {
-	if _, ok := err.(path.ErrNoLink); ok {
+	if _, ok := err.(resolver.ErrNoLink); ok {
 		webErrorWithCode(w, message, err, http.StatusNotFound)
 	} else if err == routing.ErrNotFound {
 		webErrorWithCode(w, message, err, http.StatusNotFound)