From 38abb05f7072dd904914bf4900e6330e9d4af790 Mon Sep 17 00:00:00 2001
From: Will Scott <will.scott@protocol.ai>
Date: Fri, 26 May 2023 16:18:51 -0700
Subject: [PATCH] Remove global variable

---
 decode.go | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/decode.go b/decode.go
index 63e8549..f8fdbc2 100644
--- a/decode.go
+++ b/decode.go
@@ -26,31 +26,36 @@ type codecConverter struct {
 	converter NodeConverter
 }
 
-var codecTable = map[uint64]codecConverter{}
-
-// RegisterCodec registers a specialized prototype & converter for a specific codec
-func RegisterCodec(codec uint64, prototype ipld.NodePrototype, converter NodeConverter) {
-	codecTable[codec] = codecConverter{prototype, converter}
+type Decoder struct {
+	codecTable     map[uint64]codecConverter
+	linkSystemBase ipld.LinkSystem
 }
 
-var linkSystemBase ipld.LinkSystem
+func NewDecoder() *Decoder {
+	lsb := cidlink.DefaultLinkSystem()
+	lsb.TrustedStorage = true
+	return &Decoder{
+		codecTable:     map[uint64]codecConverter{},
+		linkSystemBase: lsb,
+	}
+}
 
-func init() {
-	linkSystemBase = cidlink.DefaultLinkSystem()
-	linkSystemBase.TrustedStorage = true
+// RegisterCodec registers a specialized prototype & converter for a specific codec
+func (d *Decoder) RegisterCodec(codec uint64, prototype ipld.NodePrototype, converter NodeConverter) {
+	d.codecTable[codec] = codecConverter{prototype, converter}
 }
 
 // DecodeNode builds a UniversalNode from a block
-func DecodeNode(ctx context.Context, b blocks.Block) (UniversalNode, error) {
+func (d *Decoder) DecodeNode(ctx context.Context, b blocks.Block) (UniversalNode, error) {
 	c := b.Cid()
 	link := cidlink.Link{Cid: c}
-	lsys := linkSystemBase
+	lsys := d.linkSystemBase
 	lsys.StorageReadOpener = func(lnkCtx ipld.LinkContext, lnk ipld.Link) (io.Reader, error) {
 		return bytes.NewBuffer(b.RawData()), nil
 	}
 
 	var prototype ipld.NodePrototype = basicnode.Prototype.Any
-	converter, hasConverter := codecTable[c.Prefix().Codec]
+	converter, hasConverter := d.codecTable[c.Prefix().Codec]
 	if hasConverter {
 		prototype = converter.prototype
 	}