diff --git a/char.go b/char.go
index 1c54611..e453f34 100644
--- a/char.go
+++ b/char.go
@@ -28,7 +28,7 @@ func newChar(
 
 func (p *charParser) nodeName() string { return p.name }
 func (p *charParser) nodeID() int      { return p.id }
-func (p *charParser) setID(id int)     { p.id = p.id }
+func (p *charParser) setID(id int)     { p.id = id }
 
 func (p *charParser) parser(r *registry, parsers *idSet) (parser, error) {
 	if parsers.has(p.id) {
@@ -85,7 +85,7 @@ func (p *charParser) parse(t Trace, c *context) {
 		return
 	}
 
-	if _, ok := c.fromStore(p.name); ok {
+	if _, ok := c.fromStore(p.id); ok {
 		// t.Out1("found in store, match:", m)
 		return
 	}
@@ -93,7 +93,7 @@ func (p *charParser) parse(t Trace, c *context) {
 	if tok, ok := c.token(); ok && p.match(tok) {
 		// t.Out1("success", string(tok))
 		n := newNode(p.name, p.id, c.offset, c.offset+1, p.commit)
-		c.store.set(c.offset, p.name, n)
+		c.store.set(c.offset, p.id, n)
 		for _, includedBy := range p.includedBy {
 			includedBy.storeIncluded(c, n)
 		}
@@ -102,7 +102,7 @@ func (p *charParser) parse(t Trace, c *context) {
 		return
 	} else {
 		// t.Out1("fail", string(tok))
-		c.store.set(c.offset, p.name, nil)
+		c.store.set(c.offset, p.id, nil)
 		c.fail(c.offset)
 		return
 	}
diff --git a/choice.go b/choice.go
index 1441f26..79b2cbe 100644
--- a/choice.go
+++ b/choice.go
@@ -92,7 +92,7 @@ func (p *choiceParser) storeIncluded(c *context, n *Node) {
 
 	nc := newNode(p.name, p.id, n.From, n.To, p.commit)
 	nc.append(n)
-	c.store.set(nc.From, p.name, nc)
+	c.store.set(nc.From, p.id, nc)
 
 	for _, includedBy := range p.includedBy {
 		includedBy.storeIncluded(c, nc)
@@ -109,7 +109,7 @@ func (p *choiceParser) parse(t Trace, c *context) {
 		return
 	}
 
-	if _, ok := c.fromStore(p.name); ok {
+	if _, ok := c.fromStore(p.id); ok {
 		// t.Out1("found in store, match:", m)
 		return
 	}
@@ -144,7 +144,7 @@ func (p *choiceParser) parse(t Trace, c *context) {
 			node = newNode(p.name, p.id, c.offset, c.offset, p.commit)
 			node.append(c.node)
 
-			c.store.set(node.From, p.name, node)
+			c.store.set(node.From, p.id, node)
 			for _, includedBy := range p.includedBy {
 				includedBy.storeIncluded(c, node)
 			}
@@ -163,7 +163,7 @@ func (p *choiceParser) parse(t Trace, c *context) {
 	}
 
 	// t.Out1("fail")
-	c.store.set(node.From, p.name, nil)
+	c.store.set(node.From, p.id, nil)
 	c.fail(node.From)
 	c.include(initialOffset, p.id) // TODO: test if can be optimized
 }
diff --git a/context.go b/context.go
index a3c99b5..d80f12e 100644
--- a/context.go
+++ b/context.go
@@ -104,8 +104,8 @@ func (c *context) include(offset int, id int) {
 	c.isExcluded[offset].unset(id)
 }
 
-func (c *context) fromStore(name string) (bool, bool) {
-	n, m, ok := c.store.get(c.offset, name)
+func (c *context) fromStore(id int) (bool, bool) {
+	n, m, ok := c.store.get(c.offset, id)
 	if !ok {
 		return false, false
 	}
diff --git a/sequence.go b/sequence.go
index 8144a9f..219a9bc 100644
--- a/sequence.go
+++ b/sequence.go
@@ -113,7 +113,7 @@ func (p *sequenceParser) storeIncluded(c *context, n *Node) {
 
 	nc := newNode(p.name, p.id, n.From, n.To, p.commit)
 	nc.append(n)
-	c.store.set(nc.From, p.name, nc)
+	c.store.set(nc.From, p.id, nc)
 
 	for _, includedBy := range p.includedBy {
 		includedBy.storeIncluded(c, nc)
@@ -145,7 +145,7 @@ func (p *sequenceParser) parse(t Trace, c *context) {
 	node := newNode(p.name, p.id, c.offset, c.offset, p.commit)
 
 	for len(items) > 0 {
-		m, ok := c.fromStore(items[0].nodeName())
+		m, ok := c.fromStore(items[0].nodeID())
 		if ok {
 			// t.Out1("sequence item found in store, match:", m, items[0].nodeName(), c.offset)
 		} else {
@@ -156,7 +156,7 @@ func (p *sequenceParser) parse(t Trace, c *context) {
 		if !m {
 			if currentCount < ranges[0][0] {
 				// t.Out1("fail, item failed")
-				c.store.set(node.From, p.name, nil)
+				c.store.set(node.From, p.id, nil)
 				c.fail(node.From)
 				c.include(initialOffset, p.id)
 				return
@@ -182,7 +182,7 @@ func (p *sequenceParser) parse(t Trace, c *context) {
 
 	// t.Out1("success, items parsed")
 
-	c.store.set(node.From, p.name, node)
+	c.store.set(node.From, p.id, node)
 	for _, includedBy := range p.includedBy {
 		includedBy.storeIncluded(c, node)
 	}
diff --git a/store.go b/store.go
index 6ca99b8..1f94e0f 100644
--- a/store.go
+++ b/store.go
@@ -1,91 +1,83 @@
 package treerack
 
-type storedItem struct {
-	name string
-	node *Node
-}
-
 type storeEntry struct {
-	match   []*storedItem
-	noMatch []string
+	match   *idSet
+	noMatch *idSet
+	nodes   []*Node
 }
 
 type store struct {
-	tokens []*storeEntry
+	entries []*storeEntry
 }
 
-func (c *store) get(offset int, name string) (*Node, bool, bool) {
-	if len(c.tokens) <= offset {
+func (c *store) get(offset int, id int) (*Node, bool, bool) {
+	if len(c.entries) <= offset {
 		return nil, false, false
 	}
 
-	tc := c.tokens[offset]
+	tc := c.entries[offset]
 	if tc == nil {
 		return nil, false, false
 	}
 
-	for _, i := range tc.noMatch {
-		if i == name {
-			return nil, false, true
-		}
+	if tc.noMatch.has(id) {
+		return nil, false, true
 	}
 
-	for _, i := range tc.match {
-		if i.name == name {
-			return i.node, true, true
+	if !tc.match.has(id) {
+		return nil, false, false
+	}
+
+	for _, n := range tc.nodes {
+		if n.id == id {
+			return n, true, true
 		}
 	}
 
 	return nil, false, false
 }
 
-func (c *store) set(offset int, name string, n *Node) {
+func (c *store) set(offset int, id int, n *Node) {
 	var tc *storeEntry
-	if len(c.tokens) > offset {
-		tc = c.tokens[offset]
+	if len(c.entries) > offset {
+		tc = c.entries[offset]
 	} else {
-		if cap(c.tokens) > offset {
-			c.tokens = c.tokens[:offset+1]
+		if cap(c.entries) > offset {
+			c.entries = c.entries[:offset+1]
 		} else {
-			c.tokens = c.tokens[:cap(c.tokens)]
-			for len(c.tokens) <= offset {
-				c.tokens = append(c.tokens, nil)
+			c.entries = c.entries[:cap(c.entries)]
+			for len(c.entries) <= offset {
+				c.entries = append(c.entries, nil)
 			}
 		}
 
-		tc = &storeEntry{}
-		c.tokens[offset] = tc
+		tc = &storeEntry{
+			match:   &idSet{},
+			noMatch: &idSet{},
+		}
+
+		c.entries[offset] = tc
 	}
 
 	if n == nil {
-		for _, i := range tc.match {
-			if i.name == name {
-				return
-			}
+		if tc.match.has(id) {
+			return
 		}
 
-		for _, i := range tc.noMatch {
-			if i == name {
-				return
-			}
-		}
-
-		tc.noMatch = append(tc.noMatch, name)
+		tc.noMatch.set(id)
 		return
 	}
 
-	for _, i := range tc.match {
-		if i.name == name {
-			if n.tokenLength() > i.node.tokenLength() {
-				i.node = n
+	tc.match.set(id)
+	for i, ni := range tc.nodes {
+		if ni.id == id {
+			if n.tokenLength() > ni.tokenLength() {
+				tc.nodes[i] = n
 			}
 
 			return
 		}
 	}
 
-	tc.match = append(tc.match, &storedItem{
-		name: name,
-		node: n,
-	})
+	tc.nodes = append(tc.nodes, n)
 }