InnerPrefixes is also used to store prefix lens

trie/nodes.proto

@@ -150,6 +150,11 @@ message Nodes {
 
 
     // InnerPrefixes of inner nodes.
+    // There are two usages with this field:
+    // - If inner node prefix is stored, it is a var-len array of stored prefix string.
+    // - If only inner node prefix length is stored, it is a array with fixed-size elts. An array elt is the length in 4-bit of a prefix.
+    //
+    // In full-prefix mode:
     // An array element is a control byte followed by several data bytes.
     //
     // The 0-th bit in the control byte indicates whether a prefix is
@@ -175,16 +180,10 @@ message Nodes {
     VLenArray InnerPrefixes = 38;
 
 
-    // InnerPrefixLens stores how many bits to move forword before looking up a key on an
-    // inner node.
-    // The length of this array is len(inner nodes).
-    // Whether an inner node has prefix is stored in InnerPrefixBM.
+    // LeafPrefixes stores prefix of every leaf if it is not nil.
+    // A leaf prefix unlike inner node prefix, is just a byte sequence, without a control byte.
     //
     // Since 0.5.10
-    bytes  InnerPrefixLens = 51;
-
-
-
     VLenArray LeafPrefixes = 58;
 
 

trie/slimtrie.go

@@ -182,7 +182,7 @@ func (st *SlimTrie) content() []string {
 	if ns.InnerPrefixes.PositionBM != nil {
 		rst = append(rst, fmt.Sprintf(`PrefixStarts: %+v`, bitmap.ToArray(ns.InnerPrefixes.PositionBM.Words)))
 	} else {
-		rst = append(rst, fmt.Sprintf(`Steps: %+v`, ns.InnerPrefixLens))
+		rst = append(rst, fmt.Sprintf(`Steps: %+v`, ns.InnerPrefixes.Bytes))
 	}
 
 	return rst

trie/slimtrie_create.go

@@ -378,7 +378,8 @@ func (c *creator) build(e encode.Encoder) *SlimTrie {
 		ns.InnerPrefixes.Bytes = c.prefixes
 
 	} else {
-		ns.InnerPrefixLens = c.prefix4BitLens
+		ns.InnerPrefixes.FixedSize = 2
+		ns.InnerPrefixes.Bytes = c.prefix4BitLens
 	}
 
 	// TODO separate leaf init

trie/slimtrie_query.go

@@ -467,7 +467,7 @@ func (st *SlimTrie) getInner(nodeid int32, qr *querySession) {
 			qr.hasPrefixContent = true
 
 		} else {
-			qr.prefixLen = decStep(ns.InnerPrefixLens[ithPref<<1:])
+			qr.prefixLen = decStep(ns.InnerPrefixes.Bytes[ithPref<<1:])
 		}
 	}
 }