Add NameTrie for predictable, correct name autocomplete

chat/room.go

@@ -232,3 +232,8 @@ func (r *Room) NamesPrefix(prefix string) []string {
 	}
 	return names
 }
+
+func (r *Room) CompleteName(prefix string) string {
+	name, _ := r.Members.CompleteName(prefix)
+	return name
+}

host.go

@@ -192,13 +192,7 @@ func (h *Host) Serve() {
 }
 
 func (h *Host) completeName(partial string) string {
-	names := h.NamesPrefix(partial)
-	if len(names) == 0 {
-		// Didn't find anything
-		return ""
-	}
-
-	return names[len(names)-1]
+	return h.CompleteName(partial)
 }
 
 func (h *Host) completeCommand(partial string) string {

set/name_trie.go

@@ -0,0 +1,83 @@
+package set
+
+import (
+    "fmt"
+    "sort"
+)
+
+type NameTrie struct {
+    children   map[rune]*NameTrie
+    terminates bool
+}
+
+func createNameTrie() *NameTrie {
+    return &NameTrie{make(map[rune]*NameTrie), false}
+}
+
+func (tree *NameTrie) Exists(name string) bool {
+    nameSlice := []rune(name)
+    node, ok := tree.traverse(nameSlice, false)
+    return ok && node.terminates
+}
+
+func (tree *NameTrie) Insert(name string) {
+    nameSlice := []rune(name)
+    node, ok := tree.traverse(nameSlice, true)
+    if ok {
+        node.terminates = true
+    }
+}
+
+func (tree *NameTrie) Delete(name string) {
+    nameSlice := []rune(name)
+    node, ok := tree.traverse(nameSlice, false)
+    if ok {
+        node.terminates = false
+    }
+}
+
+func (tree *NameTrie) ClosestName(prefix string) (name string, ok bool) {
+    fmt.Println(tree, prefix)
+    nameslice := []rune(prefix)
+    node, ok := tree.traverse(nameslice, false)
+    if !ok {
+        return "", false
+    }
+    return node.closestName(prefix)
+}
+
+func (node *NameTrie) closestName(prefix string) (name string, ok bool) {
+    if node.terminates {
+        return prefix, true
+    }
+    keys := []string{}
+    for suffix := range(node.children){keys = append(keys, string(suffix))}
+    sort.Strings(keys)
+    fmt.Println(keys)
+    for i := range keys {
+        child := node.children[[]rune(keys[i])[0]]
+        name, ok := child.closestName(prefix + keys[i])
+        if ok{
+            return name, true
+        }
+    }
+    return "", false    
+}
+
+func (tree *NameTrie) traverse(remainder []rune, create bool) (nextTree *NameTrie, ok bool) {
+    nextRune := remainder[0]
+    nextTree, ok = tree.children[nextRune]
+    if !ok {
+        if create {
+            tree.children[nextRune] = createNameTrie()
+            nextTree = tree.children[nextRune]
+        } else {
+            return createNameTrie(), false
+        }
+    }
+    if len(remainder) < 2 {
+        return nextTree, true
+    } else {
+        return nextTree.traverse(remainder[1:], create)
+    }
+}

set/set.go

@@ -21,6 +21,7 @@ type Set struct {
 	sync.RWMutex
 	lookup    map[string]Item
 	normalize func(string) string
+	names *NameTrie
 }
 
 // New creates a new set with case-insensitive keys
@@ -28,6 +29,7 @@ func New() *Set {
 	return &Set{
 		lookup:    map[string]Item{},
 		normalize: normalize,
+		names: createNameTrie(),
 	}
 }
 
@@ -36,6 +38,7 @@ func (s *Set) Clear() int {
 	s.Lock()
 	n := len(s.lookup)
 	s.lookup = map[string]Item{}
+	s.names = createNameTrie()
 	s.Unlock()
 	return n
 }
@@ -102,6 +105,7 @@ func (s *Set) Add(item Item) error {
 	}
 
 	s.lookup[key] = item
+	s.names.Insert(key)
 	return nil
 }
 
@@ -117,6 +121,7 @@ func (s *Set) Remove(key string) error {
 		return ErrMissing
 	}
 	delete(s.lookup, key)
+	s.names.Delete(key)
 	return nil
 }
 
@@ -187,6 +192,10 @@ func (s *Set) ListPrefix(prefix string) []Item {
 	return r
 }
 
+func (s *Set) CompleteName(name string) (string, bool) {
+	return s.names.ClosestName(name)
+}
+
 func normalize(key string) string {
 	return strings.ToLower(key)
 }