From 17a5fde6aa1f71c999cb1c2e2b58a40720f59d31 Mon Sep 17 00:00:00 2001
From: Honza Dvorsky <honza@swiftkey.com>
Date: Sun, 6 Sep 2015 02:22:44 +0100
Subject: [PATCH] fixed Trie search for single-character queries

---
 hit.podspec              |  2 +-
 hit/Trie.swift           |  7 ++++---
 hitTests/TrieTests.swift | 21 ++++++++++++++++++---
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/hit.podspec b/hit.podspec
index c0f89a7..c041496 100644
--- a/hit.podspec
+++ b/hit.podspec
@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
   s.name         = "hit"
-  s.version      = "0.2"
+  s.version      = "0.3"
   s.summary      = "Lightweight full-text search written in Swift"
 
   s.description  = <<-DESC
diff --git a/hit/Trie.swift b/hit/Trie.swift
index 08687da..8ee116b 100644
--- a/hit/Trie.swift
+++ b/hit/Trie.swift
@@ -53,14 +53,15 @@ public struct Trie {
         
         let prefixHeadRange = TokenRange(start: prefix.startIndex, end: prefix.startIndex.advancedBy(1))
         let prefixHead = prefix.substringWithRange(prefixHeadRange)
-        
-        if length == 1 {
+        let emptyTrie = trie.token.characters.count == 0
+
+        if length == 1 && !emptyTrie {
+            
             //potentially might be found if trie matches
             let match = (trie.token == prefixHead)
             return match ? trie : nil
         }
         
-        let emptyTrie = trie.token.characters.count == 0
         let tokenMatches = trie.token == prefixHead
         if emptyTrie || tokenMatches {
             
diff --git a/hitTests/TrieTests.swift b/hitTests/TrieTests.swift
index 0c8a1e6..bbf40bc 100644
--- a/hitTests/TrieTests.swift
+++ b/hitTests/TrieTests.swift
@@ -11,10 +11,14 @@ import XCTest
 @testable import hit
 
 class TrieTests: HitTestCase {
-
+    
+    func commonWords() -> [String] {
+        let strings = ["swiftkey", "swype", "hello", "london", "reality", "fantasy", "stuff"]
+        return strings
+    }
+    
     func testTrieCreation_exactMatches() {
-        
-        let strings = ["swiftkey", "swype", "hello", "london", "reality", "fantasy"]
+        let strings = self.commonWords()
         let trie = Trie(strings: strings)
         
         let foundStrings = trie.stringsMatchingPrefix("sw")
@@ -54,6 +58,17 @@ class TrieTests: HitTestCase {
             _ = trie.stringsMatchingPrefix("sw")
         }
     }
+    
+    func testCorrectness_singleCharSearch() {
+        let strings = self.commonWords()
+        let trie = Trie(strings: strings)
+        
+        let foundStrings = Set(trie.stringsMatchingPrefix("s"))
+        XCTAssertEqual(foundStrings.count, 3)
+        XCTAssert(foundStrings.contains("swiftkey"))
+        XCTAssert(foundStrings.contains("swype"))
+        XCTAssert(foundStrings.contains("stuff"))
+    }
 
     
 }