From 74a20ae795aa2f21b897cf21ef8dc431fa24467f Mon Sep 17 00:00:00 2001
From: Victor <melnikukr@mail.ru>
Date: Fri, 10 Apr 2015 23:39:51 +0300
Subject: [PATCH] =?UTF-8?q?=D0=94=D0=BE=D0=B1=D0=B0=D0=B2=D0=BB=D0=B5?=
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---
 res/values/strings.xml                        |  4 +++
 src/com/annimon/everlastingsummer/Parser.java | 33 +++++++++++++++++++
 .../everlastingsummer/ViewActivity.java       |  6 ++++
 3 files changed, 43 insertions(+)

diff --git a/res/values/strings.xml b/res/values/strings.xml
index 3d77d33..62087d1 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -2,9 +2,13 @@
 
     <string name="app_name">RpyPlayer. Everlasting Summer</string>
     <string name="actions">Действия</string>
+    <string name="to_prev_scene">Предыдущая сцена</string>
+    <string name="to_next_scene">Следующая сцена</string>
     <string name="navigate">Навигация</string>
 
     <string-array name="menu_items">
+        <item>@string/to_prev_scene</item>
+        <item>@string/to_next_scene</item>
         <item>@string/navigate</item>
     </string-array>
 
diff --git a/src/com/annimon/everlastingsummer/Parser.java b/src/com/annimon/everlastingsummer/Parser.java
index bac15f8..b608a50 100644
--- a/src/com/annimon/everlastingsummer/Parser.java
+++ b/src/com/annimon/everlastingsummer/Parser.java
@@ -71,6 +71,39 @@ public final class Parser {
         } while (!terminal);
     }
     
+    public void prevScene() {
+        // Для перехода к предыдущей сцене, следует два раза найти токен SCENE,
+        // т.к. при первом поиске мы найдём лишь текущую.
+        final int currentScene = find(TokenType.SCENE, -1);
+        final int pos = findFrom(currentScene, TokenType.SCENE, -1);
+        // Если не нашли - перематываем на начало.
+        if (pos == position) position = 0;
+        else position = pos;
+        next();
+    }
+    
+    public void nextScene() {
+        position = find(TokenType.SCENE, 1);
+        next();
+    }
+    
+    private int find(TokenType which, int step) {
+        return findFrom(position, which, step);
+    }
+    
+    private int findFrom(int from, TokenType which, int step) {
+        int pos = from;
+        while (true) {
+            pos += step;
+            if (pos < 0 || pos >= tokensCount) break;
+            
+            final Token token = tokens.get(pos);
+            if (which == token.getType()) return pos;
+        }
+        // Возвращаем текущее значение во избежание лишних проверок.
+        return from;
+    }
+    
     private boolean statement() {
     	// http://www.renpy.org/wiki/renpy/doc/reference/The_Ren%27Py_Language#Grammar_Rules
         final Token token = get(0);
diff --git a/src/com/annimon/everlastingsummer/ViewActivity.java b/src/com/annimon/everlastingsummer/ViewActivity.java
index d41351f..321d589 100644
--- a/src/com/annimon/everlastingsummer/ViewActivity.java
+++ b/src/com/annimon/everlastingsummer/ViewActivity.java
@@ -153,6 +153,12 @@ public final class ViewActivity extends Activity implements TouchGesture.OnTouch
     private void onMenuItemSelected(int item) {
         switch (item) {
             case 0:
+                Parser.getInstance().prevScene();
+                break;
+            case 1:
+                Parser.getInstance().nextScene();
+                break;
+            case 2:
                 Dialogs.with(getInstance()).showNavigate();
                 break;
         }