From 66b2474fa212b9ccb5a74b68579aa59399f849ad Mon Sep 17 00:00:00 2001
From: FoggyFinder <FoggyFinder@yandex.ua>
Date: Thu, 15 Aug 2019 11:06:08 +0300
Subject: [PATCH] fix slash handler

---
 CSharpMath.Editor.Tests/MathKeyboardTests.cs | 52 ++++++++++++++++++++
 CSharpMath.Editor/Keyboards/MathKeyboard.cs  |  7 ++-
 2 files changed, 55 insertions(+), 4 deletions(-)
 create mode 100644 CSharpMath.Editor.Tests/MathKeyboardTests.cs

diff --git a/CSharpMath.Editor.Tests/MathKeyboardTests.cs b/CSharpMath.Editor.Tests/MathKeyboardTests.cs
new file mode 100644
index 000000000..6fa0b08aa
--- /dev/null
+++ b/CSharpMath.Editor.Tests/MathKeyboardTests.cs
@@ -0,0 +1,52 @@
+using CSharpMath.Editor;
+using CSharpMath.FrontEnd;
+using CSharpMath.Tests.FrontEnd;
+using Xunit;
+
+public class MathKeyboardTests {
+
+  public const float FontSize = 20;
+  public static readonly TestFont Font = new TestFont(FontSize);
+  private static readonly TypesettingContext<TestFont, char> context = TestTypesettingContexts.Instance;
+
+  [Fact]
+  // https://github.com/verybadcat/CSharpMath/issues/39
+  public void SlashInsideOfPowerTest() {
+    var keyboard = new MathKeyboard<TestFont, char>(context);
+    keyboard.KeyPress(MathKeyboardInput.SmallX);
+    keyboard.KeyPress(MathKeyboardInput.Power);
+    keyboard.KeyPress(MathKeyboardInput.D2);
+    keyboard.KeyPress(MathKeyboardInput.Slash);
+    Assert.Equal("x^{\\frac{2}{■}}", keyboard.LaTeX);
+  }
+
+  [Fact]
+  public void SlashInsideOfPowerTest2() {
+    var keyboard = new MathKeyboard<TestFont, char>(context);
+    keyboard.KeyPress(MathKeyboardInput.SmallX);
+    keyboard.KeyPress(MathKeyboardInput.Power);
+    keyboard.KeyPress(MathKeyboardInput.D1);
+    keyboard.KeyPress(MathKeyboardInput.D2);
+    keyboard.KeyPress(MathKeyboardInput.D3);
+    keyboard.KeyPress(MathKeyboardInput.Slash);
+    Assert.Equal("x^{\\frac{123}{■}}", keyboard.LaTeX);
+  }
+
+  [Fact]
+  public void DefaultNumeratorTest() {
+    var keyboard = new MathKeyboard<TestFont, char>(context);
+    keyboard.KeyPress(MathKeyboardInput.Slash);
+    Assert.Equal("\\frac{1}{■}", keyboard.LaTeX);
+  }
+
+  [Fact]
+  // https://github.com/kostub/MathEditor/issues/18
+  public void SlashAfterSlashTest() {
+    var keyboard = new MathKeyboard<TestFont, char>(context);
+    keyboard.KeyPress(MathKeyboardInput.D4);
+    keyboard.KeyPress(MathKeyboardInput.Slash);
+    keyboard.KeyPress(MathKeyboardInput.D4);
+    keyboard.KeyPress(MathKeyboardInput.Slash);
+    Assert.Equal("\\frac{4}{\\frac{4}{■}}", keyboard.LaTeX);
+  }
+}
diff --git a/CSharpMath.Editor/Keyboards/MathKeyboard.cs b/CSharpMath.Editor/Keyboards/MathKeyboard.cs
index 45be7bdb9..d03b0eba6 100644
--- a/CSharpMath.Editor/Keyboards/MathKeyboard.cs
+++ b/CSharpMath.Editor/Keyboards/MathKeyboard.cs
@@ -247,7 +247,7 @@ void HandleSlashButton() {
               //Add the number to the beginning of the list
               numerator.Insert(0, a);
           }
-          if (current.AtomIndex == _insertionIndex.AtomIndex) {
+          if (numerator.Count == 0) {
             // so we didn't really find any numbers before this, so make the numerator 1
             numerator.Add(MathAtoms.ForCharacter('1'));
             if (!current.AtBeginningOfLine) {
@@ -259,9 +259,8 @@ void HandleSlashButton() {
               }
             }
           } else
-            // delete stuff in the Mathlist from current to insertionIndex
-            MathList.RemoveAtoms(
-              new MathListRange(current, _insertionIndex.AtomIndex - current.AtomIndex));
+            // delete stuff in the Mathlist
+            MathList.RemoveAtoms(new MathListRange(current, numerator.Count));
 
           //Create the fraction
           var frac = new Fraction { Numerator = numerator, Denominator = MathAtoms.PlaceholderList };