From 9756519f13713d592269f391613ff295fe02e78b Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 28 Oct 2016 21:51:51 -0400
Subject: [PATCH] Fix PieceTable::Cursor::prev_line and next_line to support
 empty pieces

---
 src/core/PieceTable.cc | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/core/PieceTable.cc b/src/core/PieceTable.cc
index e7d09c0..9a36aa9 100644
--- a/src/core/PieceTable.cc
+++ b/src/core/PieceTable.cc
@@ -351,35 +351,35 @@ bool PieceTable::Cursor::is_end_of_line()
 
 PieceTable::Piece * PieceTable::Cursor::prev_line() const
 {
-    Piece * p = iterator.piece;
-    while ((!p->prev->eol()) && (p->prev != iterator.piece_table->start_piece))
-    {
-        p = p->prev;
-    }
-    if (p->prev == iterator.piece_table->start_piece)
+    if (!iterator.valid())
     {
         return nullptr;
     }
-    p = p->prev;
-    while ((!p->prev->eol()) && (p->prev != iterator.piece_table->start_piece))
+    Cursor cursor2 = *this;
+    cursor2.go_start_of_line();
+    cursor2.iterator.go_prev_position();
+    if (!cursor2.iterator.valid())
     {
-        p = p->prev;
+        return nullptr;
     }
-    return p;
+    cursor2.go_start_of_line();
+    return cursor2.iterator.piece;
 }
 
 PieceTable::Piece * PieceTable::Cursor::next_line() const
 {
-    Piece * p = iterator.piece;
-    while ((!p->eol()) && (p->next != iterator.piece_table->end_piece))
-    {
-        p = p->next;
-    }
-    if (p->next == iterator.piece_table->end_piece)
+    if (!iterator.valid())
     {
         return nullptr;
     }
-    return p->next;
+    Cursor cursor2 = *this;
+    cursor2.go_end_of_line(true);
+    cursor2.iterator.go_next_position();
+    if (!cursor2.iterator.valid())
+    {
+        return nullptr;
+    }
+    return cursor2.iterator.piece;
 }
 
 void PieceTable::Cursor::init_column()