From 99bbe81f6b0eeca1e130fc34f280330c6ddc37c5 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Wed, 5 Oct 2016 22:47:08 -0400
Subject: [PATCH] add PieceTable::begin_insert()

---
 src/core/PieceTable.cc | 69 +++++++++++++++++++++++++++++++++++++++---
 src/core/PieceTable.h  | 38 ++++++++++++++---------
 src/gui/Window.cc      |  3 ++
 3 files changed, 90 insertions(+), 20 deletions(-)

diff --git a/src/core/PieceTable.cc b/src/core/PieceTable.cc
index 2b113c2..eaee9ae 100644
--- a/src/core/PieceTable.cc
+++ b/src/core/PieceTable.cc
@@ -11,7 +11,7 @@ PieceTable::PieceTable(const uint8_t * file_buffer, unsigned long file_buffer_si
     m_piece_index = 2u;
     tabstop = 4u;
     m_append_buffer_index = 0u;
-    m_changes_buffer_index = 0u;
+    m_changes_index = 0u;
 }
 
 void PieceTable::append_initial_line_piece(uint8_t * start, uint32_t length, bool eol)
@@ -334,6 +334,65 @@ void PieceTable::Cursor::forward_to_column(uint32_t c)
     }
 }
 
+void PieceTable::begin_insert(const Cursor & cursor, bool before)
+{
+    Piece * piece = cursor.iterator.piece;
+    uint32_t offset = cursor.iterator.offset;
+    if (!before && cursor.iterator.has_char())
+    {
+        offset += cursor.iterator.num_bytes_in_code_point();
+    }
+    if (offset == 0u)
+    {
+        /* Insert happens at piece boundary between piece->prev and piece. */
+        m_insert_before_piece = piece->prev;
+    }
+    else if (offset >= piece->length)
+    {
+        /* Insert happens at piece boundary between piece and piece->next. */
+        m_insert_before_piece = piece;
+    }
+    else
+    {
+        /* Insert happens in the middle of a current piece. The piece must
+         * be split up. */
+        Piece * new_piece_1 = add_piece();
+        new_piece_1->start = piece->start;
+        new_piece_1->length = offset;
+        new_piece_1->flags = 0u;
+
+        Piece * new_piece_2 = add_piece();
+        new_piece_2->start = piece->start + offset;
+        new_piece_2->length = piece->length - offset;
+        new_piece_2->flags = piece->flags;
+
+        new_piece_1->prev = piece->prev;
+        new_piece_1->next = new_piece_2;
+        new_piece_2->prev = new_piece_1;
+        new_piece_2->next = piece->next;
+
+        Change * change = add_change();
+        change->links[0][0][0] = piece->prev;
+        change->links[0][0][1] = piece;
+        change->links[0][1][0] = piece;
+        change->links[0][1][1] = piece->next;
+        change->links[1][0][0] = piece->prev;
+        change->links[1][0][1] = new_piece_1;
+        change->links[1][1][0] = new_piece_2;
+        change->links[1][1][1] = piece->next;
+
+        apply_change(change, 1u);
+    }
+}
+
+void PieceTable::insert_code_point(uint32_t code_point)
+{
+}
+
+void PieceTable::end_insert()
+{
+}
+
 void PieceTable::insertion_test(Cursor & c)
 {
     Piece * piece = add_piece();
@@ -344,7 +403,7 @@ void PieceTable::insertion_test(Cursor & c)
     m_append_buffer[m_append_buffer_index++] = 'y';
     m_append_buffer[m_append_buffer_index++] = 'z';
 
-    Change * change = &m_changes_buffer[m_changes_buffer_index++];
+    Change * change = &m_changes[m_changes_index++];
 
     if (c.iterator.valid())
     {
@@ -412,10 +471,10 @@ void PieceTable::insertion_test(Cursor & c)
 
 void PieceTable::undo()
 {
-    if (m_changes_buffer_index > 0u)
+    if (m_changes_index > 0u)
     {
-        m_changes_buffer_index--;
-        apply_change(&m_changes_buffer[m_changes_buffer_index], 0u);
+        m_changes_index--;
+        apply_change(&m_changes[m_changes_index], 0u);
     }
 }
 
diff --git a/src/core/PieceTable.h b/src/core/PieceTable.h
index 9c9494c..af385da 100644
--- a/src/core/PieceTable.h
+++ b/src/core/PieceTable.h
@@ -145,6 +145,20 @@ public:
 
     PieceTable(const uint8_t * file_buffer, unsigned long file_buffer_size);
 
+    uint32_t get_num_lines() { return m_num_lines; }
+
+    void append_initial_line_piece(uint8_t * start, uint32_t length, bool eol);
+
+    std::shared_ptr<Cursor> add_cursor();
+
+    void begin_insert(const Cursor & cursor, bool before);
+    void insert_code_point(uint32_t code_point);
+    void end_insert();
+    void insertion_test(Cursor & c);
+
+    void undo();
+
+protected:
     Piece * add_piece()
     {
         return &m_pieces[m_piece_index++];
@@ -155,31 +169,25 @@ public:
         return m_pieces[index];
     }
 
-    uint32_t get_num_lines() { return m_num_lines; }
-
-    void append_initial_line_piece(uint8_t * start, uint32_t length, bool eol);
-
-    std::shared_ptr<Cursor> add_cursor();
-
-    void insertion_test(Cursor & c);
-
-    void undo();
+    Change * add_change()
+    {
+        return &m_changes[m_changes_index++];
+    }
 
     void apply_change(Change * change, uint8_t forward);
 
-protected:
     const uint8_t * m_file_buffer;
     unsigned long m_file_buffer_size;
     uint32_t m_num_lines;
 
-    /** Next available piece index. */
-    uint32_t m_piece_index;
-
     PagedBuffer<uint8_t> m_append_buffer;
     uint32_t m_append_buffer_index;
     PagedBuffer<Piece> m_pieces;
-    PagedBuffer<Change> m_changes_buffer;
-    uint32_t m_changes_buffer_index;
+    /** Next available piece index. */
+    uint32_t m_piece_index;
+    PagedBuffer<Change> m_changes;
+    uint32_t m_changes_index;
+    Piece * m_insert_before_piece;
 
     std::list<std::shared_ptr<Cursor>> m_cursors;
 };
diff --git a/src/gui/Window.cc b/src/gui/Window.cc
index 25adc7f..5996d6b 100644
--- a/src/gui/Window.cc
+++ b/src/gui/Window.cc
@@ -274,6 +274,9 @@ void Window::handle_key(uint32_t scancode, uint32_t mod)
         m_buffer->piece_table->undo();
         redraw();
         break;
+    case SDL_SCANCODE_I:
+        m_buffer->piece_table->begin_insert(*m_cursor, true);
+        break;
     }
 }