Fix the Buffer::end() madness

Until now, buffer had multiple recognized end coordinates, either
{ line_count, 0 } or { line_count - 1, line[line_count - 1].length }.

Now the only correct end coord is { line_count, 0 }, removing the need
for various special cases.

5 files changed, 30 insertions, 66 deletions

diff --git a/src/buffer.cc b/src/buffer.cc
index 1a92b8da..dc0dd93b 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -88,7 +88,7 @@ Buffer::Buffer(String name, Flags flags, StringView data,
     #endif
     static_cast<BufferLines&>(m_lines) = std::move(parsed_lines.lines);
 
-    m_changes.push_back({ Change::Insert, true, {0,0}, line_count() });
+    m_changes.push_back({ Change::Insert, {0,0}, line_count() });
 
     apply_options(options(), parsed_lines);
 
@@ -241,11 +241,11 @@ void Buffer::reload(StringView data, timespec fs_timestamp)
 
     if (not record_undo)
     {
-        m_changes.push_back({ Change::Erase, true, {0,0}, line_count() });
+        m_changes.push_back({ Change::Erase, {0,0}, line_count() });
 
         static_cast<BufferLines&>(m_lines) = std::move(parsed_lines.lines);
 
-        m_changes.push_back({ Change::Insert, true, {0,0}, line_count() });
+        m_changes.push_back({ Change::Insert, {0,0}, line_count() });
     }
     else
     {
@@ -268,7 +268,7 @@ void Buffer::reload(StringView data, timespec fs_timestamp)
                         Modification::Insert, cur_line + line,
                         parsed_lines.lines[(int)(d.posB + line)]);
 
-                m_changes.push_back({ Change::Insert, it == m_lines.end(), cur_line, cur_line + d.len });
+                m_changes.push_back({ Change::Insert, cur_line, cur_line + d.len });
                 m_lines.insert(it, &parsed_lines.lines[d.posB], &parsed_lines.lines[d.posB + d.len]);
                 it = m_lines.begin() + (int)(cur_line + d.len);
             }
@@ -282,7 +282,7 @@ void Buffer::reload(StringView data, timespec fs_timestamp)
                         m_lines.get_storage(cur_line + line));
 
                 it = m_lines.erase(it, it + d.len);
-                m_changes.push_back({ Change::Erase, it == m_lines.end(), cur_line, cur_line + d.len });
+                m_changes.push_back({ Change::Erase, cur_line, cur_line + d.len });
             }
         }
     }
@@ -453,8 +453,6 @@ BufferCoord Buffer::do_insert(BufferCoord pos, StringView content)
 
     const bool at_end = is_end(pos);
     const bool append_lines = at_end and (m_lines.empty() or byte_at(back_coord()) == '\n');
-    if (at_end)
-        pos = append_lines ? line_count() : end_coord();
 
     const StringView prefix = append_lines ?
         StringView{} : m_lines[pos.line].substr(0, pos.column);
@@ -490,7 +488,7 @@ BufferCoord Buffer::do_insert(BufferCoord pos, StringView content)
     const auto end = at_end ? line_count()
                             : BufferCoord{ last_line, m_lines[last_line].length() - suffix.length() };
 
-    m_changes.push_back({ Change::Insert, at_end, pos, end });
+    m_changes.push_back({ Change::Insert, pos, end });
     return pos;
 }
 
@@ -502,7 +500,7 @@ BufferCoord Buffer::do_erase(BufferCoord begin, BufferCoord end)
     kak_assert(is_valid(begin));
     kak_assert(is_valid(end));
     StringView prefix = m_lines[begin.line].substr(0, begin.column);
-    StringView suffix = m_lines[end.line].substr(end.column);
+    StringView suffix = end.line == line_count() ? StringView{} : m_lines[end.line].substr(end.column);
 
     BufferCoord next;
     if (not prefix.empty() or not suffix.empty())
@@ -514,11 +512,11 @@ BufferCoord Buffer::do_erase(BufferCoord begin, BufferCoord end)
     }
     else
     {
-        m_lines.erase(m_lines.begin() + (int)begin.line, m_lines.begin() + (int)end.line + 1);
-        next = is_end(begin) ? end_coord() : BufferCoord{begin.line, 0};
+        m_lines.erase(m_lines.begin() + (int)begin.line, m_lines.begin() + (int)end.line);
+        next = begin.line;
     }
 
-    m_changes.push_back({ Change::Erase, is_end(begin), begin, end });
+    m_changes.push_back({ Change::Erase, begin, end });
     return next;
 }
 
@@ -584,24 +582,11 @@ BufferCoord Buffer::erase(BufferCoord begin, BufferCoord end)
 
 BufferCoord Buffer::replace(BufferCoord begin, BufferCoord end, StringView content)
 {
-    if (not (m_flags & Flags::NoUndo))
-        m_current_undo_group.emplace_back(Modification::Erase, begin,
-                                          intern(string(begin, end)));
-    auto pos = do_erase(begin, end);
+    if (is_end(end) and not content.empty() and content.back() == '\n')
+        content = content.substr(0, content.length() - 1);
 
-    StringDataPtr real_content;
-    if (is_end(pos) and content.back() != '\n')
-        real_content = intern(content + "\n");
-    else
-        real_content = intern(content);
-
-    bool last_char_is_eol = not (m_lines.empty() or
-                                 m_lines.back().empty() or
-                                 m_lines.back().back() != '\n');
-    auto coord = is_end(pos) and last_char_is_eol ? line_count() : pos;
-    if (not (m_flags & Flags::NoUndo))
-        m_current_undo_group.emplace_back(Modification::Insert, coord, real_content);
-    return do_insert(pos, real_content->strview());
+    auto pos = erase(begin, end);
+    return insert(pos, content);
 }
 
 bool Buffer::is_modified() const
@@ -662,8 +647,6 @@ BufferCoord Buffer::char_next(BufferCoord coord) const
             coord.column = 0;
         }
     }
-    else if (coord.line == m_lines.size() - 1)
-        coord.column = m_lines.back().length();
     else
     {
         ++coord.line;
@@ -675,9 +658,7 @@ BufferCoord Buffer::char_next(BufferCoord coord) const
 BufferCoord Buffer::char_prev(BufferCoord coord) const
 {
     kak_assert(is_valid(coord));
-    if (is_end(coord))
-        return {(int)m_lines.size()-1, m_lines.back().length() - 1};
-    else if (coord.column == 0)
+    if (coord.column == 0)
     {
         if (coord.line > 0)
             coord.column = m_lines[--coord.line].length() - 1;
diff --git a/src/buffer.hh b/src/buffer.hh
index d0fdffcb..d2679ba1 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -89,9 +89,9 @@ public:
 
 private:
     SafePtr<const Buffer> m_buffer;
-    StringView m_line;
     BufferCoord m_coord;
-    LineCount m_last_line;
+    LineCount m_line_count;
+    StringView m_line;
 };
 
 using BufferLines = Vector<StringDataPtr, MemoryDomain::BufferContent>;
@@ -205,7 +205,6 @@ public:
     {
         enum Type : char { Insert, Erase };
         Type type;
-        bool at_end;
         BufferCoord begin;
         BufferCoord end;
     };
diff --git a/src/buffer.inl.hh b/src/buffer.inl.hh
index 7d987c26..5904b9ff 100644
--- a/src/buffer.inl.hh
+++ b/src/buffer.inl.hh
@@ -17,8 +17,6 @@ inline BufferCoord Buffer::next(BufferCoord coord) const
 {
     if (coord.column < m_lines[coord.line].length() - 1)
         ++coord.column;
-    else if (coord.line == m_lines.size() - 1)
-        coord.column = m_lines.back().length();
     else
     {
         ++coord.line;
@@ -59,7 +57,6 @@ inline bool Buffer::is_valid(BufferCoord c) const
         return false;
 
     return (c.line < line_count() and c.column < m_lines[c.line].length()) or
-           (c.line == line_count() - 1 and c.column == m_lines.back().length()) or
            (c.line == line_count() and c.column == 0);
 }
 
@@ -110,14 +107,13 @@ inline BufferCoord Buffer::back_coord() const
 
 inline BufferCoord Buffer::end_coord() const
 {
-    return m_lines.empty() ?
-        BufferCoord{0,0} : BufferCoord{ line_count() - 1, m_lines.back().length() };
+    return line_count();
 }
 
 inline BufferIterator::BufferIterator(const Buffer& buffer, BufferCoord coord) noexcept
-    : m_buffer(&buffer), m_coord(coord),
-      m_line((*m_buffer)[coord.line]),
-      m_last_line(buffer.line_count()-1) {}
+    : m_buffer{&buffer}, m_coord{coord},
+      m_line_count{buffer.line_count()},
+      m_line{coord.line < buffer.line_count() ? (*m_buffer)[coord.line] : StringView{}} {}
 
 inline bool BufferIterator::operator==(const BufferIterator& iterator) const noexcept
 {
@@ -197,9 +193,10 @@ inline BufferIterator& BufferIterator::operator-=(ByteCount size)
 
 inline BufferIterator& BufferIterator::operator++()
 {
-    if (++m_coord.column == m_line.length() and m_coord.line != m_last_line)
+    if (++m_coord.column == m_line.length())
     {
-        m_line = (*m_buffer)[++m_coord.line];
+        m_line = (++m_coord.line < m_line_count) ?
+            (*m_buffer)[m_coord.line] : StringView{};
         m_coord.column = 0;
     }
     return *this;
@@ -207,7 +204,7 @@ inline BufferIterator& BufferIterator::operator++()
 
 inline BufferIterator& BufferIterator::operator--()
 {
-    if (m_coord.column == 0 and m_coord.line > 0)
+    if (m_coord.column == 0)
     {
         m_line = (*m_buffer)[--m_coord.line];
         m_coord.column = m_line.length() - 1;
diff --git a/src/line_modification.cc b/src/line_modification.cc
index 3d6617dd..df2b9cbc 100644
--- a/src/line_modification.cc
+++ b/src/line_modification.cc
@@ -10,22 +10,11 @@ static LineModification make_line_modif(const Buffer::Change& change)
 {
     LineCount num_added = 0, num_removed = 0;
     if (change.type == Buffer::Change::Insert)
-    {
         num_added = change.end.line - change.begin.line;
-         // inserted a new line at buffer end but end coord is on same line
-        if (change.at_end and change.end.column != 0)
-            ++num_added;
-    }
     else
-    {
         num_removed = change.end.line - change.begin.line;
-        // removed last line, but end coord is on same line
-        if (change.at_end and change.end.column != 0)
-            ++num_removed;
-    }
     // modified a line
-    if (not change.at_end and
-        (change.begin.column != 0 or change.end.column != 0))
+    if ((change.begin.column != 0 or change.end.column != 0))
     {
         ++num_removed;
         ++num_added;
@@ -116,7 +105,7 @@ UnitTest test_line_modifications{[]()
     {
         Buffer buffer("test", Buffer::Flags::None, "line 1\nline 2\n");
         auto ts = buffer.timestamp();
-        buffer.insert({1, 7}, "line 3");
+        buffer.insert({2, 0}, "line 3");
 
         auto modifs = compute_line_modifications(buffer, ts);
         kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 2, 2, 0, 1 });
diff --git a/src/selection.cc b/src/selection.cc
index 05095dfa..4724e896 100644
--- a/src/selection.cc
+++ b/src/selection.cc
@@ -448,17 +448,15 @@ void SelectionList::erase()
         kak_assert(m_buffer->is_valid(sel.cursor()));
 
         auto pos = Kakoune::erase(*m_buffer, sel);
-        sel.anchor() = sel.cursor() = m_buffer->clamp(pos);
+        sel.anchor() = sel.cursor() = pos;
         changes_tracker.update(*m_buffer, m_timestamp);
     }
 
     BufferCoord back_coord = m_buffer->back_coord();
     for (auto& sel : m_selections)
     {
-        if (sel.anchor() > back_coord)
-            sel.anchor() = back_coord;
-        if (sel.cursor() > back_coord)
-            sel.cursor() = back_coord;
+        auto pos = m_buffer->clamp(sel.cursor());
+        sel.anchor() = sel.cursor() = std::min(pos, back_coord);
     }
 
     m_buffer->check_invariant();