Add Buffer::{next,prev,at}(BufferCoord) methods and use them in iterators

src/buffer.cc

@@ -637,6 +637,35 @@ BufferCoord Buffer::advance(BufferCoord coord, ByteCount count) const
     return { LineCount{ (int)(it - m_lines.begin()) }, off - it->start };
 }
 
+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;
+        coord.column = 0;
+    }
+    return coord;
+}
+
+BufferCoord Buffer::prev(BufferCoord coord) const
+{
+    if (coord.column == 0)
+    {
+        if (coord.line > 0)
+        {
+            --coord.line;
+            coord.column = m_lines[coord.line].length() - 1;
+        }
+    }
+    else
+       --coord.column;
+    return coord;
+}
+
 ByteCount Buffer::distance(const BufferCoord& begin, const BufferCoord& end) const
 {
     return offset(end) - offset(begin);
@@ -662,4 +691,10 @@ bool Buffer::is_end(const BufferCoord& c) const
            (c.line == line_count() - 1 and c.column == m_lines.back().length());
 }
 
+char Buffer::at(const BufferCoord& c) const
+{
+    kak_assert(c.line < line_count() and c.column < m_lines[c.line].length());
+    return m_lines[c.line].content[c.column];
+}
+
 }

src/buffer.hh

@@ -123,9 +123,13 @@ public:
 
     String         string(const BufferCoord& begin,
                           const BufferCoord& end) const;
+    char           at(const BufferCoord& c) const;
     ByteCount      offset(const BufferCoord& c) const;
-    ByteCount   distance(const BufferCoord& begin, const BufferCoord& end) const;
+    ByteCount      distance(const BufferCoord& begin,
+                            const BufferCoord& end) const;
     BufferCoord    advance(BufferCoord coord, ByteCount count) const;
+    BufferCoord    next(BufferCoord coord) const;
+    BufferCoord    prev(BufferCoord coord) const;
     bool           is_valid(const BufferCoord& c) const;
     bool           is_end(const BufferCoord& c) const;
 

src/buffer_iterator.inl.hh

@@ -65,7 +65,7 @@ inline bool BufferIterator::operator>=(const BufferIterator& iterator) const
 
 inline char BufferIterator::operator*() const
 {
-    return m_buffer->m_lines[m_coord.line].content[m_coord.column];
+    return m_buffer->at(m_coord);
 }
 
 inline ByteCount BufferIterator::offset() const
@@ -103,30 +103,13 @@ inline BufferIterator& BufferIterator::operator-=(ByteCount size)
 
 inline BufferIterator& BufferIterator::operator++()
 {
-    if (m_coord.column < m_buffer->m_lines[m_coord.line].length() - 1)
+    m_coord = m_buffer->next(m_coord);
-        ++m_coord.column;
-    else if (m_coord.line == m_buffer->m_lines.size() - 1)
-        m_coord.column = m_buffer->m_lines.back().length();
-    else
-    {
-        ++m_coord.line;
-        m_coord.column = 0;
-    }
     return *this;
 }
 
 inline BufferIterator& BufferIterator::operator--()
 {
-    if (column() == 0)
+    m_coord = m_buffer->prev(m_coord);
-    {
-        if (line() > 0)
-        {
-            --m_coord.line;
-            m_coord.column = m_buffer->m_lines[m_coord.line].length() - 1;
-        }
-    }
-    else
-       --m_coord.column;
     return *this;
 }