move character iteration logic from BufferView to BufferLineWalker

src/core/BufferLineWalker.cc

@@ -0,0 +1,101 @@
+#include "BufferLineWalker.h"
+
+/**
+ * Construct a BufferLineWalker.
+ */
+BufferLineWalker::BufferLineWalker(
+        std::shared_ptr<Buffer> buffer,
+        CharacterWidthDeterminer & character_width_determiner)
+    : m_buffer(buffer),
+      m_character_width_determiner(character_width_determiner)
+{
+    m_width = 1;
+}
+
+/**
+ * Set the view width.
+ *
+ * @param width View width.
+ */
+void BufferLineWalker::set_width(int width)
+{
+    m_width = std::max(1, width);
+}
+
+/**
+ * Invoke the callback for each character in the buffer line, wrapping to the
+ * next screen line and taking into account multi-column characters.
+ *
+ * Callback parameters:
+ * - row_offset
+ * - screen column
+ * - virtual column
+ * - character width
+ * - buffer iterator
+ * If the callback function returns true, iteration continues. Otherwise
+ * iteration is terminated.
+ *
+ * @param start_of_line Buffer iterator pointing to the beginning of the buffer line.
+ * @param callback Function to call for each character in the line.
+ */
+void BufferLineWalker::walk_line(
+        const Buffer::Iterator & start_of_line,
+        std::function<bool(int, int, int, int, const Buffer::Iterator &)> callback)
+{
+    int row_offset = 0;
+    int screen_column = 0;
+    int virtual_column = 0;
+    Buffer::Iterator i = start_of_line;
+    for (;;)
+    {
+        uint32_t code_point = *i;
+        if ((code_point == '\n') || (!i.valid()))
+        {
+            callback(row_offset, screen_column, virtual_column, 0, i);
+            break;
+        }
+        int c_width;
+        if (code_point == '\t')
+        {
+            uint8_t tabstop = m_buffer->tabstop();
+            c_width = tabstop - virtual_column % tabstop;
+        }
+        else
+        {
+            c_width = m_character_width_determiner(code_point);
+            if (((screen_column + c_width) > m_width) &&
+                    (screen_column > 0))
+            {
+                row_offset++;
+                screen_column = 0;
+            }
+        }
+        if (!callback(row_offset, screen_column, virtual_column, c_width, i))
+        {
+            break;
+        }
+        virtual_column += c_width;
+        if (code_point == '\t')
+        {
+            screen_column += c_width;
+            while (screen_column >= m_width)
+            {
+                screen_column -= m_width;
+                row_offset++;
+            }
+        }
+        else
+        {
+            if ((screen_column + c_width) >= m_width)
+            {
+                row_offset++;
+                screen_column = 0;
+            }
+            else
+            {
+                screen_column += c_width;
+            }
+        }
+        i.go_forward();
+    }
+}

src/core/BufferLineWalker.h

@@ -0,0 +1,29 @@
+#ifndef BUFFERLINEWALKER_H
+#define BUFFERLINEWALKER_H
+
+#include "Buffer.h"
+#include "CharacterWidthDeterminer.h"
+#include <functional>
+
+/**
+ * Provides functionality to walk a line of a buffer taking into account the
+ * view width and multi-column characters.
+ */
+class BufferLineWalker
+{
+public:
+    BufferLineWalker(
+            std::shared_ptr<Buffer> buffer,
+            CharacterWidthDeterminer & character_width_determiner);
+    void set_width(int width);
+    void walk_line(
+            const Buffer::Iterator & start_of_line,
+            std::function<bool(int, int, int, int, const Buffer::Iterator &)> callback);
+
+protected:
+    std::shared_ptr<Buffer> m_buffer;
+    CharacterWidthDeterminer & m_character_width_determiner;
+    int m_width;
+};
+
+#endif

src/core/BufferView.cc

@@ -23,60 +23,3 @@ void BufferView::set_scroll_offset(int scroll_offset)
 {
     m_scroll_offset = std::max(0, scroll_offset);
 }
-
-void BufferView::iter_cols(const Buffer::Iterator & start_of_line, std::function<void(int, int, int, int, const Buffer::Iterator &)> callback)
-{
-    int row_offset = 0;
-    int screen_column = 0;
-    int virtual_column = 0;
-    Buffer::Iterator i = start_of_line;
-    for (;;)
-    {
-        uint32_t code_point = *i;
-        if ((code_point == '\n') || (!i.valid()))
-        {
-            callback(row_offset, screen_column, virtual_column, 0, i);
-            break;
-        }
-        int c_width;
-        if (code_point == '\t')
-        {
-            uint8_t tabstop = m_buffer->tabstop();
-            c_width = tabstop - virtual_column % tabstop;
-        }
-        else
-        {
-            c_width = m_character_width_determiner(code_point);
-            if (((screen_column + c_width) > m_width) &&
-                    (screen_column > 0))
-            {
-                row_offset++;
-                screen_column = 0;
-            }
-        }
-        callback(row_offset, screen_column, virtual_column, c_width, i);
-        virtual_column += c_width;
-        if (code_point == '\t')
-        {
-            screen_column += c_width;
-            while (screen_column >= m_width)
-            {
-                screen_column -= m_width;
-                row_offset++;
-            }
-        }
-        else
-        {
-            if ((screen_column + c_width) >= m_width)
-            {
-                row_offset++;
-                screen_column = 0;
-            }
-            else
-            {
-                screen_column += c_width;
-            }
-        }
-        i.go_forward();
-    }
-}

src/core/BufferView.h

@@ -18,7 +18,6 @@ public:
     void resize(int width, int height);
     void set_scroll_offset(int scroll_offset);
     void iter_lines(std::function<bool(const Buffer::Iterator &)> callback);
-    void iter_cols(const Buffer::Iterator & start_of_line, std::function<void(int, int, int, int, const Buffer::Iterator &)> callback);
 
 protected:
     std::shared_ptr<Buffer> m_buffer;