assembler: Allow cursor to be moved forwards

include/biscuit/assembler.hpp

@@ -112,6 +112,18 @@ class Assembler {
         m_buffer.RewindCursor(offset);
     }
 
+    /**
+     * Allows advancing of the code buffer cursor.
+     * 
+     * @param offset The offset to advance the cursor by.
+     *
+     * @note The offset may not be smaller than the current cursor offset 
+     *       and may not be larger than the current buffer capacity.
+     */
+    void AdvanceBuffer(ptrdiff_t offset) {
+        m_buffer.AdvanceCursor(offset);
+    }
+
     /// Retrieves the cursor pointer for the underlying code buffer.
     [[nodiscard]] uint8_t* GetCursorPointer() noexcept {
         return m_buffer.GetCursorPointer();

include/biscuit/code_buffer.hpp

@@ -88,14 +88,16 @@ class CodeBuffer {
 
     /// Retrieves the pointer to an arbitrary location within the buffer.
     [[nodiscard]] uint8_t* GetOffsetPointer(ptrdiff_t offset) noexcept {
-        BISCUIT_ASSERT(offset >= 0 && offset <= GetCursorOffset());
-        return m_buffer + offset;
+        auto pointer = m_buffer + offset;
+        BISCUIT_ASSERT(pointer >= m_buffer && pointer < m_buffer + m_capacity);
+        return pointer;
     }
 
     /// Retrieves the pointer to an arbitrary location within the buffer.
     [[nodiscard]] const uint8_t* GetOffsetPointer(ptrdiff_t offset) const noexcept {
-        BISCUIT_ASSERT(offset >= 0 && offset <= GetCursorOffset());
-        return m_buffer + offset;
+        auto pointer = m_buffer + offset;
+        BISCUIT_ASSERT(pointer >= m_buffer && pointer < m_buffer + m_capacity);
+        return pointer;
     }
 
     /**
@@ -115,6 +117,20 @@ class CodeBuffer {
         m_cursor = rewound;
     }
 
+    /**
+     * Allows advancing of the code buffer cursor.
+     * 
+     * @param offset The offset to advance the cursor by.
+     *
+     * @note The offset may not be smaller than the current cursor offset 
+     *       and may not be larger than the current buffer capacity.
+     */
+    void AdvanceCursor(ptrdiff_t offset) noexcept {
+        auto* forward = m_buffer + offset;
+        BISCUIT_ASSERT(m_cursor <= forward && forward < m_buffer + m_capacity);
+        m_cursor = forward;
+    }
+
     /**
      * Whether or not the underlying buffer has enough room for the
      * given number of bytes.