Add comments.

3 files changed, 36 insertions, 19 deletions

diff --git a/c/common.cpp b/c/common.cpp
index 494c382..a91836d 100644
--- a/c/common.cpp
+++ b/c/common.cpp
@@ -2,6 +2,8 @@
 
 #include "common.h"
 
+/* Win32Error: Exception for Windows API errors. */
+
 Win32Error::Win32Error(const DWORD dwErr) : m_dwErr(dwErr) {}
 
 Win32Error::~Win32Error()
@@ -46,6 +48,8 @@ const TCHAR* Win32Error::twhat() const noexcept
 #undef M
 }
 
+/* Library: Wrapper for loading and freeing dynamically linked libraries. */
+
 Library::Library(const TCHAR* const tszLibrary)
 {
 	m_hModule = LoadLibrary(tszLibrary);
@@ -66,21 +70,22 @@ static LRESULT CALLBACK CBTProc(const int nCode, const WPARAM wParam, const LPAR
 		return CallNextHookEx(0, nCode, wParam, lParam);
 
 	HWND hWnd = (HWND)wParam;
-	if (long lStyle = GetWindowLong(hWnd, GWL_STYLE))
-		if (lStyle & WS_POPUP) {
-			RECT rcMain, rcMsg;
-			GetWindowRect(g_hWnd, &rcMain);
-			GetWindowRect(hWnd, &rcMsg);
-			SetWindowPos(hWnd, NULL,
-			    rcMain.left+(rcMain.right-rcMain.left)/2-(rcMsg.right-rcMsg.left)/2,
-			    rcMain.top+(rcMain.bottom-rcMain.top)/2-(rcMsg.bottom-rcMsg.top)/2,
-			    -1, -1,
-			    SWP_NOZORDER|SWP_NOSIZE|SWP_NOACTIVATE);
-		}
+	long lStyle = GetWindowLong(hWnd, GWL_STYLE);
+	if (!(lStyle & WS_POPUP)) return 0;
+
+	RECT rcMain, rcMsg;
+	GetWindowRect(g_hWnd, &rcMain);
+	GetWindowRect(hWnd, &rcMsg);
+	SetWindowPos(hWnd, NULL,
+	    rcMain.left+(rcMain.right-rcMain.left)/2-(rcMsg.right-rcMsg.left)/2,
+	    rcMain.top+(rcMain.bottom-rcMain.top)/2-(rcMsg.bottom-rcMsg.top)/2,
+	    -1, -1,
+	    SWP_NOZORDER|SWP_NOSIZE|SWP_NOACTIVATE);
 
 	return 0;
 }
 
+/* Show message box owned by and centered in the main window. */
 int EBMessageBox(const TCHAR* const tszText, const TCHAR* const tszCaption, const unsigned uType)
 {
 	extern HWND g_hWnd;
diff --git a/c/pl.cpp b/c/pl.cpp
index fb3d4af..ef8aaf9 100644
--- a/c/pl.cpp
+++ b/c/pl.cpp
@@ -3,6 +3,8 @@
 
 #include "pl.h"
 
+/* Frame: Wrapper for opening and closing Prolog foreign frames. */
+
 Frame::Frame()
 {
 	m_f = PL_open_foreign_frame();
@@ -18,6 +20,7 @@ void Frame::Close()
 	PL_close_foreign_frame(m_f);
 }
 
+/* Close foreign frame and invalidate associated data. */
 void Frame::Discard()
 {
 	PL_discard_foreign_frame(m_f);
@@ -28,6 +31,8 @@ void Frame::Rewind()
 	PL_rewind_foreign_frame(m_f);
 }
 
+/* Mark: Wrapper for marking and releasing strings on the Prolog stack. */
+
 Mark::Mark()
 {
 	PL_mark_string_buffers(&m_m);
@@ -38,6 +43,8 @@ Mark::~Mark()
 	PL_release_string_buffers_from_mark(m_m);
 }
 
+/* Query: Wrapper for opening, solving and cutting Prolog query. */
+
 Query::Query(const module_t ctx, const predicate_t p, const term_t t0)
 {
 	m_q = PL_open_query(ctx, PL_Q_CATCH_EXCEPTION, p, t0);
@@ -55,6 +62,7 @@ int Query::Cut()
 	return 0;
 }
 
+/* Cut query and invalidate associated data. */
 int Query::Close()
 {
 	if (PL_close_query(m_q)) return 1;
@@ -69,6 +77,7 @@ int Query::NextSolution()
 	return 0;
 }
 
+/* Convert Prolog term to normal or wide characters. */
 int PL_get_tchars(const term_t t, TCHAR** const pTsz, const int iFlags)
 {
 #ifdef UNICODE
@@ -83,6 +92,7 @@ int PL_get_tchars(const term_t t, TCHAR** const pTsz, const int iFlags)
 #endif
 }
 
+/* Call nullary Prolog predicate, propagating Prolog exceptions. */
 int Plx(const char* const szMod, const char* const szPred)
 {
 	Frame f;
@@ -90,3 +100,13 @@ int Plx(const char* const szMod, const char* const szPred)
 	Query q(NULL, PL_predicate(szPred, 0, szMod), t);
 	return q.NextSolution();
 }
+
+/* Call nullary Prolog predicate, ignoring Prolog exceptions. */
+int Pl(const char* const szMod, const char* const szPred)
+{
+	try {
+		return Plx(szMod, szPred);
+	} catch (term_t& t) {
+		return 0;
+	}
+}
diff --git a/c/pl.h b/c/pl.h
index d4bf18b..00285e0 100644
--- a/c/pl.h
+++ b/c/pl.h
@@ -95,14 +95,6 @@ int Plx(const char* const szMod, const char* const szPred, T... args)
 }
 
 /* Call Prolog predicate, ignoring Prolog exceptions. */
-inline int Pl(const char* const szMod, const char* const szPred)
-{
-	try {
-		return Plx(szMod, szPred);
-	} catch (term_t& t) {
-		return 0;
-	}
-}
 template <typename ...T>
 int Pl(const char* const szMod, const char* const szPred, T... args)
 {