moving: make the generic paragraph movement functions work on any buffer

The functions do_para_begin() and do_para_end() can now move through any
buffer, while the functions do_para_begin_void() and do_para_end_void()
operate on the current buffer.  The latter function also returns TRUE
if the last line in the buffer is part of the paragraph.

src/move.c

@@ -172,39 +172,41 @@ void do_page_down(void)
 #ifdef ENABLE_JUSTIFY
 /* Move to the beginning of the first-found beginning-of-paragraph line
  * before the current line. */
-void do_para_begin(void)
+void do_para_begin(filestruct **line)
 {
-	if (openfile->current != openfile->fileage)
-		openfile->current = openfile->current->prev;
+	if ((*line)->prev != NULL)
+		*line = (*line)->prev;
 
-	while (!begpar(openfile->current, 0))
-		openfile->current = openfile->current->prev;
-
-	openfile->current_x = 0;
+	while (!begpar(*line, 0))
+		*line = (*line)->prev;
 }
 
 /* Move down to the beginning of the last line of the current paragraph.
  * Then move down one line farther if there is such a line, or to the
- * end of the current line if not.  A line is the last line of a paragraph
- * if it is in a paragraph, and the next line either is the beginning line
- * of a paragraph or isn't in a paragraph. */
-void do_para_end(void)
+ * end of the current line if not.
+ * A line is the last line of a paragraph if it is
+ * in a paragraph, and the next line either is the beginning line of a
+ * paragraph or isn't in a paragraph.  Return whether the last line of
+ * the paragraph is part of the paragraph (instead of the line following
+ * the paragraph). */
+bool do_para_end(filestruct **line)
 {
-	while (openfile->current != openfile->filebot &&
-				!inpar(openfile->current))
-		openfile->current = openfile->current->next;
+	while ((*line)->next != NULL &&
+				!inpar(*line))
+		*line = (*line)->next;
 
-	while (openfile->current != openfile->filebot &&
-				inpar(openfile->current->next) &&
-				!begpar(openfile->current->next, 0)) {
-		openfile->current = openfile->current->next;
+	while ((*line)->next != NULL &&
+				inpar((*line)->next) &&
+				!begpar((*line)->next, 0)) {
+		*line = (*line)->next;
 	}
 
-	if (openfile->current != openfile->filebot) {
-		openfile->current = openfile->current->next;
-		openfile->current_x = 0;
-	} else
-		openfile->current_x = strlen(openfile->current->data);
+	if ((*line)->next != NULL) {
+		*line = (*line)->next;
+		return FALSE;
+	}
+
+	return TRUE;
 }
 
 /* Move up to first start of a paragraph before the current line. */
@@ -212,7 +214,8 @@ void do_para_begin_void(void)
 {
 	filestruct *was_current = openfile->current;
 
-	do_para_begin();
+	do_para_begin(&openfile->current);
+	openfile->current_x = 0;
 
 	edit_redraw(was_current, CENTERING);
 }
@@ -222,7 +225,10 @@ void do_para_end_void(void)
 {
 	filestruct *was_current = openfile->current;
 
-	do_para_end();
+	if (do_para_end(&openfile->current))
+		openfile->current_x = strlen(openfile->current->data);
+	else
+		openfile->current_x = 0;
 
 	edit_redraw(was_current, CENTERING);
 }

src/proto.h

@@ -363,8 +363,8 @@ void to_last_line(void);
 void do_page_up(void);
 void do_page_down(void);
 #ifdef ENABLE_JUSTIFY
-void do_para_begin(void);
-void do_para_end(void);
+void do_para_begin(filestruct **line);
+bool do_para_end(filestruct **line);
 void do_para_begin_void(void);
 void do_para_end_void(void);
 #endif

src/text.c

@@ -2131,7 +2131,8 @@ bool find_paragraph(size_t *const quote, size_t *const par)
 	/* If the current line isn't in a paragraph, move forward to the
 	 * last line of the next paragraph, if any. */
 	if (!inpar(openfile->current)) {
-		do_para_end();
+		if (do_para_end(&openfile->current))
+			openfile->current_x = strlen(openfile->filebot->data);
 
 		/* If we end up past the beginning of the line, it means that
 		 * we're at the end of the last line of the file, and the line
@@ -2153,14 +2154,15 @@ bool find_paragraph(size_t *const quote, size_t *const par)
 	/* If the current line is in a paragraph and isn't its first line, move
 	 * back to the first line of the paragraph. */
 	if (inpar(openfile->current) && !begpar(openfile->current, 0))
-		do_para_begin();
+		do_para_begin(&openfile->current);
 
 	/* Now current is the first line of the paragraph.  Set quote_len to
 	 * the quotation length of that line, and set par_len to the number
 	 * of lines in this paragraph. */
 	quote_len = quote_length(openfile->current->data);
 	current_save = openfile->current;
-	do_para_end();
+	if (do_para_end(&openfile->current))
+		openfile->current_x = strlen(openfile->filebot->data);
 	par_len = openfile->current->lineno - current_save->lineno;
 
 	/* If we end up past the beginning of the line, it means that we're at