revised and improved the Unicode glyph-to-byte conversion heuristics

Previously almost all glyph-to-byte offset conversions consulted
Scintilla's line index and counted characters on the resulting line.
For instance a simple expression like `.+1J` would scan the same line
twice completely, which would be very slow on pathologically long lines.
Even insertions did that due to having to update the ^Y ranges.
If you repeat such an operation over all characters as in `<.+1:J;>`
you would have complexity O(n^2) for n = line length.
Only commands with an explicit relative nature like `C` and `A` would
use teco_view_glyph2bytes_relative() which scans beginning at dot
as long as the relative movement is less than 1024 glyphs.

Wit the new heuristics almost all glyph-to-byte and byte-to-glyph
conversions can make use of that optimization.
This requires that dot must at all times be known in glyphs as well -
the byte position is managed by Scintilla (SCI_GETCURRENTPOS).
We therefore introduced teco_current_doc_set_dot() and
teco_current_doc_get_dot() to update dot in the current buffer or
Q-Register -- it cannot be stored along with the view since
Q-Registers share a single view.
A number of auxiliary functions have been introduced for
converting relative to a known (glyphs,bytes) offset pair
and for converting absolute and relative positions with regard
to the current doc and SCI_GETCURRENTPOS position.
Of course this is error-prone since the glyph and dot positions
are interdependant - they must always be kept in sync.

With these new optimizations even pathologically long lines can
(usually) be managed even in UTF-8 documents.
It does not address slow-downs in Scintilla's line layout, yet.
grosciteco.tes for instance runs twice as fast now.

1 files changed, 13 insertions, 5 deletions

diff --git a/src/qreg.c b/src/qreg.c
index 8ef82c0..dae4c9b 100644
--- a/src/qreg.c
+++ b/src/qreg.c
@@ -237,8 +237,10 @@ teco_qreg_plain_get_character(teco_qreg_t *qreg, teco_int_t position,
 
 	teco_doc_edit(&qreg->string, teco_default_codepage());
 
+	sptr_t curpos = teco_view_ssm(teco_qreg_view, SCI_GETCURRENTPOS, 0, 0);
 	sptr_t len = teco_view_ssm(teco_qreg_view, SCI_GETLENGTH, 0, 0);
-	gssize off = teco_view_glyphs2bytes(teco_qreg_view, position);
+	gssize off = teco_view_glyphs2bytes_rel(teco_qreg_view, qreg->string.dot, curpos,
+	                                        position - qreg->string.dot);
 
 	*chr = off >= 0 && off != len ? teco_view_get_character(teco_qreg_view, off, len) : -1;
 
@@ -256,8 +258,10 @@ teco_qreg_plain_get_length(teco_qreg_t *qreg, GError **error)
 
 	teco_doc_edit(&qreg->string, teco_default_codepage());
 
+	sptr_t curpos = teco_view_ssm(teco_qreg_view, SCI_GETCURRENTPOS, 0, 0);
 	sptr_t len = teco_view_ssm(teco_qreg_view, SCI_GETLENGTH, 0, 0);
-	teco_int_t ret = teco_view_bytes2glyphs(teco_qreg_view, len);
+	teco_int_t ret = teco_view_bytes2glyphs_rel(teco_qreg_view, qreg->string.dot,
+	                                            curpos, len - curpos);
 
 	if (teco_qreg_current)
 		teco_doc_edit(&teco_qreg_current->string, 0);
@@ -396,7 +400,7 @@ teco_qreg_plain_new(const gchar *name, gsize len)
 static gboolean
 teco_qreg_dot_set_integer(teco_qreg_t *qreg, teco_int_t value, GError **error)
 {
-	gssize pos = teco_interface_glyphs2bytes(value);
+	gssize pos = teco_interface_glyphs2bytes_absdot(value);
 	if (pos < 0) {
 		g_set_error_literal(error, TECO_ERROR, TECO_ERROR_MOVE,
 		                    "Attempt to move pointer off page when setting Q-Register \":\"");
@@ -404,6 +408,11 @@ teco_qreg_dot_set_integer(teco_qreg_t *qreg, teco_int_t value, GError **error)
 	}
 
 	teco_interface_ssm(SCI_GOTOPOS, pos, 0);
+	/*
+	 * FIXME: Currently emits undo tokens.
+	 * But we could just get rid of the undo_set_integer() callback.
+	 */
+	teco_current_doc_set_dot(value);
 	return TRUE;
 }
 
@@ -420,8 +429,7 @@ teco_qreg_dot_undo_set_integer(teco_qreg_t *qreg, GError **error)
 static gboolean
 teco_qreg_dot_get_integer(teco_qreg_t *qreg, teco_int_t *ret, GError **error)
 {
-	sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
-	*ret = teco_interface_bytes2glyphs(pos);
+	*ret = teco_current_doc_get_dot();
 	return TRUE;
 }