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, 58 insertions, 6 deletions

diff --git a/src/interface.h b/src/interface.h
index a7968d1..9c3d31e 100644
--- a/src/interface.h
+++ b/src/interface.h
@@ -211,21 +211,73 @@ teco_interface_get_codepage(void)
 }
 
 static inline gssize
-teco_interface_glyphs2bytes(teco_int_t pos)
+teco_interface_glyphs2bytes_rel(teco_int_t pos_glyphs, gsize pos, teco_int_t n)
 {
-	return teco_view_glyphs2bytes(teco_interface_current_view, pos);
+	return teco_view_glyphs2bytes_rel(teco_interface_current_view,
+	                                  pos_glyphs, pos, n);
 }
 
 static inline teco_int_t
-teco_interface_bytes2glyphs(gsize pos)
+teco_interface_bytes2glyphs_rel(teco_int_t pos_glyphs, gsize pos, gssize n)
 {
-	return teco_view_bytes2glyphs(teco_interface_current_view, pos);
+	return teco_view_bytes2glyphs_rel(teco_interface_current_view,
+	                                  pos_glyphs, pos, n);
 }
 
+/**
+ * Convert absolute glyph position to bytes.
+ *
+ * This allows for scanning around dot and should be used if
+ * pos can be expected to be close to dot.
+ * Dot in glyphs as set by teco_current_doc_set_dot()
+ * \b must be up to date for this to work.
+ */
+static inline gssize
+teco_interface_glyphs2bytes_absdot(teco_int_t pos)
+{
+	teco_int_t dot = teco_current_doc_get_dot();
+	gsize curpos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+	return teco_interface_glyphs2bytes_rel(dot, curpos, pos-dot);
+}
+
+/**
+ * Convert absolute byte position to glyphs.
+ *
+ * @see teco_interface_glyphs2bytes_absdot
+ */
+static inline teco_int_t
+teco_interface_bytes2glyphs_absdot(gsize pos)
+{
+	teco_int_t dot = teco_current_doc_get_dot();
+	gsize curpos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+	return teco_interface_bytes2glyphs_rel(dot, curpos, pos-curpos);
+}
+
+/**
+ * Convert relative glyph position to bytes.
+ *
+ * Dot in glyphs as set by teco_current_doc_set_dot()
+ * \b must be up to date for this to work.
+ */
 static inline gssize
-teco_interface_glyphs2bytes_relative(gsize pos, teco_int_t n)
+teco_interface_glyphs2bytes_reldot(teco_int_t n)
+{
+	teco_int_t dot = teco_current_doc_get_dot();
+	gsize curpos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+	return teco_interface_glyphs2bytes_rel(dot, curpos, n);
+}
+
+/**
+ * Convert relative byte position to glyphs.
+ *
+ * @see teco_interface_glyphs2bytes_reldot
+ */
+static inline teco_int_t
+teco_interface_bytes2glyphs_reldot(gssize n)
 {
-	return teco_view_glyphs2bytes_relative(teco_interface_current_view, pos, n);
+	teco_int_t dot = teco_current_doc_get_dot();
+	gsize curpos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+	return teco_interface_bytes2glyphs_rel(dot, curpos, n);
 }
 
 static inline teco_int_t