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, 17 insertions, 7 deletions

diff --git a/src/doc.h b/src/doc.h
index 3218a70..c4e0f3a 100644
--- a/src/doc.h
+++ b/src/doc.h
@@ -51,10 +51,17 @@ typedef struct {
 
 	/*
 	 * The so called "parameters".
+	 * They are all in bytes.
 	 * Updated/restored only when required
 	 */
-	gint anchor, dot;
-	gint first_line, xoffset;
+	gsize anchor, pos;
+	guint first_line, xoffset;
+
+	/**
+	 * Dot in glyphs.
+	 * This field is always kept up to date.
+	 */
+	teco_int_t dot;
 } teco_doc_t;
 
 /** @memberof teco_doc_t */
@@ -85,8 +92,9 @@ void teco_doc_update_from_doc(teco_doc_t *ctx, const teco_doc_t *from);
 static inline void
 teco_doc_reset(teco_doc_t *ctx)
 {
-	ctx->anchor = ctx->dot = 0;
+	ctx->anchor = ctx->pos = 0;
 	ctx->first_line = ctx->xoffset = 0;
+	ctx->dot = 0;
 }
 
 /** @memberof teco_doc_t */
@@ -98,10 +106,12 @@ teco_doc_undo_reset(teco_doc_t *ctx)
 	 * and called with teco_undo_call() if we really
 	 * wanted to save more memory.
 	 */
-	teco_undo_gint(ctx->anchor);
-	teco_undo_gint(ctx->dot);
-	teco_undo_gint(ctx->first_line);
-	teco_undo_gint(ctx->xoffset);
+	teco_undo_gsize(ctx->anchor);
+	teco_undo_gsize(ctx->pos);
+	teco_undo_guint(ctx->first_line);
+	teco_undo_guint(ctx->xoffset);
+
+	teco_undo_int(ctx->dot);
 }
 
 void teco_doc_exchange(teco_doc_t *ctx, teco_doc_t *other);