Unicode support for the Q-Register commands (refs #5)

* this required adding several Q-Register vtable methods
* it should still be investigated whether the repeated calling of
  SCI_ALLOCATELINECHARACTERINDEX causes any overhead.

1 files changed, 94 insertions, 6 deletions

diff --git a/src/view.c b/src/view.c
index 6fecdc0..4f959a3 100644
--- a/src/view.c
+++ b/src/view.c
@@ -112,18 +112,20 @@ teco_view_setup(teco_view_t *ctx)
 	teco_view_ssm(ctx, SCI_STYLESETBACK, STYLE_CALLTIP, 0xFFFFFF);
 
 	/*
-	 * Documents are UTF-8 by default and all UTF-8 documents
-	 * are expected to have a character index.
-	 */
-	teco_view_ssm(ctx, SCI_ALLOCATELINECHARACTERINDEX, SC_LINECHARACTERINDEX_UTF32, 0);
-
-	/*
 	 * Since we have patched out Scintilla's original SetRepresentations(),
 	 * it no longer resets them on SCI_SETDOCPOINTER.
 	 * Therefore it is sufficient for all kinds of views to initialize
 	 * the representations only once.
 	 */
 	teco_view_set_representations(ctx);
+
+	/*
+	 * Documents are UTF-8 by default and all UTF-8 documents
+	 * are expected to have a character index.
+	 * This is a property of the document, instead of the view.
+	 */
+	teco_view_ssm(ctx, SCI_ALLOCATELINECHARACTERINDEX,
+	              SC_LINECHARACTERINDEX_UTF32, 0);
 }
 
 TECO_DEFINE_UNDO_CALL(teco_view_ssm, teco_view_t *, unsigned int, uptr_t, sptr_t);
@@ -455,3 +457,89 @@ teco_view_save_to_file(teco_view_t *ctx, const gchar *filename, GError **error)
 
 	return TRUE;
 }
+
+/**
+ * Convert a glyph index to a byte offset as used by Scintilla.
+ *
+ * This is optimized with the "line character index",
+ * which must always be enabled in UTF-8 documents.
+ *
+ * It is also used to validate glyph indexes.
+ *
+ * @param ctx The view to operate on.
+ * @param pos Position in glyphs/characters.
+ * @return Position in bytes or -1 if pos is out of bounds.
+ */
+gssize
+teco_view_glyphs2bytes(teco_view_t *ctx, teco_int_t pos)
+{
+	if (pos < 0)
+		return -1; /* invalid position */
+	if (!pos)
+		return 0;
+
+	if (!(teco_view_ssm(ctx, SCI_GETLINECHARACTERINDEX, 0, 0) &
+	      SC_LINECHARACTERINDEX_UTF32))
+		/* assume single-byte encoding */
+		return pos <= teco_view_ssm(ctx, SCI_GETLENGTH, 0, 0) ? pos : -1;
+
+	sptr_t line = teco_view_ssm(ctx, SCI_LINEFROMINDEXPOSITION, pos,
+	                            SC_LINECHARACTERINDEX_UTF32);
+	sptr_t line_bytes = teco_view_ssm(ctx, SCI_POSITIONFROMLINE, line, 0);
+	pos -= teco_view_ssm(ctx, SCI_INDEXPOSITIONFROMLINE, line,
+	                     SC_LINECHARACTERINDEX_UTF32);
+	return teco_view_ssm(ctx, SCI_POSITIONRELATIVE, line_bytes, pos) ? : -1;
+}
+
+/**
+ * Convert byte offset to glyph/character index without bounds checking.
+ */
+teco_int_t
+teco_view_bytes2glyphs(teco_view_t *ctx, gsize pos)
+{
+	if (!pos)
+		return 0;
+
+	if (!(teco_view_ssm(ctx, SCI_GETLINECHARACTERINDEX, 0, 0) &
+	      SC_LINECHARACTERINDEX_UTF32))
+		/* assume single-byte encoding */
+		return pos;
+
+	sptr_t line = teco_view_ssm(ctx, SCI_LINEFROMPOSITION, pos, 0);
+	sptr_t line_bytes = teco_view_ssm(ctx, SCI_POSITIONFROMLINE, line, 0);
+	return teco_view_ssm(ctx, SCI_INDEXPOSITIONFROMLINE, line,
+	                     SC_LINECHARACTERINDEX_UTF32) +
+	       teco_view_ssm(ctx, SCI_COUNTCHARACTERS, line_bytes, pos);
+}
+
+#define TECO_RELATIVE_LIMIT 1024
+
+/**
+ * Convert a glyph index relative to a byte position to
+ * a byte position.
+ *
+ * Can be used to implement commands with relative character
+ * ranges.
+ * As an optimization, this always counts characters for deltas
+ * smaller than TECO_RELATIVE_LIMIT, so it will be fast
+ * even where the character-index based lookup is too slow
+ * (as on exceedingly long lines).
+ *
+ * @param ctx The view to operate on.
+ * @param pos Byte position to start.
+ * @param n Number of glyphs/characters to the left (negative) or
+ *   right (positive) of pos.
+ * @return Position in bytes or -1 if the resulting position is out of bounds.
+ */
+gssize
+teco_view_glyphs2bytes_relative(teco_view_t *ctx, gsize pos, teco_int_t n)
+{
+	if (!n)
+		return pos;
+	if (ABS(n) > TECO_RELATIVE_LIMIT)
+		return teco_view_glyphs2bytes(ctx, teco_view_bytes2glyphs(ctx, pos) + n);
+
+	sptr_t res = teco_view_ssm(ctx, SCI_POSITIONRELATIVE, pos, n);
+	/* SCI_POSITIONRELATIVE may return 0 even if the offset is valid */
+	return res ? : n > 0 ? -1 : teco_view_bytes2glyphs(ctx, pos)+n >= 0 ? 0 : -1;
+}