the SciTECO parser is Unicode-based now (refs #5)

The following rules apply:
 * All SciTECO macros __must__ be in valid UTF-8, regardless of the
   the register's configured encoding.
   This is checked against before execution, so we can use glib's non-validating
   UTF-8 API afterwards.
 * Things will inevitably get slower as we have to validate all macros first
   and convert to gunichar for each and every character passed into the parser.
   As an optimization, it may make sense to have our own inlineable version of
   g_utf8_get_char() (TODO).
   Also, Unicode glyphs in syntactically significant positions may be case-folded -
   just like ASCII chars were. This is is of course slower than case folding
   ASCII. The impact of this should be measured and perhaps we should restrict
   case folding to a-z via teco_ascii_toupper().
 * The language itself does not use any non-ANSI characters, so you don't have to
   use UTF-8 characters.
 * Wherever the parser expects a single character, it will now accept an arbitrary
   Unicode/UTF-8 glyph as well.
   In other words, you can call macros like M§ instead of having to write M[§].
   You can also get the codepoint of any Unicode character with ^^x.
   Pressing an Unicode character in the start state or in Ex and Fx will now
   give a sane error message.
 * When pressing a key which produces a multi-byte UTF-8 sequence, the character
   gets translated back and forth multiple times:
   1. It's converted to an UTF-8 string, either buffered or by IME methods (Gtk).
      On Curses we could directly get a wide char using wget_wch(), but it's
      not currently used, so we don't depend on widechar curses.
   2. Parsed into gunichar for passing into the edit command callbacks.
      This also validates the codepoint - everything later on can assume valid
      codepoints and valid UTF-8 strings.
   3. Once the edit command handling decides to insert the key into the command line,
      it is serialized back into an UTF-8 string as the command line macro has
      to be in UTF-8 (like all other macros).
   4. The parser reads back gunichars without validation for passing into
      the parser callbacks.
 * Flickering in the Curses UI and Pango warnings in Gtk, due to incompletely
   inserted and displayed UTF-8 sequences, are now fixed.

1 files changed, 14 insertions, 6 deletions

diff --git a/doc/sciteco.7.template b/doc/sciteco.7.template
index a5b7f4a..d0574d7 100644
--- a/doc/sciteco.7.template
+++ b/doc/sciteco.7.template
@@ -87,10 +87,6 @@ regular commands for command-line editing.
 .
 When the user presses a key or key-combination it is first translated
 to an UTF-8 string.
-All immediate editing commands and regular \*(ST commands however operate on
-a language based solely on
-.B ASCII
-codes, which is a subset of Unicode.
 The rules for translating keys are as follows:
 .RS
 .IP 1. 4
@@ -138,6 +134,18 @@ This feature is called function key macros and explained in the
 next subsection.
 .RE
 .
+.LP
+All immediate editing commands and regular \*(ST commands however operate on
+a language based solely on
+.B ASCII
+codes, which is a subset of Unicode.
+\# This is because we cannot assume the presence of any particular non-ANSI
+\# symbol on a user's keyboard.
+Since the \*(ST parser is Unicode-aware, this does not exclude
+using Unicode glyphs wherever a single character is expected,
+ie. \fB^^\fIx\fR and \fBU\fIq\fR works with arbitrary Unicode glyphs.
+All \*(ST macros must be in valid UTF-8.
+.
 .SS Function Key Macros
 .
 .SCITECO_TOPIC "function key"
@@ -1082,8 +1090,8 @@ Consequently when querying the code at a character position
 or inserting characters by code, the code may be an Unicode
 codepoint instead of byte-sized integer.
 .LP
-Currently, \*(ST supports UTF-8 and single-byte ANSI encodings,
-that can also be used for editing raw binary files.
+Currently, \*(ST supports buffers in UTF-8 and single-byte
+ANSI encodings, that can also be used for editing raw binary files.
 \# You can configure other single-byte code pages with EE,
 \# but there isn't yet any way to insert characters.
 UTF-8 is the default codepage for new buffers and Q-Registers