implemented Scintilla lexer for SciTECO code, i.e. TECO syntax highlighting

* this works by embedding the SciTECO parser and driving it always (exclusively)
  in parse-only mode.
* A new teco_state_t::style determines the Scintilla style for any character
  accepted in the given state.
* Therefore, the SciTECO lexer is always 100% exact and corresponds to the current
  SciTECO grammer - it does not have to be maintained separately.
  There are a few exceptions and tweaks, though.
* The contents of curly-brace escapes (`@^Uq{...}`) are rendered as ordinary
  code using a separate parser instance.
  This can be disabled with the lexer.sciteco.macrodef property.
  Unfortunately, SciTECO does not currently allow setting lexer properties (FIXME).
* Labels and comments are currently styled the same.
  This could change in the future once we introduce real comments.
* Lexers are usually implemented in C++, but I did not want to draw in C++.
  Especially not since we'd have to include parser.h and other SciTECO headers,
  that really do not want to keep C++-compatible.
  Instead, the lexer is implemented "in the container".
  @ES/SCI_SETILEXER/sciteco/ is internally translated to SCI_SETILEXER(NULL)
  and we get Scintilla notifications when styling the view becomes necessary.
  This is then centrally forwarded to the teco_lexer_style() which
  uses the ordinary teco_view_ssm() API for styling.
* Once the command line becomes a Scintilla view even on Curses,
  we can enabled syntax highlighting of the command line macro.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/lexer.h b/src/lexer.h
new file mode 100644
index 0000000..87b0d0f
--- /dev/null
+++ b/src/lexer.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2012-2024 Robin Haberkorn
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <glib.h>
+
+#include "view.h"
+
+/** Scintilla style ids for lexing SciTECO code */
+typedef enum {
+	SCE_SCITECO_DEFAULT	= 0,
+	SCE_SCITECO_COMMAND	= 1,
+	SCE_SCITECO_OPERATOR	= 2,
+	SCE_SCITECO_QREG	= 3,
+	SCE_SCITECO_STRING	= 4,
+	SCE_SCITECO_NUMBER	= 5,
+	SCE_SCITECO_LABEL	= 6,
+	SCE_SCITECO_COMMENT	= 7,
+	SCE_SCITECO_INVALID	= 8
+} teco_style_t;
+
+void teco_lexer_style(teco_view_t *view, gsize end);