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, 8 insertions, 3 deletions

diff --git a/src/symbols.c b/src/symbols.c
index 944d01d..798b89c 100644
--- a/src/symbols.c
+++ b/src/symbols.c
@@ -321,8 +321,13 @@ teco_state_scintilla_lparam_done(teco_machine_main_t *ctx, const teco_string_t *
 
 	sptr_t lParam = 0;
 
+	if (ctx->scintilla.iMessage == SCI_SETILEXER &&
+	    !teco_string_cmp(str, "sciteco", 7)) {
+		/* perform lexing in the container (see teco_lexer_style()) */
+		lParam = 0;
+	}
 #ifdef HAVE_LEXILLA
-	if (ctx->scintilla.iMessage == SCI_SETILEXER) {
+	else if (ctx->scintilla.iMessage == SCI_SETILEXER) {
 		if (teco_string_contains(str, '\0')) {
 			g_set_error_literal(error, TECO_ERROR, TECO_ERROR_FAILED,
 			                    "Lexer name must not contain null-byte.");
@@ -336,9 +341,9 @@ teco_state_scintilla_lparam_done(teco_machine_main_t *ctx, const teco_string_t *
 			            "Lexilla lexer \"%s\" not found.", lexer);
 			return NULL;
 		}
-	} else
+	}
 #endif
-	if (str->len > 0) {
+	else if (str->len > 0) {
 		/*
 		 * NOTE: There may even be messages that read strings
 		 * with embedded nulls.