From: David Kastrup <dak@gnu.org>
Date: Mon, 12 Jun 2017 11:44:51 +0000 (+0200)
Subject: Issue 5145/2: Allow $... to specify a markup command
X-Git-Url: https://git.donarmstrong.com/?p=lilypond.git;a=commitdiff_plain;h=c3b51542671a9af5647d4cbc63f7c8ae98c1c2bd

Issue 5145/2: Allow $... to specify a markup command

This is a partial (though more flexible) substitute for \on-the-fly
since it allows to replace

\on-the-fly #(lambda (layout props args) ...)

with

$(let ((fun (lambda (layout props args) ...)))
   (set! (markup-command-signature fun) (list markup?))
   fun)

Namely: ad-hoc written functions (probably most useful when written
using macros) can be employed as markup commands when preceded with $
as long as they have a suitable markup command signature attached.
This feature is mainly added for consistency with music functions.
---

diff --git a/lily/include/lily-imports.hh b/lily/include/lily-imports.hh
index d930f69cf9..1b63a53717 100644
--- a/lily/include/lily-imports.hh
+++ b/lily/include/lily-imports.hh
@@ -86,6 +86,7 @@ namespace Lily {
   extern Variable make_safe_lilypond_module;
   extern Variable make_span_event;
   extern Variable markup_p;
+  extern Variable markup_command_signature;
   extern Variable markup_list_p;
   extern Variable midi_program;
 #if !GUILEV2
diff --git a/lily/lexer.ll b/lily/lexer.ll
index 19f84616f3..21d2fc1acc 100644
--- a/lily/lexer.ll
+++ b/lily/lexer.ll
@@ -417,6 +417,20 @@ BOM_UTF8	\357\273\277
 
 	sval = eval_scm (sval, hi, '$');
 
+	if (YYSTATE == markup && ly_is_procedure (sval))
+	{
+		SCM sig = Lily::markup_command_signature (sval);
+		if (scm_is_true (sig))
+		{
+			yylval = sval;
+			int token = MARKUP_FUNCTION;
+			if (scm_is_true (scm_object_property
+					 (sval, ly_symbol2scm ("markup-list-command"))))
+				token = MARKUP_LIST_FUNCTION;
+			push_markup_predicates (sig);
+			return token;
+		}
+	}
 	int token = scan_scm_id (sval);
 	if (!scm_is_eq (yylval, SCM_UNSPECIFIED))
 		return token;
diff --git a/lily/lily-imports.cc b/lily/lily-imports.cc
index 62e58b603c..f3cd3b1ab2 100644
--- a/lily/lily-imports.cc
+++ b/lily/lily-imports.cc
@@ -80,6 +80,7 @@ namespace Lily {
   Variable make_safe_lilypond_module ("make-safe-lilypond-module");
   Variable make_span_event ("make-span-event");
   Variable markup_p ("markup?");
+  Variable markup_command_signature ("markup-command-signature");
   Variable markup_list_p ("markup-list?");
   Variable midi_program ("midi-program");
 #if !GUILEV2