From ff49e9c43cf3180ee1d0f0a7c63d50a926e2fb5e Mon Sep 17 00:00:00 2001
From: Han-Wen Nienhuys <hanwen@xs4all.nl>
Date: Sat, 18 Sep 2004 08:56:08 +0000
Subject: [PATCH] (keepWithTag): add music functions keepWithTag and
 removeWithTag.

---
 ChangeLog                         |  3 +++
 Documentation/user/notation.itely |  9 +++++----
 input/regression/tag-filter.ly    |  8 ++++----
 ly/music-functions-init.ly        | 21 +++++++++++++++++++++
 scm/music-functions.scm           | 10 +---------
 scripts/convert-ly.py             |  3 ++-
 6 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 9cac9e3e14..27e9139270 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2004-09-18  Han-Wen Nienhuys   <hanwen@xs4all.nl>
 
+	* ly/music-functions-init.ly (keepWithTag): add music functions
+	keepWithTag and removeWithTag
+
 	* lily/quote-iterator.cc (Quote_iterator): init transposed_musics_.
 
 	* lily/accidental-engraver.cc (recent_enough): interpret laziness
diff --git a/Documentation/user/notation.itely b/Documentation/user/notation.itely
index d1c0efa885..58673e3da6 100644
--- a/Documentation/user/notation.itely
+++ b/Documentation/user/notation.itely
@@ -5383,19 +5383,20 @@ to an articulation, for example,
 
 This defines a note with a conditional fingering indication.
 
-By applying the @code{remove-tag} function, tagged expressions can be
-filtered.  For example,
+By applying the @code{removeTag} music function, tagged expressions
+can be filtered.  For example,
 @example
 <<
   @var{the music}
-  \applymusic #(remove-tag 'score) @var{the music}
-  \applymusic #(remove-tag 'part) @var{the music}
+  \onlyWithTag #'score @var{the music}
+  \onlyWithTag #'part @var{the music}
 >>
 @end example
 would yield
 
 @lilypondfile[quote]{tag-filter.ly}
 
+
 The argument of the @code{\tag} command should be a symbol, or a list
 of symbols, for example,
 @example
diff --git a/input/regression/tag-filter.ly b/input/regression/tag-filter.ly
index 5b2bd7df08..004f308631 100644
--- a/input/regression/tag-filter.ly
+++ b/input/regression/tag-filter.ly
@@ -1,5 +1,5 @@
 
-\version "2.3.16"
+\version "2.3.17"
 \header {
 
 texidoc = "The @code{\\tag} command marks music expressions with a
@@ -31,18 +31,18 @@ common =
 
 
 \score {
-     \simultaneous { 
+    \simultaneous { 
     \new Staff {
 	\set Staff.instrument = #"both"
 	\common
 	}
     \new Staff {
 	\set Staff.instrument = #"part"
-	\applymusic #(remove-tag 'score) \common
+	\keepWithTag #'part \common
 	}
     \new Staff {
 	\set Staff.instrument = #"score"
-	\applymusic #(remove-tag 'part) \common
+	\keepWithTag #'score \common
 	}
     }
 }
diff --git a/ly/music-functions-init.ly b/ly/music-functions-init.ly
index a36284df32..0410976cbb 100644
--- a/ly/music-functions-init.ly
+++ b/ly/music-functions-init.ly
@@ -48,6 +48,27 @@ makeClusters = #(def-music-function
 		(music-map note-to-cluster arg))
 
 
+removeWithTag = 
+#(def-music-function
+  (location tag music) (symbol? ly:music?)
+  (music-filter
+   (lambda (m)
+    (let* ((tags (ly:music-property m 'tags))
+	    (res (memq tag tags)))
+       (not res)))))
+	      
+keepWithTag =
+#(def-music-function
+  (location tag music) (symbol? ly:music?)
+  (music-filter
+   (lambda (m)
+    (let* ((tags (ly:music-property m 'tags))
+	    (res (memq tag tags)))
+       (or
+	(eq? tags '())
+	(memq tag tags))))
+   music))
+
 %{
 
 TODO:
diff --git a/scm/music-functions.scm b/scm/music-functions.scm
index aa3ecb9fb0..20b88d111c 100644
--- a/scm/music-functions.scm
+++ b/scm/music-functions.scm
@@ -48,7 +48,7 @@
       (set! (ly:music-property music 'elements) filtered-es)
       (set! (ly:music-property music 'articulations) filtered-as)
       ;; if filtering emptied the expression, we remove it completely.
-      (if (or (pred? music)
+      (if (or (not (pred? music))
 	      (and (eq? filtered-es '()) (not (ly:music? e))
 		   (or (not (eq? es '()))
 		       (ly:music? e))))
@@ -60,14 +60,6 @@
       music
       (make-music 'Music)))	  ;must return music.
 
-(define-public (remove-tag tag)
-  (lambda (mus)
-    (music-filter
-     (lambda (m)
-       (let* ((tags (ly:music-property m 'tags))
-	      (res (memq tag tags)))
-	 res))
-     mus)))
 
 (define-public (display-music music)
   "Display music, not done with music-map for clarity of presentation."
diff --git a/scripts/convert-ly.py b/scripts/convert-ly.py
index ad5bfd3cc1..74a62ff7d2 100644
--- a/scripts/convert-ly.py
+++ b/scripts/convert-ly.py
@@ -2199,7 +2199,8 @@ fold \new FooContext \foomode into \foo.'''))
 
 def conv (str):
 	str = re.sub (r'(slur|stem|phrasingSlur|tie|dynamic|dots|tuplet|arpeggio|)Both', r'\1Neutral', str)
-
+	str = re.sub (r"\\applymusic\s*#\(remove-tag\s*'([a-z-0-9]+)\)",
+		      r"\\removeTag #'\1", str)
 	return str
 
 conversions.append (((2, 3, 17), conv,
-- 
2.39.2