Imported Upstream version 2.16.0

[lilypond.git] / input / regression / optional-args-backup.ly

diff --git a/input/regression/optional-args-backup.ly b/input/regression/optional-args-backup.ly
new file mode 100644 (file)
index 0000000..e48cc28
--- /dev/null
+++ b/input/regression/optional-args-backup.ly
@@ -0,0 +1,31 @@
+\version "2.16.0"
+
+\header{
+  texidoc= "Test backup of predicate-based optional music function arguments.
+
+Unit expressions like @code{3\cm} can't be parsed as optional
+arguments in one go since they would require lookahead after @code{3}.
+The predicate is checked after @code{3}, and if it is suitable,
+Lilypond commits to parsing as a unit number, and checks the result
+again.  For the predicate @code{integer?} and @code{3\cm}, you would
+actually get a syntax error (since the combination is no longer an
+integer) rather than Lilypond trying to see @code{3\cm} as two
+separate arguments."
+
+}
+
+\layout { ragged-right = ##t }
+
+test=#(define-void-function (parser location expect . rest)
+       (list? (string? "def1") (integer? "def2") (fraction? "def3") integer?)
+       (if (not (equal? expect rest))
+       (ly:parser-error parser
+        (format #f "Expected ~s, got ~s.\n" expect rest)
+        location)))
+
+twice=2
+
+\test #'("x" 3 (3 . 4) 8)        x 3 3/4 4\twice
+\test #'("x" 3 "def3" 8)         x 3 4\twice
+\test #'("x" 8 "def3" 10)        x 4\twice 5\twice
+\test #'("def1" "def2" "def3" 8) 4\twice