Display dictionary entries with empty values on the same line.

* ccwl/yaml.scm (display-dictionary-entry): If value is an empty array
or dictionary, display it on the same line.
(scm->yaml): Go to next line after printing empty array.
* tests/yaml.scm: New file.
* tests/yaml.scm ("dictionary entries with empty arrays and
dictionaries for values must render on the same line"): New test case.

2 files changed, 24 insertions, 6 deletions

diff --git a/ccwl/yaml.scm b/ccwl/yaml.scm
index f24d27e..0c0bf1d 100644
--- a/ccwl/yaml.scm
+++ b/ccwl/yaml.scm
@@ -53,13 +53,16 @@ ATOM is a symbol."
      (display-atom key port)
      (display ":" port)
      (match value
-       ((or #(_ ...)
-            ((_ . _) (_ . _) ...))
+       ;; If value is an empty array or dictionary, display it on the
+       ;; same line.
+       ((or #() ())
+        (display " " port)
+        (scm->yaml value port level))
+       ;; Else, display it on the next line.
+       (_
         (newline port)
         (indent-level port (1+ level))
-        (scm->yaml value port (1+ level)))
-       (_ (display " " port)
-          (scm->yaml value port level))))))
+        (scm->yaml value port (1+ level)))))))
 
 (define* (scm->yaml scm #:optional (port (current-output-port)) (level 0))
   "Convert SCM, an S-expression tree, to YAML and display to
@@ -72,7 +75,8 @@ PORT. LEVEL is an internal recursion variable."
                  (display-array-element element port level))
                tail))
     (#()
-     (display "[]" port))
+     (display "[]" port)
+     (newline port))
     ((head tail ...)
      (display-dictionary-entry head port level)
      (for-each (lambda (entry)
diff --git a/tests/yaml.scm b/tests/yaml.scm
new file mode 100644
index 0000000..767cdff
--- /dev/null
+++ b/tests/yaml.scm
@@ -0,0 +1,14 @@
+(use-modules (ccwl yaml)
+             (srfi srfi-64))
+
+(test-begin "yaml")
+
+(test-equal "dictionary entries with empty arrays and dictionaries for values must render on the same line"
+  (scm->yaml-string
+   '((foo . #())
+     (bar)))
+  "foo: []
+bar: {}
+")
+
+(test-end "yaml")