1 files changed, 73 insertions, 0 deletions
diff --git a/pandoc-fable-filter b/pandoc-fable-filter
new file mode 100755
index 0000000..0efcc06
--- /dev/null
+++ b/pandoc-fable-filter
@@ -0,0 +1,73 @@
+#!/usr/bin/env python3
+
+"""
+Pandoc filter to process code blocks with class "plantuml" into
+plant-generated images.
+Needs `plantuml.jar` from http://plantuml.com/.
+"""
+
+import os
+import sys
+import subprocess
+
+from pandocfilters import toJSONFilter, Para, Image
+from pandocfilters import get_filename4code, get_caption, get_extension
+
+
+kinds = {
+    'plantuml': {
+        'tag': 'plantuml',
+        'argv': lambda src, dest: ['plantuml', '-tsvg', '-o', '.', src],
+        'ext': '.uml',
+        'prefix': b'@startuml\n',
+        'suffix': b'\n@enduml\n',
+    },
+    'dot': {
+        'tag': 'dot',
+        'argv': lambda src, dest: ['dot', '-Tsvg', '-o', dest, src],
+        'ext': '.dot',
+        'prefix': b'digraph foo {\n',
+        'suffix': b'}\n',
+    },
+}
+
+
+def process_to_svg(kind, ident, classes, keyvals, code, format_):
+    caption, typef, keyvals = get_caption(keyvals)
+
+    filename = get_filename4code(kind['tag'], code)
+    filetype = get_extension(format_, "png", html="svg", latex="svg")
+
+    src = filename + kind['ext']
+    dest = filename + '.' + filetype
+
+    if not os.path.isfile(dest):
+        txt = code.encode(sys.getfilesystemencoding())
+        txt = kind['prefix'] + txt + kind['suffix']
+        with open(src, "wb") as f:
+            f.write(txt)
+
+        func = kind['argv']
+        argv = func(src, dest)
+        subprocess.check_call(argv)
+        sys.stderr.write('Created image ' + dest + '\n')
+
+    return Para([Image([ident, [], keyvals], caption, [dest, typef])])
+
+
+def combo(key, value, format_, _):
+    if key == 'CodeBlock':
+        [[ident, classes, keyvals], code] = value
+
+        for tag, kind in kinds.items():
+            if tag in classes:
+                return process_to_svg(
+                    kind, ident, classes, keyvals, code, format_)
+
+
+def main():
+    toJSONFilter(combo)
+
+
+if __name__ == "__main__":
+    main()