# HG changeset patch
# User Tero Marttila <terom@paivola.fi>
# Date 1425936103 -7200
# Node ID 6ba76ac0bc7285d056728c511d353cb64b69fac1
# Parent  75938aa0390b0862885e90e8536c570f57a5b52f
pvl.dot: dot graph output

diff -r 75938aa0390b -r 6ba76ac0bc72 pvl/dot.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pvl/dot.py	Mon Mar 09 23:21:43 2015 +0200
@@ -0,0 +1,85 @@
+import contextlib
+import string
+
+"""
+    Syntax sugar for generating .dot files
+    
+        http://www.graphviz.org/content/dot-language
+        http://www.graphviz.org/content/attrs
+"""
+
+ID = string.ascii_letters + string.digits + '_'
+
+def quote (value):
+    """
+        (quoted) dot word.
+
+        >>> print quote('foo')
+        foo
+        >>> print quote(5)
+        5
+        >>> print quote("five two")
+        "five two"
+    """
+
+    value = str(value)
+    
+    if all(c in ID for c in value):
+        return value
+    else:
+        return '"{value}"'.format(value=value)
+
+def attr_list (**attrs):
+    for name, value in attrs.iteritems():
+        if value is None:
+            continue
+        
+        yield '{name}={value}'.format(name=name, value=quote(value))
+
+def print_stmt (*line, **attrs) :
+    """
+        >>> print_stmt(quote("Foo"), foo="bar")
+          Foo [foo=bar];
+        >>> print_stmt(quote("Foo"), asdf=5, quux="Test Me")
+          Foo [quux="Test Me", asdf=5];
+    """
+
+    print "  {line}{attrs};".format(
+            line    = ' '.join(item for item in line if item is not None),
+            attrs   = ' [' + ', '.join(attr_list(**attrs)) + ']' if attrs else '',
+    )
+
+def print_edge(left, edgeop, right, **attrs):
+    print_stmt(quote(left), edgeop, quote(right), **attrs)
+
+@contextlib.contextmanager
+def print_block (*block, **attrs):
+    """
+        >>> with print_block('graph', 'foo'):
+        ...     print_stmt('foo', '--', 'bar')
+        graph foo {
+          foo -- bar;
+        }
+    """
+
+    print ' '.join(item for item in block if item is not None) + ' {'
+    for attr in attr_list(**attrs):
+        print '  {attr};'.format(attr=attr)
+    yield
+    print '}'
+
+def print_node(node, **attrs):
+    print_stmt(quote(node), **attrs)
+
+def print_graph(id=None, **attrs):
+    """
+        >>> with print_graph(): print_node("foo", label="Foo Bar")
+        graph {
+          foo [label="Foo Bar"];
+        }
+    """
+
+    return print_block('graph', quote(id) if id else None, **attrs)
+
+def print_subgraph(id=None):
+    return print_block('subgraph', quote(id) if id else None)
diff -r 75938aa0390b -r 6ba76ac0bc72 setup.py
--- a/setup.py	Mon Mar 09 21:17:06 2015 +0200
+++ b/setup.py	Mon Mar 09 23:21:43 2015 +0200
@@ -57,6 +57,9 @@
         'pvl.dns',
         'pvl.hosts',
     ],
+    py_modules  = [
+        'pvl.dot',
+    ],
 
     # lib/pvl
     data_files = [