add petri net renderer (graphviz-based)

examples/petrinet/renderer.py

@@ -0,0 +1,29 @@
+from api.od import ODAPI
+from concrete_syntax.graphviz.make_url import make_url
+
+def render_petri_net(od: ODAPI):
+    dot = ""
+    dot += "rankdir=LR;"
+    dot += "center=true;"
+    dot += "margin=1;"
+    dot += "nodesep=1;"
+    dot += "edge [arrowhead=vee];"
+    dot += "node[fontname=Arial,fontsize=10];\n"
+    dot += "subgraph places {"
+    dot += "  node [shape=circle,fixedsize=true,label=\"\", height=.3,width=.3];"
+    for _, place_state in od.get_all_instances("PlaceState"):
+        place = od.get_target(od.get_outgoing(place_state, "of")[0])
+        place_name = od.get_name(place)
+        num_tokens = od.get_slot_value(place_state, "numTokens")
+        dot += f"  {place_name} [label=\"{place_name}\\n\\n{'●'*num_tokens}\\n\\n­\"];\n"
+    dot += "}\n"
+    dot += "subgraph transitions {"
+    dot += "  node [shape=rect,fixedsize=true,height=.4,width=.15,style=filled,fillcolor=black,color=white];\n"
+    for transition_name, _ in od.get_all_instances("Transition"):
+        dot += f"  {transition_name} [label=\"{transition_name}\\n\\n\\n\\n­\"];\n"
+    dot += "}\n"
+    for _, arc in od.get_all_instances("arc"):
+        src_name = od.get_name(od.get_source(arc))
+        tgt_name = od.get_name(od.get_target(arc))
+        dot += f"{src_name} -> {tgt_name};"
+    return make_url(dot, engine="circo")