Python: Copy Python extractor to codeql repo

python/extractor/tsg-python/tsg_to_dot.py

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+# Convert output of tree-sitter-graph to dot format.
+
+import sys
+import re
+
+# regular expression to match a node
+node_re = re.compile(r"node (?P<id>\d+)")
+
+# regular expression to match an edge
+edge_re = re.compile(r"edge (?P<from>\d+) -> (?P<to>\d+)")
+
+# regular expression to match a property
+prop_re = re.compile(r"\s+(?P<key>\w+): (?P<value>.*)")
+
+# regular expression to match a link: "[graph node n]"
+link_re = re.compile(r"\[graph node (?P<id>\d+)\]")
+
+with open(sys.argv[1], 'r') as f, open(sys.argv[2], 'w') as out:
+    out.write("digraph G {\n")
+    label = []
+    inside = False
+    node_id = 0
+    links = {}
+    for line in f:
+
+        m = node_re.match(line)
+        if m:
+            if inside:
+                out.write('\\n'.join(label) + "\"];\n")
+            for k, v in links.items():
+                out.write("{} -> {} [label=\"{}\"];\n".format(node_id, v, k))
+            out.write("{id} [label=\"".format(**m.groupdict()))
+            label = ["id={id}".format(**m.groupdict())]
+            inside = True
+            node_id = m.group('id')
+            links = {}
+
+        m = edge_re.match(line)
+        if m:
+            if inside:
+                out.write('\\n'.join(label) + "\"];\n")
+            for k, v in links.items():
+                out.write("{} -> {} [label=\"{}\"];\n".format(node_id, v, k))
+            out.write("{from} -> {to} [label=\"".format(**m.groupdict()))
+            label = []
+            inside = True
+            node_id = 0
+            links = {}
+
+        m = prop_re.match(line)
+        if m:
+            # escape quotes in value
+            label.append("{key}={value}".format(**m.groupdict()).replace('"', '\\"').replace('\\\\"', ''))
+            l = link_re.match(m.group('value'))
+            if l:
+                links[m.group('key')] = l.group('id')
+    out.write('\\n'.join(label) + "\"];\n")
+    for k, v in links.items():
+        out.write("{} -> {} [label=\"{}\"];\n".format(node_id, v, k))
+    out.write("}\n")