Merge pull request protocolbuffers#481 from haberman/wrapping-upb-doc

First version of a doc describing how to wrap upb

.gitignore

@@ -1,4 +1,4 @@
-*.s??
+*.sw?
 obj/
 lib/
 bazel-*

doc/render.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+
+import subprocess
+import sys
+import shutil
+import os
+
+if len(sys.argv) < 2:
+    print("Must pass a filename argument")
+    sys.exit(1)
+
+in_filename = sys.argv[1]
+out_filename = in_filename.replace(".in.md", ".md")
+out_dir = in_filename.replace(".in.md", "")
+
+if in_filename == out_filename:
+    print("File must end in .in.md")
+    sys.exit(1)
+
+if os.path.isdir(out_dir):
+    shutil.rmtree(out_dir)
+
+os.mkdir(out_dir)
+file_num = 1
+
+with open(out_filename, "wb") as out_file, open(in_filename, "rb") as in_file:
+    for line in in_file:
+        if line.startswith(b"```dot"):
+            dot_lines = []
+            while True:
+                dot_line = next(in_file)
+                if dot_line == b"```\n":
+                    break
+                dot_lines.append(dot_line)
+            dot_input = b"".join(dot_lines)
+            svg_filename = out_dir + "/" + str(file_num) + ".svg"
+            svg = subprocess.check_output(['dot', '-Tsvg', '-o', svg_filename], input=dot_input)
+            out_file.write(b"<div align=center>\n")
+            out_file.write(b"<img src='%s'/>\n" % (svg_filename.encode('utf-8')))
+            out_file.write(b"</div>\n")
+            file_num += 1
+        else:
+            out_file.write(line)