From 02e614f3fa17986c1d15060d159a66dc77c38c36 Mon Sep 17 00:00:00 2001
From: Ian Gulliver <flamingcow@gmail.com>
Date: Sun, 5 Jun 2016 17:24:03 -0700
Subject: [PATCH] Initial commit

---
 minheader.py | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100755 minheader.py

diff --git a/minheader.py b/minheader.py
new file mode 100755
index 0000000..453af4a
--- /dev/null
+++ b/minheader.py
@@ -0,0 +1,142 @@
+#!/usr/bin/python3
+
+import argparse
+import functools
+import os
+import re
+import subprocess
+import sys
+
+
+parser = argparse.ArgumentParser(description='minheader')
+parser.add_argument(
+  '--include-path',
+  dest='include_paths',
+  action='append',
+  required=True)
+parser.add_argument(
+  '--source-file',
+  dest='source_files',
+  action='append',
+  required=True)
+parser.add_argument(
+  '--test-command',
+  dest='test_command',
+  action='store',
+  required=True)
+FLAGS = parser.parse_args()
+
+
+class Error(Exception):
+  pass
+
+
+class IncludeNotFound(Error):
+  pass
+
+
+class MinHeader(object):
+
+  _INCLUDE_RE = re.compile('^#include ["<](?P<include_path>[^>"]+\.[^>"]+)[>"]')
+
+  def __init__(self, include_paths, test_command):
+    self._include_paths = include_paths
+    self._test_command = test_command
+
+  def Minify(self, path):
+    self._Log('%s:\n' % path)
+    self._ClearCaches()
+    assert(self._TestPasses())
+    known_required = {}
+    while self._MinifyPass(path, known_required):
+      pass
+
+  def _MinifyPass(self, path, known_required):
+    lines = self._LoadFile(path)
+    includes = self._FindIncludes(lines)
+    for inc_i, inc_path in includes:
+      if inc_path in known_required:
+        continue
+
+      self._Log('\t%s: ' % inc_path)
+
+      sub_includes = self._FindSubIncludes(inc_path)
+
+      # Is the include useful at all?
+      if self._TestReplacement(path, lines, inc_i, []):
+        self._Log('USELESS\n')
+        return True
+      elif self._TestReplacement(path, lines, inc_i, sub_includes):
+        self._Log('OVERBROAD\n')
+        return True
+      else:
+        self._Log('REQUIRED\n')
+        known_required.add(inc_path)
+        continue
+    return False
+
+  def _Log(self, msg):
+    print(msg, file=sys.stderr, flush=True, end='')
+
+  def _ClearCaches(self):
+    self._FindSubIncludes.cache_clear()
+
+  def _LoadFile(self, path):
+    with open(path, 'r') as fh:
+      return list(fh)
+
+  def _WriteFile(self, path, lines):
+    with open(path, 'w') as fh:
+      for line in lines:
+        fh.write(line)
+
+  def _ReplaceAndWrite(self, path, lines, replace_i, replace_includes):
+    new_lines = list(lines)
+    new_lines[replace_i:replace_i + 1] = ['#include "%s"\n' % x for x in replace_includes]
+    self._WriteFile(path, new_lines)
+
+  def _TestReplacement(self, path, lines, replace_i, replace_includes):
+    try:
+      self._ReplaceAndWrite(path, lines, replace_i, replace_includes)
+      if self._TestPasses():
+        return True
+      else:
+        self._WriteFile(path, lines)
+        return False
+    except:
+      self._WriteFile(path, lines)
+
+  def _FindIncludes(self, lines):
+    ret = []
+    for i, line in enumerate(lines):
+      match = self._INCLUDE_RE.match(line)
+      if match:
+        ret.append((i, match.group('include_path')))
+    return ret
+
+  @functools.lru_cache()
+  def _FindSubIncludes(self, path):
+    full_path = self._FindFile(path)
+    return [x[1] for x in self._FindIncludes(self._LoadFile(full_path))]
+
+  def _FindFile(self, path):
+    for include_path in self._include_paths:
+      full_path = os.path.join(include_path, path)
+      if os.path.exists(full_path):
+        return full_path
+    raise IncludeNotFound(path)
+
+  def _TestPasses(self):
+    return subprocess.call(self._test_command, shell=True) == 0
+
+
+def main():
+  minheader = MinHeader(
+    FLAGS.include_paths,
+    FLAGS.test_command)
+  for path in FLAGS.source_files:
+    minheader.Minify(path)
+
+
+if __name__ == '__main__':
+  main()