add new, faster css prettifier :tada:

1 files changed, 56 insertions, 11 deletions

diff --git a/mitmproxy/contentviews/css.py b/mitmproxy/contentviews/css.py
index 353a3257..8fa09ed3 100644
--- a/mitmproxy/contentviews/css.py
+++ b/mitmproxy/contentviews/css.py
@@ -1,8 +1,51 @@
-import logging
+import re
+import time
 
-import cssutils
+from mitmproxy.contentviews import base
+from mitmproxy.utils import strutils
 
-from . import base
+"""
+A custom CSS prettifier. Compared to other prettifiers, its main features are:
+
+- Implemented in pure Python.
+- Modifies whitespace only.
+- Works with any input.
+- Considerably faster than e.g. cssutils.
+"""
+
+CSS_SPECIAL_AREAS = (
+    ("'", strutils.NO_ESCAPE + "'"),
+    ('"', strutils.NO_ESCAPE + '"'),
+    (r"/\*", r"\*/"),
+    ("//", "$")
+)
+CSS_SPECIAL_CHARS = "{};:"
+
+
+def beautify(data: str, indent: str = "    "):
+    """Beautify a string containing CSS code"""
+    data = strutils.escape_special_areas(
+        data.strip(),
+        CSS_SPECIAL_AREAS,
+        CSS_SPECIAL_CHARS,
+    )
+
+    # Add newlines
+    data = re.sub(r"\s*;\s*", ";\n", data)
+    data = re.sub(r"\s*{\s*", " {\n", data)
+    data = re.sub(r"\s*}\s*", "\n}\n\n", data)
+
+    # Fix incorrect ":" placement
+    data = re.sub(r"\s*:\s*(?=[^{]+})", ": ", data)
+    # Fix no space after ","
+    data = re.sub(r"\s*,\s*", ", ", data)
+
+    # indent
+    data = re.sub("\n[ \t]+", "\n", data)
+    data = re.sub("\n(?![}\n])(?=[^{]*})", "\n" + indent, data)
+
+    data = strutils.unescape_special_areas(data)
+    return data.rstrip("\n") + "\n"
 
 
 class ViewCSS(base.View):
@@ -13,13 +56,15 @@ class ViewCSS(base.View):
     ]
 
     def __call__(self, data, **metadata):
-        cssutils.log.setLevel(logging.CRITICAL)
-        cssutils.ser.prefs.keepComments = True
-        cssutils.ser.prefs.omitLastSemicolon = False
-        cssutils.ser.prefs.indentClosingBrace = False
-        cssutils.ser.prefs.validOnly = False
+        data = data.decode("utf8", "surrogateescape")
+        beautified = beautify(data)
+        return "CSS", base.format_text(beautified)
 
-        sheet = cssutils.parseString(data)
-        beautified = sheet.cssText
 
-        return "CSS", base.format_text(beautified)
+if __name__ == "__main__":  # pragma: no cover
+    with open("../tools/web/static/vendor.css") as f:
+        data = f.read()
+
+    t = time.time()
+    x = beautify(data)
+    print("Beautifying vendor.css took {:.2}s".format(time.time() - t))