Add Filter interace, class for context used by filters

* Move filter utils to a new file

http/filters/common.py

@@ -1,31 +1,7 @@
 # Common filters
+from filters.utils import encode_number, decode_number
 
-def encode_number(number):
-    result = ''
-
-    while number != 0:
-        number, rem = divmod(number, 10)
-
-        rem = chr(ord('A') + rem)
-
-        result = rem + result
-
-    return result
-
-
-def decode_number(string):
-    result = ''
-
-    while string != '':
-        string, char = string[:-1], string[-1]
-
-        char = str(ord(char) - ord('A'))
-
-        result = char + result
-
-    return int(result)
-
-
+new_filters = []
 filters = []
 exec(open('dtscomp.py').read())
 exec(open('ident.py').read())

http/filters/utils.py

@@ -0,0 +1,86 @@
+import re
+import os
+from dataclasses import dataclass
+from typing import Callable, List
+from query import Query
+
+# Context data used by Filters
+# tag: browsed version, unqoted
+# family: family of file
+# path: path of file
+# get_ident_url: function that returns URL to identifier passed as argument
+# get_absolute_source_url: function that returns a URL to file with absolute path passed as an argument
+# get_relative_source_url: function that returns a URL to file in directory of current file
+@dataclass
+class FilterContext:
+    query: Query
+    tag: str
+    family: str
+    filepath: str
+    get_ident_url: str
+    get_absolute_source_url: Callable[[str], str]
+    get_relative_source_url: Callable[[str], str]
+
+# Filter interface/base class
+class Filter:
+    def __init__(self, path_exceptions: List[str] = []):
+        self.path_exceptions = path_exceptions
+
+    # Return True if filter can be applied to file with path
+    def check_if_applies(self, ctx: FilterContext) -> bool:
+        for p in self.path_exceptions:
+            if re.match(p, ctx.filepath):
+                return False
+
+        return True
+
+    # Add information required by filter by transforming raw source code.
+    # Known identifiers are marked by '\033[31m' and '\033[0m'
+    def transform_raw_code(self, ctx: FilterContext, code: str) -> str:
+        return code
+
+    # Replace information left by `transform_raw_code` with target HTML
+    # html: HTML output from code formatter
+    def untransform_formatted_code(self, ctx: FilterContext, html: str) -> str:
+        return html
+
+
+# Returns true if filename from filepath, with removed extension, is in the
+# allowed_filenames_without_ext iterable
+def filename_without_ext_matches(filepath: str, allowed_filenames_without_ext) -> bool:
+    filename = os.path.basename(filepath)
+    filename_without_ext, _ = os.path.splitext(filename)
+    return filename_without_ext in allowed_filenames_without_ext
+
+# Returns true if extension of filename from filepath is in the
+# allowed_extensions iterable
+def extension_matches(filepath: str, allowed_extensions) -> bool:
+    _, file_ext_dot = os.path.splitext(filepath)
+    file_ext = file_ext_dot[1:].lower()
+    return file_ext in allowed_extensions
+
+
+# Encodes an integer into a string of characters (A-J)
+# encode_number(10239) = 'BACDJ'
+def encode_number(number):
+    result = ''
+
+    while number != 0:
+        number, rem = divmod(number, 10)
+        rem = chr(ord('A') + rem)
+        result = rem + result
+
+    return result
+
+# Decodes a string of characters returned by encode_number into an integer
+# decode_number('BACDJ') = 10239
+def decode_number(string):
+    result = ''
+
+    while string != '':
+        string, char = string[:-1], string[-1]
+        char = str(ord(char) - ord('A'))
+        result = char + result
+
+    return int(result)
+