[util] implement 'compile_filter()' (#5262)

https://github.com/mikf/gallery-dl/issues/5262#issuecomment-2477029728

allow (theoretically*) all filter expression statements
to be a list of individual filters

(*) except for 'filename' and 'directory' conditionals,
as dict keys cannot be lists

gallery_dl/job.py

@@ -598,7 +598,7 @@ class DownloadJob(Job):
 
                 skip_filter = cfg("skip-filter")
                 if skip_filter:
-                    self._skipftr = util.compile_expression(skip_filter)
+                    self._skipftr = util.compile_filter(skip_filter)
                 else:
                     self._skipftr = None
         else:
@@ -660,7 +660,7 @@ class DownloadJob(Job):
         expr = options.get("filter") if options else None
 
         if expr:
-            condition = util.compile_expression(expr)
+            condition = util.compile_filter(expr)
             for hook, callback in hooks.items():
                 self.hooks[hook].append(functools.partial(
                     self._call_hook, callback, condition))

gallery_dl/path.py

@@ -38,7 +38,7 @@ class PathFormat():
                 filename_fmt = extractor.filename_fmt
             elif isinstance(filename_fmt, dict):
                 self.filename_conditions = [
-                    (util.compile_expression(expr),
+                    (util.compile_filter(expr),
                      formatter.parse(fmt, kwdefault).format_map)
                     for expr, fmt in filename_fmt.items() if expr
                 ]
@@ -57,7 +57,7 @@ class PathFormat():
                 directory_fmt = extractor.directory_fmt
             elif isinstance(directory_fmt, dict):
                 self.directory_conditions = [
-                    (util.compile_expression(expr), [
+                    (util.compile_filter(expr), [
                         formatter.parse(fmt, kwdefault).format_map
                         for fmt in fmts
                     ])

gallery_dl/util.py

@@ -734,6 +734,12 @@ def compile_expression_tryexcept(expr, name="<expr>", globals=None):
 compile_expression = compile_expression_tryexcept
 
 
+def compile_filter(expr, name="<filter>", globals=None):
+    if not isinstance(expr, str):
+        expr = "(" + ") and (".join(expr) + ")"
+    return compile_expression(expr, name, globals)
+
+
 def import_file(path):
     """Import a Python module from a filesystem path"""
     path, name = os.path.split(path)
@@ -964,10 +970,8 @@ class FilterPredicate():
     """Predicate; True if evaluating the given expression returns True"""
 
     def __init__(self, expr, target="image"):
-        if not isinstance(expr, str):
-            expr = "(" + ") and (".join(expr) + ")"
         name = "<{} filter>".format(target)
-        self.expr = compile_expression(expr, name)
+        self.expr = compile_filter(expr, name)
 
     def __call__(self, _, kwdict):
         try:

test/test_util.py

@@ -349,6 +349,15 @@ class TestCompileExpression(unittest.TestCase):
         with self.assertRaises(AttributeError):
             expr({"a": 2})
 
+    def test_compile_filter(self):
+        expr = util.compile_filter("a + b * c")
+        self.assertEqual(expr({"a": 1, "b": 2, "c": 3}), 7)
+        self.assertEqual(expr({"a": 9, "b": 9, "c": 9}), 90)
+
+        expr = util.compile_filter(["a % 2 == 0", "b % 3 == 0", "c % 5 == 0"])
+        self.assertTrue(expr({"a": 4, "b": 6, "c": 10}))
+        self.assertFalse(expr({"a": 1, "b": 2, "c": 3}))
+
     def test_custom_globals(self):
         value = {"v": "foobar"}
         result = "8843d7f92416211de9ebb963ff4ce28125932878"