files structure: move src_paths as a dynamic property, add remove

Plugins wishing to manipulate the Files structure have an append
method but can't dynamically work on src_paths since it's computed
once on Files instanciation

This commits allows plugins to manipulate Files trough append and
remove of file objects while not having to care about the src_paths
since it's now a dynamically computed property

docs/about/release-notes.md

@@ -100,6 +100,9 @@ up horizontal space for better rendering of content like tables (#2193).
   filtering for sections (#2203).
 * Official support for Python 3.9 has been added and support for Python 3.5
   has been dropped.
+* Structure Files object now has a `remove` method to help plugin developers
+  manipulate the Files tree. The corresponding `src_paths` has become a
+  property to accomodate this possible dynamic behavior. See #2305.
 
 ## Version 1.1.2 (2020-05-14)
 

mkdocs/structure/files.py

@@ -15,7 +15,6 @@ class Files:
     """ A collection of File objects. """
     def __init__(self, files):
         self._files = files
-        self.src_paths = {file.src_path: file for file in files}
 
     def __iter__(self):
         return iter(self._files)
@@ -26,6 +25,10 @@ class Files:
     def __contains__(self, path):
         return path in self.src_paths
 
+    @property
+    def src_paths(self):
+        return {file.src_path: file for file in self._files}
+
     def get_file_from_path(self, path):
         """ Return a File instance with File.src_path equal to path. """
         return self.src_paths.get(os.path.normpath(path))
@@ -33,7 +36,10 @@ class Files:
     def append(self, file):
         """ Append file to Files collection. """
         self._files.append(file)
-        self.src_paths[file.src_path] = file
+
+    def remove(self, file):
+        """ Remove file from Files collection. """
+        self._files.remove(file)
 
     def copy_static_files(self, dirty=False):
         """ Copy static files from source to destination. """

mkdocs/tests/structure/file_tests.py

@@ -674,3 +674,26 @@ class TestFiles(PathAssertionMixin, unittest.TestCase):
         self.assertPathIsFile(dest_path)
         with open(dest_path, 'r', encoding='utf-8') as f:
             self.assertEqual(f.read(), 'destination content')
+
+    def test_files_append_remove_src_paths(self):
+        fs = [
+            File('index.md', '/path/to/docs', '/path/to/site', use_directory_urls=True),
+            File('foo/bar.md', '/path/to/docs', '/path/to/site', use_directory_urls=True),
+            File('foo/bar.html', '/path/to/docs', '/path/to/site', use_directory_urls=True),
+            File('foo/bar.jpg', '/path/to/docs', '/path/to/site', use_directory_urls=True),
+            File('foo/bar.js', '/path/to/docs', '/path/to/site', use_directory_urls=True),
+            File('foo/bar.css', '/path/to/docs', '/path/to/site', use_directory_urls=True)
+        ]
+        files = Files(fs)
+        self.assertEqual(len(files), 6)
+        self.assertEqual(len(files.src_paths), 6)
+        extra_file = File('extra.md', '/path/to/docs', '/path/to/site', use_directory_urls=True)
+        self.assertFalse(extra_file.src_path in files)
+        files.append(extra_file)
+        self.assertEqual(len(files), 7)
+        self.assertEqual(len(files.src_paths), 7)
+        self.assertTrue(extra_file.src_path in files)
+        files.remove(extra_file)
+        self.assertEqual(len(files), 6)
+        self.assertEqual(len(files.src_paths), 6)
+        self.assertFalse(extra_file.src_path in files)