Add sqlite3/Files/README.md

sqlite3/Files/README.md

@@ -0,0 +1,49 @@
+```
+import sqlite3, pandas as pd
+
+class Files:
+    def __init__(self, db='files.sqlite'):
+        self.conn = sqlite3.connect(db, isolation_level=None)
+        self.conn.row_factory = sqlite3.Row
+        self('PRAGMA journal_mode=WAL')
+        self('CREATE TABLE IF NOT EXISTS files (filename TEXT PRIMARY KEY, content BLOB)')
+
+    def __call__(self, *args) -> pd.DataFrame:
+        return pd.DataFrame(dict(row) for row in self.conn.execute(*args))
+
+    def __setitem__(self, filename, content) -> None:
+        assert isinstance(filename, str)
+        if isinstance(content, str): content = content.encode()
+        assert isinstance(content, bytes)
+        self('INSERT OR REPLACE INTO files VALUES (?,?)', (filename, content))
+
+    def __getitem__(self, filename) -> bytes:
+        return self('SELECT content FROM files WHERE filename=?', (filename,)).content[0]
+
+    def __delitem__(self, filename) -> None:
+        self('DELETE FROM files WHERE filename=?', (filename,))
+
+    def __iter__(self):
+        df = self('SELECT filename FROM files')
+        return iter([] if df.empty else df.filename)
+
+    def __contains__(self, filename: str) -> bool:
+        return not self('SELECT 1 FROM files WHERE filename=?', (filename,)).empty
+
+    def __len__(self) -> int:
+        return self('SELECT COUNT(*) FROM files').iloc[0, 0]
+
+files = Files()
+for filename in files:
+    print(files[filename])
+files['hello'] = 'world'
+print(files['hello'])
+print(len(files))
+print('hello' in files)
+for filename in files:
+    print(filename)
+
+del files['hello']
+for filename in files:
+    print(filename)
+```