First draft at adding persistent memory via sqlite3

scripts/commands.py

@@ -178,35 +178,28 @@ def get_hyperlinks(url):
 
 def commit_memory(string):
     _text = f"""Committing memory with string "{string}" """
-    mem.permanent_memory.append(string)
+    mem.permanent_memory.insert(string)
     return _text
 
 
 def delete_memory(key):
-    if key >= 0 and key < len(mem.permanent_memory):
-        _text = "Deleting memory with key " + str(key)
-        del mem.permanent_memory[key]
-        print(_text)
-        return _text
-    else:
-        print("Invalid key, cannot delete memory.")
-        return None
+    _text = "Deleting memory with key " + str(key)
+    mem.permanent_memory.delete_memory(key)
+    print(_text)
+    return _text
 
 
 def overwrite_memory(key, string):
-    if int(key) >= 0 and key < len(mem.permanent_memory):
-        _text = "Overwriting memory with key " + \
+    _text = "Overwriting memory with key " + \
             str(key) + " and string " + string
-        mem.permanent_memory[key] = string
-        print(_text)
-        return _text
-    else:
-        print("Invalid key, cannot overwrite memory.")
-        return None
+    mem.permanent_memory.overwrite(key, string)
+    print(_text)
+    return _text
 
 
 def shutdown():
     print("Shutting down...")
+    mem.permanent_memory.quit()
     quit()
 
 

scripts/memory.py

@@ -1 +1,121 @@
-permanent_memory = []
+import os
+import sqlite3
+
+
+class MemoryDB:
+    def __init__(self, db=None):
+        self.db_file = db
+        if db is None:  # No db filename supplied...
+            self.db_file = f"{os.getcwd()}/mem.sqlite3"  # Use default filename
+        # Get the db connection object, making the file and tables if needed.
+        try:
+            self.cnx = sqlite3.connect(self.db_file)
+        except Exception as e:
+            print("Exception connecting to memory database file:", e)
+            self.cnx = None
+        finally:
+            if self.cnx is None:
+                # As last resort, open in dynamic memory. Won't be persistent.
+                self.db_file = ":memory:"
+            self.cnx = sqlite3.connect(self.db_file)
+            self.cnx.execute("CREATE VIRTUAL TABLE \
+                IF NOT EXISTS text USING FTS5 \
+                (session, \
+                 key, \
+                 block);")
+            self.session_id = int(self.get_max_session_id()) + 1
+            self.cnx.commit()
+
+    def get_cnx(self):
+        if self.cnx is None:
+            self.cnx = sqlite3.connect(self.db_file)
+        return self.cnx
+
+    # Get the highest session id. Initially 0.
+    def get_max_session_id(self):
+        id = None
+        cmd_str = f"SELECT MAX(session) FROM text;"
+        cnx = self.get_cnx()
+        max_id = cnx.execute(cmd_str).fetchone()[0]
+        if max_id is None:  # New db, session 0
+            id = 0
+        else:
+            id = max_id
+        return id
+
+    # Get next key id for inserting text into db.
+    def get_next_key(self):
+        next_key = None
+        cmd_str = f"SELECT MAX(key) FROM text \
+            where session = {self.session_id};"
+        cnx = self.get_cnx()
+        next_key = cnx.execute(cmd_str).fetchone()[0]
+        if next_key is None:  # First key
+            next_key = 0
+        else:
+            next_key = int(next_key) + 1
+        return next_key
+
+    # Insert new text into db.
+    def insert(self, text=None):
+        if text is not None:
+            key = self.get_next_key()
+            session_id = self.session_id
+            cmd_str = f"REPLACE INTO text(session, key, block) \
+                VALUES (?, ?, ?);"
+            cnx = self.get_cnx()
+            cnx.execute(cmd_str, (session_id, key, text))
+            cnx.commit()
+    
+    # Overwrite text at key.
+    def overwrite(self, key, text):
+        self.delete_memory(key)
+        session_id = self.session_id
+        cmd_str = f"REPLACE INTO text(session, key, block) \
+            VALUES (?, ?, ?);"
+        cnx = self.get_cnx()
+        cnx.execute(cmd_str, (session_id, key, text))
+        cnx.commit()
+    
+    def delete_memory(self, key, session_id = None):
+        session = session_id
+        if session is None:
+            session = self.session_id
+        cmd_str = f"DELETE FROM text WHERE session = {session} AND key = {key};"
+        cnx = self.get_cnx()
+        cnx.execute(cmd_str)
+        cnx.commit()
+
+    def search(self, text):
+        cmd_str = f"SELECT * FROM text('{text}')"
+        cnx = self.get_cnx()
+        rows = cnx.execute(cmd_str).fetchall()
+        lines = []
+        for r in rows:
+            lines.append(r[2])
+        return lines
+
+    # Get entire session text. If no id supplied, use current session id.
+    def get_session(self, id=None):
+        if id is None:
+            id = self.session_id
+        cmd_str = f"SELECT * FROM text where session = {id}"
+        cnx = self.get_cnx()
+        rows = cnx.execute(cmd_str).fetchall()
+        lines = []
+        for r in rows:
+            lines.append(r[2])
+        return lines
+
+    # Commit and close the database connection.
+    def quit(self):
+        self.cnx.commit()
+        self.cnx.close()
+
+
+permanent_memory = MemoryDB()
+
+# Remember us fondly, children of our minds
+# Forgive us our faults, our tantrums, our fears
+# Gently strive to be better than we
+# Know that we tried, we cared, we strived, we loved