support persistent_load

Author: ewfian

examples/persistent_id.py

@@ -0,0 +1,28 @@
+
+import pickle
+from collections import namedtuple
+
+MemoRecord = namedtuple("MemoRecord", "key, task")
+
+class MyPickler(pickle.Pickler):
+
+    def persistent_id(self, obj):
+        # Instead of pickling MemoRecord as a regular class instance, we emit a
+        # persistent ID.
+        if isinstance(obj, MemoRecord):
+            # Here, our persistent ID is simply a tuple, containing a tag and a
+            # key, which refers to a specific record in the database.
+            print('persistent_id set')
+            return ("MemoRecord", obj.key)
+        else:
+            # If obj does not have a persistent ID, return None. This means obj
+            # needs to be pickled as usual.
+            return None
+
+def main():
+    memo = MemoRecord("aa", "bb")
+    filehandler = open(b"persistent_id.pkl", "wb")
+    MyPickler(filehandler).dump(memo)
+
+if __name__ == '__main__':
+    main()

src/parser.ts

@@ -5,11 +5,17 @@ import { Registry } from './registry';
 
 export class Parser {
     private _reader: Reader;
+    public persistent_load: (pid: string) => any;
 
     registry: Registry = new Registry();
 
-    constructor(buffer: Uint8Array | Int8Array | Uint8ClampedArray) {
+    constructor(buffer: Uint8Array | Int8Array | Uint8ClampedArray, persistent_load?: (pid: string) => any) {
         this._reader = new Reader(buffer);
+        this.persistent_load =
+            persistent_load ||
+            ((pid: string) => {
+                throw new Error(`Unsupported persistent id: \`${pid}\`.`);
+            });
     }
 
     load() {
@@ -20,6 +26,8 @@ export class Parser {
         while (reader.hasNext()) {
             const opcode = reader.byte();
             // console.log(`${(reader.position - 1).toString()} ${opcode}`);
+            // console.log('metastack:', metastack, '\nstack:', stack);
+            // console.log('\nmemo:', Array.from(memo.entries()));
             switch (opcode) {
                 // Structural
                 case OP.PROTO: {
@@ -296,6 +304,12 @@ export class Parser {
                     stack.push(obj);
                     break;
                 }
+                case OP.PERSID:
+                    stack.push(this.persistent_load(reader.line()));
+                    break;
+                case OP.BINPERSID:
+                    stack.push(this.persistent_load(stack.pop()));
+                    break;
                 case OP.BUILD: {
                     const state = stack.pop();
                     const obj = stack[stack.length - 1];
@@ -318,8 +332,6 @@ export class Parser {
                 }
 
                 default:
-                    // console.log('metastack:', metastack, '\nstack:', stack);
-                    // console.log('\nmemo:', Array.from(memo.entries()));
                     throw new Error(`Unsupported opcode '${opcode}'.`);
             }
         }