Add old shell compatibility for Timestamp for JS Engine (#18)

Author: LijieZhang1998

snippets/mongocompat/mongotypes.js

@@ -1,5 +1,59 @@
 // Date and time types
 if (typeof (Timestamp) != "undefined") {
+    const OriginalTimestamp = Timestamp;
+
+    // Reference: https://github.com/mongodb/mongo/blob/c4d21d3346572e28df2f174df4d87e7618df4a77/src/mongo/scripting/mozjs/timestamp.cpp#L67-L78
+    function validateTimestampComponent(component, name) {
+        const MAX_UINT32 = 4294967295; 
+
+        if (typeof component !== 'number') {
+            throw new TypeError(`${name} must be a number`);
+        }
+
+        const val = Math.floor(component);
+        if (val < 0 || val > MAX_UINT32) {
+            throw new TypeError(
+                `${name} must be non-negative and not greater than ${MAX_UINT32}, got ${val}`
+            );
+        }
+
+        return val;
+    }
+
+    Timestamp = function(t, i) {
+        if (arguments.length === 0) {
+            return new OriginalTimestamp({ t: 0, i: 0 });
+        }
+
+        if (arguments.length === 1) {
+            const proto = Object.getPrototypeOf(t);
+            if ((proto === null || proto === Object.prototype) && ('t' in t || 'i' in t)) {
+                const validatedT = validateTimestampComponent(t.t || 0, "Timestamp time (seconds)");
+                const validatedI = validateTimestampComponent(t.i || 0, "Timestamp increment");
+                return new OriginalTimestamp({ t: validatedT, i: validatedI });
+            }
+            return new OriginalTimestamp(t);
+        }
+
+        // Reference: https://github.com/mongodb/mongo/blob/c4d21d3346572e28df2f174df4d87e7618df4a77/src/mongo/scripting/mozjs/timestamp.cpp#L91-L98
+        if (arguments.length === 2) {
+            const validatedT = validateTimestampComponent(t, "Timestamp time (seconds)");
+            const validatedI = validateTimestampComponent(i, "Timestamp increment");
+            return new OriginalTimestamp({ t: validatedT, i: validatedI });
+        }
+
+        throw new Error("Timestamp needs 0 or 2 arguments");
+    };
+
+    Timestamp.prototype = OriginalTimestamp.prototype;
+
+    for (const key of Object.getOwnPropertyNames(OriginalTimestamp)) {
+        // Skip prototype, length, name(function internals)
+        if (key !== 'prototype' && key !== 'length' && key !== 'name') {
+            Timestamp[key] = OriginalTimestamp[key];
+        }
+    }
+
     Timestamp.prototype.tojson = function() {
         return this.toStringIncomparable();
     };

snippets/mongocompat/test.js

@@ -22,6 +22,51 @@ assert.strictEqual(minLong.bottom, 0);
 assert.strictEqual(minLong.exactValueString, "-9223372036854775808");
 const nl2 = NumberLong("200");
 assert.strictEqual(maxLong.compare(nl2), 1);
+
 const decimal = NumberDecimal("1.1");
 assert.strictEqual(decimal.toString(), 'NumberDecimal("1.1")');
 assert.strictEqual(decimal.tojson(), 'NumberDecimal("1.1")');
+
+const ts1 = Timestamp();
+assert.strictEqual(ts1.toString(), 'Timestamp(0, 0)');
+const ts2 = Timestamp(100, 200);
+assert.strictEqual(ts2.toString(), 'Timestamp(100, 200)');
+const ts3 = Timestamp(1.9, 2.1);
+assert.strictEqual(ts3.toString(), 'Timestamp(1, 2)');
+try {
+    Timestamp(-1, 0);
+    assert.fail('Should throw for negative time');
+} catch (e) {
+    assert(e.message.includes('must be non-negative'));
+}
+try {
+    Timestamp(0, 5000000000);
+    assert.fail('Should throw for i > uint32 max');
+} catch (e) {
+    assert(e.message.includes('not greater than 4294967295'));
+}
+const ts4 = Timestamp(123, 456);
+assert(ts4 instanceof Timestamp);
+assert.strictEqual(ts4.toString(), 'Timestamp(123, 456)');
+assert.strictEqual(ts4.tojson(), 'Timestamp(123, 456)');
+assert.strictEqual(ts4.getTime(), 123);
+assert.strictEqual(ts4.getInc(), 456);
+assert.strictEqual(ts4._bsontype, 'Timestamp');
+const tsFromBits = Timestamp.fromBits(100, 200);
+assert(tsFromBits instanceof Timestamp);
+assert.strictEqual(tsFromBits.i, 100);
+assert.strictEqual(tsFromBits.t, 200);
+assert.strictEqual(tsFromBits.toString(), 'Timestamp(200, 100)');
+const tsFromInt = Timestamp.fromInt(12345);
+assert.strictEqual(tsFromInt._bsontype, 'Timestamp');
+assert.strictEqual(tsFromInt.i, 12345);
+assert.strictEqual(tsFromInt.t, 0);
+const tsFromNum = Timestamp.fromNumber(67890);
+assert.strictEqual(tsFromNum._bsontype, 'Timestamp');
+assert.strictEqual(tsFromNum.i, 67890);
+assert.strictEqual(tsFromNum.t, 0);
+const tsFromStr = Timestamp.fromString('ff', 16);
+assert.strictEqual(tsFromStr.i, 255);
+assert.strictEqual(tsFromStr.t, 0);
+assert.strictEqual(Timestamp.MAX_VALUE._bsontype, 'Long');
+assert.strictEqual(Timestamp.MAX_VALUE, Long.MAX_UNSIGNED_VALUE);