Support invoking JS operators through dart:js_util.

Some JS functionality is only exposed through operators, such as
implicit type conversions and BigInt arithmetic. Other than requiring
some minor additions for the exponentiation (`**`) operator, supporting
these through `dart:js_util` is trivial.

Change-Id: I010674303e4f99b42d43b73095de69b8ddcdeb47
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/242680
Reviewed-by: Joshua Litt <joshualitt@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Stephen Adams <sra@google.com>

pkg/compiler/lib/src/js/size_estimator.dart

@@ -678,6 +678,11 @@ class SizeEstimator implements NodeVisitor {
         // We cannot remove parenthesis for "*" because of precision issues.
         rightPrecedenceRequirement = UNARY;
         break;
+      case "**":
+        leftPrecedenceRequirement = EXPONENTIATION;
+        // We cannot remove parenthesis for "**" because of precision issues.
+        rightPrecedenceRequirement = UNARY;
+        break;
       default:
         throw UnsupportedError("Forgot operator: $op");
     }

pkg/compiler/test/js/js_parser_test.dart

@@ -258,4 +258,12 @@ void main() {
   bar() {
   }
 }""");
+
+  // Exponentiation operator.
+  testExpression("a ** b");
+  //* Parsed with incorrect association:
+  testExpression("a ** b ** c", "(a ** b) ** c");
+  testExpression("(a ** b) ** c", "(a ** b) ** c");
+  testExpression("a ** (b ** c)", "a ** b ** c");
+  testExpression("a **= b");
 }

pkg/dev_compiler/lib/src/js_ast/builder.dart

@@ -609,6 +609,7 @@ class MiniJsParser {
     '<<=': 17,
     '>>=': 17,
     '>>>=': 17,
+    '**=': 17,
     '=': 17,
     '||': 14,
     '&&': 13,
@@ -632,7 +633,8 @@ class MiniJsParser {
     '-': 6,
     '*': 5,
     '/': 5,
-    '%': 5
+    '%': 5,
+    '**': 4,
   };
   static final UNARY_OPERATORS = {
     '++',

pkg/dev_compiler/lib/src/js_ast/nodes.dart

@@ -1291,6 +1291,8 @@ class Binary extends Expression {
   int get precedenceLevel {
     // TODO(floitsch): switch to constant map.
     switch (op) {
+      case '**':
+        return EXPONENTIATION;
       case '*':
       case '/':
       case '%':

pkg/dev_compiler/lib/src/js_ast/precedence.dart

@@ -28,7 +28,8 @@ const RELATIONAL = EQUALITY + 1;
 const SHIFT = RELATIONAL + 1;
 const ADDITIVE = SHIFT + 1;
 const MULTIPLICATIVE = ADDITIVE + 1;
-const UNARY = MULTIPLICATIVE + 1;
+const EXPONENTIATION = MULTIPLICATIVE + 1;
+const UNARY = EXPONENTIATION + 1;
 const LEFT_HAND_SIDE = UNARY + 1;
 const CALL = LEFT_HAND_SIDE;
 // We always emit `new` with parenthesis, so it uses ACCESS as its precedence.

pkg/dev_compiler/lib/src/js_ast/printer.dart

@@ -856,6 +856,12 @@ class Printer implements NodeVisitor {
         // We cannot remove parenthesis for "*" because of precision issues.
         rightPrecedenceRequirement = UNARY;
         break;
+      case '**':
+        // 'a ** b ** c' parses as 'a ** (b ** c)', so the left must have higher
+        // precedence.
+        leftPrecedenceRequirement = UNARY;
+        rightPrecedenceRequirement = EXPONENTIATION;
+        break;
       default:
         leftPrecedenceRequirement = EXPRESSION;
         rightPrecedenceRequirement = EXPRESSION;

pkg/js_ast/lib/src/builder.dart

@@ -535,6 +535,7 @@ class MiniJsParser {
     '<<=': 17,
     '>>=': 17,
     '>>>=': 17,
+    '**=': 17,
     '=': 17,
     '||': 14,
     '&&': 13,
@@ -558,7 +559,8 @@ class MiniJsParser {
     '-': 6,
     '*': 5,
     '/': 5,
-    '%': 5
+    '%': 5,
+    '**': 4,
   };
   static final UNARY_OPERATORS = {
     '++',

pkg/js_ast/lib/src/nodes.dart

@@ -1638,6 +1638,8 @@ class Binary extends Expression {
   int get precedenceLevel {
     // TODO(floitsch): switch to constant map.
     switch (op) {
+      case '**':
+        return EXPONENTIATION;
       case '*':
       case '/':
       case '%':

pkg/js_ast/lib/src/precedence.dart

@@ -16,7 +16,8 @@ const RELATIONAL = EQUALITY + 1;
 const SHIFT = RELATIONAL + 1;
 const ADDITIVE = SHIFT + 1;
 const MULTIPLICATIVE = ADDITIVE + 1;
-const UNARY = MULTIPLICATIVE + 1;
+const EXPONENTIATION = MULTIPLICATIVE + 1;
+const UNARY = EXPONENTIATION + 1;
 const CALL = UNARY + 1;
 const LEFT_HAND_SIDE = CALL + 1;
 const PRIMARY = LEFT_HAND_SIDE + 1;

pkg/js_ast/lib/src/printer.dart

@@ -970,6 +970,12 @@ class Printer implements NodeVisitor<void> {
         // We cannot remove parenthesis for "*" because of precision issues.
         rightPrecedenceRequirement = UNARY;
         break;
+      case '**':
+        // 'a ** b ** c' parses as 'a ** (b ** c)', so the left must have higher
+        // precedence.
+        leftPrecedenceRequirement = UNARY;
+        rightPrecedenceRequirement = EXPONENTIATION;
+        break;
       default:
         leftPrecedenceRequirement = EXPRESSION;
         rightPrecedenceRequirement = EXPRESSION;

sdk/lib/js_util/js_util.dart

@@ -285,6 +285,90 @@ T _callConstructorUnchecked4<T>(
       'Object', 'new #(#, #, #, #)', constr, arg1, arg2, arg3, arg4);
 }
 
+/// Perform JavaScript addition (`+`) on two values.
+@pragma('dart2js:tryInline')
+T add<T>(Object? first, Object? second) {
+  return JS<dynamic>('Object', '# + #', first, second);
+}
+
+/// Perform JavaScript subtraction (`-`) on two values.
+@pragma('dart2js:tryInline')
+T subtract<T>(Object? first, Object? second) {
+  return JS<dynamic>('Object', '# - #', first, second);
+}
+
+/// Perform JavaScript multiplication (`*`) on two values.
+@pragma('dart2js:tryInline')
+T multiply<T>(Object? first, Object? second) {
+  return JS<dynamic>('Object', '# * #', first, second);
+}
+
+/// Perform JavaScript division (`/`) on two values.
+@pragma('dart2js:tryInline')
+T divide<T>(Object? first, Object? second) {
+  return JS<dynamic>('Object', '# / #', first, second);
+}
+
+/// Perform JavaScript exponentiation (`**`) on two values.
+@pragma('dart2js:tryInline')
+T exponentiate<T>(Object? first, Object? second) {
+  return JS<dynamic>('Object', '# ** #', first, second);
+}
+
+/// Perform JavaScript remainder (`%`) on two values.
+@pragma('dart2js:tryInline')
+T modulo<T>(Object? first, Object? second) {
+  return JS<dynamic>('Object', '# % #', first, second);
+}
+
+/// Perform JavaScript equality comparison (`==`) on two values.
+@pragma('dart2js:tryInline')
+bool equal<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# == #', first, second);
+}
+
+/// Perform JavaScript strict equality comparison (`===`) on two values.
+@pragma('dart2js:tryInline')
+bool strictEqual<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# === #', first, second);
+}
+
+/// Perform JavaScript inequality comparison (`!=`) on two values.
+@pragma('dart2js:tryInline')
+bool notEqual<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# != #', first, second);
+}
+
+/// Perform JavaScript strict inequality comparison (`!==`) on two values.
+@pragma('dart2js:tryInline')
+bool strictNotEqual<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# !== #', first, second);
+}
+
+/// Perform JavaScript greater than comparison (`>`) of two values.
+@pragma('dart2js:tryInline')
+bool greaterThan<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# > #', first, second);
+}
+
+/// Perform JavaScript greater than or equal comparison (`>=`) of two values.
+@pragma('dart2js:tryInline')
+bool greaterThanOrEqual<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# >= #', first, second);
+}
+
+/// Perform JavaScript less than comparison (`<`) of two values.
+@pragma('dart2js:tryInline')
+bool lessThan<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# < #', first, second);
+}
+
+/// Perform JavaScript less than or equal comparison (`<=`) of two values.
+@pragma('dart2js:tryInline')
+bool lessThanOrEqual<T>(Object? first, Object? second) {
+  return JS<bool>('bool', '# <= #', first, second);
+}
+
 /// Exception for when the promise is rejected with a `null` or `undefined`
 /// value.
 ///

tests/lib/js/js_util/bigint_test.dart

@@ -0,0 +1,110 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests invoking JS BigInt functionality through js_util. This interop
+// requires usage of the operator functions exposed through js_util.
+
+@JS()
+library js_util_bigint_test;
+
+import 'package:js/js.dart';
+import 'package:js/js_util.dart' as js_util;
+import 'package:expect/minitest.dart';
+
+@JS('BigInt')
+external Object BigInt(Object value);
+
+main() {
+  group('bigint', () {
+    test('addition', () {
+      final one = BigInt('1');
+      final two = BigInt('2');
+      final three = BigInt('3');
+      expect(js_util.strictEqual(js_util.add(one, two), three), isTrue);
+      expect(js_util.strictEqual(js_util.add(one, one), three), isFalse);
+    });
+
+    test('subtraction', () {
+      final one = BigInt('1');
+      final two = BigInt('2');
+      final three = BigInt('3');
+      expect(js_util.strictEqual(js_util.subtract(three, one), two), isTrue);
+      expect(js_util.strictEqual(js_util.subtract(three, two), two), isFalse);
+    });
+
+    test('multiplication', () {
+      final two = BigInt('2');
+      final four = BigInt('4');
+      expect(js_util.strictEqual(js_util.multiply(two, two), four), isTrue);
+      expect(js_util.strictEqual(js_util.multiply(two, four), four), isFalse);
+    });
+
+    test('division', () {
+      final two = BigInt('2');
+      final four = BigInt('4');
+      expect(js_util.strictEqual(js_util.divide(four, two), two), isTrue);
+      expect(js_util.strictEqual(js_util.divide(four, four), two), isFalse);
+    });
+
+    test('exponentiation', () {
+      final two = BigInt('2');
+      final three = BigInt('3');
+      final nine = BigInt('9');
+      expect(
+          js_util.strictEqual(js_util.exponentiate(three, two), nine), isTrue);
+      expect(js_util.strictEqual(js_util.exponentiate(three, three), nine),
+          isFalse);
+    });
+
+    test('exponentiation2', () {
+      final two = BigInt('2');
+      final three = BigInt('3');
+      final five = BigInt('5');
+      expect(
+          js_util.add(
+              '', js_util.exponentiate(js_util.exponentiate(five, three), two)),
+          '15625');
+      expect(
+          js_util.add(
+              '', js_util.exponentiate(five, js_util.exponentiate(three, two))),
+          '1953125');
+    });
+
+    test('modulo', () {
+      final zero = BigInt('0');
+      final three = BigInt('3');
+      final nine = BigInt('9');
+      expect(js_util.strictEqual(js_util.modulo(nine, three), zero), isTrue);
+      expect(js_util.strictEqual(js_util.modulo(nine, three), nine), isFalse);
+    });
+
+    test('equality', () {
+      final one = BigInt('1');
+      expect(js_util.equal(one, 1), isTrue);
+      expect(js_util.strictEqual(one, 1), isFalse);
+      expect(js_util.notEqual(one, 1), isFalse);
+      expect(js_util.strictNotEqual(one, 1), isTrue);
+    });
+
+    test('comparisons', () {
+      final zero = BigInt('0');
+      final one = BigInt('1');
+      final otherOne = BigInt('1');
+      expect(js_util.greaterThan(one, zero), isTrue);
+      expect(js_util.greaterThan(one, 0), isTrue);
+      expect(js_util.greaterThan(2, one), isTrue);
+      expect(js_util.greaterThanOrEqual(one, otherOne), isTrue);
+      expect(js_util.greaterThanOrEqual(one, 1), isTrue);
+      expect(js_util.greaterThanOrEqual(one, 2), isFalse);
+
+      expect(js_util.lessThan(one, zero), isFalse);
+      expect(js_util.lessThan(zero, one), isTrue);
+      expect(js_util.lessThan(one, 2), isTrue);
+      expect(js_util.lessThan(one, 0), isFalse);
+      expect(js_util.lessThanOrEqual(one, otherOne), isTrue);
+      expect(js_util.lessThanOrEqual(one, 1), isTrue);
+      expect(js_util.lessThanOrEqual(2, one), isFalse);
+    });
+  });
+}

tests/lib_2/js/js_util/bigint_test.dart

@@ -0,0 +1,110 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests invoking JS BigInt functionality through js_util. This interop
+// requires usage of the operator functions exposed through js_util.
+
+@JS()
+library js_util_bigint_test;
+
+import 'package:js/js.dart';
+import 'package:js/js_util.dart' as js_util;
+import 'package:expect/minitest.dart';
+
+@JS('BigInt')
+external Object BigInt(Object value);
+
+main() {
+  group('bigint', () {
+    test('addition', () {
+      final one = BigInt('1');
+      final two = BigInt('2');
+      final three = BigInt('3');
+      expect(js_util.strictEqual(js_util.add(one, two), three), isTrue);
+      expect(js_util.strictEqual(js_util.add(one, one), three), isFalse);
+    });
+
+    test('subtraction', () {
+      final one = BigInt('1');
+      final two = BigInt('2');
+      final three = BigInt('3');
+      expect(js_util.strictEqual(js_util.subtract(three, one), two), isTrue);
+      expect(js_util.strictEqual(js_util.subtract(three, two), two), isFalse);
+    });
+
+    test('multiplication', () {
+      final two = BigInt('2');
+      final four = BigInt('4');
+      expect(js_util.strictEqual(js_util.multiply(two, two), four), isTrue);
+      expect(js_util.strictEqual(js_util.multiply(two, four), four), isFalse);
+    });
+
+    test('division', () {
+      final two = BigInt('2');
+      final four = BigInt('4');
+      expect(js_util.strictEqual(js_util.divide(four, two), two), isTrue);
+      expect(js_util.strictEqual(js_util.divide(four, four), two), isFalse);
+    });
+
+    test('exponentiation', () {
+      final two = BigInt('2');
+      final three = BigInt('3');
+      final nine = BigInt('9');
+      expect(
+          js_util.strictEqual(js_util.exponentiate(three, two), nine), isTrue);
+      expect(js_util.strictEqual(js_util.exponentiate(three, three), nine),
+          isFalse);
+    });
+
+    test('exponentiation2', () {
+      final two = BigInt('2');
+      final three = BigInt('3');
+      final five = BigInt('5');
+      expect(
+          js_util.add(
+              '', js_util.exponentiate(js_util.exponentiate(five, three), two)),
+          '15625');
+      expect(
+          js_util.add(
+              '', js_util.exponentiate(five, js_util.exponentiate(three, two))),
+          '1953125');
+    });
+
+    test('modulo', () {
+      final zero = BigInt('0');
+      final three = BigInt('3');
+      final nine = BigInt('9');
+      expect(js_util.strictEqual(js_util.modulo(nine, three), zero), isTrue);
+      expect(js_util.strictEqual(js_util.modulo(nine, three), nine), isFalse);
+    });
+
+    test('equality', () {
+      final one = BigInt('1');
+      expect(js_util.equal(one, 1), isTrue);
+      expect(js_util.strictEqual(one, 1), isFalse);
+      expect(js_util.notEqual(one, 1), isFalse);
+      expect(js_util.strictNotEqual(one, 1), isTrue);
+    });
+
+    test('comparisons', () {
+      final zero = BigInt('0');
+      final one = BigInt('1');
+      final otherOne = BigInt('1');
+      expect(js_util.greaterThan(one, zero), isTrue);
+      expect(js_util.greaterThan(one, 0), isTrue);
+      expect(js_util.greaterThan(2, one), isTrue);
+      expect(js_util.greaterThanOrEqual(one, otherOne), isTrue);
+      expect(js_util.greaterThanOrEqual(one, 1), isTrue);
+      expect(js_util.greaterThanOrEqual(one, 2), isFalse);
+
+      expect(js_util.lessThan(one, zero), isFalse);
+      expect(js_util.lessThan(zero, one), isTrue);
+      expect(js_util.lessThan(one, 2), isTrue);
+      expect(js_util.lessThan(one, 0), isFalse);
+      expect(js_util.lessThanOrEqual(one, otherOne), isTrue);
+      expect(js_util.lessThanOrEqual(one, 1), isTrue);
+      expect(js_util.lessThanOrEqual(2, one), isFalse);
+    });
+  });
+}