Expose public equality comparison and sameness public API. (#373)

* Expose public equality comparison and sameness public API.
- add `JS_IsEqual` (operator `==`), returns an `int`: `-1` if an exception was thrown
- add `JS_IsStrictEqual` (operator `===`) always succeeds, returns a `JS_BOOL`
- add `JS_IsSameValue` always succeeds, returns a `JS_BOOL`
- add `JS_IsSameValueZero` always succeeds, returns a `JS_BOOL`

quickjs.c

@@ -51915,6 +51915,30 @@ void JS_AddPerformance(JSContext *ctx)
     JS_FreeValue(ctx, performance);
 }
 
+/* Equality comparisons and sameness */
+int JS_IsEqual(JSContext *ctx, JSValue op1, JSValue op2)
+{
+    JSValue sp[2] = { js_dup(op1), js_dup(op2) };
+    if (js_eq_slow(ctx, endof(sp), 0))
+        return -1;
+    return JS_VALUE_GET_BOOL(sp[0]);
+}
+
+JS_BOOL JS_IsStrictEqual(JSContext *ctx, JSValue op1, JSValue op2)
+{
+    return js_strict_eq2(ctx, js_dup(op1), js_dup(op2), JS_EQ_STRICT);
+}
+
+JS_BOOL JS_IsSameValue(JSContext *ctx, JSValue op1, JSValue op2)
+{
+    return js_same_value(ctx, op1, op2);
+}
+
+JS_BOOL JS_IsSameValueZero(JSContext *ctx, JSValue op1, JSValue op2)
+{
+    return js_same_value_zero(ctx, op1, op2);
+}
+
 /* WeakRef */
 
 typedef struct JSWeakRefData {

quickjs.h

@@ -334,6 +334,13 @@ JS_EXTERN void JS_AddIntrinsicBigInt(JSContext *ctx);
 JS_EXTERN void JS_AddIntrinsicWeakRef(JSContext *ctx);
 JS_EXTERN void JS_AddPerformance(JSContext *ctx);
 
+/* for equality comparisons and sameness */
+JS_EXTERN int JS_IsEqual(JSContext *ctx, JSValue op1, JSValue op2);
+JS_EXTERN JS_BOOL JS_IsStrictEqual(JSContext *ctx, JSValue op1, JSValue op2);
+JS_EXTERN JS_BOOL JS_IsSameValue(JSContext *ctx, JSValue op1, JSValue op2);
+/* Similar to same-value equality, but +0 and -0 are considered equal. */
+JS_EXTERN JS_BOOL JS_IsSameValueZero(JSContext *ctx, JSValue op1, JSValue op2);
+
 /* Only used for running 262 tests. TODO(saghul) add build time flag. */
 JS_EXTERN JSValue js_string_codePointRange(JSContext *ctx, JSValue this_val,
                                  int argc, JSValue *argv);