Add JS_TryGetProperty (#337)

* Optimize `JS_GetPropertyInt64` and `JS_TryGetPropertyInt64`

- add `js_get_fast_array_element()` to special case arrays and typed arrays
- use `js_get_fast_array_element()` in `JS_GetPropertyValue()`,
  `JS_TryGetPropertyInt64()` and `JS_GetPropertyInt64()`.
- simplify `js_array_at()`

quickjs.c

@@ -7936,6 +7936,61 @@ JSAtom JS_ValueToAtom(JSContext *ctx, JSValue val)
     return atom;
 }
 
+static BOOL js_get_fast_array_element(JSContext *ctx, JSObject *p,
+                                      uint32_t idx, JSValue *pval)
+{
+    switch(p->class_id) {
+    case JS_CLASS_ARRAY:
+    case JS_CLASS_ARGUMENTS:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_dup(p->u.array.u.values[idx]);
+        return TRUE;
+    case JS_CLASS_INT8_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_int32(p->u.array.u.int8_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_UINT8C_ARRAY:
+    case JS_CLASS_UINT8_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_int32(p->u.array.u.uint8_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_INT16_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_int32(p->u.array.u.int16_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_UINT16_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_int32(p->u.array.u.uint16_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_INT32_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_int32(p->u.array.u.int32_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_UINT32_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_uint32(p->u.array.u.uint32_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_BIG_INT64_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = JS_NewBigInt64(ctx, p->u.array.u.int64_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_BIG_UINT64_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = JS_NewBigUint64(ctx, p->u.array.u.uint64_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_FLOAT32_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_float64(p->u.array.u.float_ptr[idx]);
+        return TRUE;
+    case JS_CLASS_FLOAT64_ARRAY:
+        if (unlikely(idx >= p->u.array.count)) return FALSE;
+        *pval = js_float64(p->u.array.u.double_ptr[idx]);
+        return TRUE;
+    default:
+        return FALSE;
+    }
+}
+
 static JSValue JS_GetPropertyValue(JSContext *ctx, JSValue this_obj,
                                    JSValue prop)
 {
@@ -7944,99 +7999,59 @@ static JSValue JS_GetPropertyValue(JSContext *ctx, JSValue this_obj,
 
     if (likely(JS_VALUE_GET_TAG(this_obj) == JS_TAG_OBJECT &&
                JS_VALUE_GET_TAG(prop) == JS_TAG_INT)) {
-        JSObject *p;
+        JSObject *p = JS_VALUE_GET_OBJ(this_obj);
-        uint32_t idx;
+        uint32_t idx = JS_VALUE_GET_INT(prop);
-        /* fast path for array access */
+        JSValue val;
-        p = JS_VALUE_GET_OBJ(this_obj);
+        /* fast path for array and typed array access */
-        idx = JS_VALUE_GET_INT(prop);
+        if (js_get_fast_array_element(ctx, p, idx, &val))
-        switch(p->class_id) {
+            return val;
-        case JS_CLASS_ARRAY:
-        case JS_CLASS_ARGUMENTS:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_dup(p->u.array.u.values[idx]);
-        case JS_CLASS_INT8_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_int32(p->u.array.u.int8_ptr[idx]);
-        case JS_CLASS_UINT8C_ARRAY:
-        case JS_CLASS_UINT8_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_int32(p->u.array.u.uint8_ptr[idx]);
-        case JS_CLASS_INT16_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_int32(p->u.array.u.int16_ptr[idx]);
-        case JS_CLASS_UINT16_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_int32(p->u.array.u.uint16_ptr[idx]);
-        case JS_CLASS_INT32_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_int32(p->u.array.u.int32_ptr[idx]);
-        case JS_CLASS_UINT32_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_uint32(p->u.array.u.uint32_ptr[idx]);
-        case JS_CLASS_BIG_INT64_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return JS_NewBigInt64(ctx, p->u.array.u.int64_ptr[idx]);
-        case JS_CLASS_BIG_UINT64_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return JS_NewBigUint64(ctx, p->u.array.u.uint64_ptr[idx]);
-        case JS_CLASS_FLOAT32_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_float64(p->u.array.u.float_ptr[idx]);
-        case JS_CLASS_FLOAT64_ARRAY:
-            if (unlikely(idx >= p->u.array.count)) goto slow_path;
-            return js_float64(p->u.array.u.double_ptr[idx]);
-        default:
-            goto slow_path;
-        }
-    } else {
-    slow_path:
-        atom = JS_ValueToAtom(ctx, prop);
-        JS_FreeValue(ctx, prop);
-        if (unlikely(atom == JS_ATOM_NULL))
-            return JS_EXCEPTION;
-        ret = JS_GetProperty(ctx, this_obj, atom);
-        JS_FreeAtom(ctx, atom);
-        return ret;
     }
+    atom = JS_ValueToAtom(ctx, prop);
+    JS_FreeValue(ctx, prop);
+    if (unlikely(atom == JS_ATOM_NULL))
+        return JS_EXCEPTION;
+    ret = JS_GetProperty(ctx, this_obj, atom);
+    JS_FreeAtom(ctx, atom);
+    return ret;
 }
 
 JSValue JS_GetPropertyUint32(JSContext *ctx, JSValue this_obj,
                              uint32_t idx)
 {
-    return JS_GetPropertyValue(ctx, this_obj, js_uint32(idx));
+    return JS_GetPropertyInt64(ctx, this_obj, idx);
 }
 
 /* Check if an object has a generalized numeric property. Return value:
-   -1 for exception,
+   -1 for exception, *pval set to JS_EXCEPTION
    TRUE if property exists, stored into *pval,
-   FALSE if proprty does not exist.
+   FALSE if property does not exist. *pval set to JS_UNDEFINED.
  */
 static int JS_TryGetPropertyInt64(JSContext *ctx, JSValue obj, int64_t idx, JSValue *pval)
 {
-    JSValue val = JS_UNDEFINED;
+    JSValue val;
     JSAtom prop;
     int present;
 
-    if (likely((uint64_t)idx <= JS_ATOM_MAX_INT)) {
+    if (likely(JS_VALUE_GET_TAG(obj) == JS_TAG_OBJECT &&
-        /* fast path */
+               (uint64_t)idx <= INT32_MAX)) {
-        present = JS_HasProperty(ctx, obj, __JS_AtomFromUInt32(idx));
+        /* fast path for array and typed array access */
+        JSObject *p = JS_VALUE_GET_OBJ(obj);
+        if (js_get_fast_array_element(ctx, p, idx, pval))
+            return TRUE;
+    }
+    val = JS_EXCEPTION;
+    present = -1;
+    prop = JS_NewAtomInt64(ctx, idx);
+    if (likely(prop != JS_ATOM_NULL)) {
+        present = JS_HasProperty(ctx, obj, prop);
         if (present > 0) {
-            val = JS_GetPropertyValue(ctx, obj, js_int32(idx));
+            val = JS_GetProperty(ctx, obj, prop);
             if (unlikely(JS_IsException(val)))
                 present = -1;
+        } else if (present == FALSE) {
+            val = JS_UNDEFINED;
         }
-    } else {
+        JS_FreeAtom(ctx, prop);
-        prop = JS_NewAtomInt64(ctx, idx);
-        present = -1;
-        if (likely(prop != JS_ATOM_NULL)) {
-            present = JS_HasProperty(ctx, obj, prop);
-            if (present > 0) {
-                val = JS_GetProperty(ctx, obj, prop);
-                if (unlikely(JS_IsException(val)))
-                    present = -1;
-            }
-            JS_FreeAtom(ctx, prop);
-        }
     }
     *pval = val;
     return present;
@@ -8047,9 +8062,12 @@ JSValue JS_GetPropertyInt64(JSContext *ctx, JSValue obj, int64_t idx)
     JSAtom prop;
     JSValue val;
 
-    if ((uint64_t)idx <= INT32_MAX) {
+    if (likely(JS_VALUE_GET_TAG(obj) == JS_TAG_OBJECT &&
-        /* fast path for fast arrays */
+               (uint64_t)idx <= INT32_MAX)) {
-        return JS_GetPropertyValue(ctx, obj, js_int32(idx));
+        /* fast path for array and typed array access */
+        JSObject *p = JS_VALUE_GET_OBJ(obj);
+        if (js_get_fast_array_element(ctx, p, idx, &val))
+            return val;
     }
     prop = JS_NewAtomInt64(ctx, idx);
     if (prop == JS_ATOM_NULL)
@@ -34907,6 +34925,7 @@ static int js_obj_to_desc(JSContext *ctx, JSPropertyDescriptor *d,
                           JSValue desc)
 {
     JSValue val, getter, setter;
+    int present;
     int flags;
 
     if (!JS_IsObject(desc)) {
@@ -34917,7 +34936,10 @@ static int js_obj_to_desc(JSContext *ctx, JSPropertyDescriptor *d,
     val = JS_UNDEFINED;
     getter = JS_UNDEFINED;
     setter = JS_UNDEFINED;
-    if (JS_HasProperty(ctx, desc, JS_ATOM_enumerable)) {
+    present = JS_HasProperty(ctx, desc, JS_ATOM_enumerable);
+    if (present < 0)
+        goto fail;
+    if (present) {
         JSValue prop = JS_GetProperty(ctx, desc, JS_ATOM_enumerable);
         if (JS_IsException(prop))
             goto fail;
@@ -34925,7 +34947,10 @@ static int js_obj_to_desc(JSContext *ctx, JSPropertyDescriptor *d,
         if (JS_ToBoolFree(ctx, prop))
             flags |= JS_PROP_ENUMERABLE;
     }
-    if (JS_HasProperty(ctx, desc, JS_ATOM_configurable)) {
+    present = JS_HasProperty(ctx, desc, JS_ATOM_configurable);
+    if (present < 0)
+        goto fail;
+    if (present) {
         JSValue prop = JS_GetProperty(ctx, desc, JS_ATOM_configurable);
         if (JS_IsException(prop))
             goto fail;
@@ -34933,13 +34958,19 @@ static int js_obj_to_desc(JSContext *ctx, JSPropertyDescriptor *d,
         if (JS_ToBoolFree(ctx, prop))
             flags |= JS_PROP_CONFIGURABLE;
     }
-    if (JS_HasProperty(ctx, desc, JS_ATOM_value)) {
+    present = JS_HasProperty(ctx, desc, JS_ATOM_value);
+    if (present < 0)
+        goto fail;
+    if (present) {
         flags |= JS_PROP_HAS_VALUE;
         val = JS_GetProperty(ctx, desc, JS_ATOM_value);
         if (JS_IsException(val))
             goto fail;
     }
-    if (JS_HasProperty(ctx, desc, JS_ATOM_writable)) {
+    present = JS_HasProperty(ctx, desc, JS_ATOM_writable);
+    if (present < 0)
+        goto fail;
+    if (present) {
         JSValue prop = JS_GetProperty(ctx, desc, JS_ATOM_writable);
         if (JS_IsException(prop))
             goto fail;
@@ -34947,7 +34978,10 @@ static int js_obj_to_desc(JSContext *ctx, JSPropertyDescriptor *d,
         if (JS_ToBoolFree(ctx, prop))
             flags |= JS_PROP_WRITABLE;
     }
-    if (JS_HasProperty(ctx, desc, JS_ATOM_get)) {
+    present = JS_HasProperty(ctx, desc, JS_ATOM_get);
+    if (present < 0)
+        goto fail;
+    if (present) {
         flags |= JS_PROP_HAS_GET;
         getter = JS_GetProperty(ctx, desc, JS_ATOM_get);
         if (JS_IsException(getter) ||
@@ -34956,7 +34990,10 @@ static int js_obj_to_desc(JSContext *ctx, JSPropertyDescriptor *d,
             goto fail;
         }
     }
-    if (JS_HasProperty(ctx, desc, JS_ATOM_set)) {
+    present = JS_HasProperty(ctx, desc, JS_ATOM_set);
+    if (present < 0)
+        goto fail;
+    if (present) {
         flags |= JS_PROP_HAS_SET;
         setter = JS_GetProperty(ctx, desc, JS_ATOM_set);
         if (JS_IsException(setter) ||
@@ -36995,10 +37032,8 @@ static JSValue js_array_at(JSContext *ctx, JSValue this_val,
 
     if (idx < 0 || idx >= len) {
         ret = JS_UNDEFINED;
-    } else if (js_get_fast_array(ctx, obj, &arrp, &count) && count == len) {
+    } else {
-        ret = js_dup(arrp[idx]);
+        ret = JS_GetPropertyInt64(ctx, obj, idx);
-    } else if (!JS_TryGetPropertyInt64(ctx, obj, idx, &ret)) {
-        ret = JS_UNDEFINED;
     }
 
  exception: