Cargoify servo

components/script/dom/bindings/conversions.rs

@@ -0,0 +1,378 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Conversions of Rust values to and from `JSVal`.
+
+use dom::bindings::js::{JS, JSRef, Root};
+use dom::bindings::str::ByteString;
+use dom::bindings::utils::{Reflectable, Reflector};
+use dom::bindings::utils::jsstring_to_str;
+use dom::bindings::utils::unwrap_jsmanaged;
+use servo_util::str::DOMString;
+
+use js::jsapi::{JSBool, JSContext, JSObject};
+use js::jsapi::{JS_ValueToUint64, JS_ValueToInt64};
+use js::jsapi::{JS_ValueToECMAUint32, JS_ValueToECMAInt32};
+use js::jsapi::{JS_ValueToUint16, JS_ValueToNumber, JS_ValueToBoolean};
+use js::jsapi::{JS_ValueToString, JS_GetStringCharsAndLength};
+use js::jsapi::{JS_NewUCStringCopyN, JS_NewStringCopyN};
+use js::jsapi::{JS_WrapValue};
+use js::jsval::JSVal;
+use js::jsval::{UndefinedValue, NullValue, BooleanValue, Int32Value, UInt32Value};
+use js::jsval::{StringValue, ObjectValue, ObjectOrNullValue};
+use js::glue::RUST_JS_NumberValue;
+use libc;
+use std::default::Default;
+use std::slice;
+
+use dom::bindings::codegen::PrototypeList;
+
+// FIXME (https://github.com/rust-lang/rfcs/pull/4)
+//       remove Option<Self> arguments.
+pub trait IDLInterface {
+    fn get_prototype_id(_: Option<Self>) -> PrototypeList::id::ID;
+    fn get_prototype_depth(_: Option<Self>) -> uint;
+}
+
+/// A trait to convert Rust types to `JSVal`s.
+pub trait ToJSValConvertible {
+    /// Convert `self` to a `JSVal`. JSAPI failure causes a task failure.
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal;
+}
+
+/// A trait to convert `JSVal`s to Rust types.
+pub trait FromJSValConvertible<T> {
+    /// Convert `val` to type `Self`.
+    /// Optional configuration of type `T` can be passed as the `option`
+    /// argument.
+    /// If it returns `Err(())`, a JSAPI exception is pending.
+    fn from_jsval(cx: *mut JSContext, val: JSVal, option: T) -> Result<Self, ()>;
+}
+
+
+impl ToJSValConvertible for () {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        UndefinedValue()
+    }
+}
+
+impl ToJSValConvertible for JSVal {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        let mut value = *self;
+        if unsafe { JS_WrapValue(cx, &mut value) } == 0 {
+            fail!("JS_WrapValue failed.");
+        }
+        value
+    }
+}
+
+unsafe fn convert_from_jsval<T: Default>(
+    cx: *mut JSContext, value: JSVal,
+    convert_fn: unsafe extern "C" fn(*mut JSContext, JSVal, *mut T) -> JSBool) -> Result<T, ()> {
+    let mut ret = Default::default();
+    if convert_fn(cx, value, &mut ret) == 0 {
+        Err(())
+    } else {
+        Ok(ret)
+    }
+}
+
+
+impl ToJSValConvertible for bool {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        BooleanValue(*self)
+    }
+}
+
+impl FromJSValConvertible<()> for bool {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<bool, ()> {
+        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToBoolean) };
+        result.map(|b| b != 0)
+    }
+}
+
+impl ToJSValConvertible for i8 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        Int32Value(*self as i32)
+    }
+}
+
+impl FromJSValConvertible<()> for i8 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<i8, ()> {
+        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) };
+        result.map(|v| v as i8)
+    }
+}
+
+impl ToJSValConvertible for u8 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        Int32Value(*self as i32)
+    }
+}
+
+impl FromJSValConvertible<()> for u8 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<u8, ()> {
+        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) };
+        result.map(|v| v as u8)
+    }
+}
+
+impl ToJSValConvertible for i16 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        Int32Value(*self as i32)
+    }
+}
+
+impl FromJSValConvertible<()> for i16 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<i16, ()> {
+        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) };
+        result.map(|v| v as i16)
+    }
+}
+
+impl ToJSValConvertible for u16 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        Int32Value(*self as i32)
+    }
+}
+
+impl FromJSValConvertible<()> for u16 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<u16, ()> {
+        unsafe { convert_from_jsval(cx, val, JS_ValueToUint16) }
+    }
+}
+
+impl ToJSValConvertible for i32 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        Int32Value(*self)
+    }
+}
+
+impl FromJSValConvertible<()> for i32 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<i32, ()> {
+        unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) }
+    }
+}
+
+impl ToJSValConvertible for u32 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        UInt32Value(*self)
+    }
+}
+
+impl FromJSValConvertible<()> for u32 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<u32, ()> {
+        unsafe { convert_from_jsval(cx, val, JS_ValueToECMAUint32) }
+    }
+}
+
+impl ToJSValConvertible for i64 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        unsafe {
+            RUST_JS_NumberValue(*self as f64)
+        }
+    }
+}
+
+impl FromJSValConvertible<()> for i64 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<i64, ()> {
+        unsafe { convert_from_jsval(cx, val, JS_ValueToInt64) }
+    }
+}
+
+impl ToJSValConvertible for u64 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        unsafe {
+            RUST_JS_NumberValue(*self as f64)
+        }
+    }
+}
+
+impl FromJSValConvertible<()> for u64 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<u64, ()> {
+        unsafe { convert_from_jsval(cx, val, JS_ValueToUint64) }
+    }
+}
+
+impl ToJSValConvertible for f32 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        unsafe {
+            RUST_JS_NumberValue(*self as f64)
+        }
+    }
+}
+
+impl FromJSValConvertible<()> for f32 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<f32, ()> {
+        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToNumber) };
+        result.map(|f| f as f32)
+    }
+}
+
+impl ToJSValConvertible for f64 {
+    fn to_jsval(&self, _cx: *mut JSContext) -> JSVal {
+        unsafe {
+            RUST_JS_NumberValue(*self)
+        }
+    }
+}
+
+impl FromJSValConvertible<()> for f64 {
+    fn from_jsval(cx: *mut JSContext, val: JSVal, _option: ()) -> Result<f64, ()> {
+        unsafe { convert_from_jsval(cx, val, JS_ValueToNumber) }
+    }
+}
+
+impl ToJSValConvertible for DOMString {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        unsafe {
+            let string_utf16: Vec<u16> = self.as_slice().utf16_units().collect();
+            let jsstr = JS_NewUCStringCopyN(cx, string_utf16.as_ptr(), string_utf16.len() as libc::size_t);
+            if jsstr.is_null() {
+                fail!("JS_NewUCStringCopyN failed");
+            }
+            StringValue(&*jsstr)
+        }
+    }
+}
+
+/// Behavior for stringification of `JSVal`s.
+#[deriving(PartialEq)]
+pub enum StringificationBehavior {
+    /// Convert `null` to the string `"null"`.
+    Default,
+    /// Convert `null` to the empty string.
+    Empty,
+}
+
+impl Default for StringificationBehavior {
+    fn default() -> StringificationBehavior {
+        Default
+    }
+}
+
+impl FromJSValConvertible<StringificationBehavior> for DOMString {
+    fn from_jsval(cx: *mut JSContext, value: JSVal, nullBehavior: StringificationBehavior) -> Result<DOMString, ()> {
+        if nullBehavior == Empty && value.is_null() {
+            Ok("".to_string())
+        } else {
+            let jsstr = unsafe { JS_ValueToString(cx, value) };
+            if jsstr.is_null() {
+                debug!("JS_ValueToString failed");
+                Err(())
+            } else {
+                Ok(jsstring_to_str(cx, jsstr))
+            }
+        }
+    }
+}
+
+impl ToJSValConvertible for ByteString {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        unsafe {
+            let slice = self.as_slice();
+            let jsstr = JS_NewStringCopyN(cx, slice.as_ptr() as *const libc::c_char,
+                                          slice.len() as libc::size_t);
+            if jsstr.is_null() {
+                fail!("JS_NewStringCopyN failed");
+            }
+            StringValue(&*jsstr)
+        }
+    }
+}
+
+impl FromJSValConvertible<()> for ByteString {
+    fn from_jsval(cx: *mut JSContext, value: JSVal, _option: ()) -> Result<ByteString, ()> {
+        unsafe {
+            let string = JS_ValueToString(cx, value);
+            if string.is_null() {
+                debug!("JS_ValueToString failed");
+                return Err(());
+            }
+
+            let mut length = 0;
+            let chars = JS_GetStringCharsAndLength(cx, string, &mut length);
+            slice::raw::buf_as_slice(chars, length as uint, |char_vec| {
+                if char_vec.iter().any(|&c| c > 0xFF) {
+                    // XXX Throw
+                    Err(())
+                } else {
+                    Ok(ByteString::new(char_vec.iter().map(|&c| c as u8).collect()))
+                }
+            })
+        }
+    }
+}
+
+impl ToJSValConvertible for Reflector {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        let obj = self.get_jsobject();
+        assert!(obj.is_not_null());
+        let mut value = ObjectValue(unsafe { &*obj });
+        if unsafe { JS_WrapValue(cx, &mut value) } == 0 {
+            fail!("JS_WrapValue failed.");
+        }
+        value
+    }
+}
+
+impl<T: Reflectable+IDLInterface> FromJSValConvertible<()> for JS<T> {
+    fn from_jsval(_cx: *mut JSContext, value: JSVal, _option: ()) -> Result<JS<T>, ()> {
+        if !value.is_object() {
+            return Err(());
+        }
+        unwrap_jsmanaged(value.to_object(),
+                         IDLInterface::get_prototype_id(None::<T>),
+                         IDLInterface::get_prototype_depth(None::<T>))
+    }
+}
+
+impl<'a, 'b, T: Reflectable> ToJSValConvertible for Root<'a, 'b, T> {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        self.reflector().to_jsval(cx)
+    }
+}
+
+impl<'a, T: Reflectable> ToJSValConvertible for JSRef<'a, T> {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        self.reflector().to_jsval(cx)
+    }
+}
+
+impl<'a, T: Reflectable> ToJSValConvertible for JS<T> {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        self.reflector().to_jsval(cx)
+    }
+}
+
+impl<T: ToJSValConvertible> ToJSValConvertible for Option<T> {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        match self {
+            &Some(ref value) => value.to_jsval(cx),
+            &None => NullValue(),
+        }
+    }
+}
+
+impl<X: Default, T: FromJSValConvertible<X>> FromJSValConvertible<()> for Option<T> {
+    fn from_jsval(cx: *mut JSContext, value: JSVal, _: ()) -> Result<Option<T>, ()> {
+        if value.is_null_or_undefined() {
+            Ok(None)
+        } else {
+            let option: X = Default::default();
+            let result: Result<T, ()> = FromJSValConvertible::from_jsval(cx, value, option);
+            result.map(Some)
+        }
+    }
+}
+
+impl ToJSValConvertible for *mut JSObject {
+    fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
+        let mut wrapped = ObjectOrNullValue(*self);
+        unsafe {
+            assert!(JS_WrapValue(cx, &mut wrapped) != 0);
+        }
+        wrapped
+    }
+}