1 files changed, 114 insertions, 0 deletions
diff --git a/components/script/dom/bindings/error.rs b/components/script/dom/bindings/error.rs
new file mode 100644
index 00000000000..cb39e4f0755
--- /dev/null
+++ b/components/script/dom/bindings/error.rs
@@ -0,0 +1,114 @@
+/* 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/. */
+
+//! Utilities to throw exceptions from Rust bindings.
+
+use dom::bindings::conversions::ToJSValConvertible;
+use dom::bindings::global::GlobalRef;
+use dom::domexception::DOMException;
+
+use js::jsapi::{JSContext, JSBool, JSObject};
+use js::jsapi::{JS_IsExceptionPending, JS_SetPendingException, JS_ReportPendingException};
+use js::jsapi::{JS_ReportErrorNumber, JSErrorFormatString, JSEXN_TYPEERR};
+use js::jsapi::{JS_SaveFrameChain, JS_RestoreFrameChain};
+use js::glue::{ReportError};
+use js::rust::with_compartment;
+
+use libc;
+use std::ptr;
+
+/// DOM exceptions that can be thrown by a native DOM method.
+#[deriving(Show)]
+pub enum Error {
+    IndexSize,
+    FailureUnknown,
+    NotFound,
+    HierarchyRequest,
+    InvalidCharacter,
+    NotSupported,
+    InvalidState,
+    Syntax,
+    NamespaceError,
+    InvalidAccess,
+    Security,
+    Network,
+    Abort,
+    Timeout
+}
+
+/// The return type for IDL operations that can throw DOM exceptions.
+pub type Fallible<T> = Result<T, Error>;
+
+/// The return type for IDL operations that can throw DOM exceptions and
+/// return `()`.
+pub type ErrorResult = Fallible<()>;
+
+/// Set a pending DOM exception for the given `result` on `cx`.
+pub fn throw_dom_exception(cx: *mut JSContext, global: &GlobalRef,
+                           result: Error) {
+    assert!(unsafe { JS_IsExceptionPending(cx) } == 0);
+    let exception = DOMException::new_from_error(global, result).root();
+    let thrown = exception.to_jsval(cx);
+    unsafe {
+        JS_SetPendingException(cx, thrown);
+    }
+}
+
+/// Report a pending exception, thereby clearing it.
+pub fn report_pending_exception(cx: *mut JSContext, obj: *mut JSObject) {
+    unsafe {
+        if JS_IsExceptionPending(cx) != 0 {
+            let saved = JS_SaveFrameChain(cx);
+            with_compartment(cx, obj, || {
+                JS_ReportPendingException(cx);
+            });
+            if saved != 0 {
+                JS_RestoreFrameChain(cx);
+            }
+        }
+    }
+}
+
+/// Throw an exception to signal that a `JSVal` can not be converted to any of
+/// the types in an IDL union type.
+pub fn throw_not_in_union(cx: *mut JSContext, names: &'static str) -> JSBool {
+    assert!(unsafe { JS_IsExceptionPending(cx) } == 0);
+    let message = format!("argument could not be converted to any of: {}", names);
+    message.with_c_str(|string| {
+        unsafe { ReportError(cx, string) };
+    });
+    return 0;
+}
+
+/// Format string used to throw `TypeError`s.
+static ERROR_FORMAT_STRING_STRING: [libc::c_char, ..4] = [
+    '{' as libc::c_char,
+    '0' as libc::c_char,
+    '}' as libc::c_char,
+    0 as libc::c_char,
+];
+
+/// Format string struct used to throw `TypeError`s.
+static ERROR_FORMAT_STRING: JSErrorFormatString = JSErrorFormatString {
+    format: &ERROR_FORMAT_STRING_STRING as *const libc::c_char,
+    argCount: 1,
+    exnType: JSEXN_TYPEERR as i16,
+};
+
+/// Callback used to throw `TypeError`s.
+extern fn get_error_message(_user_ref: *mut libc::c_void,
+                            _locale: *const libc::c_char,
+                            error_number: libc::c_uint) -> *const JSErrorFormatString
+{
+    assert_eq!(error_number, 0);
+    &ERROR_FORMAT_STRING as *const JSErrorFormatString
+}
+
+/// Throw a `TypeError` with the given message.
+pub fn throw_type_error(cx: *mut JSContext, error: &str) {
+    let error = error.to_c_str();
+    unsafe {
+        JS_ReportErrorNumber(cx, Some(get_error_message), ptr::mut_null(), 0, error.as_ptr());
+    }
+}