Add V8::set_flags_from_string() (#457)

src/V8.rs

@@ -11,6 +11,7 @@ use crate::support::UniqueRef;
 
 extern "C" {
   fn v8__V8__SetFlagsFromCommandLine(argc: *mut c_int, argv: *mut *mut c_char);
+  fn v8__V8__SetFlagsFromString(flags: *const u8, length: usize);
   fn v8__V8__GetVersion() -> *const c_char;
   fn v8__V8__InitializePlatform(platform: *mut Platform);
   fn v8__V8__Initialize();
@@ -79,6 +80,13 @@ pub fn set_flags_from_command_line(args: Vec<String>) -> Vec<String> {
     .collect()
 }
 
+/// Sets V8 flags from a string.
+pub fn set_flags_from_string(flags: &str) {
+  unsafe {
+    v8__V8__SetFlagsFromString(flags.as_ptr(), flags.len());
+  }
+}
+
 /// Get the version string.
 pub fn get_version() -> &'static str {
   let version = unsafe { v8__V8__GetVersion() };

src/binding.cc

@@ -93,6 +93,10 @@ void v8__V8__SetFlagsFromCommandLine(int* argc, char** argv) {
   v8::V8::SetFlagsFromCommandLine(argc, argv, true);
 }
 
+void v8__V8__SetFlagsFromString(const char* flags, size_t length) {
+  v8::V8::SetFlagsFromString(flags, length);
+}
+
 const char* v8__V8__GetVersion() { return v8::V8::GetVersion(); }
 
 void v8__V8__InitializePlatform(v8::Platform* platform) {

tests/test_api_flags.rs

@@ -0,0 +1,19 @@
+// Tests from the same file run in a single process. That's why this test
+// is in its own file, because changing flags affects the whole process.
+use rusty_v8 as v8;
+
+#[test]
+fn set_flags_from_string() {
+  v8::V8::set_flags_from_string("--use_strict");
+  v8::V8::initialize_platform(v8::new_default_platform().unwrap());
+  v8::V8::initialize();
+  let isolate = &mut v8::Isolate::new(Default::default());
+  let scope = &mut v8::HandleScope::new(isolate);
+  let context = v8::Context::new(scope);
+  let scope = &mut v8::ContextScope::new(scope, context);
+  let source = "(function() { return this })()";
+  let source = v8::String::new(scope, source).unwrap();
+  let script = v8::Script::compile(scope, source, None).unwrap();
+  let result = script.run(scope).unwrap();
+  assert!(result.is_undefined()); // Because of --use_strict.
+}