Basic Local<String> support (#27)

BUILD.gn

@@ -10,10 +10,11 @@ v8_static_library("rusty_v8") {
     "src/inspector/client.cc",
     "src/isolate.cc",
     "src/locker.cc",
+    "src/number.cc",
     "src/platform/mod.cc",
     "src/platform/task.cc",
+    "src/string.cc",
     "src/string_buffer.cc",
-    "src/value.cc",
   ]
   deps = [
     ":v8",

Cargo.lock

@@ -20,6 +20,11 @@ dependencies = [
  "libc 0.2.65 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "cargo_gn"
 version = "0.0.13"
@@ -62,6 +67,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "rusty_v8"
 version = "0.0.7"
 dependencies = [
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "cargo_gn 0.0.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.65 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -80,6 +86,7 @@ dependencies = [
 [metadata]
 "checksum backtrace 0.3.40 (registry+https://github.com/rust-lang/crates.io-index)" = "924c76597f0d9ca25d762c25a4d369d51267536465dc5064bdf0eb073ed477ea"
 "checksum backtrace-sys 0.1.32 (registry+https://github.com/rust-lang/crates.io-index)" = "5d6575f128516de27e3ce99689419835fce9643a9b215a14d2b5b685be018491"
+"checksum bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 "checksum cargo_gn 0.0.13 (registry+https://github.com/rust-lang/crates.io-index)" = "0a679c108cad6ee19a25f4dbaf1b4e1fadf303e707fa1e2d060b4c169faeb836"
 "checksum cc 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)" = "4fc9a35e1f4290eb9e5fc54ba6cf40671ed2a2514c3eeb2b2a908dda2ea5a1be"
 "checksum cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"

Cargo.toml

@@ -50,6 +50,7 @@ exclude = [
 [dependencies]
 lazy_static = "1.4.0"
 libc = "0.2.65"
+bitflags = "1.2.1"
 
 [build-dependencies]
 cargo_gn = "0.0.13"

src/lib.rs

@@ -5,6 +5,8 @@
 #![allow(clippy::new_without_default)]
 #![allow(dead_code)]
 
+#[macro_use]
+extern crate bitflags;
 #[macro_use]
 extern crate lazy_static;
 extern crate libc;
@@ -14,13 +16,14 @@ mod inspector;
 mod isolate;
 mod local;
 mod locker;
+mod number;
 mod string_buffer;
 mod string_view;
 mod support;
-mod value;
 
 pub mod array_buffer;
 pub mod platform;
+pub mod string;
 // This module is intentionally named "V8" rather than "v8" to match the
 // C++ namespace "v8::V8".
 #[allow(non_snake_case)]
@@ -30,6 +33,7 @@ pub use handle_scope::HandleScope;
 pub use isolate::Isolate;
 pub use local::Local;
 pub use locker::Locker;
+pub use number::{Integer, Number};
+pub use string::String;
 pub use string_buffer::StringBuffer;
 pub use string_view::StringView;
-pub use value::{Integer, Number};

src/string.cc

@@ -0,0 +1,29 @@
+#include <cstdint>
+
+#include "support.h"
+#include "v8/include/v8.h"
+
+using namespace v8;
+using namespace support;
+
+extern "C" {
+String* v8__String__NewFromUtf8(Isolate* isolate,
+                                const char* data,
+                                NewStringType type,
+                                int length) {
+  return maybe_local_ptr(String::NewFromUtf8(isolate, data, type, length));
+}
+
+int v8__String__Utf8Length(const String& self, Isolate* isolate) {
+  return self.Utf8Length(isolate);
+}
+
+int v8__String__WriteUtf8(const String& self,
+                          Isolate* isolate,
+                          char* buffer,
+                          int length,
+                          int* nchars_ref,
+                          int options) {
+  return self.WriteUtf8(isolate, buffer, length, nchars_ref, options);
+}
+}

src/string.rs

@@ -0,0 +1,135 @@
+use std::convert::TryInto;
+use std::default::Default;
+use std::mem::forget;
+use std::slice;
+
+use crate::isolate::CxxIsolate;
+use crate::isolate::LockedIsolate;
+use crate::support::char;
+use crate::support::int;
+use crate::support::Opaque;
+use crate::HandleScope;
+use crate::Local;
+
+extern "C" {
+  fn v8__String__NewFromUtf8(
+    isolate: *mut CxxIsolate,
+    data: *const char,
+    new_type: NewStringType,
+    length: int,
+  ) -> *const String;
+
+  fn v8__String__Utf8Length(this: &String, isolate: *mut CxxIsolate) -> int;
+
+  fn v8__String__WriteUtf8(
+    this: &String,
+    isolate: *mut CxxIsolate,
+    buffer: *mut char,
+    length: int,
+    nchars_ref: *mut int,
+    options: WriteOptions,
+  ) -> int;
+}
+
+#[repr(C)]
+pub enum NewStringType {
+  Normal,
+  Internalized,
+}
+
+impl Default for NewStringType {
+  fn default() -> Self {
+    NewStringType::Normal
+  }
+}
+
+bitflags! {
+  #[derive(Default)]
+  #[repr(transparent)]
+  pub struct WriteOptions: int {
+    const NO_OPTIONS = 0;
+    const HINT_MANY_WRITES_EXPECTED = 1;
+    const NO_NULL_TERMINATION = 2;
+    const PRESERVE_ONE_BYTE_NULL = 4;
+    // Used by WriteUtf8 to replace orphan surrogate code units with the
+    // unicode replacement character. Needs to be set to guarantee valid UTF-8
+    // output.
+    const REPLACE_INVALID_UTF8 = 8;
+  }
+}
+
+#[repr(C)]
+pub struct String(Opaque);
+
+impl String {
+  pub fn new_from_utf8<'sc>(
+    scope: &mut HandleScope<'sc>,
+    buffer: &[u8],
+    new_type: NewStringType,
+  ) -> Option<Local<'sc, String>> {
+    unsafe {
+      let ptr = v8__String__NewFromUtf8(
+        scope.cxx_isolate(),
+        buffer.as_ptr() as *const char,
+        new_type,
+        buffer.len().try_into().ok()?,
+      );
+      Local::from_raw(ptr)
+    }
+  }
+
+  pub fn utf8_length(&self, isolate: &mut impl LockedIsolate) -> usize {
+    unsafe { v8__String__Utf8Length(self, isolate.cxx_isolate()) as usize }
+  }
+
+  pub fn write_utf8(
+    &self,
+    isolate: &mut impl LockedIsolate,
+    buffer: &mut [u8],
+    nchars_ref: Option<&mut usize>,
+    options: WriteOptions,
+  ) -> usize {
+    let mut nchars_ref_int: int = 0;
+    let bytes = unsafe {
+      v8__String__WriteUtf8(
+        self,
+        isolate.cxx_isolate(),
+        buffer.as_mut_ptr() as *mut char,
+        buffer.len().try_into().unwrap_or(int::max_value()),
+        &mut nchars_ref_int,
+        options,
+      )
+    };
+    if let Some(r) = nchars_ref {
+      *r = nchars_ref_int as usize;
+    }
+    bytes as usize
+  }
+
+  // Convenience function not present in the original V8 API.
+  pub fn new<'sc>(
+    scope: &mut HandleScope<'sc>,
+    value: &str,
+    new_type: NewStringType,
+  ) -> Option<Local<'sc, String>> {
+    Self::new_from_utf8(scope, value.as_ref(), new_type)
+  }
+
+  // Convenience function not present in the original V8 API.
+  pub fn to_rust_string_lossy(
+    &self,
+    isolate: &mut impl LockedIsolate,
+  ) -> std::string::String {
+    let capacity = self.utf8_length(isolate);
+    let mut string = std::string::String::with_capacity(capacity);
+    let data = string.as_mut_ptr();
+    forget(string);
+    let length = self.write_utf8(
+      isolate,
+      unsafe { slice::from_raw_parts_mut(data, capacity) },
+      None,
+      WriteOptions::NO_NULL_TERMINATION | WriteOptions::REPLACE_INVALID_UTF8,
+    );
+    unsafe { std::string::String::from_raw_parts(data, length, capacity) }
+  }
+}

src/support.h

@@ -7,6 +7,8 @@
 #include <type_traits>
 #include <utility>
 
+#include "v8/include/v8.h"
+
 // Check assumptions made in binding code.
 // TODO(ry) re-enable the following
 // static_assert(sizeof(bool) == sizeof(uint8_t));
@@ -33,4 +35,9 @@ void construct_in_place(uninit_t<T>& buf, Args... args) {
 }
 }  // namespace support
 
+template <class T>
+inline static T* maybe_local_ptr(v8::MaybeLocal<T> value) {
+  return *value.FromMaybe(v8::Local<T>());
+}
+
 #endif  // SUPPORT_H_

src/support.rs

@@ -6,6 +6,7 @@ use std::ops::Deref;
 use std::ops::DerefMut;
 use std::ptr::NonNull;
 
+pub use std::os::raw::c_char as char;
 pub use std::os::raw::c_int as int;
 
 pub type Opaque = [usize; 0];

tests/test_api.rs

@@ -76,6 +76,24 @@ fn handle_scope_numbers() {
   drop(g);
 }
 
+#[test]
+fn test_string() {
+  setup();
+  let mut params = v8::Isolate::create_params();
+  params.set_array_buffer_allocator(
+    v8::array_buffer::Allocator::new_default_allocator(),
+  );
+  let mut isolate = v8::Isolate::new(params);
+  let mut locker = v8::Locker::new(&mut isolate);
+  v8::HandleScope::enter(&mut locker, |scope| {
+    let reference = "Hello 🦕 world!";
+    let local =
+      v8::String::new(scope, reference, v8::string::NewStringType::Normal)
+        .unwrap();
+    assert_eq!(reference, local.to_rust_string_lossy(scope));
+  });
+}
+
 #[test]
 fn isolate_new() {
   let g = setup();