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Created November 27, 2020 14:05
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QuickJS engine sample project - shows how to embedded in C++
cmake_minimum_required(VERSION 3.9)
project(QuickJS-Experiment)
#========== Global Configurations =============#
#----------------------------------------------#
set( CMAKE_CXX_STANDARD 17 )
set( CMAKE_VERBOSE_MAKEFILE ON )
set( CMAKE_CXX_EXTENSIONS OFF)
# ------------ Download CPM CMake Script ----------------#
## Automatically donwload and use module CPM.cmake
file(DOWNLOAD https://raw.githubusercontent.com/TheLartians/CPM.cmake/v0.26.2/cmake/CPM.cmake
"${CMAKE_BINARY_DIR}/CPM.cmake")
include("${CMAKE_BINARY_DIR}/CPM.cmake")
#----------- Add dependencies --------------------------#
CPMAddPackage(
NAME quickjs
GITHUB_REPOSITORY bellard/quickjs
GIT_TAG 204682fb87ab9312f0cf81f959ecd181180457bc
# DOWNLOAD_ONLY YES
)
# Add this directory where is this file (CMakeLists.txt) to include path.
include_directories( ${CMAKE_CURRENT_LIST_DIR} )
# =============== QuickJS settings ====================================#
include_directories( ${quickjs_SOURCE_DIR}/ )
message([TRACE] " quickjs source = ${quickjs_SOURCE_DIR} ")
file(GLOB quickjs_hpp ${quickjs_SOURCE_DIR}/*.h )
file(GLOB quickjs_src ${quickjs_SOURCE_DIR}/quickjs.c
${quickjs_SOURCE_DIR}/libregexp.c
${quickjs_SOURCE_DIR}/libunicode.c
${quickjs_SOURCE_DIR}/cutils.c
${quickjs_SOURCE_DIR}/quickjs-libc.c
${quickjs_SOURCE_DIR}/libbf.c
)
add_library( qjs-engine ${quickjs_src} ${quickjs_hpp} )
target_compile_options( qjs-engine PRIVATE
-MMD -MF
-Wno-sign-compare
-Wno-missing-field-initializers
-Wundef -Wuninitialized
-Wundef -Wuninitialized -Wwrite-strings -Wchar-subscripts
)
target_compile_definitions( qjs-engine PUBLIC
CONFIG_BIGNUM=y
CONFIG_VERSION="2020-11-08"
_GNU_SOURCE
)
if(UNIX)
target_link_libraries( qjs-engine PRIVATE m pthread dl)
endif()
# =========== Target Settings =========================================#
# QuickJS compiler.
add_executable( qjsc ${quickjs_SOURCE_DIR}/qjsc.c )
target_compile_definitions( qjsc PUBLIC CONFIG_BIGNUM=y CONFIG_VERSION="2020-11-08" _GNU_SOURCE )
target_link_libraries( qjsc qjs-engine )
# Sample application that embeds the quickJS Javascript engine.
add_executable( main main.cpp )
target_link_libraries( main qjs-engine )
#include <iostream>
#include <quickjspp.hpp>
class ChartXY
{
private:
double x = 0.0, y = 0.0;
double width = 100.0, height = 100.0;
public:
ChartXY()
{ }
ChartXY(double w, double h): width(w), height(h)
{ }
void show() const
{
std::cout << " [ĆhartXY Object] x = " << x << " ; y = " << y
<< " ; width = " << width << " height = " << height
<< '\n';
}
void set_width(double width)
{
this->width = width;
std::fprintf(stdout, " [ChartXY] Width set to %f \n", width);
}
void set_height(double height)
{
this->height = height;
std::fprintf(stdout, " [ChartXY] Height set to %f \n", height);
}
double get_height() const { return this->height; }
double get_width () const { return this->width; }
void plot_points(std::vector<double> const& points)
{
std::cout << " [ChartXY] Plotting points =>> ";
for(auto p : points) { std::cout << " " << p; }
std::cout << "\n";
}
};
qjs::Value
try_eval_module(
qjs::Context& context
, qjs::Runtime& runtime
, std::string const& code)
{
try
{
return context.eval(code, "<eval>", JS_EVAL_TYPE_MODULE);
} catch( const qjs::exception& ex)
{
//js_std_dump_error(ctx);
auto exc = context.getException();
std::cerr << (exc.isError() ? "Error: " : "Throw: ") << (std::string)exc << std::endl;
if((bool)exc["stack"])
std::cerr << (std::string)exc["stack"] << std::endl;
js_std_free_handlers(runtime.rt);
return context.newObject();
}
}
int main(int argc, char** argv)
{
std::cout << " [INFO] Started Ok" << std::endl;
using namespace qjs;
Runtime runtime;
//JSRuntime* rt = runtime.rt;
Context context(runtime);
//JSContext* ctx = context.ctx;
js_std_init_handlers(runtime.rt);
/* loader for ES6 modules */
JS_SetModuleLoaderFunc(runtime.rt, nullptr, js_module_loader, nullptr);
js_std_add_helpers(context.ctx, argc - 1, argv + 1);
/* system modules */
js_init_module_std(context.ctx, "std");
js_init_module_os(context.ctx, "os");
std::fprintf(stderr, " [TRACE] Before loading code. \n");
const char* str = R"(
/*
import * as std from 'std';
import * as os from 'os';
globalThis.std = std;
globalThis.os = os;
*/
console.log(" [QUICJS] => =>> Script loaded. Ok. \n");
for(n = 1; n <= 5; n++){
console.log(` [QUICKJS-TRACE] n = ${n}/5 `);
}
// ----- Define user variables here ----
asset_path = "/Users/mydir-macosx/data/blackjack.txt";
game_score = 0.25156;
let x = 10.352;
datapoints = [ 0.251, 19.2363, 9.262, 100.125 ];
console.log(`\n [QUICKJS] asset_path = ${asset_path}` );
console.log(` [QUICKJS] score = ${100.0 * game_score} (in percent) \n`);
console.log(` [QUICKJS] data points = ${datapoints} `)
)";
try
{
context.eval(str); //, "", JS_EVAL_TYPE_MODULE);
} catch( const qjs::exception& ex)
{
//js_std_dump_error(ctx);
auto exc = context.getException();
std::cerr << (exc.isError() ? "Error: " : "Throw: ") << (std::string)exc << std::endl;
if((bool)exc["stack"])
std::cerr << (std::string)exc["stack"] << std::endl;
js_std_free_handlers(runtime.rt);
return 1;
}
std::fprintf(stderr, " [TRACE] After loading code. \n");
int number = (int) context.eval(" 10 * (3 + 1 + 10 ) - 1000 * 2");
std::cout << " [RESULT] number = " << number << '\n';
std::puts("\n [*] ===== Read configuration variables defined in the js code. ====\n");
{
auto var_asset_path = context.global()["asset_path"].as<std::string>();
std::cout << " =>> asset_path = " << var_asset_path << '\n';
auto score = context.global()["game_score"].as<double>();
std::cout << " =>> game_score (%) = " << 100.0 * score << '\n';
auto points = context.global()["datapoints"].as<std::vector<double>>();
std::cout << " ==>> datapoints = [" << points.size() << "]( ";
for(auto p : points) { std::cout << p << ' '; }
std::cout << " ) \n";
}
std::puts("\n [*] ===== Define variables in C++-side ====\n");
{
context.global()["user_name"] = context.newValue("Gaius Julius Caesar");
context.global()["user_points"] = context.newValue(101235);
auto data = std::vector<std::string>{ "ADA", "RUST", "C++11", "C++17", "C++20"
, "Dlang", "OCaml", "C#(Csharp)" };
context.global()["user_data"] = context.newValue(data);
// Note: This code should be within an exception handler.
context.eval(R"(
console.log(` [STEP 2] user_name = ${user_name} ; points = ${user_points} `);
console.log(` [STEP 2] user_data = ${user_data} ; type = ${ typeof(user_data) } `);
console.log(` [STEP 2] user_data[5] = ${ user_data[5] } `)
// Iterate over the array
for(let x in user_data){ console.log(user_data[x]); }
)");
}
std::puts("\n [*] ===== Register class ChartXY ====\n");
auto& module = context.addModule("chart");
module.class_<ChartXY>("ChartXY")
.constructor()
.constructor<double, double>()
.fun<&ChartXY::show>("show")
.fun<&ChartXY::set_height>("set_height")
.fun<&ChartXY::set_width>("set_width")
.fun<&ChartXY::plot_points>("plot_points")
.property<&ChartXY::get_width, &ChartXY::set_width>("width")
.property<&ChartXY::get_height, &ChartXY::set_height>("height")
;
module.add("user_path", "/Users/data/assets/game/score/marks");
module.add("user_points", 1023523);
module.function("myfunc", [](double x, double y){ return 4.61 * x + 10 * y * y; });
const char* module_code = R"(
import { ChartXY } from "chart";
import * as chart from "chart"
console.log(` [SCRIPT] chart.user_path = ${chart.user_path} \n\n`);
console.log(` [SCRIPT] chart.user_points = ${chart.user_points} \n\n`);
console.log(` [SCRIPT] Result = ${ chart.myfunc(5.61, 9.821) } \n`);
let ch = new ChartXY(200, 600);
ch.show();
ch.set_width(800.0);
ch.set_height(700.0)
ch.show();
console.log(" [QUICKJS] Change chart dimensions using properties ");
ch.width = 500;
ch.height = 660;
console.log(`\n <QUICKJS> Chart width = ${ch.width} ; Chart height = ${ch.height} \n`);
ch.plot_points( [ 10.522, 8.261, -100.24, 7.2532, 56.123, 89.23 ] );
)";
try_eval_module(context, runtime, module_code);
js_std_loop(context.ctx);
// ----- Shutdown virtual machine ---------------//
js_std_free_handlers(runtime.rt);
return 0;
}
/* Original project (autorship): https://github.com/ftk/quickjspp (Credits goes to this files)
*
* "QuickJSPP is header-only - put quickjspp.hpp into your include search path.
* Compiler that supports C++17 or later is required. The program needs to be linked against
* QuickJS. Sample CMake project files are provided.
*
* Original file URL: https://raw.githubusercontent.com/ftk/quickjspp/fd9e30676cf18e6c22a26d6731516fe96d757c28/quickjspp.hpp
*/
#pragma once
#include <quickjs.h>
#include <quickjs-libc.h>
#include <vector>
#include <string_view>
#include <string>
#include <cassert>
#include <memory>
#include <cstddef>
#include <algorithm>
#include <tuple>
#include <functional>
#include <stdexcept>
namespace qjs {
/** Exception type.
* Indicates that exception has occured in JS context.
*/
class exception {};
/** Javascript conversion traits.
* Describes how to convert type R to/from JSValue. Second template argument can be used for SFINAE/enable_if type filters.
*/
template <typename R, typename /*_SFINAE*/ = void>
struct js_traits
{
/** Create an object of C++ type R given JSValue v and JSContext.
* This function is intentionally not implemented. User should implement this function for their own type.
* @param v This value is passed as JSValueConst so it should be freed by the caller.
* @throws exception in case of conversion error
*/
static R unwrap(JSContext * ctx, JSValueConst v);
/** Create JSValue from an object of type R and JSContext.
* This function is intentionally not implemented. User should implement this function for their own type.
* @return Returns JSValue which should be freed by the caller or JS_EXCEPTION in case of error.
*/
static JSValue wrap(JSContext * ctx, R value);
};
/** Conversion traits for JSValue (identity).
*/
template <>
struct js_traits<JSValue>
{
static JSValue unwrap(JSContext * ctx, JSValueConst v) noexcept
{
return JS_DupValue(ctx, v);
}
static JSValue wrap(JSContext * ctx, JSValue v) noexcept
{
return v;
}
};
/** Conversion traits for integers.
*/
template <typename Int>
struct js_traits<Int, std::enable_if_t<std::is_integral_v<Int> && sizeof(Int) <= sizeof(int64_t)>>
{
/// @throws exception
static Int unwrap(JSContext * ctx, JSValueConst v)
{
if constexpr (sizeof(Int) > sizeof(int32_t))
{
int64_t r;
if(JS_ToInt64(ctx, &r, v))
throw exception{};
return static_cast<Int>(r);
}
else
{
int32_t r;
if(JS_ToInt32(ctx, &r, v))
throw exception{};
return static_cast<Int>(r);
}
}
static JSValue wrap(JSContext * ctx, Int i) noexcept
{
if constexpr (std::is_same_v<Int, uint32_t> || sizeof(Int) > sizeof(int32_t))
return JS_NewInt64(ctx, static_cast<Int>(i));
else
return JS_NewInt32(ctx, static_cast<Int>(i));
}
};
/** Conversion traits for boolean.
*/
template <>
struct js_traits<bool>
{
static bool unwrap(JSContext * ctx, JSValueConst v) noexcept
{
return JS_ToBool(ctx, v);
}
static JSValue wrap(JSContext * ctx, bool i) noexcept
{
return JS_NewBool(ctx, i);
}
};
/** Conversion trait for void.
*/
template <>
struct js_traits<void>
{
/// @throws exception if jsvalue is neither undefined nor null
static void unwrap(JSContext * ctx, JSValueConst value)
{
if(JS_IsException(value))
throw exception{};
}
};
/** Conversion traits for float64/double.
*/
template <>
struct js_traits<double>
{
/// @throws exception
static double unwrap(JSContext * ctx, JSValueConst v)
{
double r;
if(JS_ToFloat64(ctx, &r, v))
throw exception{};
return r;
}
static JSValue wrap(JSContext * ctx, double i) noexcept
{
return JS_NewFloat64(ctx, i);
}
};
namespace detail {
/** Fake std::string_view which frees the string on destruction.
*/
class js_string : public std::string_view
{
using Base = std::string_view;
JSContext * ctx = nullptr;
friend struct js_traits<std::string_view>;
js_string(JSContext * ctx, const char * ptr, std::size_t len) : Base(ptr, len), ctx(ctx)
{}
public:
template <typename... Args>
js_string(Args&& ... args) : Base(std::forward<Args>(args)...), ctx(nullptr)
{}
js_string(const js_string& other) = delete;
operator const char * () const {
return this->data();
}
~js_string()
{
if(ctx)
JS_FreeCString(ctx, this->data());
}
};
} // namespace detail
/** Conversion traits from std::string_view and to detail::js_string. */
template <>
struct js_traits<std::string_view>
{
static detail::js_string unwrap(JSContext * ctx, JSValueConst v)
{
size_t plen;
const char * ptr = JS_ToCStringLen(ctx, &plen, v);
if(!ptr)
throw exception{};
return detail::js_string{ctx, ptr, plen};
}
static JSValue wrap(JSContext * ctx, std::string_view str) noexcept
{
return JS_NewStringLen(ctx, str.data(), str.size());
}
};
/** Conversion traits for std::string */
template <> // slower
struct js_traits<std::string>
{
static std::string unwrap(JSContext * ctx, JSValueConst v)
{
auto str_view = js_traits<std::string_view>::unwrap(ctx, v);
return std::string{str_view.data(), str_view.size()};
}
static JSValue wrap(JSContext * ctx, const std::string& str) noexcept
{
return JS_NewStringLen(ctx, str.data(), str.size());
}
};
/** Conversion from const char * */
template <>
struct js_traits<const char *>
{
static JSValue wrap(JSContext * ctx, const char * str) noexcept
{
return JS_NewString(ctx, str);
}
static detail::js_string unwrap(JSContext * ctx, JSValueConst v)
{
return js_traits<std::string_view>::unwrap(ctx, v);
}
};
namespace detail {
/** Helper function to convert and then free JSValue. */
template <typename T>
T unwrap_free(JSContext * ctx, JSValue val)
{
if constexpr(std::is_same_v<T, void>)
{
JS_FreeValue(ctx, val);
return js_traits<T>::unwrap(ctx, val);
} else
{
try
{
T result = js_traits<std::decay_t<T>>::unwrap(ctx, val);
JS_FreeValue(ctx, val);
return result;
}
catch(...)
{
JS_FreeValue(ctx, val);
throw;
}
}
}
template <class Tuple, std::size_t... I>
Tuple unwrap_args_impl(JSContext * ctx, JSValueConst * argv, std::index_sequence<I...>)
{
return Tuple{js_traits<std::decay_t<std::tuple_element_t<I, Tuple>>>::unwrap(ctx, argv[I])...};
}
/** Helper function to convert an array of JSValues to a tuple.
* @tparam Args C++ types of the argv array
*/
template <typename... Args>
std::tuple<std::decay_t<Args>...> unwrap_args(JSContext * ctx, JSValueConst * argv)
{
return unwrap_args_impl<std::tuple<std::decay_t<Args>...>>(ctx, argv, std::make_index_sequence<sizeof...(Args)>());
}
/** Helper function to call f with an array of JSValues.
* @tparam R return type of f
* @tparam Args argument types of f
* @tparam Callable type of f (inferred)
* @param ctx JSContext
* @param f callable object
* @param argv array of JSValue's
* @return converted return value of f or JS_NULL if f returns void
*/
template <typename R, typename... Args, typename Callable>
JSValue wrap_call(JSContext * ctx, Callable&& f, JSValueConst * argv) noexcept
{
try
{
if constexpr(std::is_same_v<R, void>)
{
std::apply(std::forward<Callable>(f), unwrap_args<Args...>(ctx, argv));
return JS_NULL;
} else
{
return js_traits<std::decay_t<R>>::wrap(ctx,
std::apply(std::forward<Callable>(f),
unwrap_args<Args...>(ctx, argv)));
}
}
catch(exception)
{
return JS_EXCEPTION;
}
}
/** Same as wrap_call, but pass this_value as first argument.
* @tparam FirstArg type of this_value
*/
template <typename R, typename FirstArg, typename... Args, typename Callable>
JSValue wrap_this_call(JSContext * ctx, Callable&& f, JSValueConst this_value, JSValueConst * argv) noexcept
{
try
{
if constexpr(std::is_same_v<R, void>)
{
std::apply(std::forward<Callable>(f), std::tuple_cat(unwrap_args<FirstArg>(ctx, &this_value),
unwrap_args<Args...>(ctx, argv)));
return JS_NULL;
} else
{
return js_traits<std::decay_t<R>>::wrap(ctx,
std::apply(std::forward<Callable>(f),
std::tuple_cat(
unwrap_args<FirstArg>(ctx, &this_value),
unwrap_args<Args...>(ctx, argv))));
}
}
catch(exception)
{
return JS_EXCEPTION;
}
}
template <class Tuple, std::size_t... I>
void wrap_args_impl(JSContext * ctx, JSValue * argv, Tuple tuple, std::index_sequence<I...>)
{
((argv[I] = js_traits<std::decay_t<std::tuple_element_t<I, Tuple>>>::wrap(ctx, std::get<I>(tuple))), ...);
}
/** Converts C++ args to JSValue array.
* @tparam Args argument types
* @param argv array of size at least sizeof...(Args)
*/
template <typename... Args>
void wrap_args(JSContext * ctx, JSValue * argv, Args&& ... args)
{
wrap_args_impl(ctx, argv, std::make_tuple(std::forward<Args>(args)...),
std::make_index_sequence<sizeof...(Args)>());
}
} // namespace detail
/** A wrapper type for free and class member functions.
* Pointer to function F is a template argument.
* @tparam F either a pointer to free function or a pointer to class member function
* @tparam PassThis if true and F is a pointer to free function, passes Javascript "this" value as first argument:
*/
template <auto F, bool PassThis = false /* pass this as the first argument */>
struct fwrapper
{
/// "name" property of the JS function object (not defined if nullptr)
const char * name = nullptr;
};
/** Conversion to JSValue for free function in fwrapper. */
template <typename R, typename... Args, R (* F)(Args...), bool PassThis>
struct js_traits<fwrapper<F, PassThis>>
{
static JSValue wrap(JSContext * ctx, fwrapper<F, PassThis> fw) noexcept
{
return JS_NewCFunction(ctx, [](JSContext * ctx, JSValueConst this_value, int argc,
JSValueConst * argv) noexcept -> JSValue {
if constexpr(PassThis)
return detail::wrap_this_call<R, Args...>(ctx, F, this_value, argv);
else
return detail::wrap_call<R, Args...>(ctx, F, argv);
}, fw.name, sizeof...(Args));
}
};
/** Conversion to JSValue for class member function in fwrapper. PassThis is ignored and treated as true */
template <typename R, class T, typename... Args, R (T::*F)(Args...), bool PassThis/*=ignored*/>
struct js_traits<fwrapper<F, PassThis>>
{
static JSValue wrap(JSContext * ctx, fwrapper<F, PassThis> fw) noexcept
{
return JS_NewCFunction(ctx, [](JSContext * ctx, JSValueConst this_value, int argc,
JSValueConst * argv) noexcept -> JSValue {
return detail::wrap_this_call<R, std::shared_ptr<T>, Args...>(ctx, F, this_value, argv);
}, fw.name, sizeof...(Args));
}
};
/** Conversion to JSValue for const class member function in fwrapper. PassThis is ignored and treated as true */
template <typename R, class T, typename... Args, R (T::*F)(Args...) const, bool PassThis/*=ignored*/>
struct js_traits<fwrapper<F, PassThis>>
{
static JSValue wrap(JSContext * ctx, fwrapper<F, PassThis> fw) noexcept
{
return JS_NewCFunction(ctx, [](JSContext * ctx, JSValueConst this_value, int argc,
JSValueConst * argv) noexcept -> JSValue {
return detail::wrap_this_call<R, std::shared_ptr<T>, Args...>(ctx, F, this_value, argv);
}, fw.name, sizeof...(Args));
}
};
/** A wrapper type for constructor of type T with arguments Args.
* Compilation fails if no such constructor is defined.
* @tparam Args constructor arguments
*/
template <class T, typename... Args>
struct ctor_wrapper
{
static_assert(std::is_constructible<T, Args...>::value, "no such constructor!");
/// "name" property of JS constructor object
const char * name = nullptr;
};
/** Conversion to JSValue for ctor_wrapper. */
template <class T, typename... Args>
struct js_traits<ctor_wrapper<T, Args...>>
{
static JSValue wrap(JSContext * ctx, ctor_wrapper<T, Args...> cw) noexcept
{
return JS_NewCFunction2(ctx, [](JSContext * ctx, JSValueConst this_value, int argc,
JSValueConst * argv) noexcept -> JSValue {
if(js_traits<std::shared_ptr<T>>::QJSClassId == 0) // not registered
{
#if defined(__cpp_rtti)
// automatically register class on first use (no prototype)
js_traits<std::shared_ptr<T>>::register_class(ctx, typeid(T).name());
#else
JS_ThrowTypeError(ctx, "quickjspp ctor_wrapper<T>::wrap: Class is not registered");
return JS_EXCEPTION;
#endif
}
auto proto = JS_GetPropertyStr(ctx, this_value, "prototype");
if (JS_IsException(proto))
return proto;
auto jsobj = JS_NewObjectProtoClass(ctx, proto, js_traits<std::shared_ptr<T>>::QJSClassId);
JS_FreeValue(ctx, proto);
if (JS_IsException(jsobj))
return jsobj;
std::shared_ptr<T> ptr = std::apply(std::make_shared<T, Args...>, detail::unwrap_args<Args...>(ctx, argv));
JS_SetOpaque(jsobj, new std::shared_ptr<T>(std::move(ptr)));
return jsobj;
// return detail::wrap_call<std::shared_ptr<T>, Args...>(ctx, std::make_shared<T, Args...>, argv);
}, cw.name, sizeof...(Args), JS_CFUNC_constructor, 0);
}
};
/** Conversions for std::shared_ptr<T>.
* T should be registered to a context before conversions.
* @tparam T class type
*/
template <class T>
struct js_traits<std::shared_ptr<T>>
{
/// Registered class id in QuickJS.
inline static JSClassID QJSClassId = 0;
/** Register class in QuickJS context.
*
* @param ctx context
* @param name class name
* @param proto class prototype or JS_NULL
* @throws exception
*/
static void register_class(JSContext * ctx, const char * name, JSValue proto = JS_NULL)
{
if(QJSClassId == 0)
{
JS_NewClassID(&QJSClassId);
}
auto rt = JS_GetRuntime(ctx);
if(!JS_IsRegisteredClass(rt, QJSClassId))
{
JSClassDef def{
name,
// destructor
[](JSRuntime * rt, JSValue obj) noexcept {
auto pptr = reinterpret_cast<std::shared_ptr<T> *>(JS_GetOpaque(obj, QJSClassId));
delete pptr;
}
};
int e = JS_NewClass(rt, QJSClassId, &def);
if(e < 0)
{
JS_ThrowInternalError(ctx, "Cant register class %s", name);
throw exception{};
}
}
JS_SetClassProto(ctx, QJSClassId, proto);
}
/** Create a JSValue from std::shared_ptr<T>.
* Creates an object with class if #QJSClassId and sets its opaque pointer to a new copy of #ptr.
*/
static JSValue wrap(JSContext * ctx, std::shared_ptr<T> ptr)
{
if(QJSClassId == 0) // not registered
{
#if defined(__cpp_rtti)
// automatically register class on first use (no prototype)
register_class(ctx, typeid(T).name());
#else
JS_ThrowTypeError(ctx, "quickjspp std::shared_ptr<T>::wrap: Class is not registered");
return JS_EXCEPTION;
#endif
}
auto jsobj = JS_NewObjectClass(ctx, QJSClassId);
if(JS_IsException(jsobj))
return jsobj;
auto pptr = new std::shared_ptr<T>(std::move(ptr));
JS_SetOpaque(jsobj, pptr);
return jsobj;
}
/// @throws exception if #v doesn't have the correct class id
static const std::shared_ptr<T>& unwrap(JSContext * ctx, JSValueConst v)
{
auto ptr = reinterpret_cast<std::shared_ptr<T> *>(JS_GetOpaque2(ctx, v, QJSClassId));
if(!ptr)
throw exception{};
return *ptr;
}
};
/** Conversions for non-owning pointers to class T.
* @tparam T class type
*/
template <class T>
struct js_traits<T *, std::enable_if_t<std::is_class_v<T>>>
{
static JSValue wrap(JSContext * ctx, T * ptr)
{
if(js_traits<std::shared_ptr<T>>::QJSClassId == 0) // not registered
{
#if defined(__cpp_rtti)
js_traits<std::shared_ptr<T>>::register_class(ctx, typeid(T).name());
#else
JS_ThrowTypeError(ctx, "quickjspp js_traits<T *>::wrap: Class is not registered");
return JS_EXCEPTION;
#endif
}
auto jsobj = JS_NewObjectClass(ctx, js_traits<std::shared_ptr<T>>::QJSClassId);
if(JS_IsException(jsobj))
return jsobj;
// shared_ptr with empty deleter since we don't own T*
auto pptr = new std::shared_ptr<T>(ptr, [](T *){});
JS_SetOpaque(jsobj, pptr);
return jsobj;
}
static T * unwrap(JSContext * ctx, JSValueConst v)
{
auto ptr = reinterpret_cast<std::shared_ptr<T> *>(JS_GetOpaque2(ctx, v,
js_traits<std::shared_ptr<T>>::QJSClassId));
if(!ptr)
throw exception{};
return ptr->get();
}
};
namespace detail {
/** A faster std::function-like object with type erasure.
* Used to convert any callable objects (including lambdas) to JSValue.
*/
struct function
{
JSValue
(* invoker)(function * self, JSContext * ctx, JSValueConst this_value, int argc, JSValueConst * argv) = nullptr;
void (* destroyer)(function * self) = nullptr;
alignas(std::max_align_t) char functor[];
template <typename Functor>
static function * create(JSRuntime * rt, Functor&& f)
{
auto fptr = reinterpret_cast<function *>(js_malloc_rt(rt, sizeof(function) + sizeof(Functor)));
if(!fptr)
throw std::bad_alloc{};
new(fptr) function;
auto functorptr = reinterpret_cast<Functor *>(fptr->functor);
new(functorptr) Functor(std::forward<Functor>(f));
fptr->destroyer = nullptr;
if constexpr(!std::is_trivially_destructible_v<Functor>)
{
fptr->destroyer = [](function * fptr) {
auto functorptr = reinterpret_cast<Functor *>(fptr->functor);
functorptr->~Functor();
};
}
return fptr;
}
};
static_assert(std::is_trivially_destructible_v<function>);
}
template <>
struct js_traits<detail::function>
{
inline static JSClassID QJSClassId = 0;
// TODO: replace ctx with rt
static void register_class(JSContext * ctx, const char * name)
{
if(QJSClassId == 0)
{
JS_NewClassID(&QJSClassId);
}
auto rt = JS_GetRuntime(ctx);
if(JS_IsRegisteredClass(rt, QJSClassId))
return;
JSClassDef def{
name,
// destructor
[](JSRuntime * rt, JSValue obj) noexcept {
auto fptr = reinterpret_cast<detail::function *>(JS_GetOpaque(obj, QJSClassId));
assert(fptr);
if(fptr->destroyer)
fptr->destroyer(fptr);
js_free_rt(rt, fptr);
},
nullptr, // mark
// call
[](JSContext * ctx, JSValueConst func_obj, JSValueConst this_val, int argc,
JSValueConst * argv, int flags) -> JSValue {
auto ptr = reinterpret_cast<detail::function *>(JS_GetOpaque2(ctx, func_obj, QJSClassId));
if(!ptr)
return JS_EXCEPTION;
return ptr->invoker(ptr, ctx, this_val, argc, argv);
}
};
int e = JS_NewClass(rt, QJSClassId, &def);
if(e < 0)
throw std::runtime_error{"Cannot register C++ function class"};
}
};
/** Traits for accessing object properties.
* @tparam Key property key type (uint32 and strings are supported)
*/
template <typename Key>
struct js_property_traits
{
static void set_property(JSContext * ctx, JSValue this_obj, Key key, JSValue value);
static JSValue get_property(JSContext * ctx, JSValue this_obj, Key key);
};
template <>
struct js_property_traits<const char *>
{
static void set_property(JSContext * ctx, JSValue this_obj, const char * name, JSValue value)
{
int err = JS_SetPropertyStr(ctx, this_obj, name, value);
if(err < 0)
throw exception{};
}
static JSValue get_property(JSContext * ctx, JSValue this_obj, const char * name) noexcept
{
return JS_GetPropertyStr(ctx, this_obj, name);
}
};
template <>
struct js_property_traits<uint32_t>
{
static void set_property(JSContext * ctx, JSValue this_obj, uint32_t idx, JSValue value)
{
int err = JS_SetPropertyUint32(ctx, this_obj, idx, value);
if(err < 0)
throw exception{};
}
static JSValue get_property(JSContext * ctx, JSValue this_obj, uint32_t idx) noexcept
{
return JS_GetPropertyUint32(ctx, this_obj, idx);
}
};
class Value;
namespace detail {
template <typename Key>
struct property_proxy
{
JSContext * ctx;
JSValue this_obj;
Key key;
/** Conversion helper function */
template <typename T>
T as() const
{
return unwrap_free<T>(ctx, js_property_traits<Key>::get_property(ctx, this_obj, key));
}
/** Explicit conversion operator (to any type) */
template <typename T>
explicit operator T() const { return as<T>(); }
/** Implicit converion to qjs::Value */
operator Value() const; // defined later due to Value being incomplete type
template <typename Value>
property_proxy& operator =(Value value)
{
js_property_traits<Key>::set_property(ctx, this_obj, key,
js_traits<Value>::wrap(ctx, std::move(value)));
return *this;
}
};
// class member variable getter/setter
template <auto M>
struct get_set {};
template <class T, typename R, R T::*M>
struct get_set<M>
{
using is_const = std::is_const<R>;
static const R& get(const std::shared_ptr<T>& ptr)
{
return *ptr.*M;
}
static R& set(const std::shared_ptr<T>& ptr, R value)
{
return *ptr.*M = std::move(value);
}
};
} // namespace detail
/** JSValue with RAAI semantics.
* A wrapper over (JSValue v, JSContext * ctx).
* Calls JS_FreeValue(ctx, v) on destruction. Can be copied and moved.
* A JSValue can be released by either JSValue x = std::move(value); or JSValue x = value.release(), then the Value becomes invalid and FreeValue won't be called
* Can be converted to C++ type, for example: auto string = value.as<std::string>(); qjs::exception would be thrown on error
* Properties can be accessed (read/write): value["property1"] = 1; value[2] = "2";
*/
class Value
{
public:
JSValue v;
JSContext * ctx = nullptr;
public:
/** Use context.newValue(val) instead */
template <typename T>
Value(JSContext * ctx, T&& val) : ctx(ctx)
{
v = js_traits<std::decay_t<T>>::wrap(ctx, std::forward<T>(val));
if(JS_IsException(v))
throw exception{};
}
Value(const Value& rhs)
{
ctx = rhs.ctx;
v = JS_DupValue(ctx, rhs.v);
}
Value(Value&& rhs)
{
std::swap(ctx, rhs.ctx);
v = rhs.v;
}
Value& operator=(Value rhs)
{
std::swap(ctx, rhs.ctx);
std::swap(v, rhs.v);
return *this;
}
bool operator==(JSValueConst other) const
{
return JS_VALUE_GET_TAG(v) == JS_VALUE_GET_TAG(other) && JS_VALUE_GET_PTR(v) == JS_VALUE_GET_PTR(other);
}
bool operator!=(JSValueConst other) const { return !((*this) == other); }
/** Returns true if 2 values are the same (equality for arithmetic types or point to the same object) */
bool operator==(const Value& rhs) const
{
return ctx == rhs.ctx && (*this == rhs.v);
}
bool operator!=(const Value& rhs) const { return !((*this) == rhs); }
~Value()
{
if(ctx) JS_FreeValue(ctx, v);
}
bool isError() const { return JS_IsError(ctx, v); }
/** Conversion helper function: value.as<T>()
* @tparam T type to convert to
* @return type returned by js_traits<std::decay_t<T>>::unwrap that should be implicitly convertible to T
* */
template <typename T>
auto as() const { return js_traits<std::decay_t<T>>::unwrap(ctx, v); }
/** Explicit conversion: static_cast<T>(value) or (T)value */
template <typename T>
explicit operator T() const { return as<T>(); }
JSValue release() // dont call freevalue
{
ctx = nullptr;
return v;
}
/** Implicit conversion to JSValue (rvalue only). Example: JSValue v = std::move(value); */
operator JSValue() && { return release(); }
/** Access JS properties. Returns proxy type which is implicitly convertible to qjs::Value */
template <typename Key>
detail::property_proxy<Key> operator [](Key key)
{
return {ctx, v, std::move(key)};
}
// add("f", []() {...});
template <typename Function>
Value& add(const char * name, Function&& f)
{
(*this)[name] = js_traits<decltype(std::function{std::forward<Function>(f)})>::wrap(ctx,
std::forward<Function>(f));
return *this;
}
// add<&f>("f");
// add<&T::f>("f");
template <auto F>
std::enable_if_t<!std::is_member_object_pointer_v<decltype(F)>, Value&>
add(const char * name)
{
(*this)[name] = fwrapper<F>{name};
return *this;
}
// add_getter_setter<&T::get_member, &T::set_member>("member");
template <auto FGet, auto FSet>
Value& add_getter_setter(const char * name)
{
auto prop = JS_NewAtom(ctx, name);
using fgetter = fwrapper<FGet, true>;
using fsetter = fwrapper<FSet, true>;
int ret = JS_DefinePropertyGetSet(ctx, v, prop,
js_traits<fgetter>::wrap(ctx, fgetter{name}),
js_traits<fsetter>::wrap(ctx, fsetter{name}),
JS_PROP_CONFIGURABLE | JS_PROP_WRITABLE | JS_PROP_ENUMERABLE
);
JS_FreeAtom(ctx, prop);
if(ret < 0)
throw exception{};
return *this;
}
// add_getter<&T::get_member>("member");
template <auto FGet>
Value& add_getter(const char * name)
{
auto prop = JS_NewAtom(ctx, name);
using fgetter = fwrapper<FGet, true>;
int ret = JS_DefinePropertyGetSet(ctx, v, prop,
js_traits<fgetter>::wrap(ctx, fgetter{name}),
JS_UNDEFINED,
JS_PROP_CONFIGURABLE | JS_PROP_ENUMERABLE
);
JS_FreeAtom(ctx, prop);
if(ret < 0)
throw exception{};
return *this;
}
// add<&T::member>("member");
template <auto M>
std::enable_if_t<std::is_member_object_pointer_v<decltype(M)>, Value&>
add(const char * name)
{
if constexpr (detail::get_set<M>::is_const::value)
{
return add_getter<detail::get_set<M>::get>(name);
}
else
{
return add_getter_setter<detail::get_set<M>::get, detail::get_set<M>::set>(name);
}
}
std::string toJSON(const Value& replacer = Value{nullptr, JS_UNDEFINED}, const Value& space = Value{nullptr, JS_UNDEFINED})
{
assert(ctx);
assert(!replacer.ctx || ctx == replacer.ctx);
assert(!space.ctx || ctx == space.ctx);
JSValue json = JS_JSONStringify(ctx, v, replacer.v, space.v);
return (std::string)Value{ctx, json};
}
};
/** Thin wrapper over JSRuntime * rt
* Calls JS_FreeRuntime on destruction. noncopyable.
*/
class Runtime
{
public:
JSRuntime * rt;
Runtime()
{
rt = JS_NewRuntime();
if(!rt)
throw std::runtime_error{"qjs: Cannot create runtime"};
}
// noncopyable
Runtime(const Runtime&) = delete;
~Runtime()
{
JS_FreeRuntime(rt);
}
};
/** Wrapper over JSContext * ctx
* Calls JS_SetContextOpaque(ctx, this); on construction and JS_FreeContext on destruction
*/
class Context
{
public:
JSContext * ctx;
/** Module wrapper
* Workaround for lack of opaque pointer for module load function by keeping a list of modules in qjs::Context.
*/
class Module
{
friend class Context;
JSModuleDef * m;
JSContext * ctx;
const char * name;
using nvp = std::pair<const char *, Value>;
std::vector<nvp> exports;
public:
Module(JSContext * ctx, const char * name) : ctx(ctx), name(name)
{
m = JS_NewCModule(ctx, name, [](JSContext * ctx, JSModuleDef * m) noexcept {
auto& context = Context::get(ctx);
auto it = std::find_if(context.modules.begin(), context.modules.end(),
[m](const Module& module) { return module.m == m; });
if(it == context.modules.end())
return -1;
for(const auto& e : it->exports)
{
if(JS_SetModuleExport(ctx, m, e.first, JS_DupValue(ctx, e.second.v)) != 0)
return -1;
}
return 0;
});
if(!m)
throw exception{};
}
Module& add(const char * name, JSValue value)
{
exports.push_back({name, {ctx, value}});
JS_AddModuleExport(ctx, m, name);
return *this;
}
Module& add(const char * name, Value value)
{
assert(value.ctx == ctx);
exports.push_back({name, std::move(value)});
JS_AddModuleExport(ctx, m, name);
return *this;
}
template <typename T>
Module& add(const char * name, T value)
{
return add(name, js_traits<T>::wrap(ctx, std::move(value)));
}
Module(const Module&) = delete;
Module(Module&&) = default;
//Module& operator=(Module&&) = default;
// function wrappers
/** Add free function F.
* Example:
* module.function<static_cast<double (*)(double)>(&::sin)>("sin");
*/
template <auto F>
Module& function(const char * name)
{
return add(name, qjs::fwrapper<F>{name});
}
/** Add function object f.
* Slower than template version.
* Example: module.function("sin", [](double x) { return ::sin(x); });
*/
template <typename F>
Module& function(const char * name, F&& f)
{
return add(name, js_traits<decltype(std::function{std::forward<F>(f)})>::wrap(ctx, std::forward<F>(f)));
}
// class register wrapper
private:
/** Helper class to register class members and constructors.
* See fun, constructor.
* Actual registration occurs at object destruction.
*/
template <class T>
class class_registrar
{
const char * name;
qjs::Value prototype;
qjs::Context::Module& module;
qjs::Context& context;
public:
explicit class_registrar(const char * name, qjs::Context::Module& module, qjs::Context& context) :
name(name),
prototype(context.newObject()),
module(module),
context(context)
{
}
class_registrar(const class_registrar&) = delete;
/** Add functional object f
*/
template <typename F>
class_registrar& fun(const char * name, F&& f)
{
prototype.add(name, std::forward<F>(f));
return *this;
}
/** Add class member function or class member variable F
* Example:
* struct T { int var; int func(); }
* auto& module = context.addModule("module");
* module.class_<T>("T").fun<&T::var>("var").fun<&T::func>("func");
*/
template <auto F>
class_registrar& fun(const char * name)
{
prototype.add<F>(name);
return *this;
}
template <auto FGet, auto FSet = nullptr>
class_registrar& property(const char * name)
{
if /*constexpr*/ (FSet == nullptr)
prototype.add_getter<FGet>(name);
else
prototype.add_getter_setter<FGet, FSet>(name);
return *this;
}
/** Add class constructor
* @tparam Args contructor arguments
* @param name constructor name (if not specified class name will be used)
*/
template <typename... Args>
class_registrar& constructor(const char * name = nullptr)
{
if(!name)
name = this->name;
Value ctor = context.newValue(qjs::ctor_wrapper<T, Args...>{name});
JS_SetConstructor(context.ctx, ctor.v, prototype.v);
module.add(name, std::move(ctor));
return *this;
}
/* TODO: needs casting to base class
template <class B>
class_registrar& base()
{
assert(js_traits<std::shared_ptr<B>>::QJSClassId && "base class is not registered");
auto base_proto = JS_GetClassProto(context.ctx, js_traits<std::shared_ptr<B>>::QJSClassId);
int err = JS_SetPrototype(context.ctx, prototype.v, base_proto);
JS_FreeValue(context.ctx, base_proto);
if(err < 0)
throw exception{};
return *this;
}
*/
~class_registrar()
{
context.registerClass<T>(name, std::move(prototype));
}
};
public:
/** Add class to module.
* See \ref class_registrar.
*/
template <class T>
class_registrar<T> class_(const char * name)
{
return class_registrar<T>{name, *this, qjs::Context::get(ctx)};
}
};
std::vector<Module> modules;
private:
void init()
{
JS_SetContextOpaque(ctx, this);
js_traits<detail::function>::register_class(ctx, "C++ function");
}
public:
Context(Runtime& rt) : Context(rt.rt)
{}
Context(JSRuntime * rt)
{
ctx = JS_NewContext(rt);
if(!ctx)
throw std::runtime_error{"qjs: Cannot create context"};
init();
}
Context(JSContext * ctx) : ctx{ctx}
{
init();
}
// noncopyable
Context(const Context&) = delete;
~Context()
{
modules.clear();
JS_FreeContext(ctx);
}
/** Create module and return a reference to it */
Module& addModule(const char * name)
{
modules.emplace_back(ctx, name);
return modules.back();
}
/** returns globalThis */
Value global() { return Value{ctx, JS_GetGlobalObject(ctx)}; }
/** returns new Object() */
Value newObject() { return Value{ctx, JS_NewObject(ctx)}; }
/** returns JS value converted from c++ object val */
template <typename T>
Value newValue(T&& val) { return Value{ctx, std::forward<T>(val)}; }
/** returns current exception associated with context, and resets it. Should be called when qjs::exception is caught */
Value getException() { return Value{ctx, JS_GetException(ctx)}; }
/** Register class T for conversions to/from std::shared_ptr<T> to work.
* Wherever possible module.class_<T>("T")... should be used instead.
* @tparam T class type
* @param name class name in JS engine
* @param proto JS class prototype or JS_UNDEFINED
*/
template <class T>
void registerClass(const char * name, JSValue proto = JS_NULL)
{
js_traits<std::shared_ptr<T>>::register_class(ctx, name, proto);
}
Value eval(std::string_view buffer, const char * filename = "<eval>", unsigned eval_flags = 0)
{
assert(buffer.data()[buffer.size()] == '\0' && "eval buffer is not null-terminated"); // JS_Eval requirement
JSValue v = JS_Eval(ctx, buffer.data(), buffer.size(), filename, eval_flags);
return Value{ctx, v};
}
Value evalFile(const char * filename, unsigned eval_flags = 0)
{
size_t buf_len;
auto deleter = [this](void * p) { js_free(ctx, p); };
auto buf = std::unique_ptr<uint8_t, decltype(deleter)>{js_load_file(ctx, &buf_len, filename), deleter};
if(!buf)
throw std::runtime_error{std::string{"evalFile: can't read file: "} + filename};
return eval({reinterpret_cast<char *>(buf.get()), buf_len}, filename, eval_flags);
}
Value fromJSON(std::string_view buffer, const char * filename = "<fromJSON>")
{
assert(buffer.data()[buffer.size()] == '\0' && "fromJSON buffer is not null-terminated"); // JS_ParseJSON requirement
JSValue v = JS_ParseJSON(ctx, buffer.data(), buffer.size(), filename);
return Value{ctx, v};
}
/** Get qjs::Context from JSContext opaque pointer */
static Context& get(JSContext * ctx)
{
void * ptr = JS_GetContextOpaque(ctx);
assert(ptr);
return *reinterpret_cast<Context *>(ptr);
}
};
/** Conversion traits for Value.
*/
template <>
struct js_traits<Value>
{
static Value unwrap(JSContext * ctx, JSValueConst v)
{
return Value{ctx, JS_DupValue(ctx, v)};
}
static JSValue wrap(JSContext * ctx, Value v) noexcept
{
assert(ctx == v.ctx);
return v.release();
}
};
/** Convert to/from std::function. Actually accepts/returns callable object that is compatible with function<R (Args...)>.
* @tparam R return type
* @tparam Args argument types
*/
template <typename R, typename... Args>
struct js_traits<std::function<R(Args...)>>
{
static auto unwrap(JSContext * ctx, JSValueConst fun_obj)
{
const int argc = sizeof...(Args);
if constexpr(argc == 0)
{
return[jsfun_obj = Value{ ctx, JS_DupValue(ctx, fun_obj) }]()->R {
JSValue result = JS_Call(jsfun_obj.ctx, jsfun_obj.v, JS_UNDEFINED, 0, nullptr);
if(JS_IsException(result))
{
JS_FreeValue(jsfun_obj.ctx, result);
throw exception{};
}
return detail::unwrap_free<R>(jsfun_obj.ctx, result);
};
}
else
{
return[jsfun_obj = Value{ ctx, JS_DupValue(ctx, fun_obj) }](Args&& ... args)->R {
JSValue argv[argc];
detail::wrap_args(jsfun_obj.ctx, argv, std::forward<Args>(args)...);
JSValue result = JS_Call(jsfun_obj.ctx, jsfun_obj.v, JS_UNDEFINED, argc, const_cast<JSValueConst*>(argv));
for(int i = 0; i < argc; i++) JS_FreeValue(jsfun_obj.ctx, argv[i]);
if(JS_IsException(result))
{
JS_FreeValue(jsfun_obj.ctx, result);
throw exception{};
}
return detail::unwrap_free<R>(jsfun_obj.ctx, result);
};
}
}
/** Convert from function object functor to JSValue.
* Uses detail::function for type-erasure.
*/
template <typename Functor>
static JSValue wrap(JSContext * ctx, Functor&& functor)
{
using detail::function;
assert(js_traits<function>::QJSClassId);
auto obj = JS_NewObjectClass(ctx, js_traits<function>::QJSClassId);
if(JS_IsException(obj))
return JS_EXCEPTION;
auto fptr = function::create(JS_GetRuntime(ctx), std::forward<Functor>(functor));
fptr->invoker = [](function * self, JSContext * ctx, JSValueConst this_value, int argc, JSValueConst * argv) {
assert(self);
auto f = reinterpret_cast<Functor *>(&self->functor);
return detail::wrap_call<R, Args...>(ctx, *f, argv);
};
JS_SetOpaque(obj, fptr);
return obj;
}
};
/** Convert from std::vector<T> to Array and vice-versa. If Array holds objects that are non-convertible to T throws qjs::exception */
template <class T>
struct js_traits<std::vector<T>>
{
static JSValue wrap(JSContext * ctx, const std::vector<T>& arr) noexcept
{
try
{
auto jsarray = Value{ctx, JS_NewArray(ctx)};
for(uint32_t i = 0; i < (uint32_t) arr.size(); i++)
jsarray[i] = arr[i];
return jsarray.release();
}
catch(exception)
{
return JS_EXCEPTION;
}
}
static std::vector<T> unwrap(JSContext * ctx, JSValueConst jsarr)
{
int e = JS_IsArray(ctx, jsarr);
if(e == 0)
JS_ThrowTypeError(ctx, "js_traits<std::vector<T>>::unwrap expects array");
if(e <= 0)
throw exception{};
Value jsarray{ctx, JS_DupValue(ctx, jsarr)};
std::vector<T> arr;
auto len = static_cast<int32_t>(jsarray["length"]);
arr.reserve((uint32_t) len);
for(uint32_t i = 0; i < (uint32_t) len; i++)
arr.push_back(static_cast<T>(jsarray[i]));
return arr;
}
};
namespace detail {
template <typename Key>
property_proxy<Key>::operator Value() const
{
return as<Value>();
}
}
} // namespace qjs
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