v8/samples/hello-world.cc

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// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "include/libplatform/libplatform.h"
#include "include/v8.h"
int main(int argc, char* argv[]) {
// Initialize V8.
v8::V8::InitializeICUDefaultLocation(argv[0]);
v8::V8::InitializeExternalStartupData(argv[0]);
std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
v8::V8::InitializePlatform(platform.get());
v8::V8::Initialize();
// Create a new Isolate and make it the current one.
v8::Isolate::CreateParams create_params;
create_params.array_buffer_allocator =
v8::ArrayBuffer::Allocator::NewDefaultAllocator();
v8::Isolate* isolate = v8::Isolate::New(create_params);
{
v8::Isolate::Scope isolate_scope(isolate);
// Create a stack-allocated handle scope.
v8::HandleScope handle_scope(isolate);
// Create a new context.
v8::Local<v8::Context> context = v8::Context::New(isolate);
// Enter the context for compiling and running the hello world script.
v8::Context::Scope context_scope(context);
{
// Create a string containing the JavaScript source code.
v8::Local<v8::String> source =
[api] Create v8::String::NewFromLiteral that returns Local<String> String::NewFromLiteral is a templated function that takes a char[N] argument that can be used as an alternative to String::NewFromUtf8 and returns a Local<String> rather than a MaybeLocal<String> reducing the number of ToLocalChecked() or other checks. Since the string length is known at compile time, it can statically assert that the length is less than String::kMaxLength, which means that it can never fail at runtime. This also converts all found uses of NewFromUtf8 taking a string literal or a variable initialized from a string literal to use the new API. In some cases the types of stored string literals are changed from const char* to const char[] to ensure the size is retained. This API does introduce a small difference compared to NewFromUtf8. For a case like "abc\0def", NewFromUtf8 (using length -1 to infer length) would treat this as a 3 character string, whereas the new API will treat it as a 7 character string. As a drive-by fix, this also fixes all redundant uses of v8::NewStringType::kNormal when passed to any of the String::New* functions. Change-Id: Id96a44bc068d9c4eaa634aea688e024675a0e5b3 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2089935 Commit-Queue: Dan Elphick <delphick@chromium.org> Reviewed-by: Mathias Bynens <mathias@chromium.org> Reviewed-by: Mythri Alle <mythria@chromium.org> Reviewed-by: Clemens Backes <clemensb@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Cr-Commit-Position: refs/heads/master@{#66622}
2020-03-09 10:41:45 +00:00
v8::String::NewFromUtf8Literal(isolate, "'Hello' + ', World!'");
// Compile the source code.
v8::Local<v8::Script> script =
v8::Script::Compile(context, source).ToLocalChecked();
// Run the script to get the result.
v8::Local<v8::Value> result = script->Run(context).ToLocalChecked();
// Convert the result to an UTF8 string and print it.
v8::String::Utf8Value utf8(isolate, result);
printf("%s\n", *utf8);
}
{
// Use the JavaScript API to generate a WebAssembly module.
//
// |bytes| contains the binary format for the following module:
//
// (func (export "add") (param i32 i32) (result i32)
// get_local 0
// get_local 1
// i32.add)
//
[api] Create v8::String::NewFromLiteral that returns Local<String> String::NewFromLiteral is a templated function that takes a char[N] argument that can be used as an alternative to String::NewFromUtf8 and returns a Local<String> rather than a MaybeLocal<String> reducing the number of ToLocalChecked() or other checks. Since the string length is known at compile time, it can statically assert that the length is less than String::kMaxLength, which means that it can never fail at runtime. This also converts all found uses of NewFromUtf8 taking a string literal or a variable initialized from a string literal to use the new API. In some cases the types of stored string literals are changed from const char* to const char[] to ensure the size is retained. This API does introduce a small difference compared to NewFromUtf8. For a case like "abc\0def", NewFromUtf8 (using length -1 to infer length) would treat this as a 3 character string, whereas the new API will treat it as a 7 character string. As a drive-by fix, this also fixes all redundant uses of v8::NewStringType::kNormal when passed to any of the String::New* functions. Change-Id: Id96a44bc068d9c4eaa634aea688e024675a0e5b3 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2089935 Commit-Queue: Dan Elphick <delphick@chromium.org> Reviewed-by: Mathias Bynens <mathias@chromium.org> Reviewed-by: Mythri Alle <mythria@chromium.org> Reviewed-by: Clemens Backes <clemensb@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Cr-Commit-Position: refs/heads/master@{#66622}
2020-03-09 10:41:45 +00:00
const char csource[] = R"(
let bytes = new Uint8Array([
0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x07, 0x01,
0x60, 0x02, 0x7f, 0x7f, 0x01, 0x7f, 0x03, 0x02, 0x01, 0x00, 0x07,
0x07, 0x01, 0x03, 0x61, 0x64, 0x64, 0x00, 0x00, 0x0a, 0x09, 0x01,
0x07, 0x00, 0x20, 0x00, 0x20, 0x01, 0x6a, 0x0b
]);
let module = new WebAssembly.Module(bytes);
let instance = new WebAssembly.Instance(module);
instance.exports.add(3, 4);
)";
// Create a string containing the JavaScript source code.
v8::Local<v8::String> source =
[api] Create v8::String::NewFromLiteral that returns Local<String> String::NewFromLiteral is a templated function that takes a char[N] argument that can be used as an alternative to String::NewFromUtf8 and returns a Local<String> rather than a MaybeLocal<String> reducing the number of ToLocalChecked() or other checks. Since the string length is known at compile time, it can statically assert that the length is less than String::kMaxLength, which means that it can never fail at runtime. This also converts all found uses of NewFromUtf8 taking a string literal or a variable initialized from a string literal to use the new API. In some cases the types of stored string literals are changed from const char* to const char[] to ensure the size is retained. This API does introduce a small difference compared to NewFromUtf8. For a case like "abc\0def", NewFromUtf8 (using length -1 to infer length) would treat this as a 3 character string, whereas the new API will treat it as a 7 character string. As a drive-by fix, this also fixes all redundant uses of v8::NewStringType::kNormal when passed to any of the String::New* functions. Change-Id: Id96a44bc068d9c4eaa634aea688e024675a0e5b3 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2089935 Commit-Queue: Dan Elphick <delphick@chromium.org> Reviewed-by: Mathias Bynens <mathias@chromium.org> Reviewed-by: Mythri Alle <mythria@chromium.org> Reviewed-by: Clemens Backes <clemensb@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Cr-Commit-Position: refs/heads/master@{#66622}
2020-03-09 10:41:45 +00:00
v8::String::NewFromUtf8Literal(isolate, csource);
// Compile the source code.
v8::Local<v8::Script> script =
v8::Script::Compile(context, source).ToLocalChecked();
// Run the script to get the result.
v8::Local<v8::Value> result = script->Run(context).ToLocalChecked();
// Convert the result to a uint32 and print it.
uint32_t number = result->Uint32Value(context).ToChecked();
printf("3 + 4 = %u\n", number);
}
}
// Dispose the isolate and tear down V8.
isolate->Dispose();
v8::V8::Dispose();
v8::V8::ShutdownPlatform();
delete create_params.array_buffer_allocator;
return 0;
}