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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.
#ifndef V8_WASM_WASM_RESULT_H_
#define V8_WASM_WASM_RESULT_H_
#include <cstdarg>
#include <memory>
#include "src/base/compiler-specific.h"
#include "src/base/macros.h"
#include "src/base/platform/platform.h"
#include "src/common/globals.h"
namespace v8 {
namespace internal {
class Isolate;
template <typename T>
class Handle;
namespace wasm {
class V8_EXPORT_PRIVATE WasmError {
public:
WasmError() = default;
WasmError(uint32_t offset, std::string message)
: offset_(offset), message_(std::move(message)) {
// The error message must not be empty, otherwise {empty()} would be true.
DCHECK(!message_.empty());
}
PRINTF_FORMAT(3, 4)
WasmError(uint32_t offset, const char* format, ...) : offset_(offset) {
va_list args;
va_start(args, format);
message_ = FormatError(format, args);
va_end(args);
// The error message must not be empty, otherwise {empty()} would be true.
DCHECK(!message_.empty());
}
bool empty() const { return message_.empty(); }
bool has_error() const { return !message_.empty(); }
uint32_t offset() const { return offset_; }
const std::string& message() const& { return message_; }
std::string&& message() && { return std::move(message_); }
protected:
static std::string FormatError(const char* format, va_list args);
private:
uint32_t offset_ = 0;
std::string message_;
};
// Either a result of type T, or a WasmError.
template <typename T>
class Result {
public:
Result() = default;
template <typename S>
explicit Result(S&& value) : value_(std::forward<S>(value)) {}
template <typename S>
Result(Result<S>&& other) V8_NOEXCEPT : value_(std::move(other.value_)),
error_(std::move(other.error_)) {}
explicit Result(WasmError error) : error_(std::move(error)) {}
template <typename S>
Result& operator=(Result<S>&& other) V8_NOEXCEPT {
value_ = std::move(other.value_);
error_ = std::move(other.error_);
return *this;
}
bool ok() const { return error_.empty(); }
bool failed() const { return error_.has_error(); }
const WasmError& error() const& { return error_; }
WasmError&& error() && { return std::move(error_); }
// Accessor for the value. Returns const reference if {this} is l-value or
// const, and returns r-value reference if {this} is r-value. This allows to
// extract non-copyable values like {std::unique_ptr} by using
// {std::move(result).value()}.
const T& value() const & {
DCHECK(ok());
return value_;
}
T&& value() && {
DCHECK(ok());
return std::move(value_);
}
private:
template <typename S>
friend class Result;
T value_ = T{};
WasmError error_;
DISALLOW_COPY_AND_ASSIGN(Result);
};
// A helper for generating error messages that bubble up to JS exceptions.
class V8_EXPORT_PRIVATE ErrorThrower {
public:
ErrorThrower(Isolate* isolate, const char* context)
: isolate_(isolate), context_(context) {}
// Explicitly allow move-construction. Disallow copy (below).
ErrorThrower(ErrorThrower&& other) V8_NOEXCEPT;
~ErrorThrower();
PRINTF_FORMAT(2, 3) void TypeError(const char* fmt, ...);
PRINTF_FORMAT(2, 3) void RangeError(const char* fmt, ...);
PRINTF_FORMAT(2, 3) void CompileError(const char* fmt, ...);
PRINTF_FORMAT(2, 3) void LinkError(const char* fmt, ...);
PRINTF_FORMAT(2, 3) void RuntimeError(const char* fmt, ...);
void CompileFailed(const WasmError& error) {
DCHECK(error.has_error());
CompileError("%s @+%u", error.message().c_str(), error.offset());
}
// Create and return exception object.
V8_WARN_UNUSED_RESULT Handle<Object> Reify();
// Reset any error which was set on this thrower.
void Reset();
bool error() const { return error_type_ != kNone; }
bool wasm_error() { return error_type_ >= kFirstWasmError; }
const char* error_msg() { return error_msg_.c_str(); }
Isolate* isolate() const { return isolate_; }
private:
enum ErrorType {
kNone,
// General errors.
kTypeError,
kRangeError,
// Wasm errors.
kCompileError,
kLinkError,
kRuntimeError,
// Marker.
kFirstWasmError = kCompileError
};
void Format(ErrorType error_type_, const char* fmt, va_list);
Isolate* isolate_;
const char* context_;
ErrorType error_type_ = kNone;
std::string error_msg_;
// ErrorThrower should always be stack-allocated, since it constitutes a scope
// (things happen in the destructor).
DISALLOW_NEW_AND_DELETE()
DISALLOW_COPY_AND_ASSIGN(ErrorThrower);
};
// Use {nullptr_t} as data value to indicate that this only stores the error,
// but no result value (the only valid value is {nullptr}).
// [Storing {void} would require template specialization.]
using VoidResult = Result<std::nullptr_t>;
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_WASM_WASM_RESULT_H_