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// Copyright 2021 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0(the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SRC_SEM_CONSTANT_H_
#define SRC_SEM_CONSTANT_H_
#include <vector>
#include "src/program_builder.h"
#include "src/sem/type.h"
namespace tint {
namespace sem {
/// A Constant is compile-time known expression value, expressed as a flattened
/// list of scalar values. Value may be of a scalar or vector type.
class Constant {
using i32 = ProgramBuilder::i32;
using u32 = ProgramBuilder::u32;
using f32 = ProgramBuilder::f32;
public:
/// Scalar holds a single constant scalar value, as a union of an i32, u32,
/// f32 or boolean.
union Scalar {
/// The scalar value as a i32
int32_t i32;
/// The scalar value as a u32
uint32_t u32;
/// The scalar value as a f32
float f32;
/// The scalar value as a bool
bool bool_;
/// Constructs the scalar with the i32 value `v`
/// @param v the value of the Scalar
Scalar(ProgramBuilder::i32 v) : i32(v) {} // NOLINT
/// Constructs the scalar with the u32 value `v`
/// @param v the value of the Scalar
Scalar(ProgramBuilder::u32 v) : u32(v) {} // NOLINT
/// Constructs the scalar with the f32 value `v`
/// @param v the value of the Scalar
Scalar(ProgramBuilder::f32 v) : f32(v) {} // NOLINT
/// Constructs the scalar with the bool value `v`
/// @param v the value of the Scalar
Scalar(bool v) : bool_(v) {} // NOLINT
};
/// Scalars is a list of scalar values
using Scalars = std::vector<Scalar>;
/// Constructs an invalid Constant
Constant();
/// Constructs a Constant of the given type and element values
/// @param ty the Constant type
/// @param els the Constant element values
Constant(const Type* ty, Scalars els);
/// Copy constructor
Constant(const Constant&);
/// Destructor
~Constant();
/// Copy assignment
/// @param other the Constant to copy
/// @returns this Constant
Constant& operator=(const Constant& other);
/// @returns true if the Constant has been initialized
bool IsValid() const { return type_ != nullptr; }
/// @return true if the Constant has been initialized
operator bool() const { return IsValid(); }
/// @returns the type of the Constant
const sem::Type* Type() const { return type_; }
/// @returns the element type of the Constant
const sem::Type* ElementType() const { return elem_type_; }
/// @returns the constant's scalar elements
const Scalars& Elements() const { return elems_; }
/// @returns true if any scalar element is zero
bool AnyZero() const;
/// Calls `func(s)` with s being the current scalar value at `index`.
/// `func` is typically a lambda of the form '[](auto&& s)'.
/// @param index the index of the scalar value
/// @param func a function with signature `T(S)`
/// @return the value returned by func.
template <typename Func>
auto WithScalarAt(size_t index, Func&& func) const {
auto* elem_type = ElementType();
if (elem_type->Is<I32>()) {
return func(elems_[index].i32);
}
if (elem_type->Is<U32>()) {
return func(elems_[index].u32);
}
if (elem_type->Is<F32>()) {
return func(elems_[index].f32);
}
if (elem_type->Is<Bool>()) {
return func(elems_[index].bool_);
}
diag::List diags;
TINT_UNREACHABLE(Semantic, diags)
<< "invalid scalar type " << type_->type_name();
return func(~0);
}
/// @param index the index of the scalar value
/// @return the value of the scalar `static_cast` to type T.
template <typename T>
T ElementAs(size_t index) const {
return WithScalarAt(index, [](auto val) { return static_cast<T>(val); });
}
private:
const sem::Type* type_ = nullptr;
const sem::Type* elem_type_ = nullptr;
Scalars elems_;
};
} // namespace sem
} // namespace tint
#endif // SRC_SEM_CONSTANT_H_