src/transform/wrap_arrays_in_structs.h

// 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_TRANSFORM_WRAP_ARRAYS_IN_STRUCTS_H_
#define SRC_TRANSFORM_WRAP_ARRAYS_IN_STRUCTS_H_

#include <string>
#include <unordered_map>

#include "src/transform/transform.h"

// Forward declarations
namespace tint {
namespace ast {
class Type;
}  // namespace ast
}  // namespace tint

namespace tint {
namespace transform {

/// WrapArraysInStructs is a transform that replaces all array types with a
/// structure holding a single field of that array type.
/// Array index expressions and constructors are also adjusted to deal with this
/// wrapping.
/// This transform helps with backends that cannot directly return arrays or use
/// them as parameters.
class WrapArraysInStructs : public Castable<WrapArraysInStructs, Transform> {
 public:
  /// Constructor
  WrapArraysInStructs();

  /// Destructor
  ~WrapArraysInStructs() override;

  /// @param program the program to inspect
  /// @param data optional extra transform-specific input data
  /// @returns true if this transform should be run for the given program
  bool ShouldRun(const Program* program,
                 const DataMap& data = {}) const override;

 protected:
  /// Runs the transform using the CloneContext built for transforming a
  /// program. Run() is responsible for calling Clone() on the CloneContext.
  /// @param ctx the CloneContext primed with the input program and
  /// ProgramBuilder
  /// @param inputs optional extra transform-specific input data
  /// @param outputs optional extra transform-specific output data
  void Run(CloneContext& ctx,
           const DataMap& inputs,
           DataMap& outputs) const override;

 private:
  struct WrappedArrayInfo {
    WrappedArrayInfo();
    WrappedArrayInfo(const WrappedArrayInfo&);
    ~WrappedArrayInfo();

    Symbol wrapper_name;
    std::function<const ast::Type*(CloneContext&)> array_type;

    operator bool() { return wrapper_name.IsValid(); }
  };

  /// WrapArray wraps the fixed-size array type in a new structure (if it hasn't
  /// already been wrapped). WrapArray will recursively wrap arrays-of-arrays.
  /// The new structure will be added to module-scope type declarations of
  /// `ctx.dst`.
  /// @param ctx the CloneContext
  /// @param wrapped_arrays a map of src array type to the wrapped structure
  /// name
  /// @param array the array type
  /// @return the name of the structure that wraps the array, or an invalid
  /// Symbol if this array should not be wrapped
  WrappedArrayInfo WrapArray(
      CloneContext& ctx,
      std::unordered_map<const sem::Array*, WrappedArrayInfo>& wrapped_arrays,
      const sem::Array* array) const;
};

}  // namespace transform
}  // namespace tint

#endif  // SRC_TRANSFORM_WRAP_ARRAYS_IN_STRUCTS_H_