path: root/libsolidity/codegen/ArrayUtils.h

/*
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2015
 * Code generation utils that handle arrays.
 */

#pragma once

#include <memory>

namespace dev
{
namespace solidity
{

class CompilerContext;
class Type;
class ArrayType;
using TypePointer = std::shared_ptr<Type const>;

/**
 * Class that provides code generation for handling arrays.
 */
class ArrayUtils
{
public:
    explicit ArrayUtils(CompilerContext& _context): m_context(_context) {}

    /// Copies an array to an array in storage. The arrays can be of different types only if
    /// their storage representation is the same.
    /// Stack pre: source_reference [source_length] target_reference
    /// Stack post: target_reference
    void copyArrayToStorage(ArrayType const& _targetType, ArrayType const& _sourceType) const;
    /// Copies the data part of an array (which cannot be dynamically nested) from anywhere
    /// to a given position in memory.
    /// This always copies contained data as is (i.e. structs and fixed-size arrays are copied in
    /// place as required by the ABI encoding). Use CompilerUtils::convertType if you want real
    /// memory copies of nested arrays.
    /// Stack pre: memory_offset source_item
    /// Stack post: memory_offest + length(padded)
    void copyArrayToMemory(ArrayType const& _sourceType, bool _padToWordBoundaries = true) const;
    /// Clears the given dynamic or static array.
    /// Stack pre: storage_ref storage_byte_offset
    /// Stack post:
    void clearArray(ArrayType const& _type) const;
    /// Clears the length and data elements of the array referenced on the stack.
    /// Stack pre: reference (excludes byte offset)
    /// Stack post:
    void clearDynamicArray(ArrayType const& _type) const;
    /// Changes the size of a dynamic array and clears the tail if it is shortened.
    /// Stack pre: reference (excludes byte offset) new_length
    /// Stack post:
    void resizeDynamicArray(ArrayType const& _type) const;
    /// Appends a loop that clears a sequence of storage slots of the given type (excluding end).
    /// Stack pre: end_ref start_ref
    /// Stack post: end_ref
    void clearStorageLoop(TypePointer const& _type) const;
    /// Converts length to size (number of storage slots or calldata/memory bytes).
    /// if @a _pad then add padding to multiples of 32 bytes for calldata/memory.
    /// Stack pre: length
    /// Stack post: size
    void convertLengthToSize(ArrayType const& _arrayType, bool _pad = false) const;
    /// Retrieves the length (number of elements) of the array ref on the stack. This also
    /// works for statically-sized arrays.
    /// @param _stackDepth number of stack elements between top of stack and top (!) of reference
    /// Stack pre: reference (excludes byte offset for dynamic storage arrays)
    /// Stack post: reference length
    void retrieveLength(ArrayType const& _arrayType, unsigned _stackDepth = 0) const;
    /// Stores the length of an array of type @a _arrayType in storage. The length itself is stored
    /// on the stack at position @a _stackDepthLength and the storage reference at @a _stackDepthRef.
    /// If @a _arrayType is a byte array, takes tight coding into account.
    void storeLength(ArrayType const& _arrayType, unsigned _stackDepthLength = 0, unsigned _stackDepthRef = 1) const;
    /// Performs bounds checking and returns a reference on the stack.
    /// Stack pre: reference [length] index
    /// Stack post (storage): storage_slot byte_offset
    /// Stack post: memory/calldata_offset
    void accessIndex(ArrayType const& _arrayType, bool _doBoundsCheck = true) const;

private:
    /// Adds the given number of bytes to a storage byte offset counter and also increments
    /// the storage offset if adding this number again would increase the counter over 32.
    /// @param byteOffsetPosition the stack offset of the storage byte offset
    /// @param storageOffsetPosition the stack offset of the storage slot offset
    void incrementByteOffset(unsigned _byteSize, unsigned _byteOffsetPosition, unsigned _storageOffsetPosition) const;

    CompilerContext& m_context;
};

}
}