Contract Source Code:

// SPDX-License-Identifier: Apache-2.0

pragma solidity 0.8.13;

import {Ownable} from "Ownable.sol";
import {IStdReference} from "IStdReference.sol";
import {StdReferenceBase} from "StdReferenceBase.sol";

contract StdReferenceProxy is Ownable, StdReferenceBase {
    IStdReference public ref;

    constructor(IStdReference _ref, address _owner) {
        ref = _ref;
        _transferOwnership(_owner);
    }

    /// @notice Updates standard reference implementation. Only callable by the owner.
    /// @param _ref Address of the new standard reference contract
    function setRef(IStdReference _ref) public onlyOwner {
        ref = _ref;
    }

    /// @notice Returns the price data for the given base/quote pair. Revert if not available.
    /// @param base The base symbol of the token pair
    /// @param quote The quote symbol of the token pair
    function getReferenceData(string memory base, string memory quote) public view override returns (ReferenceData memory) {
        return ref.getReferenceData(base, quote);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

import "Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// SPDX-License-Identifier: Apache-2.0

pragma solidity 0.8.13;

interface IStdReference {
    /// A structure returned whenever someone requests for standard reference data.
    struct ReferenceData {
        uint256 rate; // base/quote exchange rate, multiplied by 1e18.
        uint256 lastUpdatedBase; // UNIX epoch of the last time when base price gets updated.
        uint256 lastUpdatedQuote; // UNIX epoch of the last time when quote price gets updated.
    }

    /// Returns the price data for the given base/quote pair. Revert if not available.
    function getReferenceData(string memory _base, string memory _quote) external view returns (ReferenceData memory);

    /// Similar to getReferenceData, but with multiple base/quote pairs at once.
    function getReferenceDataBulk(string[] memory _bases, string[] memory _quotes) external view returns (ReferenceData[] memory);
}

// SPDX-License-Identifier: Apache-2.0

pragma solidity 0.8.13;

import {IStdReference} from "IStdReference.sol";

abstract contract StdReferenceBase is IStdReference {
    function getReferenceData(string memory _base, string memory _quote) public view virtual override returns (ReferenceData memory);

    function getReferenceDataBulk(string[] memory _bases, string[] memory _quotes) public view override returns (ReferenceData[] memory) {
        require(_bases.length == _quotes.length, "BAD_INPUT_LENGTH");
        uint256 len = _bases.length;
        ReferenceData[] memory results = new ReferenceData[](len);
        for (uint256 idx = 0; idx < len; idx++) {
            results[idx] = getReferenceData(_bases[idx], _quotes[idx]);
        }
        return results;
    }
}