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63 lines
1.8 KiB
Solidity
63 lines
1.8 KiB
Solidity
// SPDX-License-Identifier: MIT
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// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/extensions/ERC721URIStorage.sol)
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pragma solidity ^0.8.0;
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import "../ERC721.sol";
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/**
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* @dev ERC721 token with storage based token URI management.
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*/
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abstract contract ERC721URIStorage is ERC721 {
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using Strings for uint256;
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// Optional mapping for token URIs
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mapping(uint256 => string) private _tokenURIs;
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/**
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* @dev See {IERC721Metadata-tokenURI}.
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*/
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function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
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_requireMinted(tokenId);
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string memory _tokenURI = _tokenURIs[tokenId];
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string memory base = _baseURI();
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// If there is no base URI, return the token URI.
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if (bytes(base).length == 0) {
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return _tokenURI;
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}
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// If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
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if (bytes(_tokenURI).length > 0) {
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return string(abi.encodePacked(base, _tokenURI));
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}
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return super.tokenURI(tokenId);
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}
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/**
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* @dev Sets `_tokenURI` as the tokenURI of `tokenId`.
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*
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* Requirements:
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*
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* - `tokenId` must exist.
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*/
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function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
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require(_exists(tokenId), "ERC721URIStorage: URI set of nonexistent token");
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_tokenURIs[tokenId] = _tokenURI;
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}
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/**
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* @dev See {ERC721-_burn}. This override additionally checks to see if a
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* token-specific URI was set for the token, and if so, it deletes the token URI from
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* the storage mapping.
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*/
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function _burn(uint256 tokenId) internal virtual override {
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super._burn(tokenId);
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if (bytes(_tokenURIs[tokenId]).length != 0) {
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delete _tokenURIs[tokenId];
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}
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}
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}
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