ITokenMetadata.sol

```
interface ITokenMetadata {
    struct tokenOutput {
        // text/html, image/svg+xml, image/png, ...
        string mimeType;
        bytes output;
    };

    function getTokenPreview(uint256 tokenId) external view returns (string memory);

    function getTokenOutput(uint256 tokenId) external view returns (string memory);


    enum DataType {
        BOOLEAN,
        STRING,
        // Use whole range of int256
        INT,
        // Still an int256, and we decide a scaling, e.g. 1e18, and we determine the float by dividing by 1e18
        FLOAT,
        // Unix timestamp
        DATE
    }

    // Define an attr (color of type string, altitude of type float, ...)
    struct Attribute {
        string name;
        DataType dataType;
    }

    // Return an array of all attributes in the collection
    function getAttributes() external view returns (Attribute[] memory);


    // Get a single attribute from a token
    // The value is returned as raw bytes : to display it, the reader has to cast it
    function getTokenAttribute(uint256 tokenId, string memory attrName) external view returns (bytes memory);

    // Get all attributes of a token
    struct TokenAttribute {
        Attribute attribute;
        bytes value;
    }
    function getTokenAttribute(uint256 tokenId) external view returns (TokenAttribute[]);
}

interface ITokenMetadataSearchable /* is ITokenMetadata */ {
    // We could decide to implement a subset of searchable attrs only
    function isAttributeSearcheable(string memory attrName) external view returns (bool);

    // For a given attribute value, returns all the tokens that have it
    function getTokensOfAttribute(string memory attrName, bytes attrValue) external view returns (uint256[] memory);


    enum searchOperator {
        EQUAL,
        CONTAINS,
        HIGHER_THAN,
        LOWER_THAN,
        HIGHER_THAN_OR_EQUAL,
        LOWER_THAN_OR_EQUAL,
    }

    // Search with an operator
    function getTokensOfAttributeWithOperator(string memory attrName, searchOperator operator, bytes operandValue) external view returns (uint256[] memory);    
}
```