add simple catch-all implementation for the metadata URI interface

contracts/token/ERC1155/ERC1155MetadataURI_CatchAll.sol

@@ -0,0 +1,38 @@
+pragma solidity ^0.5.9;
+
+import "./ERC1155.sol";
+import "./IERC1155MetadataURI.sol";
+import "../../introspection/ERC165.sol";
+
+contract ERC1155MetadataURI_CatchAll is ERC165, ERC1155, IERC1155MetadataURI {
+    // Catch-all URI with placeholders, e.g. https://example.com/{locale}/{id}.json
+    string private _uri;
+
+     /*
+     *     bytes4(keccak256('uri(uint256)')) == 0x0e89341c
+     */
+    bytes4 private constant _INTERFACE_ID_ERC1155_METADATA_URI = 0x0e89341c;
+
+    /**
+     * @dev Constructor function
+     */
+    constructor (string memory uri) public {
+        _uri = uri;
+        emit URI(_uri, 0);
+
+        // register the supported interfaces to conform to ERC1155 via ERC165
+        _registerInterface(_INTERFACE_ID_ERC1155_METADATA_URI);
+    }
+
+    /**
+     * @notice A distinct Uniform Resource Identifier (URI) for a given token.
+     * @dev URIs are defined in RFC 3986.
+     * The URI MUST point to a JSON file that conforms to the "ERC-1155 Metadata URI JSON Schema".
+     * param id uint256 ID of the token to query (ignored in this particular implementation,
+     * as an {id} parameter in the string is expected)
+     * @return URI string
+    */
+    function uri(uint256 /*id*/) external view returns (string memory) {
+        return _uri;
+    }
+}

contracts/token/ERC1155/IERC1155MetadataURI.sol

@@ -0,0 +1,11 @@
+pragma solidity ^0.5.0;
+
+import "./IERC1155.sol";
+
+/**
+ * @title ERC-1155 Multi Token Standard basic interface, optional metadata URI extension
+ * @dev See https://eips.ethereum.org/EIPS/eip-1155
+ */
+contract IERC1155MetadataURI is IERC1155 {
+    function uri(uint256 id) external view returns (string memory);
+}