UriTemplateBranchlessValidation.java

    private static final int NOT_ASCII = 128;
    private static final boolean[] RESERVED = new boolean[256];

    static {
        final int[] reservedChars = new int[] {'+', '#', '/', ';', '?', '&', ' ', '!', '=', '$', '|', '*', ':', '~', '-'};
        for (int c : reservedChars) {
            RESERVED[c] = true;
        }
        assert !RESERVED[NOT_ASCII];
    }

    public static int transformToASCIIOr128(char c) {
        int notAsciiMask = ((127 - c) >> 31);
        return (notAsciiMask & NOT_ASCII) | (~notAsciiMask & c);
    }

    private static void validateLiteral(char c) {
        final int asciiOr128 = transformToASCIIOr128(c);
        // 0xFF is used to help the JIT to skip the bound checks on RESERVED
        // given that it can proce statically that any value produced will be < 256
        if (RESERVED[asciiOr128 & 0xFF]) {
            throw new IllegalArgumentException("Illegal character identified in the token at");
        }
    }