vhdl don't care problem

Hello.. I want to make priority encoder. and I need to use "don't care"

the first code is working well. but when i tested in model_sim.

the output is always "000".

i thinks if input is "00001--" , and if I make the output "00000100" ,"00000101",

"00000110" or "00000111", the output should be "2" = "010". but it's always "000".

I use quartus2 version 12.0 and model_sim 12.0 (free_version)

(someone said i should use std_match so i made second code using std_match,

but it has error. what is the problem?)

can anyone give me the priority encoder example using don't care "-"?

I am doing this for 1 hours.. but i don't know what's wrong!!

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LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

ENTITY enco is

port(

input : in std_logic_vector(7 downto 0);

binary_out : out std_logic_vector(2 downto 0));

end enco;

ARCHITECTURE arc of enco is

begin

process(input)

begin

case input is

when "00000001" => binary_out <= "000";

when "0000001-" => binary_out <= "001";

when "000001--" => binary_out <= "010";

when "00001---" => binary_out <= "011";

when "0001----" => binary_out <= "100";

when "001-----" => binary_out <= "101";

when "010-----" => binary_out <= "110";

when "1-------" => binary_out <= "111";

when others => binary_out <= "000";

end case;

end process;

end arc;

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LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

ENTITY enco1 is

port(

input : in std_logic_vector(7 downto 0); -- 8bit vector &#47484; &#51060;&#50857;&#54644; input0~input7&#47484; &#54620;&#48264;&#50640; &#47564;&#46316;

binary_out : out std_logic_vector(2 downto 0)); -- 3bit vector &#47484; &#51060;&#50857;&#54644; input1,input2,input3&#47484; &#54620;&#48264;&#50640; &#50670;&#51020;

end enco1;

ARCHITECTURE arc of enco1 is

begin

process(input)

begin

if std_match(input, "00000001") then binary_out <= "000";

elsif std_match(input, "0000001-") then binary_out <= "001";

elsif std_match(input,"000001--") then binary_out<="010";

elsif std_match(input,"00001---") then binary_out<="011";

elsif std_match(input,"0001----") then binary_out<="100";

elsif std_match(input,"001-----") then binary_out<="101";

elsif std_match(input,"01------") then binary_out<="110";

elsif std_match(input,"1-------") then binary_out<="111";

else binary_out<="000";

end if;

end process;

end arc;