3.8.4 ¥¹¥¿¡¼¥È¾õÂ֤˴ؤ¹¤ëÃí¡ÊFlex 2.5¤ÎÊä­¾ðÊó¡Ë

Flex 2.5¤Ç¤Ï¡¢ °Ê²¼¤Î¿·µ¡Ç½¤òÍøÍѤ¹¤ë¤³¤È¤¬¤Ç¤­¤Þ¤¹¡£

• ¥ï¥¤¥ë¥É¡¦¥«¡¼¥É

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  Î㤨¤Ð¡¢

  %x state1
  %%
  <state1>"one" printf("two");
  <*>"three"    printf("four");
  

  ¤Ï¡¢

  %s state1
  %%
  <state1>"one" printf("two");
  "three"	      printf("four");
  

  ¤ÈƱ¤¸°ÕÌ£¤Ë¤Ê¤ê¤Þ¤¹¡£

• ¥«¥ì¥ó¥È¤Ê¥¹¥¿¡¼¥È¾õÂÖ

  ¥Þ¥¯¥íYY_START¤Ë¤è¤ê¡¢ ¥«¥ì¥ó¥È¤Ê¥¹¥¿¡¼¥È¾õÂÖ¤ò»²¾È¤¹¤ë¤³¤È¤¬¤Ç¤­¤Þ¤¹¡£

  Á°Àá¡ÊStart State Notes¡Ë¤Î¡Ö¥¹¥¿¡¼¥È¾õÂÖ¤Î̾Á°¡×¤Ë¼¨¤·¤¿Îã¤Ç¤Ï¡¢ ¥«¥ì¥ó¥È¤Ê¥¹¥¿¡¼¥È¾õÂÖ¤òÇÛÎólast_state¤Ë³ÊǼ¤¹¤ë½èÍý¤ò¡¢ °Ê²¼¤Î¤è¤¦¤Ëµ­½Ò¤·¤Æ¤¤¤Þ¤¹¤¬¡¢

  FOO        {
                last_state[state_count] = FOO;
                …
             }
  

  ¤³¤ÎÂåÆþ¤Ï¡¢

                last_state[state_count] = YY_START;
  

  ¤Î¤è¤¦¤Ë½ñ¤­´¹¤¨¤ë¤³¤È¤¬¤Ç¤­¤Þ¤¹¡£

  Lex¤È¤Î¸ß´¹À­¤Î¤¿¤á¤Ë¡¢ YYSTATE¤¬¡¢ YY_START¤ÎÊÌ̾¤È¤·¤ÆÄêµÁ¤µ¤ì¤Æ¤¤¤Þ¤¹¡£

• ¥¹¥¿¡¼¥È¾õÂ֤Υ¹¥³¡¼¥×

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  ¥¹¥¿¡¼¥È¾õÂ֤Υ¹¥³¡¼¥×¤Î·Á¼°¤Ï¡¢ °Ê²¼¤Î¤È¤ª¤ê¤Ç¤¹¡£

  <start_states>{
  …
  }
  

  ¤³¤³¤Ç¡¢ start_states¤Ï¡¢ ñ°ì¤Î¥¹¥¿¡¼¥È¾õÂÖ¡¢ ¤Þ¤¿¤Ï¡¢ ¥«¥ó¥Þ¤Ç¶èÀÚ¤é¤ì¤¿¥¹¥¿¡¼¥È¾õÂ֤Υꥹ¥È¤Ç¤¹¡£ ¥¹¥¿¡¼¥È¾õÂ֤Υ¹¥³¡¼¥×¤Î¶­³¦¤Ï¡¢ ‘{’¤È‘}’¤Ë¤è¤Ã¤Æ»ØÄꤵ¤ì¤Þ¤¹¡£ ¥¹¥¿¡¼¥È¾õÂ֤Υ¹¥³¡¼¥×¤òÆþ¤ì»Ò¤Ë¤¹¤ë¤³¤È¤â²Äǽ¤Ç¤¹¡£

  Activating States¤Ë¼¨¤·¤¿Îã¤ò¡¢ ¥¹¥¿¡¼¥È¾õÂ֤Υ¹¥³¡¼¥×¤ò»È¤Ã¤Æ½ñ¤­Ä¾¤¹¤È¡¢ °Ê²¼¤Î¤è¤¦¤Ë¤Ê¤ê¤Þ¤¹¡£

  %x COMMENT
  %%
  "{"            BEGIN(COMMENT);
  <COMMENT>{
      "$R"  
      "$I"  
      "$M"  
      …  
      "}"        BEGIN(INITIAL);
  }
  

• ¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯

  ¥¹¥­¥ã¥ÊÄêµÁ¥Õ¥¡¥¤¥ë¤Ç‘%option stack’¤ò»ØÄꤹ¤ë¤È¡¢ ¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤òÍøÍѤǤ­¤Þ¤¹¡£ ¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤òÁàºî¤¹¤ë¤¿¤á¤Ë¡¢ °Ê²¼¤Î´Ø¿ô¤¬Ä󶡤µ¤ì¤Æ¤¤¤Þ¤¹¡£

  void yy_push_state(int new_state)

  ¥«¥ì¥ó¥È¤Ê¥¹¥¿¡¼¥È¾õÂÖ¤ò¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤Ë¥×¥Ã¥·¥å¤·¡¢ new_state¾õÂÖ¤ËÁ«°Ü¤·¤Þ¤¹¡£

  void yy_pop_state()

  ¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤«¤é¥¹¥¿¡¼¥È¾õÂÖ¤ò¥Ý¥Ã¥×¤·¡¢ ¤½¤Î¥Ý¥Ã¥×¤µ¤ì¤¿¥¹¥¿¡¼¥È¾õÂÖ¤ËÁ«°Ü¤·¤Þ¤¹¡£

  int yy_top_state()

  ¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤ÎÀèƬ¤Ë¤¢¤ë¥¹¥¿¡¼¥È¾õÂÖ¤òÊÖ¤·¤Þ¤¹ ¡Ê¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤ÎÆâÍƤÏÊѹ¹¤µ¤ì¤Þ¤»¤ó¡Ë¡£

  Á°Àá¡ÊStart State Notes¡Ë¤Î¡Ö¥¹¥¿¡¼¥È¾õÂÖ¤Î̾Á°¡×¤Ë¼¨¤·¤¿Îã¤ò¡¢ ¥¹¥¿¡¼¥È¾õÂÖ¥¹¥¿¥Ã¥¯¤ò»È¤Ã¤Æ½ñ¤­Ä¾¤¹¤È°Ê²¼¤Î¤è¤¦¤Ë¤Ê¤ê¤Þ¤¹¡£

  %option stack
  %x FOO BAR baz
  %%
  FOO        {
                yy_push_state(baz);
             }
  

  BAR        {
                yy_push_state(baz);
             }
  

  <baz>rule 1
       …  
  <baz>rule n
  <baz>END   {
                yy_pop_state();
             }