我在问这个问题,因为这不是我第一次看到这种编码习惯,但从来没有看到任何关于这个原因的评论:我在浏览Lua的源文件,看到他们使用'颜色'(白色,黑色)来描述对象的状态。下面是从头部lgc.h代码:使用'颜色'来定义对象的标志状态?
/*
** Layout for bit use in `marked' field:
** bit 0 - object is white (type 0)
** bit 1 - object is white (type 1)
** bit 2 - object is black
** bit 3 - for userdata: has been finalized
** bit 3 - for tables: has weak keys
** bit 4 - for tables: has weak values
** bit 5 - object is fixed (should not be collected)
** bit 6 - object is "super" fixed (only the main thread)
*/
#define WHITE0BIT 0
#define WHITE1BIT 1
#define BLACKBIT 2
#define FINALIZEDBIT 3
#define KEYWEAKBIT 3
#define VALUEWEAKBIT 4
#define FIXEDBIT 5
#define SFIXEDBIT 6
#define WHITEBITS bit2mask(WHITE0BIT, WHITE1BIT)
#define iswhite(x) test2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
#define isblack(x) testbit((x)->gch.marked, BLACKBIT)
#define isgray(x) (!isblack(x) && !iswhite(x))
#define otherwhite(g) (g->currentwhite^WHITEBITS)
#define isdead(g,v) ((v)->gch.marked & otherwhite(g) & WHITEBITS)
#define changewhite(x) ((x)->gch.marked ^= WHITEBITS)
#define gray2black(x) l_setbit((x)->gch.marked, BLACKBIT)
#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
我已经看到了在其他项目类似的东西(它甚至用“红”),但永远无法理解(也不关心)什么是颜色和物体之间的概念连接州。有什么样的约定规定'白色'应该表示'好'和'黑','坏'或类似的东西?任何人都知道这种做法的起源是什么?
您可能在红黑树的实现中看到了“红色”。那里的颜色并不重要,除了图表看起来比橙色粉红色的树更可敬。 – 2009-08-05 01:22:51