Lua-5.3.4代码分析(二)TString字符串

先看LUA中关于字符串TString的源码:

/*
** Header for string value; string bytes follow the end of this structure
** (aligned according to 'UTString'; see next).
*/
typedef struct TString {
  CommonHeader;//可GC对象的头
  lu_byte extra;  /* reserved words for short strings; "has hash" for longs */ //标记是否是虚拟机保留的字符串,如果是短字符串,1就是lua中保留的字符串(关键字),不可GC;长字符串1表示已经hash.
  lu_byte shrlen;  /* length for short strings *///短字符串的长度
  unsigned int hash;//字符串的hash值,字符串的比较可以通过hash值
  union {
    size_t lnglen;  /* length for long strings */  //长字符串的长度
    struct TString *hnext;  /* linked list for hash table *///指向下一个字符串
  } u;
} TString;


/*
** Ensures that address after this type is always fully aligned.
**L_Umaxalign是一个宏,用来保证UTString结构里的TString按照这个长度来对齐
*/
typedef union UTString {
  L_Umaxalign dummy;  /* ensures maximum alignment for strings */
  TString tsv;
} UTString;/*
** Header fo