lobject.h（5.3.4）解析

/*** $Id: lobject.h,v 2.117 2016/08/01 19:51:24 roberto Exp $** Type definitions for Lua objects** See Copyright Notice in lua.h*/#ifndef lobject_h#define lobject_h#include <stdarg.h>#include "llimits.h"#include "lua.h"/*** Extra tags for non-values*/// LUA_TPROTO代表函数原型类型，由于这并不是一个公开类型，最终用户无法得到一个Proto类型，所以LUA_TPROTO没有定义在lua.h中，而存在于lobject.h中// （LUA_TNONE排除在外，这个类型对lua不可见提供Lua API使用）#define LUA_TPROTOLUA_NUMTAGS/* function prototypes */// LUA_TDEADKEY用来标记lua数据的上限tag#define LUA_TDEADKEY(LUA_NUMTAGS+1)/* removed keys in tables *//*** number of all possible tags (including LUA_TNONE but excluding DEADKEY)*/#define LUA_TOTALTAGS(LUA_TPROTO + 2)// 这里是对TValue里面的lu_byte类型tt做的解释// tt是一个unsigned char数据// 0-3表示数据的大类型（9种类型）// 4-5表示（这个数据的扩展，比如说下面的长字符串、短字符串、浮点数、整数、lua闭包、c函数和c闭包这些数据扩展）// 6表示是否是垃圾回收对象/*** tags for Tagged Values have the following use of bits:** bits 0-3: actual tag (a LUA_T* value)** bits 4-5: variant bits** bit 6: whether value is collectable*//*** LUA_TFUNCTION variants:** 0 - Lua function** 1 - light C function** 2 - regular C function (closure)*/// 这个地方是对9中Lua类型的tag位（4和5）进行设置// 比如说LUA_TFUNCTION这个类型，45位为0时代表lua闭包，为1时代表C函数，为2时代表C闭包// 所以下面的操作是对tag位进行扩展的/* Variant tags for functions */#define LUA_TLCL(LUA_TFUNCTION | (0 << 4))  /* Lua closure */#define LUA_TLCF(LUA_TFUNCTION | (1 << 4))  /* light C function */#define LUA_TCCL(LUA_TFUNCTION | (2 << 4))  /* C closure *//* Variant tags for strings */#define LUA_TSHRSTR(LUA_TSTRING | (0 << 4))  /* short strings */#define LUA_TLNGSTR(LUA_TSTRING | (1 << 4))  /* long strings *//* Variant tags for numbers */#define LUA_TNUMFLT(LUA_TNUMBER | (0 << 4))  /* float numbers */#define LUA_TNUMINT(LUA_TNUMBER | (1 << 4))  /* integer numbers */// 这个是看tag的第六位是不是1，是1的话就属于垃圾回收，否则就不需要关心它的生命周期/* Bit mark for collectable types */#define BIT_ISCOLLECTABLE(1 << 6)// 把传过来的tag值的第六位进行标记垃圾回收/* mark a tag as collectable */#define ctb(t)((t) | BIT_ISCOLLECTABLE)/*** Common type for all collectable objects*/// GCObject是lua里面所有需要垃圾回收对象的联合体typedef struct GCObject GCObject;/*** Common Header for all collectable objects (in macro form, to be** included in other objects)*/// 所有需要GC操作的数据都会加一个CommonHeader类型的宏定义// next指向下一个GC链表的数据// tt代表数据的类型以及扩展类型以及GC位的标志// marked是执行GC的标记为，用于具体的GC算法#define CommonHeaderGCObject *next; lu_byte tt; lu_byte marked/*** Common type has only the common header*/struct GCObject {  CommonHeader;};/*** Tagged Values. This is the basic representation of values in Lua,** an actual value plus a tag with its type.*//*** Union of all Lua values*/// 然后GCObject和其他不需要进行进行GC的数据放在一个联合体里面构成了Value类型typedef union Value {  GCObject *gc;    /* collectable objects */  void *p;         /* light userdata */  int b;           /* booleans */  lua_CFunction f; /* light C functions */  lua_Integer i;   /* integer numbers */  lua_Number n;    /* float numbers */} Value;// 最后在Value的基础上又加上了tt_来标记数据到底是什么类型的#define TValuefieldsValue value_; int tt_// TValue就是最终的数据结构typedef struct lua_TValue {  TValuefields;} TValue;/* macro defining a nil value */#define NILCONSTANT{NULL}, LUA_TNIL// 获取TValue的Value部分#define val_(o)((o)->value_)// 获取TValue的tt_部分/* raw type tag of a TValue */#define rttype(o)((o)->tt_)// 用来获取tag的后四位/* tag with no variants (bits 0-3) */#define novariant(x)((x) & 0x0F)// 用来获取tag的后六位/* type tag of a TValue (bits 0-3 for tags + variant bits 4-5) */#define ttype(o)(rttype(o) & 0x3F)/* type tag of a TValue with no variants (bits 0-3) */#define ttnov(o)(novariant(rttype(o)))// 下面这些宏是用来判断o的tag是不是满足条件// 比如说是否是float、int、table等等/* Macros to test type */#define checktag(o,t)(rttype(o) == (t))#define checktype(o,t)(ttnov(o) == (t))#define ttisnumber(o)checktype((o), LUA_TNUMBER)#define ttisfloat(o)checktag((o), LUA_TNUMFLT)#define ttisinteger(o)checktag((o), LUA_TNUMINT)#define ttisnil(o)checktag((o), LUA_TNIL)#define ttisboolean(o)checktag((o), LUA_TBOOLEAN)#define ttislightuserdata(o)checktag((o), LUA_TLIGHTUSERDATA)#define ttisstring(o)checktype((o), LUA_TSTRING)#define ttisshrstring(o)checktag((o), ctb(LUA_TSHRSTR))#define ttislngstring(o)checktag((o), ctb(LUA_TLNGSTR))#define ttistable(o)checktag((o), ctb(LUA_TTABLE))#define ttisfunction(o)checktype(o, LUA_TFUNCTION)#define ttisclosure(o)((rttype(o) & 0x1F) == LUA_TFUNCTION)#define ttisCclosure(o)checktag((o), ctb(LUA_TCCL))#define ttisLclosure(o)checktag((o), ctb(LUA_TLCL))#define ttislcf(o)checktag((o), LUA_TLCF)#define ttisfulluserdata(o)checktag((o), ctb(LUA_TUSERDATA))#define ttisthread(o)checktag((o), ctb(LUA_TTHREAD))#define ttisdeadkey(o)checktag((o), LUA_TDEADKEY)// check_exp是一个断言，定义在limits.h中// #define check_exp(c,e)    (lua_assert(c), (e))/* Macros to access values */#define ivalue(o)check_exp(ttisinteger(o), val_(o).i)#define fltvalue(o)check_exp(ttisfloat(o), val_(o).n)#define nvalue(o)check_exp(ttisnumber(o), \(ttisinteger(o) ? cast_num(ivalue(o)) : fltvalue(o)))#define gcvalue(o)check_exp(iscollectable(o), val_(o).gc)#define pvalue(o)check_exp(ttislightuserdata(o), val_(o).p)#define tsvalue(o)check_exp(ttisstring(o), gco2ts(val_(o).gc))#define uvalue(o)check_exp(ttisfulluserdata(o), gco2u(val_(o).gc))#define clvalue(o)check_exp(ttisclosure(o), gco2cl(val_(o).gc))#define clLvalue(o)check_exp(ttisLclosure(o), gco2lcl(val_(o).gc))#define clCvalue(o)check_exp(ttisCclosure(o), gco2ccl(val_(o).gc))#define fvalue(o)check_exp(ttislcf(o), val_(o).f)#define hvalue(o)check_exp(ttistable(o), gco2t(val_(o).gc))#define bvalue(o)check_exp(ttisboolean(o), val_(o).b)#define thvalue(o)check_exp(ttisthread(o), gco2th(val_(o).gc))/* a dead value may get the 'gc' field, but cannot access its contents */#define deadvalue(o)check_exp(ttisdeadkey(o), cast(void *, val_(o).gc))#define l_isfalse(o)(ttisnil(o) || (ttisboolean(o) && bvalue(o) == 0))#define iscollectable(o)(rttype(o) & BIT_ISCOLLECTABLE)/* Macros for internal tests */#define righttt(obj)(ttype(obj) == gcvalue(obj)->tt)// 检查obj的生存期// iscollectable(obj)检查obj是否为GC对象// righttt(obj)返回obj的tt_是否等于gc里面的tt// isdead(obj)返回obj是否已经被清理// 总而言之，返回true代表未被GC的和不需要GC的，返回false代表已经被GC了的#define checkliveness(L,obj) \lua_longassert(!iscollectable(obj) || \(righttt(obj) && (L == NULL || !isdead(G(L),gcvalue(obj)))))// 在lua里面的值是无关类型的，就是靠下面的操作来让变量类型相互变化// 通过改变TValue的tt_和Value里面的具体值（比如：i,n,f,b等）// set函数是设置新的值，改变的有tt_  // chg函数也是改变新的值，但是没有改变tt_    // 不需要GC的值复制操作 直接替换Value和tt，需要GC的值复制操作还要检查一下生存期/* Macros to set values */#define settt_(o,t)((o)->tt_=(t))#define setfltvalue(obj,x) \  { TValue *io=(obj); val_(io).n=(x); settt_(io, LUA_TNUMFLT); }#define chgfltvalue(obj,x) \  { TValue *io=(obj); lua_assert(ttisfloat(io)); val_(io).n=(x); }#define setivalue(obj,x) \  { TValue *io=(obj); val_(io).i=(x); settt_(io, LUA_TNUMINT); }#define chgivalue(obj,x) \  { TValue *io=(obj); lua_assert(ttisinteger(io)); val_(io).i=(x); }#define setnilvalue(obj) settt_(obj, LUA_TNIL)#define setfvalue(obj,x) \  { TValue *io=(obj); val_(io).f=(x); settt_(io, LUA_TLCF); }#define setpvalue(obj,x) \  { TValue *io=(obj); val_(io).p=(x); settt_(io, LUA_TLIGHTUSERDATA); }#define setbvalue(obj,x) \  { TValue *io=(obj); val_(io).b=(x); settt_(io, LUA_TBOOLEAN); }#define setgcovalue(L,obj,x) \  { TValue *io = (obj); GCObject *i_g=(x); \    val_(io).gc = i_g; settt_(io, ctb(i_g->tt)); }#define setsvalue(L,obj,x) \  { TValue *io = (obj); TString *x_ = (x); \    val_(io).gc = obj2gco(x_); settt_(io, ctb(x_->tt)); \    checkliveness(L,io); }#define setuvalue(L,obj,x) \  { TValue *io = (obj); Udata *x_ = (x); \    val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_TUSERDATA)); \    checkliveness(L,io); }#define setthvalue(L,obj,x) \  { TValue *io = (obj); lua_State *x_ = (x); \    val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_TTHREAD)); \    checkliveness(L,io); }#define setclLvalue(L,obj,x) \  { TValue *io = (obj); LClosure *x_ = (x); \    val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_TLCL)); \    checkliveness(L,io); }#define setclCvalue(L,obj,x) \  { TValue *io = (obj); CClosure *x_ = (x); \    val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_TCCL)); \    checkliveness(L,io); }#define sethvalue(L,obj,x) \  { TValue *io = (obj); Table *x_ = (x); \    val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_TTABLE)); \    checkliveness(L,io); }#define setdeadvalue(obj)settt_(obj, LUA_TDEADKEY)#define setobj(L,obj1,obj2) \{ TValue *io1=(obj1); *io1 = *(obj2); \  (void)L; checkliveness(L,io1); }/*** different types of assignments, according to destination*//* from stack to (same) stack */#define setobjs2ssetobj/* to stack (not from same stack) */#define setobj2ssetobj#define setsvalue2ssetsvalue#define sethvalue2ssethvalue#define setptvalue2ssetptvalue/* from table to same table */#define setobjt2tsetobj/* to new object */#define setobj2nsetobj#define setsvalue2nsetsvalue/* to table (define it as an expression to be used in macros) */#define setobj2t(L,o1,o2)  ((void)L, *(o1)=*(o2), checkliveness(L,(o1)))/*** {======================================================** types and prototypes** =======================================================*/typedef TValue *StkId;  /* index to stack elements *//*** Header for string value; string bytes follow the end of this structure** (aligned according to 'UTString'; see next).*/// TString是一个lua字符串的数据结构    // CommonHeader是一个需要GC对象的头文件    // extra用于标记是否是虚拟机保留的字符串，如果这个值为1，那么不会GC（保留字符串即是lua中的关键字）    // shrlen保留字符串的长度(因为lua并不以\0结尾来识别字符串的长度，故需要一个len域来记录其长度)    // 字符串的hash值（lua字符串的比较是用字符串的hash值来比较的）    // 下面的union联合体，lnglen表示长字符的长度    // hnext代表链接下一个字符串typedef struct TString {  CommonHeader;  lu_byte extra;  /* reserved words for short strings; "has hash" for longs */  lu_byte shrlen;  /* length for short strings */  unsigned int hash;  union {    size_t lnglen;  /* length for long strings */    struct TString *hnext;  /* linked list for hash table */  } u;} TString;/*** Ensures that address after this type is always fully aligned.*/// L_Umaxalign是一个LUAI_USER_ALIGNMENT_T的宏，这是一个联合体里面最大值的字节数量，用来保证UTString结构里面的TString按照这个长度来对齐typedef union UTString {  L_Umaxalign dummy;  /* ensures maximum alignment for strings */  TString tsv;} UTString;/*** Get the actual string (array of bytes) from a 'TString'.** (Access to 'extra' ensures that value is really a 'TString'.)*/// 获得实际的字符串（也就是上面的结构体）#define getstr(ts)  \  check_exp(sizeof((ts)->extra), cast(char *, (ts)) + sizeof(UTString))/* get the actual string (array of bytes) from a Lua value */#define svalue(o)       getstr(tsvalue(o))/* get string length from 'TString *s' */#define tsslen(s)((s)->tt == LUA_TSHRSTR ? (s)->shrlen : (s)->u.lnglen)/* get string length from 'TValue *o' */#define vslen(o)tsslen(tsvalue(o))/*** Header for userdata; memory area follows the end of this structure** (aligned according to 'UUdata'; see next).*/// UserData在lua中和string类似，可以看成是拥有独立元表，不被内部化，也不需要追加\0的字符串  // 因为UserData也是需要GC的，所以这里加上CommonHeader  // ttuv_用来标记这个数据是UserData数据  // 因为UserData数据拥有独立元表 所以这里多了一个*metatabel的数据  // len用于记录UserData长度  // user_参考上面对Value联合体的解析typedef struct Udata {  CommonHeader;  lu_byte ttuv_;  /* user value's tag */  struct Table *metatable;  size_t len;  /* number of bytes */  union Value user_;  /* user value */} Udata;/*** Ensures that address after this type is always fully aligned.*/// dummy的含义请参考上述字符串// userdata分为LUA_TLIGHTUSERDATA和LUA_TUSERDATA，其中前一种类型即为轻量级userdata（light userdata），// 轻量级userdata是一种表示C指针的值，对Lua虚拟机来说，这种数据类型不需要GC（垃圾回收），其指向的内存由用户分配和释放；// 后一种userdata类型完全userdata（full userdata），内存是由Lua虚拟机分配，并有GC机制负责处理。typedef union UUdata {  L_Umaxalign dummy;  /* ensures maximum alignment for 'local' udata */  Udata uv;} UUdata;/***  Get the address of memory block inside 'Udata'.** (Access to 'ttuv_' ensures that value is really a 'Udata'.)*/#define getudatamem(u)  \  check_exp(sizeof((u)->ttuv_), (cast(char*, (u)) + sizeof(UUdata)))// 对Udata数据进行赋值的操作，重点及时替换掉Udata结构体里面的user_和ttuv_标记（rttype来返回数据的类型）#define setuservalue(L,u,o) \{ const TValue *io=(o); Udata *iu = (u); \  iu->user_ = io->value_; iu->ttuv_ = rttype(io); \  checkliveness(L,io); }// getuservalue把u的值赋给o// settt_(o,t)更改o的类型为t#define getuservalue(L,u,o) \{ TValue *io=(o); const Udata *iu = (u); \  io->value_ = iu->user_; settt_(io, iu->ttuv_); \  checkliveness(L,io); }/*** Description of an upvalue for function prototypes*/    // 用来记录upvalue的调试信息    // name记录名字    // instack记录是否在堆栈中    // idx记录这个upvalue在函数列表中的索引typedef struct Upvaldesc {  TString *name;  /* upvalue name (for debug information) */  lu_byte instack;  /* whether it is in stack (register) */  lu_byte idx;  /* index of upvalue (in stack or in outer function's list) */} Upvaldesc;/*** Description of a local variable for function prototypes** (used for debug information)*/// 用来记录函数内部变量的调试信息// *varname记录名字// startpc和endpc分别记录生成和回收的代码点typedef struct LocVar {  TString *varname;  int startpc;  /* first point where variable is active */  int endpc;    /* first point where variable is dead */} LocVar;/*** Function Prototypes*/// 函数原型数据结构// CommonHeader是一个需要GC对象的头文件// numparams用来记录固定参数的个数// is_vararg是否支持变参。1表示使用了变参作为最后一个参数// maxstacksize记录调用这个函数需要多大的数据栈空间// sizeupvalues记录这个函数原型的upvalue的数量// sizek记录常量表的大小// sizecode记录字节码的数量// code用来记录字节码数组// **p记录函数原型的函数原型（因为lua中函数体里面可以定义函数，所以必然存在函数原型内存在函数原型）// cache的作用是用来引用生成的闭包，下次再通过这个原型生成闭包时，比较upvalue是否一致来决定复用。cache是一个弱引用，一旦在gc流程中发现引用的闭包不存在，cache将被置空// source用来记录调试信息数组。lua的调试信息很丰富。每条code中的指令都对应着line数组中的源代码行号。局部变量好upvalue的调试信息，包括名字和在源代码中的作用域都记录在Proto结构里。// *gclist记录Proto内需要GC的对象// *locvars记录函数内部变量的调试信息// *upvalues记录upvalue的调试信息typedef struct Proto {  CommonHeader;  lu_byte numparams;  /* number of fixed parameters */  lu_byte is_vararg;  lu_byte maxstacksize;  /* number of registers needed by this function */  int sizeupvalues;  /* size of 'upvalues' */  int sizek;  /* size of 'k' */  int sizecode;  int sizelineinfo;  int sizep;  /* size of 'p' */  int sizelocvars;  int linedefined;  /* debug information  */  int lastlinedefined;  /* debug information  */  TValue *k;  /* constants used by the function */  Instruction *code;  /* opcodes */  struct Proto **p;  /* functions defined inside the function */  int *lineinfo;  /* map from opcodes to source lines (debug information) */  LocVar *locvars;  /* information about local variables (debug information) */  Upvaldesc *upvalues;  /* upvalue information */  struct LClosure *cache;  /* last-created closure with this prototype */  TString  *source;  /* used for debug information */  GCObject *gclist;} Proto;/*** Lua Upvalues*/typedef struct UpVal UpVal;/*** Closures*/#define ClosureHeader \CommonHeader; lu_byte nupvalues; GCObject *gclisttypedef struct CClosure {  ClosureHeader;  lua_CFunction f;  TValue upvalue[1];  /* list of upvalues */} CClosure;typedef struct LClosure {  ClosureHeader;  struct Proto *p;  UpVal *upvals[1];  /* list of upvalues */} LClosure;typedef union Closure {  CClosure c;  LClosure l;} Closure;#define isLfunction(o)ttisLclosure(o)#define getproto(o)(clLvalue(o)->p)/*** Tables*/// 在任何时候TKey的类型只有两个，要么是整数，要么不是整数（非nil）// next在之前的版本是 struct Node *next; 类型的，5.3换成了int类型，是一个偏移。next指向冲突的下一个节点typedef union TKey {  struct {    TValuefields;    int next;  /* for chaining (offset for next node) */  } nk;  TValue tvk;} TKey;/* copy a value into a key without messing up field 'next' */#define setnodekey(L,key,obj) \{ TKey *k_=(key); const TValue *io_=(obj); \  k_->nk.value_ = io_->value_; k_->nk.tt_ = io_->tt_; \  (void)L; checkliveness(L,io_); }// 此自定义的Node节点就是table的节点值typedef struct Node {  TValue i_val;  TKey i_key;} Node;// flags表示此table中存在哪些元方法，默认是0。元方法对应的bit定义在ltm.h中// lsizenode是该表中以2为底的散列表大小的对数值。// sizearray是数组部分的大小// *array指向数组部分的指针// *node指向散列表起始位置的指针// *lastfree指向散列表最后位置的指针// *metatable存放该表的元表// *gclist：GC相关的链表typedef struct Table {  CommonHeader;  lu_byte flags;  /* 1<<p means tagmethod(p) is not present */  lu_byte lsizenode;  /* log2 of size of 'node' array */  unsigned int sizearray;  /* size of 'array' array */  TValue *array;  /* array part */  Node *node;  Node *lastfree;  /* any free position is before this position */  struct Table *metatable;  GCObject *gclist;} Table;/*** 'module' operation for hashing (size is always a power of 2)*/#define lmod(s,size) \(check_exp((size&(size-1))==0, (cast(int, (s) & ((size)-1)))))#define twoto(x)(1<<(x))#define sizenode(t)(twoto((t)->lsizenode))/*** (address of) a fixed nil value*/#define luaO_nilobject(&luaO_nilobject_)LUAI_DDEC const TValue luaO_nilobject_;/* size of buffer for 'luaO_utf8esc' function */#define UTF8BUFFSZ8LUAI_FUNC int luaO_int2fb (unsigned int x);LUAI_FUNC int luaO_fb2int (int x);LUAI_FUNC int luaO_utf8esc (char *buff, unsigned long x);LUAI_FUNC int luaO_ceillog2 (unsigned int x);LUAI_FUNC void luaO_arith (lua_State *L, int op, const TValue *p1,                           const TValue *p2, TValue *res);LUAI_FUNC size_t luaO_str2num (const char *s, TValue *o);LUAI_FUNC int luaO_hexavalue (int c);LUAI_FUNC void luaO_tostring (lua_State *L, StkId obj);LUAI_FUNC const char *luaO_pushvfstring (lua_State *L, const char *fmt,                                                       va_list argp);LUAI_FUNC const char *luaO_pushfstring (lua_State *L, const char *fmt, ...);LUAI_FUNC void luaO_chunkid (char *out, const char *source, size_t len);#endif