Lua5.1代码阅读（四）：lparser.h/lparser.c

一、概述

lparser.h/lparser.c是Lua的语法分析器。

用于分析Lua脚本的语法以及把上下文信息传递给代码生成器，

完成文本代码到二进制代码的转换，以及语法检查。

在线版：

http://www.lua.org/source/5.1/lparser.h.html

http://www.lua.org/source/5.1/lparser.c.html

lparser内部主要函数的引用图如下：（只含部分）

在Lua参考手册（LRM）中描述了Lua的基本语法，见

http://www.lua.org/manual/5.1/manual.html#8

可以画出的关系图大概是这样子：

二、枚举值

1. typedef enum {

VVOID, /* 无值 */

VNIL,

VTRUE,

VFALSE,

VK, /* info = k内常量的索引 */

VKNUM, /* nval = 数值 */

VLOCAL, /* info = 局部寄存器 */

VUPVAL, /* info = upvalues内的上值索引 */

VGLOBAL, /* info = 表索引; aux = k内全局名称的索引 */

VINDEXED, /* info = 表寄存器; aux = 索引寄存器（或k） */

VJMP, /* info = 指令pc */

VRELOCABLE, /* info = 指令pc */

VNONRELOC, /* info = 结果寄存器 */

VCALL, /* info = 指令pc */

VVARARG /* info = 指令pc */

} expkind;

三、结构体、联合体

1. typedef struct expdesc {

expkind k;

union {

struct { int info, aux; } s;

lua_Number nval;

} u;

int t; /* 真时退出的补丁列表 */

int f; /* 假时退出的补丁列表 */

} expdesc;

2. typedef struct upvaldesc {

lu_byte k;

lu_byte info;

} upvaldesc;

3. typedef struct FuncState {

Proto *f; /* 当前函数头 */

Table *h; /* 用来查找（或重用）k内元素的表*/

struct FuncState *prev; /* 闭合函数 */

struct LexState *ls; /* 词法状态 */

struct lua_State *L; /* Lua状态的复制 */

struct BlockCnt *bl; /* 当前块链 */

int pc; /* 代码的下一个位置（等价于ncode） */

int lasttarget; /* 上一次jump target的pc */

int jpc; /* 即将跳转的pc列表 */

int freereg; /* 第一个空闲的寄存器 */

int nk; /* k内的元素个数 */

int np; /* p内的元素个数 */

short nlocvars; /* locvars内的元素个数 */

lu_byte nactvar; /*激活的局部变量的个数 */

upvaldesc upvalues[LUAI_MAXUPVALUES]; /* 上值 */

unsigned short actvar[LUAI_MAXVARS]; /* 已声明变量的堆栈 */

} FuncState;

4. typedef struct BlockCnt {

struct BlockCnt *previous; /* 链 */

int breaklist; /* 跳出此循环的列表 */

lu_byte nactvar; /* 在可跳出结构外的激活局部变量 */

lu_byte upval; /* 如果块的一些变量为上值的话为真 */

lu_byte isbreakable; /* 如果块为循环的话为真 */

} BlockCnt;

5. struct ConsControl {

expdesc v; /* 上一次读入的列表项 */

expdesc *t; /* 表描述符 */

int nh; /* record元素的总数 */

int na; /* 数组元素的总数 */

int tostore; /* 将要被存储的数组元素的个数 */

};

6. static const struct {

lu_byte left; /* 每个二元操作符的左优先级 */

lu_byte right; /* 右优先级 */

} priority[] = { /* ORDER OPR */

{6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7}, /* `+' `-' `/' `%' */

{10, 9}, {5, 4}, /* 乘幂和拼接 (右结合) */

{3, 3}, {3, 3}, /* 相等和不等 */

{3, 3}, {3, 3}, {3, 3}, {3, 3}, /* 排序 */

{2, 2}, {1, 1} /* 逻辑（与或） */

};

7. struct LHS_assign {

struct LHS_assign *prev;

expdesc v; /* 变量（全局，局部，上值，或索引） */

};

四、宏

1. #define lparser_c

2. #define LUA_CORE

3. #define hasmultret(k) ((k) == VCALL || (k) == VVARARG)

4. #define getlocvar(fs, i) ((fs)->f->locvars[(fs)->actvar[i]])

5. #define luaY_checklimit(fs,v,l,m) if ((v)>(l)) errorlimit(fs,l,m)

6. #define check_condition(ls,c,msg) { if (!(c)) luaX_syntaxerror(ls, msg); }

7. #define new_localvarliteral(ls,v,n) \

new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char))-1), n)

8. #define leavelevel(ls) ((ls)->L->nCcalls--)

9. #define UNARY_PRIORITY 8 /* 一元操作符的优先级 */

五、公共全局函数

1. Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, const char *name) {

六、私有静态函数

1. static void anchor_token (LexState *ls) {

2. static void error_expected (LexState *ls, int token) {

3. static void errorlimit (FuncState *fs, int limit, const char *what) {

4. static int testnext (LexState *ls, int c) {

5. static void check (LexState *ls, int c) {

6. static void checknext (LexState *ls, int c) {

7. static void check_match (LexState *ls, int what, int who, int where) {

8. static TString *str_checkname (LexState *ls) {

9. static void init_exp (expdesc *e, expkind k, int i) {

10. static void codestring (LexState *ls, expdesc *e, TString *s) {

11. static void checkname(LexState *ls, expdesc *e) {

12. static int registerlocalvar (LexState *ls, TString *varname) {

13. static void new_localvar (LexState *ls, TString *name, int n) {

14. static void adjustlocalvars (LexState *ls, int nvars) {

15. static void removevars (LexState *ls, int tolevel) {

16. static int indexupvalue (FuncState *fs, TString *name, expdesc *v) {

17. static int searchvar (FuncState *fs, TString *n) {

18. static void markupval (FuncState *fs, int level) {

19. static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {

20. static void singlevar (LexState *ls, expdesc *var) {

21. static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {

22. static void enterlevel (LexState *ls) {

23. static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isbreakable) {

24. static void leaveblock (FuncState *fs) {

25. static void pushclosure (LexState *ls, FuncState *func, expdesc *v) {

26. static void open_func (LexState *ls, FuncState *fs) {

27. static void close_func (LexState *ls) {

28. static void field (LexState *ls, expdesc *v) {

29. static void yindex (LexState *ls, expdesc *v) {

30. static void recfield (LexState *ls, struct ConsControl *cc) {

31. static void closelistfield (FuncState *fs, struct ConsControl *cc) {

32. static void lastlistfield (FuncState *fs, struct ConsControl *cc) {

33. static void listfield (LexState *ls, struct ConsControl *cc) {

34. static void constructor (LexState *ls, expdesc *t) {

35. static void parlist (LexState *ls) {

36. static void body (LexState *ls, expdesc *e, int needself, int line) {

37. static int explist1 (LexState *ls, expdesc *v) {

38. static void funcargs (LexState *ls, expdesc *f) {

39. static void prefixexp (LexState *ls, expdesc *v) {

40. static void primaryexp (LexState *ls, expdesc *v) {

41. static void simpleexp (LexState *ls, expdesc *v) {

42. static UnOpr getunopr (int op) {

43. static BinOpr getbinopr (int op) {

44. static BinOpr subexpr (LexState *ls, expdesc *v, unsigned int limit) {

45. static void expr (LexState *ls, expdesc *v) {

46. static int block_follow (int token) {

47. static void block (LexState *ls) {

48. static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {

49. static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {

50. static int cond (LexState *ls) {

51. static void breakstat (LexState *ls) {

52. static void whilestat (LexState *ls, int line) {

53. static void repeatstat (LexState *ls, int line) {

54. static int exp1 (LexState *ls) {

55. static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {

56. static void fornum (LexState *ls, TString *varname, int line) {

57. static void forlist (LexState *ls, TString *indexname) {

58. static void forstat (LexState *ls, int line) {

59. static int test_then_block (LexState *ls) {

60. static void ifstat (LexState *ls, int line) {

61. static void localfunc (LexState *ls) {

62. static void localstat (LexState *ls) {

63. static int funcname (LexState *ls, expdesc *v) {

64. static void funcstat (LexState *ls, int line) {

65. static void exprstat (LexState *ls) {

66. static void retstat (LexState *ls) {

67. static int statement (LexState *ls) {

68. static void chunk (LexState *ls) {

七、值得观察的代码

1. luaY_parser

Lua语法分析器的入口

2. chunk/block/expr/subexpr/constructor/explist1

Lua语法中几个重要元素