lparser.h revision 344220 
1/*
2** $Id: lparser.h,v 1.76.1.1 2017/04/19 17:20:42 roberto Exp $
3** Lua Parser
4** See Copyright Notice in lua.h
5*/
6
7#ifndef lparser_h
8#define lparser_h
9
10#include "llimits.h"
11#include "lobject.h"
12#include "lzio.h"
13
14
15/*
16** Expression and variable descriptor.
17** Code generation for variables and expressions can be delayed to allow
18** optimizations; An 'expdesc' structure describes a potentially-delayed
19** variable/expression. It has a description of its "main" value plus a
20** list of conditional jumps that can also produce its value (generated
21** by short-circuit operators 'and'/'or').
22*/
23
24/* kinds of variables/expressions */
25typedef enum {
26  VVOID,  /* when 'expdesc' describes the last expression a list,
27             this kind means an empty list (so, no expression) */
28  VNIL,  /* constant nil */
29  VTRUE,  /* constant true */
30  VFALSE,  /* constant false */
31  VK,  /* constant in 'k'; info = index of constant in 'k' */
32  VKFLT,  /* floating constant; nval = numerical float value */
33  VKINT,  /* integer constant; nval = numerical integer value */
34  VNONRELOC,  /* expression has its value in a fixed register;
35                 info = result register */
36  VLOCAL,  /* local variable; info = local register */
37  VUPVAL,  /* upvalue variable; info = index of upvalue in 'upvalues' */
38  VINDEXED,  /* indexed variable;
39                ind.vt = whether 't' is register or upvalue;
40                ind.t = table register or upvalue;
41                ind.idx = key's R/K index */
42  VJMP,  /* expression is a test/comparison;
43            info = pc of corresponding jump instruction */
44  VRELOCABLE,  /* expression can put result in any register;
45                  info = instruction pc */
46  VCALL,  /* expression is a function call; info = instruction pc */
47  VVARARG  /* vararg expression; info = instruction pc */
48} expkind;
49
50
51#define vkisvar(k)	(VLOCAL <= (k) && (k) <= VINDEXED)
52#define vkisinreg(k)	((k) == VNONRELOC || (k) == VLOCAL)
53
54typedef struct expdesc {
55  expkind k;
56  union {
57    lua_Integer ival;    /* for VKINT */
58    lua_Number nval;  /* for VKFLT */
59    int info;  /* for generic use */
60    struct {  /* for indexed variables (VINDEXED) */
61      short idx;  /* index (R/K) */
62      lu_byte t;  /* table (register or upvalue) */
63      lu_byte vt;  /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */
64    } ind;
65  } u;
66  int t;  /* patch list of 'exit when true' */
67  int f;  /* patch list of 'exit when false' */
68} expdesc;
69
70
71/* description of active local variable */
72typedef struct Vardesc {
73  short idx;  /* variable index in stack */
74} Vardesc;
75
76
77/* description of pending goto statements and label statements */
78typedef struct Labeldesc {
79  TString *name;  /* label identifier */
80  int pc;  /* position in code */
81  int line;  /* line where it appeared */
82  lu_byte nactvar;  /* local level where it appears in current block */
83} Labeldesc;
84
85
86/* list of labels or gotos */
87typedef struct Labellist {
88  Labeldesc *arr;  /* array */
89  int n;  /* number of entries in use */
90  int size;  /* array size */
91} Labellist;
92
93
94/* dynamic structures used by the parser */
95typedef struct Dyndata {
96  struct {  /* list of active local variables */
97    Vardesc *arr;
98    int n;
99    int size;
100  } actvar;
101  Labellist gt;  /* list of pending gotos */
102  Labellist label;   /* list of active labels */
103} Dyndata;
104
105
106/* control of blocks */
107struct BlockCnt;  /* defined in lparser.c */
108
109
110/* state needed to generate code for a given function */
111typedef struct FuncState {
112  Proto *f;  /* current function header */
113  struct FuncState *prev;  /* enclosing function */
114  struct LexState *ls;  /* lexical state */
115  struct BlockCnt *bl;  /* chain of current blocks */
116  int pc;  /* next position to code (equivalent to 'ncode') */
117  int lasttarget;   /* 'label' of last 'jump label' */
118  int jpc;  /* list of pending jumps to 'pc' */
119  int nk;  /* number of elements in 'k' */
120  int np;  /* number of elements in 'p' */
121  int firstlocal;  /* index of first local var (in Dyndata array) */
122  short nlocvars;  /* number of elements in 'f->locvars' */
123  lu_byte nactvar;  /* number of active local variables */
124  lu_byte nups;  /* number of upvalues */
125  lu_byte freereg;  /* first free register */
126} FuncState;
127
128
129LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
130                                 Dyndata *dyd, const char *name, int firstchar);
131
132
133#endif
134