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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 */
25 typedef 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 
54 typedef 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 */
72 typedef struct Vardesc {
73   short idx;  /* variable index in stack */
74 } Vardesc;
75 
76 
77 /* description of pending goto statements and label statements */
78 typedef 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 */
87 typedef 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 */
95 typedef 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 */
107 struct BlockCnt;  /* defined in lparser.c */
108 
109 
110 /* state needed to generate code for a given function */
111 typedef 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 
129 LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
130                                  Dyndata *dyd, const char *name, int firstchar);
131 
132 
133 #endif
134