1/*
2** $Id: lparser.h $
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 of 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; ival = numerical integer value */
34  VKSTR,  /* string constant; strval = TString address;
35             (string is fixed by the lexer) */
36  VNONRELOC,  /* expression has its value in a fixed register;
37                 info = result register */
38  VLOCAL,  /* local variable; var.ridx = register index;
39              var.vidx = relative index in 'actvar.arr'  */
40  VUPVAL,  /* upvalue variable; info = index of upvalue in 'upvalues' */
41  VCONST,  /* compile-time <const> variable;
42              info = absolute index in 'actvar.arr'  */
43  VINDEXED,  /* indexed variable;
44                ind.t = table register;
45                ind.idx = key's R index */
46  VINDEXUP,  /* indexed upvalue;
47                ind.t = table upvalue;
48                ind.idx = key's K index */
49  VINDEXI, /* indexed variable with constant integer;
50                ind.t = table register;
51                ind.idx = key's value */
52  VINDEXSTR, /* indexed variable with literal string;
53                ind.t = table register;
54                ind.idx = key's K index */
55  VJMP,  /* expression is a test/comparison;
56            info = pc of corresponding jump instruction */
57  VRELOC,  /* expression can put result in any register;
58              info = instruction pc */
59  VCALL,  /* expression is a function call; info = instruction pc */
60  VVARARG  /* vararg expression; info = instruction pc */
61} expkind;
62
63
64#define vkisvar(k)	(VLOCAL <= (k) && (k) <= VINDEXSTR)
65#define vkisindexed(k)	(VINDEXED <= (k) && (k) <= VINDEXSTR)
66
67
68typedef struct expdesc {
69  expkind k;
70  union {
71    lua_Integer ival;    /* for VKINT */
72    lua_Number nval;  /* for VKFLT */
73    TString *strval;  /* for VKSTR */
74    int info;  /* for generic use */
75    struct {  /* for indexed variables */
76      short idx;  /* index (R or "long" K) */
77      lu_byte t;  /* table (register or upvalue) */
78    } ind;
79    struct {  /* for local variables */
80      lu_byte ridx;  /* register holding the variable */
81      unsigned short vidx;  /* compiler index (in 'actvar.arr')  */
82    } var;
83  } u;
84  int t;  /* patch list of 'exit when true' */
85  int f;  /* patch list of 'exit when false' */
86} expdesc;
87
88
89/* kinds of variables */
90#define VDKREG		0   /* regular */
91#define RDKCONST	1   /* constant */
92#define RDKTOCLOSE	2   /* to-be-closed */
93#define RDKCTC		3   /* compile-time constant */
94
95/* description of an active local variable */
96typedef union Vardesc {
97  struct {
98    TValuefields;  /* constant value (if it is a compile-time constant) */
99    lu_byte kind;
100    lu_byte ridx;  /* register holding the variable */
101    short pidx;  /* index of the variable in the Proto's 'locvars' array */
102    TString *name;  /* variable name */
103  } vd;
104  TValue k;  /* constant value (if any) */
105} Vardesc;
106
107
108
109/* description of pending goto statements and label statements */
110typedef struct Labeldesc {
111  TString *name;  /* label identifier */
112  int pc;  /* position in code */
113  int line;  /* line where it appeared */
114  lu_byte nactvar;  /* number of active variables in that position */
115  lu_byte close;  /* goto that escapes upvalues */
116} Labeldesc;
117
118
119/* list of labels or gotos */
120typedef struct Labellist {
121  Labeldesc *arr;  /* array */
122  int n;  /* number of entries in use */
123  int size;  /* array size */
124} Labellist;
125
126
127/* dynamic structures used by the parser */
128typedef struct Dyndata {
129  struct {  /* list of all active local variables */
130    Vardesc *arr;
131    int n;
132    int size;
133  } actvar;
134  Labellist gt;  /* list of pending gotos */
135  Labellist label;   /* list of active labels */
136} Dyndata;
137
138
139/* control of blocks */
140struct BlockCnt;  /* defined in lparser.c */
141
142
143/* state needed to generate code for a given function */
144typedef struct FuncState {
145  Proto *f;  /* current function header */
146  struct FuncState *prev;  /* enclosing function */
147  struct LexState *ls;  /* lexical state */
148  struct BlockCnt *bl;  /* chain of current blocks */
149  int pc;  /* next position to code (equivalent to 'ncode') */
150  int lasttarget;   /* 'label' of last 'jump label' */
151  int previousline;  /* last line that was saved in 'lineinfo' */
152  int nk;  /* number of elements in 'k' */
153  int np;  /* number of elements in 'p' */
154  int nabslineinfo;  /* number of elements in 'abslineinfo' */
155  int firstlocal;  /* index of first local var (in Dyndata array) */
156  int firstlabel;  /* index of first label (in 'dyd->label->arr') */
157  short ndebugvars;  /* number of elements in 'f->locvars' */
158  lu_byte nactvar;  /* number of active local variables */
159  lu_byte nups;  /* number of upvalues */
160  lu_byte freereg;  /* first free register */
161  lu_byte iwthabs;  /* instructions issued since last absolute line info */
162  lu_byte needclose;  /* function needs to close upvalues when returning */
163} FuncState;
164
165
166LUAI_FUNC int luaY_nvarstack (FuncState *fs);
167LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
168                                 Dyndata *dyd, const char *name, int firstchar);
169
170
171#endif
172