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