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