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 */ |
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; 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 | |
67 | typedef 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 */ |
95 | typedef 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 */ |
109 | typedef 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 */ |
119 | typedef 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 */ |
127 | typedef 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 */ |
139 | struct BlockCnt; /* defined in lparser.c */ |
140 | |
141 | |
142 | /* state needed to generate code for a given function */ |
143 | typedef 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 | |
165 | LUAI_FUNC int luaY_nvarstack (FuncState *fs); |
166 | LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, |
167 | Dyndata *dyd, const char *name, int firstchar); |
168 | |
169 | |
170 | #endif |
171 | |