xref: /freebsd/contrib/lua/src/lparser.h (revision 410556f1f10fd35b350102725fd8504c3cb0afc8)
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 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.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 <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 
68 typedef 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 sidx;  /* index in the stack */
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 */
96 typedef union Vardesc {
97   struct {
98     TValuefields;  /* constant value (if it is a compile-time constant) */
99     lu_byte kind;
100     lu_byte sidx;  /* index of the variable in the stack */
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 */
110 typedef 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 */
120 typedef 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 */
128 typedef 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 */
140 struct BlockCnt;  /* defined in lparser.c */
141 
142 
143 /* state needed to generate code for a given function */
144 typedef 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 
166 LUAI_FUNC int luaY_nvarstack (FuncState *fs);
167 LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
168                                  Dyndata *dyd, const char *name, int firstchar);
169 
170 
171 #endif
172