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lparser.h (6106B)


      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 scanner) */
     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 
     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 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 */
     96 typedef 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 */
    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;  /* true for 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   Table *kcache;  /* cache for reusing constants */
    150   int pc;  /* next position to code (equivalent to 'ncode') */
    151   int lasttarget;   /* 'label' of last 'jump label' */
    152   int previousline;  /* last line that was saved in 'lineinfo' */
    153   int nk;  /* number of elements in 'k' */
    154   int np;  /* number of elements in 'p' */
    155   int nabslineinfo;  /* number of elements in 'abslineinfo' */
    156   int firstlocal;  /* index of first local var (in Dyndata array) */
    157   int firstlabel;  /* index of first label (in 'dyd->label->arr') */
    158   short ndebugvars;  /* number of elements in 'f->locvars' */
    159   lu_byte nactvar;  /* number of active local variables */
    160   lu_byte nups;  /* number of upvalues */
    161   lu_byte freereg;  /* first free register */
    162   lu_byte iwthabs;  /* instructions issued since last absolute line info */
    163   lu_byte needclose;  /* function needs to close upvalues when returning */
    164 } FuncState;
    165 
    166 
    167 LUAI_FUNC lu_byte luaY_nvarstack (FuncState *fs);
    168 LUAI_FUNC void luaY_checklimit (FuncState *fs, int v, int l,
    169                                 const char *what);
    170 LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
    171                                  Dyndata *dyd, const char *name, int firstchar);
    172 
    173 
    174 #endif