mudgangster

Tiny, scriptable MUD client
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lparser.h (4381B)

      1 /*
      2 ** $Id: lparser.h,v 1.76.1.1 2017/04/19 17:20:42 roberto Exp $
      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; nval = numerical integer value */
     34   VNONRELOC,  /* expression has its value in a fixed register;
     35                  info = result register */
     36   VLOCAL,  /* local variable; info = local register */
     37   VUPVAL,  /* upvalue variable; info = index of upvalue in 'upvalues' */
     38   VINDEXED,  /* indexed variable;
     39                 ind.vt = whether 't' is register or upvalue;
     40                 ind.t = table register or upvalue;
     41                 ind.idx = key's R/K index */
     42   VJMP,  /* expression is a test/comparison;
     43             info = pc of corresponding jump instruction */
     44   VRELOCABLE,  /* expression can put result in any register;
     45                   info = instruction pc */
     46   VCALL,  /* expression is a function call; info = instruction pc */
     47   VVARARG  /* vararg expression; info = instruction pc */
     48 } expkind;
     49 
     50 
     51 #define vkisvar(k)	(VLOCAL <= (k) && (k) <= VINDEXED)
     52 #define vkisinreg(k)	((k) == VNONRELOC || (k) == VLOCAL)
     53 
     54 typedef struct expdesc {
     55   expkind k;
     56   union {
     57     lua_Integer ival;    /* for VKINT */
     58     lua_Number nval;  /* for VKFLT */
     59     int info;  /* for generic use */
     60     struct {  /* for indexed variables (VINDEXED) */
     61       short idx;  /* index (R/K) */
     62       lu_byte t;  /* table (register or upvalue) */
     63       lu_byte vt;  /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */
     64     } ind;
     65   } u;
     66   int t;  /* patch list of 'exit when true' */
     67   int f;  /* patch list of 'exit when false' */
     68 } expdesc;
     69 
     70 
     71 /* description of active local variable */
     72 typedef struct Vardesc {
     73   short idx;  /* variable index in stack */
     74 } Vardesc;
     75 
     76 
     77 /* description of pending goto statements and label statements */
     78 typedef struct Labeldesc {
     79   TString *name;  /* label identifier */
     80   int pc;  /* position in code */
     81   int line;  /* line where it appeared */
     82   lu_byte nactvar;  /* local level where it appears in current block */
     83 } Labeldesc;
     84 
     85 
     86 /* list of labels or gotos */
     87 typedef struct Labellist {
     88   Labeldesc *arr;  /* array */
     89   int n;  /* number of entries in use */
     90   int size;  /* array size */
     91 } Labellist;
     92 
     93 
     94 /* dynamic structures used by the parser */
     95 typedef struct Dyndata {
     96   struct {  /* list of active local variables */
     97     Vardesc *arr;
     98     int n;
     99     int size;
    100   } actvar;
    101   Labellist gt;  /* list of pending gotos */
    102   Labellist label;   /* list of active labels */
    103 } Dyndata;
    104 
    105 
    106 /* control of blocks */
    107 struct BlockCnt;  /* defined in lparser.c */
    108 
    109 
    110 /* state needed to generate code for a given function */
    111 typedef struct FuncState {
    112   Proto *f;  /* current function header */
    113   struct FuncState *prev;  /* enclosing function */
    114   struct LexState *ls;  /* lexical state */
    115   struct BlockCnt *bl;  /* chain of current blocks */
    116   int pc;  /* next position to code (equivalent to 'ncode') */
    117   int lasttarget;   /* 'label' of last 'jump label' */
    118   int jpc;  /* list of pending jumps to 'pc' */
    119   int nk;  /* number of elements in 'k' */
    120   int np;  /* number of elements in 'p' */
    121   int firstlocal;  /* index of first local var (in Dyndata array) */
    122   short nlocvars;  /* number of elements in 'f->locvars' */
    123   lu_byte nactvar;  /* number of active local variables */
    124   lu_byte nups;  /* number of upvalues */
    125   lu_byte freereg;  /* first free register */
    126 } FuncState;
    127 
    128 
    129 LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
    130                                  Dyndata *dyd, const char *name, int firstchar);
    131 
    132 
    133 #endif