lparser.h

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/*
** $Id: lparser.h,v 1.76.1.1 2017/04/19 17:20:42 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/

#ifndef lparser_h
#define lparser_h

#include "llimits.h"
#include "lobject.h"
#include "lzio.h"


/*
** Expression and variable descriptor.
** Code generation for variables and expressions can be delayed to allow
** optimizations; An 'expdesc' structure describes a potentially-delayed
** variable/expression. It has a description of its "main" value plus a
** list of conditional jumps that can also produce its value (generated
** by short-circuit operators 'and'/'or').
*/

/* kinds of variables/expressions */
typedef enum {
 VVOID, /* when 'expdesc' describes the last expression a list,
 this kind means an empty list (so, no expression) */
 VNIL, /* constant nil */
 VTRUE, /* constant true */
 VFALSE, /* constant false */
 VK, /* constant in 'k'; info = index of constant in 'k' */
 VKFLT, /* floating constant; nval = numerical float value */
 VKINT, /* integer constant; nval = numerical integer value */
 VNONRELOC, /* expression has its value in a fixed register;
 info = result register */
 VLOCAL, /* local variable; info = local register */
 VUPVAL, /* upvalue variable; info = index of upvalue in 'upvalues' */
 VINDEXED, /* indexed variable;
 ind.vt = whether 't' is register or upvalue;
 ind.t = table register or upvalue;
 ind.idx = key's R/K index */
 VJMP, /* expression is a test/comparison;
 info = pc of corresponding jump instruction */
 VRELOCABLE, /* expression can put result in any register;
 info = instruction pc */
 VCALL, /* expression is a function call; info = instruction pc */
 VVARARG /* vararg expression; info = instruction pc */
} expkind;


#define vkisvar(k) (VLOCAL <= (k) && (k) <= VINDEXED)
#define vkisinreg(k) ((k) == VNONRELOC || (k) == VLOCAL)

typedef struct expdesc {
 expkind k;
 union {
 lua_Integer ival; /* for VKINT */
 lua_Number nval; /* for VKFLT */
 int info; /* for generic use */
 struct { /* for indexed variables (VINDEXED) */
 short idx; /* index (R/K) */
 lu_byte t; /* table (register or upvalue) */
 lu_byte vt; /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */
 } ind;
 } u;
 int t; /* patch list of 'exit when true' */
 int f; /* patch list of 'exit when false' */
} expdesc;


/* description of active local variable */
typedef struct Vardesc {
 short idx; /* variable index in stack */
} Vardesc;


/* description of pending goto statements and label statements */
typedef struct Labeldesc {
 TString *name; /* label identifier */
 int pc; /* position in code */
 int line; /* line where it appeared */
 lu_byte nactvar; /* local level where it appears in current block */
} Labeldesc;


/* list of labels or gotos */
typedef struct Labellist {
 Labeldesc *arr; /* array */
 int n; /* number of entries in use */
 int size; /* array size */
} Labellist;


/* dynamic structures used by the parser */
typedef struct Dyndata {
 struct { /* list of active local variables */
 Vardesc *arr;
 int n;
 int size;
 } actvar;
 Labellist gt; /* list of pending gotos */
 Labellist label; /* list of active labels */
} Dyndata;


/* control of blocks */
struct BlockCnt; /* defined in lparser.c */


/* state needed to generate code for a given function */
typedef struct FuncState {
 Proto *f; /* current function header */
 struct FuncState *prev; /* enclosing function */
 struct LexState *ls; /* lexical state */
 struct BlockCnt *bl; /* chain of current blocks */
 int pc; /* next position to code (equivalent to 'ncode') */
 int lasttarget; /* 'label' of last 'jump label' */
 int jpc; /* list of pending jumps to 'pc' */
 int nk; /* number of elements in 'k' */
 int np; /* number of elements in 'p' */
 int firstlocal; /* index of first local var (in Dyndata array) */
 short nlocvars; /* number of elements in 'f->locvars' */
 lu_byte nactvar; /* number of active local variables */
 lu_byte nups; /* number of upvalues */
 lu_byte freereg; /* first free register */
} FuncState;


LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
 Dyndata *dyd, const char *name, int firstchar);


#endif