lparser.c

一个2D电磁场FEM计算的VC++源程序

/*
** $Id: lparser.c,v 1.116 2000/10/27 11:39:52 roberto Exp $
** LL(1) Parser and code generator for Lua
** See Copyright Notice in lua.h
*/


#include <stdio.h>
#include <string.h>

#include "lua.h"

#include "lcode.h"
#include "lfunc.h"
#include "llex.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"


/*
** Constructors descriptor:
** `n' indicates number of elements, and `k' signals whether
** it is a list constructor (k = 0) or a record constructor (k = 1)
** or empty (k = ';' or '}')
*/
typedef struct Constdesc {
  int n;
  int k;
} Constdesc;


typedef struct Breaklabel {
  struct Breaklabel *previous;  /* chain */
  int breaklist;
  int stacklevel;
} Breaklabel;




/*
** prototypes for recursive non-terminal functions
*/
static void body (LexState *ls, int needself, int line);
static void chunk (LexState *ls);
static void constructor (LexState *ls);
static void expr (LexState *ls, expdesc *v);
static void exp1 (LexState *ls);



static void next (LexState *ls) {
  ls->lastline = ls->linenumber;
  if (ls->lookahead.token != TK_EOS) {  /* is there a look-ahead token? */
    ls->t = ls->lookahead;  /* use this one */
    ls->lookahead.token = TK_EOS;  /* and discharge it */
  }
  else
    ls->t.token = luaX_lex(ls, &ls->t.seminfo);  /* read next token */
}


static void lookahead (LexState *ls) {
  LUA_ASSERT(ls->lookahead.token == TK_EOS, "two look-aheads");
  ls->lookahead.token = luaX_lex(ls, &ls->lookahead.seminfo);
}


static void error_expected (LexState *ls, int token) {
  char buff[100], t[TOKEN_LEN];
  luaX_token2str(token, t);
  sprintf(buff, "`%.20s' expected", t);
  luaK_error(ls, buff);
}


static void check (LexState *ls, int c) {
  if (ls->t.token != c)
    error_expected(ls, c);
  next(ls);
}


static void check_condition (LexState *ls, int c, const char *msg) {
  if (!c) luaK_error(ls, msg);
}


static int optional (LexState *ls, int c) {
  if (ls->t.token == c) {
    next(ls);
    return 1;
  }
  else return 0;
}


static void check_match (LexState *ls, int what, int who, int where) {
  if (ls->t.token != what) {
    if (where == ls->linenumber)
      error_expected(ls, what);
    else {
      char buff[100];
      char t_what[TOKEN_LEN], t_who[TOKEN_LEN];
      luaX_token2str(what, t_what);
      luaX_token2str(who, t_who);
      sprintf(buff, "`%.20s' expected (to close `%.20s' at line %d)",
              t_what, t_who, where);
      luaK_error(ls, buff);
    }
  }
  next(ls);
}


static int string_constant (FuncState *fs, TString *s) {
  Proto *f = fs->f;
  int c = s->u.s.constindex;
  if (c >= f->nkstr || f->kstr[c] != s) {
    luaM_growvector(fs->L, f->kstr, f->nkstr, 1, TString *,
                    "constant table overflow", MAXARG_U);
    c = f->nkstr++;
    f->kstr[c] = s;
    s->u.s.constindex = c;  /* hint for next time */
  }
  return c;
}


static void code_string (LexState *ls, TString *s) {
  luaK_kstr(ls, string_constant(ls->fs, s));
}


static TString *str_checkname (LexState *ls) {
  TString *ts;
  check_condition(ls, (ls->t.token == TK_NAME), "<name> expected");
  ts = ls->t.seminfo.ts;
  next(ls);
  return ts;
}


static int checkname (LexState *ls) {
  return string_constant(ls->fs, str_checkname(ls));
}


static int luaI_registerlocalvar (LexState *ls, TString *varname) {
  Proto *f = ls->fs->f;
  luaM_growvector(ls->L, f->locvars, f->nlocvars, 1, LocVar, "", MAX_INT);
  f->locvars[f->nlocvars].varname = varname;
  return f->nlocvars++;
}


static void new_localvar (LexState *ls, TString *name, int n) {
  FuncState *fs = ls->fs;
  luaX_checklimit(ls, fs->nactloc+n+1, MAXLOCALS, "local variables");
  fs->actloc[fs->nactloc+n] = luaI_registerlocalvar(ls, name);
}


static void adjustlocalvars (LexState *ls, int nvars) {
  FuncState *fs = ls->fs;
  while (nvars--)
    fs->f->locvars[fs->actloc[fs->nactloc++]].startpc = fs->pc;
}


static void removelocalvars (LexState *ls, int nvars) {
  FuncState *fs = ls->fs;
  while (nvars--)
    fs->f->locvars[fs->actloc[--fs->nactloc]].endpc = fs->pc;
}


static void new_localvarstr (LexState *ls, const char *name, int n) {
  new_localvar(ls, luaS_newfixed(ls->L, name), n);
}


static int search_local (LexState *ls, TString *n, expdesc *var) {
  FuncState *fs;
  int level = 0;
  for (fs=ls->fs; fs; fs=fs->prev) {
    int i;
    for (i=fs->nactloc-1; i >= 0; i--) {
      if (n == fs->f->locvars[fs->actloc[i]].varname) {
        var->k = VLOCAL;
        var->u.index = i;
        return level;
      }
    }
    level++;  /* `var' not found; check outer level */
  }
  var->k = VGLOBAL;  /* not found in any level; must be global */
  return -1;
}


static void singlevar (LexState *ls, TString *n, expdesc *var) {
  int level = search_local(ls, n, var);
  if (level >= 1)  /* neither local (0) nor global (-1)? */
    luaX_syntaxerror(ls, "cannot access a variable in outer scope", n->str);
  else if (level == -1)  /* global? */
    var->u.index = string_constant(ls->fs, n);
}


static int indexupvalue (LexState *ls, expdesc *v) {
  FuncState *fs = ls->fs;
  int i;
  for (i=0; i<fs->nupvalues; i++) {
    if (fs->upvalues[i].k == v->k && fs->upvalues[i].u.index == v->u.index)
      return i;
  }
  /* new one */
  luaX_checklimit(ls, fs->nupvalues+1, MAXUPVALUES, "upvalues");
  fs->upvalues[fs->nupvalues] = *v;
  return fs->nupvalues++;
}


static void pushupvalue (LexState *ls, TString *n) {
  FuncState *fs = ls->fs;
  expdesc v;
  int level = search_local(ls, n, &v);
  if (level == -1) {  /* global? */
    if (fs->prev == NULL)
      luaX_syntaxerror(ls, "cannot access upvalue in main", n->str);
    v.u.index = string_constant(fs->prev, n);
  }
  else if (level != 1)
    luaX_syntaxerror(ls,
         "upvalue must be global or local to immediately outer scope", n->str);
  luaK_code1(fs, OP_PUSHUPVALUE, indexupvalue(ls, &v));
}


static void adjust_mult_assign (LexState *ls, int nvars, int nexps) {
  FuncState *fs = ls->fs;
  int diff = nexps - nvars;
  if (nexps > 0 && luaK_lastisopen(fs)) { /* list ends in a function call */
    diff--;  /* do not count function call itself */
    if (diff <= 0) {  /* more variables than values? */
      luaK_setcallreturns(fs, -diff);  /* function call provide extra values */
      diff = 0;  /* no more difference */
    }
    else  /* more values than variables */
      luaK_setcallreturns(fs, 0);  /* call should provide no value */
  }
  /* push or pop eventual difference between list lengths */
  luaK_adjuststack(fs, diff);
}


static void code_params (LexState *ls, int nparams, int dots) {
  FuncState *fs = ls->fs;
  adjustlocalvars(ls, nparams);
  luaX_checklimit(ls, fs->nactloc, MAXPARAMS, "parameters");
  fs->f->numparams = fs->nactloc;  /* `self' could be there already */
  fs->f->is_vararg = dots;
  if (dots) {
    new_localvarstr(ls, "arg", 0);
    adjustlocalvars(ls, 1);
  }
  luaK_deltastack(fs, fs->nactloc);  /* count parameters in the stack */
}


static void enterbreak (FuncState *fs, Breaklabel *bl) {
  bl->stacklevel = fs->stacklevel;
  bl->breaklist = NO_JUMP;
  bl->previous = fs->bl;
  fs->bl = bl;
}


static void leavebreak (FuncState *fs, Breaklabel *bl) {
  fs->bl = bl->previous;
  LUA_ASSERT(bl->stacklevel == fs->stacklevel, "wrong levels");
  luaK_patchlist(fs, bl->breaklist, luaK_getlabel(fs));
}


static void pushclosure (LexState *ls, FuncState *func) {
  FuncState *fs = ls->fs;
  Proto *f = fs->f;
  int i;
  for (i=0; i<func->nupvalues; i++)
    luaK_tostack(ls, &func->upvalues[i], 1);
  luaM_growvector(ls->L, f->kproto, f->nkproto, 1, Proto *,
                  "constant table overflow", MAXARG_A);
  f->kproto[f->nkproto++] = func->f;
  luaK_code2(fs, OP_CLOSURE, f->nkproto-1, func->nupvalues);
}


static void open_func (LexState *ls, FuncState *fs) {
  Proto *f = luaF_newproto(ls->L);
  fs->prev = ls->fs;  /* linked list of funcstates */
  fs->ls = ls;
  fs->L = ls->L;
  ls->fs = fs;
  fs->stacklevel = 0;
  fs->nactloc = 0;
  fs->nupvalues = 0;
  fs->bl = NULL;
  fs->f = f;
  f->source = ls->source;
  fs->pc = 0;
  fs->lasttarget = 0;
  fs->lastline = 0;
  fs->jlt = NO_JUMP;
  f->code = NULL;
  f->maxstacksize = 0;
  f->numparams = 0;  /* default for main chunk */
  f->is_vararg = 0;  /* default for main chunk */
}


static void close_func (LexState *ls) {
  lua_State *L = ls->L;
  FuncState *fs = ls->fs;
  Proto *f = fs->f;
  luaK_code0(fs, OP_END);
  luaK_getlabel(fs);  /* close eventual list of pending jumps */
  luaM_reallocvector(L, f->code, fs->pc, Instruction);
  luaM_reallocvector(L, f->kstr, f->nkstr, TString *);
  luaM_reallocvector(L, f->knum, f->nknum, Number);
  luaM_reallocvector(L, f->kproto, f->nkproto, Proto *);
  removelocalvars(ls, fs->nactloc);
  luaM_reallocvector(L, f->locvars, f->nlocvars, LocVar);
  luaM_reallocvector(L, f->lineinfo, f->nlineinfo+1, int);
  f->lineinfo[f->nlineinfo++] = MAX_INT;  /* end flag */
  luaF_protook(L, f, fs->pc);  /* proto is ok now */
  ls->fs = fs->prev;
  LUA_ASSERT(fs->bl == NULL, "wrong list end");
}


Proto *luaY_parser (lua_State *L, ZIO *z) {
  struct LexState lexstate;
  struct FuncState funcstate;
  luaX_setinput(L, &lexstate, z, luaS_new(L, zname(z)));
  open_func(&lexstate, &funcstate);
  next(&lexstate);  /* read first token */
  chunk(&lexstate);
  check_condition(&lexstate, (lexstate.t.token == TK_EOS), "<eof> expected");
  close_func(&lexstate);
  LUA_ASSERT(funcstate.prev == NULL, "wrong list end");
  LUA_ASSERT(funcstate.nupvalues == 0, "no upvalues in main");
  return funcstate.f;
}



/*============================================================*/
/* GRAMMAR RULES */
/*============================================================*/


static int explist1 (LexState *ls) {
  /* explist1 -> expr { ',' expr } */
  int n = 1;  /* at least one expression */
  expdesc v;
  expr(ls, &v);
  while (ls->t.token == ',') {
    luaK_tostack(ls, &v, 1);  /* gets only 1 value from previous expression */
    next(ls);  /* skip comma */
    expr(ls, &v);
    n++;
  }
  luaK_tostack(ls, &v, 0);  /* keep open number of values of last expression */
  return n;
}


static void funcargs (LexState *ls, int slf) {
  FuncState *fs = ls->fs;
  int slevel = fs->stacklevel - slf - 1;  /* where is func in the stack */
  switch (ls->t.token) {
    case '(': {  /* funcargs -> '(' [ explist1 ] ')' */
      int line = ls->linenumber;
      int nargs = 0;
      next(ls);
      if (ls->t.token != ')')  /* arg list not empty? */
        nargs = explist1(ls);
      check_match(ls, ')', '(', line);
#ifdef LUA_COMPAT_ARGRET
      if (nargs > 0)  /* arg list is not empty? */
        luaK_setcallreturns(fs, 1);  /* last call returns only 1 value */
#else
      UNUSED(nargs);  /* to avoid warnings */
#endif
      break;
    }
    case '{': {  /* funcargs -> constructor */
      constructor(ls);
      break;
    }
    case TK_STRING: {  /* funcargs -> STRING */
      code_string(ls, ls->t.seminfo.ts);  /* must use `seminfo' before `next' */
      next(ls);
      break;
    }
    default: {
      luaK_error(ls, "function arguments expected");
      break;
    }
  }
  fs->stacklevel = slevel;  /* call will remove function and arguments */
  luaK_code2(fs, OP_CALL, slevel, MULT_RET);
}


static void var_or_func_tail (LexState *ls, expdesc *v) {
  for (;;) {
    switch (ls->t.token) {
      case '.': {  /* var_or_func_tail -> '.' NAME */
        next(ls);
        luaK_tostack(ls, v, 1);  /* `v' must be on stack */
        luaK_kstr(ls, checkname(ls));
        v->k = VINDEXED;
        break;
      }
      case '[': {  /* var_or_func_tail -> '[' exp1 ']' */
        next(ls);
        luaK_tostack(ls, v, 1);  /* `v' must be on stack */
        v->k = VINDEXED;
        exp1(ls);
        check(ls, ']');
        break;
      }
      case ':': {  /* var_or_func_tail -> ':' NAME funcargs */
        int name;
        next(ls);
        name = checkname(ls);
        luaK_tostack(ls, v, 1);  /* `v' must be on stack */
        luaK_code1(ls->fs, OP_PUSHSELF, name);
        funcargs(ls, 1);
        v->k = VEXP;
        v->u.l.t = v->u.l.f = NO_JUMP;
        break;
      }
      case '(': case TK_STRING: case '{': {  /* var_or_func_tail -> funcargs */
        luaK_tostack(ls, v, 1);  /* `v' must be on stack */
        funcargs(ls, 0);
        v->k = VEXP;
        v->u.l.t = v->u.l.f = NO_JUMP;
        break;
      }
      default: return;  /* should be follow... */
    }
  }
}


static void var_or_func (LexState *ls, expdesc *v) {
  /* var_or_func -> ['%'] NAME var_or_func_tail */
  if (optional(ls, '%')) {  /* upvalue? */
    pushupvalue(ls, str_checkname(ls));
    v->k = VEXP;
    v->u.l.t = v->u.l.f = NO_JUMP;
  }
  else  /* variable name */
    singlevar(ls, str_checkname(ls), v);
  var_or_func_tail(ls, v);
}



/*
** {======================================================================
** Rules for Constructors
** =======================================================================
*/


static void recfield (LexState *ls) {
  /* recfield -> (NAME | '['exp1']') = exp1 */
  switch (ls->t.token) {
    case TK_NAME: {
      luaK_kstr(ls, checkname(ls));
      break;
    }
    case '[': {
      next(ls);
      exp1(ls);
      check(ls, ']');
      break;
    }
    default: luaK_error(ls, "<name> or `[' expected");
  }
  check(ls, '=');
  exp1(ls);
}


static int recfields (LexState *ls) {
  /* recfields -> recfield { ',' recfield } [','] */
  FuncState *fs = ls->fs;
  int n = 1;  /* at least one element */
  recfield(ls);
  while (ls->t.token == ',') {
    next(ls);
    if (ls->t.token == ';' || ls->t.token == '}')
      break;
    recfield(ls);
    n++;
    if (n%RFIELDS_PER_FLUSH == 0)
      luaK_code1(fs, OP_SETMAP, RFIELDS_PER_FLUSH);
  }
  luaK_code1(fs, OP_SETMAP, n%RFIELDS_PER_FLUSH);
  return n;
}


static int listfields (LexState *ls) {
  /* listfields -> exp1 { ',' exp1 } [','] */
  FuncState *fs = ls->fs;
  int n = 1;  /* at least one element */
  exp1(ls);
  while (ls->t.token == ',') {
    next(ls);
    if (ls->t.token == ';' || ls->t.token == '}')
      break;
    exp1(ls);
    n++;
    luaX_checklimit(ls, n/LFIELDS_PER_FLUSH, MAXARG_A,
               "`item groups' in a list initializer");
    if (n%LFIELDS_PER_FLUSH == 0)
      luaK_code2(fs, OP_SETLIST, n/LFIELDS_PER_FLUSH - 1, LFIELDS_PER_FLUSH);
  }
  luaK_code2(fs, OP_SETLIST, n/LFIELDS_PER_FLUSH, n%LFIELDS_PER_FLUSH);
  return n;
}



static void constructor_part (LexState *ls, Constdesc *cd) {
  switch (ls->t.token) {
    case ';': case '}': {  /* constructor_part -> empty */
      cd->n = 0;
      cd->k = ls->t.token;
      break;
    }
    case TK_NAME: {  /* may be listfields or recfields */
      lookahead(ls);
      if (ls->lookahead.token != '=')  /* expression? */
        goto case_default;
      /* else go through to recfields */
    }
    case '[': {  /* constructor_part -> recfields */
      cd->n = recfields(ls);
      cd->k = 1;  /* record */
      break;
    }