lemon.c

一个小型的嵌入式数据库

  for(i=0; i<lemp->nstate; i++){
    for(cfp=lemp->sorted[i]->cfp; cfp; cfp=cfp->next){
      cfp->status = INCOMPLETE;
    }
  }
  
  do{
    progress = 0;
    for(i=0; i<lemp->nstate; i++){
      for(cfp=lemp->sorted[i]->cfp; cfp; cfp=cfp->next){
        if( cfp->status==COMPLETE ) continue;
        for(plp=cfp->fplp; plp; plp=plp->next){
          change = SetUnion(plp->cfp->fws,cfp->fws);
          if( change ){
            plp->cfp->status = INCOMPLETE;
            progress = 1;
	  }
	}
        cfp->status = COMPLETE;
      }
    }
  }while( progress );
}

static int resolve_conflict();

/* Compute the reduce actions, and resolve conflicts.
*/
void FindActions(lemp)
struct lemon *lemp;
{
  int i,j;
  struct config *cfp;
  struct state *stp;
  struct symbol *sp;
  struct rule *rp;

  /* Add all of the reduce actions 
  ** A reduce action is added for each element of the followset of
  ** a configuration which has its dot at the extreme right.
  */
  for(i=0; i<lemp->nstate; i++){   /* Loop over all states */
    stp = lemp->sorted[i];
    for(cfp=stp->cfp; cfp; cfp=cfp->next){  /* Loop over all configurations */
      if( cfp->rp->nrhs==cfp->dot ){        /* Is dot at extreme right? */
        for(j=0; j<lemp->nterminal; j++){
          if( SetFind(cfp->fws,j) ){
            /* Add a reduce action to the state "stp" which will reduce by the
            ** rule "cfp->rp" if the lookahead symbol is "lemp->symbols[j]" */
            Action_add(&stp->ap,REDUCE,lemp->symbols[j],(char *)cfp->rp);
          }
	}
      }
    }
  }

  /* Add the accepting token */
  if( lemp->start ){
    sp = Symbol_find(lemp->start);
    if( sp==0 ) sp = lemp->rule->lhs;
  }else{
    sp = lemp->rule->lhs;
  }
  /* Add to the first state (which is always the starting state of the
  ** finite state machine) an action to ACCEPT if the lookahead is the
  ** start nonterminal.  */
  Action_add(&lemp->sorted[0]->ap,ACCEPT,sp,0);

  /* Resolve conflicts */
  for(i=0; i<lemp->nstate; i++){
    struct action *ap, *nap;
    struct state *stp;
    stp = lemp->sorted[i];
    assert( stp->ap );
    stp->ap = Action_sort(stp->ap);
    for(ap=stp->ap; ap && ap->next; ap=ap->next){
      for(nap=ap->next; nap && nap->sp==ap->sp; nap=nap->next){
         /* The two actions "ap" and "nap" have the same lookahead.
         ** Figure out which one should be used */
         lemp->nconflict += resolve_conflict(ap,nap,lemp->errsym);
      }
    }
  }

  /* Report an error for each rule that can never be reduced. */
  for(rp=lemp->rule; rp; rp=rp->next) rp->canReduce = B_FALSE;
  for(i=0; i<lemp->nstate; i++){
    struct action *ap;
    for(ap=lemp->sorted[i]->ap; ap; ap=ap->next){
      if( ap->type==REDUCE ) ap->x.rp->canReduce = B_TRUE;
    }
  }
  for(rp=lemp->rule; rp; rp=rp->next){
    if( rp->canReduce ) continue;
    ErrorMsg(lemp->filename,rp->ruleline,"This rule can not be reduced.\n");
    lemp->errorcnt++;
  }
}

/* Resolve a conflict between the two given actions.  If the
** conflict can't be resolve, return non-zero.
**
** NO LONGER TRUE:
**   To resolve a conflict, first look to see if either action
**   is on an error rule.  In that case, take the action which
**   is not associated with the error rule.  If neither or both
**   actions are associated with an error rule, then try to
**   use precedence to resolve the conflict.
**
** If either action is a SHIFT, then it must be apx.  This
** function won't work if apx->type==REDUCE and apy->type==SHIFT.
*/
static int resolve_conflict(apx,apy,errsym)
struct action *apx;
struct action *apy;
struct symbol *errsym;   /* The error symbol (if defined.  NULL otherwise) */
{
  struct symbol *spx, *spy;
  int errcnt = 0;
  assert( apx->sp==apy->sp );  /* Otherwise there would be no conflict */
  if( apx->type==SHIFT && apy->type==REDUCE ){
    spx = apx->sp;
    spy = apy->x.rp->precsym;
    if( spy==0 || spx->prec<0 || spy->prec<0 ){
      /* Not enough precedence information. */
      apy->type = CONFLICT;
      errcnt++;
    }else if( spx->prec>spy->prec ){    /* Lower precedence wins */
      apy->type = RD_RESOLVED;
    }else if( spx->prec<spy->prec ){
      apx->type = SH_RESOLVED;
    }else if( spx->prec==spy->prec && spx->assoc==RIGHT ){ /* Use operator */
      apy->type = RD_RESOLVED;                             /* associativity */
    }else if( spx->prec==spy->prec && spx->assoc==LEFT ){  /* to break tie */
      apx->type = SH_RESOLVED;
    }else{
      assert( spx->prec==spy->prec && spx->assoc==NONE );
      apy->type = CONFLICT;
      errcnt++;
    }
  }else if( apx->type==REDUCE && apy->type==REDUCE ){
    spx = apx->x.rp->precsym;
    spy = apy->x.rp->precsym;
    if( spx==0 || spy==0 || spx->prec<0 ||
    spy->prec<0 || spx->prec==spy->prec ){
      apy->type = CONFLICT;
      errcnt++;
    }else if( spx->prec>spy->prec ){
      apy->type = RD_RESOLVED;
    }else if( spx->prec<spy->prec ){
      apx->type = RD_RESOLVED;
    }
  }else{
    assert( 
      apx->type==SH_RESOLVED ||
      apx->type==RD_RESOLVED ||
      apx->type==CONFLICT ||
      apy->type==SH_RESOLVED ||
      apy->type==RD_RESOLVED ||
      apy->type==CONFLICT
    );
    /* The REDUCE/SHIFT case cannot happen because SHIFTs come before
    ** REDUCEs on the list.  If we reach this point it must be because
    ** the parser conflict had already been resolved. */
  }
  return errcnt;
}
/********************* From the file "configlist.c" *************************/
/*
** Routines to processing a configuration list and building a state
** in the LEMON parser generator.
*/

static struct config *freelist = 0;      /* List of free configurations */
static struct config *current = 0;       /* Top of list of configurations */
static struct config **currentend = 0;   /* Last on list of configs */
static struct config *basis = 0;         /* Top of list of basis configs */
static struct config **basisend = 0;     /* End of list of basis configs */

/* Return a pointer to a new configuration */
PRIVATE struct config *newconfig(){
  struct config *new;
  if( freelist==0 ){
    int i;
    int amt = 3;
    freelist = (struct config *)malloc( sizeof(struct config)*amt );
    if( freelist==0 ){
      fprintf(stderr,"Unable to allocate memory for a new configuration.");
      exit(1);
    }
    for(i=0; i<amt-1; i++) freelist[i].next = &freelist[i+1];
    freelist[amt-1].next = 0;
  }
  new = freelist;
  freelist = freelist->next;
  return new;
}

/* The configuration "old" is no longer used */
PRIVATE void deleteconfig(old)
struct config *old;
{
  old->next = freelist;
  freelist = old;
}

/* Initialized the configuration list builder */
void Configlist_init(){
  current = 0;
  currentend = &current;
  basis = 0;
  basisend = &basis;
  Configtable_init();
  return;
}

/* Initialized the configuration list builder */
void Configlist_reset(){
  current = 0;
  currentend = &current;
  basis = 0;
  basisend = &basis;
  Configtable_clear(0);
  return;
}

/* Add another configuration to the configuration list */
struct config *Configlist_add(rp,dot)
struct rule *rp;    /* The rule */
int dot;            /* Index into the RHS of the rule where the dot goes */
{
  struct config *cfp, model;

  assert( currentend!=0 );
  model.rp = rp;
  model.dot = dot;
  cfp = Configtable_find(&model);
  if( cfp==0 ){
    cfp = newconfig();
    cfp->rp = rp;
    cfp->dot = dot;
    cfp->fws = SetNew();
    cfp->stp = 0;
    cfp->fplp = cfp->bplp = 0;
    cfp->next = 0;
    cfp->bp = 0;
    *currentend = cfp;
    currentend = &cfp->next;
    Configtable_insert(cfp);
  }
  return cfp;
}

/* Add a basis configuration to the configuration list */
struct config *Configlist_addbasis(rp,dot)
struct rule *rp;
int dot;
{
  struct config *cfp, model;

  assert( basisend!=0 );
  assert( currentend!=0 );
  model.rp = rp;
  model.dot = dot;
  cfp = Configtable_find(&model);
  if( cfp==0 ){
    cfp = newconfig();
    cfp->rp = rp;
    cfp->dot = dot;
    cfp->fws = SetNew();
    cfp->stp = 0;
    cfp->fplp = cfp->bplp = 0;
    cfp->next = 0;
    cfp->bp = 0;
    *currentend = cfp;
    currentend = &cfp->next;
    *basisend = cfp;
    basisend = &cfp->bp;
    Configtable_insert(cfp);
  }
  return cfp;
}

/* Compute the closure of the configuration list */
void Configlist_closure(lemp)
struct lemon *lemp;
{
  struct config *cfp, *newcfp;
  struct rule *rp, *newrp;
  struct symbol *sp, *xsp;
  int i, dot;

  assert( currentend!=0 );
  for(cfp=current; cfp; cfp=cfp->next){
    rp = cfp->rp;
    dot = cfp->dot;
    if( dot>=rp->nrhs ) continue;
    sp = rp->rhs[dot];
    if( sp->type==NONTERMINAL ){
      if( sp->rule==0 && sp!=lemp->errsym ){
        ErrorMsg(lemp->filename,rp->line,"Nonterminal \"%s\" has no rules.",
          sp->name);
        lemp->errorcnt++;
      }
      for(newrp=sp->rule; newrp; newrp=newrp->nextlhs){
        newcfp = Configlist_add(newrp,0);
        for(i=dot+1; i<rp->nrhs; i++){
          xsp = rp->rhs[i];
          if( xsp->type==TERMINAL ){
            SetAdd(newcfp->fws,xsp->index);
            break;
	  }else{
            SetUnion(newcfp->fws,xsp->firstset);
            if( xsp->lambda==B_FALSE ) break;
	  }
	}
        if( i==rp->nrhs ) Plink_add(&cfp->fplp,newcfp);
      }
    }
  }
  return;
}

/* Sort the configuration list */
void Configlist_sort(){
  current = (struct config *)msort((char *)current,(char **)&(current->next),Configcmp);
  currentend = 0;
  return;
}

/* Sort the basis configuration list */
void Configlist_sortbasis(){
  basis = (struct config *)msort((char *)current,(char **)&(current->bp),Configcmp);
  basisend = 0;
  return;
}

/* Return a pointer to the head of the configuration list and
** reset the list */
struct config *Configlist_return(){
  struct config *old;
  old = current;
  current = 0;
  currentend = 0;
  return old;
}

/* Return a pointer to the head of the configuration list and
** reset the list */
struct config *Configlist_basis(){
  struct config *old;
  old = basis;
  basis = 0;
  basisend = 0;
  return old;
}

/* Free all elements of the given configuration list */
void Configlist_eat(cfp)
struct config *cfp;
{
  struct config *nextcfp;
  for(; cfp; cfp=nextcfp){
    nextcfp = cfp->next;
    assert( cfp->fplp==0 );
    assert( cfp->bplp==0 );
    if( cfp->fws ) SetFree(cfp->fws);
    deleteconfig(cfp);
  }
  return;
}
/***************** From the file "error.c" *********************************/
/*
** Code for printing error message.
*/

/* Find a good place to break "msg" so that its length is at least "min"
** but no more than "max".  Make the point as close to max as possible.
*/
static int findbreak(msg,min,max)
char *msg;
int min;
int max;
{
  int i,spot;
  char c;
  for(i=spot=min; i<=max; i++){
    c = msg[i];
    if( c=='\t' ) msg[i] = ' ';
    if( c=='\n' ){ msg[i] = ' '; spot = i; break; }
    if( c==0 ){ spot = i; break; }
    if( c=='-' && i<max-1 ) spot = i+1;
    if( c==' ' ) spot = i;
  }
  return spot;
}

/*
** The error message is split across multiple lines if necessary.  The
** splits occur at a space, if there is a space available near the end
** of the line.
*/
#define ERRMSGSIZE  10000 /* Hope this is big enough.  No way to error check */
#define LINEWIDTH      79 /* Max width of any output line */
#define PREFIXLIMIT    30 /* Max width of the prefix on each line */
void ErrorMsg(const char *filename, int lineno, const char *format, ...){
  char errmsg[ERRMSGSIZE];
  char prefix[PREFIXLIMIT+10];
  int errmsgsize;
  int prefixsize;
  int availablewidth;
  va_list ap;
  int end, restart, base;

  va_start(ap, format);
  /* Prepare a prefix to be prepended to every output line */
  if( lineno>0 ){
    sprintf(prefix,"%.*s:%d: ",PREFIXLIMIT-10,filename,lineno);
  }else{
    sprintf(prefix,"%.*s: ",PREFIXLIMIT-10,filename);
  }
  prefixsize = strlen(prefix);
  availablewidth = LINEWIDTH - prefixsize;

  /* Generate the error message */
  vsprintf(errmsg,format,ap);
  va_end(ap);