Free Hero Mesh

      switch(tokenv) {
        case OP_ADD: case OP_CLIMB: case OP_HEIGHT:
        case OP_LOC: case OP_MARK: case OP_SUB:
        case OP_QUEEN: case OP_ROOK: case OP_BISHOP:
        case OP_DIR: case OP_DIR_C: case OP_DIR_E: case OP_DIR_EC:
        case OP_OBJTOPAT: case OP_OBJBOTTOMAT: case OP_CUT: case OP_MUL:
        case OP_OBJABOVE: case OP_OBJBELOW: case OP_TRACE: case OP_NEXT:
        case OP_IMAGE: case OP_IMAGE_C: case OP_DIV: case OP_DIV_C:
        case 0x0200 ... 0x02FF: // message
        case 0x4000 ... 0x7FFF: // class
        case 0xC000 ... 0xFFFF: // message
          cl->codes[ptr++]=tokenv;
          break;
        case OP_BEGIN: case OP_IF:
          if(depth==31) ParseError("Too much pattern nesting\n");

-
  Push zero to the stack.

*
  Update the current choice point with the location and direction.

/
  Succeeds only if the pattern prior to this command succeeds but the
  pattern after this command (which still has the same state as the
  prior pattern) fails. This should not be used inside of loops and
  should not be used in a (P*) or (,P*) or (=P*) block. If this command
  occurs more than once, then the most recent / that is successfully
  matched determines the return value if the final match fails.

,/
  Undoes the effect of the / command.

_
  Push a mark to the stack.

again
  End a block with begin or if, allowing it to occur more than once; it
  is repeated until it no longer matches. If the first word is begin,
  then it must match at least once; if it is if, then it can match zero

} ChoicePoint;

#define MAXCHOICE 80
static Uint32 v_pattern(Uint16*code,int ptr,Uint32 obj,char all) {
  Uint8 x=objects[obj]->x;
  Uint8 y=objects[obj]->y;
  Uint8 d=objects[obj]->dir;
  Uint32 un=VOIDLINK;
  Uint32 n=VOIDLINK;
  Uint32 m;
  Uint16 g;
  Value v;
  ChoicePoint cp[MAXCHOICE];
  Uint8 cpi=0;
  Uint16 ccl=objects[obj]->class;

      objects[obj]->dir=d;
      break;
    case OP_DIR_EC:
      if(n==VOIDLINK) Throw("No object specified in pattern");
      changed=1;
      objects[n]->dir=d;
      break;
    case OP_DIV:
      un=(n==VOIDLINK?obj_bottom_at(x,y):n);
      if(un==VOIDLINK) un=obj;
      break;
    case OP_DIV_C:
      un=VOIDLINK;
      break;
    case OP_ELSE:
      ptr--;
      while(code[ptr]==OP_ELSE) ptr=code[ptr+2];
      break;
    case OP_FUNCTION:
      StackReq(0,2);
      Push(OVALUE(n));

      break;
    case OP_RET:
      if(all) {
        if(vstackptr>=VSTACKSIZE-1) Throw("Stack overflow");
        if(n==VOIDLINK) n=obj_bottom_at(x,y);
        Push(OVALUE(n));
        goto fail;
      } else if(un==VOIDLINK) {
        return n==VOIDLINK?obj_bottom_at(x,y):n;
      } else {
        return VOIDLINK;
      }
      break;
    case OP_ROOK:
      if(cpi>=MAXCHOICE-4) Throw("Choice overflow");
      d=0;
      cpi+=3;
      cp[cpi].x=x;

  }
  goto again;
  fail:
  if(!all) {
    if(vstackptr<cp->depth) Throw("Stack underflow in pattern matching");
    vstackptr=cp[cpi].depth;
  }
  if(!cpi) return un;
  x=cp[cpi].x;
  y=cp[cpi].y;
  d=cp[cpi].dir;
  ptr=cp[cpi].ptr;
  n=VOIDLINK;
  cpi--;
  goto again;