LocationProc


1   // Copyright (c) 2005  Per M.A. Bothner.
2   // This is free software;  for terms and warranty disclaimer see ./COPYING.
3   
4   package gnu.mapping;
5   
6   /** A Procedure that evaluates to the value of a Location.
7    * Calling it with one argument sets the value, for compatibility
8    * with the "parameter objects" of SRFI-39.
9    */
10  public class LocationProc extends Procedure0or1 implements HasSetter
11  {
12    Location loc;
13  
14    public LocationProc (Location loc)
15    {
16      this.loc = loc;
17    }
18  
19    public static LocationProc makeNamed (Symbol name, Location loc)
20    {
21      LocationProc lproc = new LocationProc(loc);
22      lproc.setSymbol(name);
23      return lproc;
24    }
25  
26    public LocationProc (Location loc, Procedure converter)
27    {
28      this.loc = loc;
29      if (converter != null)
30        pushConverter(converter);
31    }
32  
33    public void pushConverter (Procedure converter)
34    {
35      loc = ConstrainedLocation.make(loc, converter);
36    }
37  
38    public Object   apply0 () throws Throwable  
39    {
40      return loc.get();
41    }
42  
43    public Object   apply1 (Object   value) throws Throwable  
44    {
45      set0(value);
46      return Values.empty;
47    }
48  
49    public void set0 (Object   value) throws Throwable  
50    {
51      loc.set(value);
52    }
53  
54    public Procedure getSetter()
55    {
56      return new Setter0(this);
57    }
58  
59    public final Location getLocation ()
60    {
61      return loc;
62    }
63  
64    public String   toString ()
65    {
66      Object   n = getSymbol();
67      if (n != null)
68        return super.toString();
69      return "#<location-proc "+loc+">";
70    }
71  }
72
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