Prolog engine (include) [1000773]

// assumes translator 747

// variable assignments
static class Ass {
  new Map<S, O> map;
  
  void assign(S var, O value) {
    O v = map.get(var);
    if (v == null)
      map.put(var, value);
    else if (!v.equals(value))
      fail("mismatch");
  }
}

static class Pred {
}

static class Assign extends Pred {
  S var;
  O value;
  
  *(S *var, O *value) {}
}

static class And extends Pred {
  new List<Pred> parts;
  
  *(Pred... parts) {
    this.parts = new ArrayList<Pred>(Arrays.asList(parts));
  }
}

static class Or extends Pred {
  new List<Pred> parts;
  
  *(Pred... parts) {
    this.parts = new ArrayList<Pred>(Arrays.asList(parts));
  }
}

static void eval(Pred p, Ass ass) {
  if (p instanceof Assign) {
    Assign a = cast p;
    ass.assign(a.var, a.value);
  } else if (p instanceof And) {
    And a = cast p;
    for (Pred part : a.parts)
      eval(part, ass);
  } else
    fail(structure(p));
}

static void shouldFail(Pred p) {
  try {
    eval(p, new Ass);
    fail("did not fail");
  } catch (RuntimeException e) {
    print("OK (expected fail): " + structure(p));
  }
}

static <X> List<X> singleton(X x) {
  new List<X> list;
  list.add(x);
  return list;
}

static abstract class Iter {
  abstract Ass next();
}

static class Singleton extends Iter {
  Ass value;
  
  *(Ass *value) {}
  
  Ass next() {
    if (value != null) {
      Ass v = value; value = null; return v;
    }
    return null;
  }
}

static class OrIterator extends Iter {
  Or o;
  int i;
  
  *(Or *o) {}
  
  public Ass next() {
    if (i >= o.parts.size()) return null;
    new Ass ass;
    eval(o.parts.get(i++), ass);
    return ass;
  }
}

static Iter multiEval(Pred p) {
  if (p instanceof Or) {
    Or o = cast p;
    return new OrIterator(o);
  } else {
    new Ass ass;
    eval(p, ass);
    return new Singleton(ass);
  }
}

p {
  new Ass ass;
  eval(new Assign("x", new Integer(1)), ass);
  print(structure(ass));
  
  ass = new Ass;
  eval(new And(
    new Assign("x", new Integer(1)),
    new Assign("y", new Integer(2))), ass);
  print(structure(ass));
  
  shouldFail(new And(
    new Assign("x", new Integer(1)),
    new Assign("x", new Integer(2))));
    
  // test multiEval
  
  L<Ass> list = all(multiEval(new Assign("a", new Integer(5))));
  assertEquals(1, list.size());
  print(structure(list));
  
  list = all(multiEval(new Or(
    new Assign("a", new Integer(5)),
    new Assign("a", new Integer(7)))));
  assertEquals(2, list.size());
  print(structure(list));
}

static L<Ass> all(Iter it) {
  new L<Ass> l;
  while (true) {
    Ass ass = it.next();
    if (ass != null)
      l.add(ass);
    else
      break;
  }
  return l;
}

static void assertEquals(O x, O y) {
  if (!(x == null ? y == null : x.equals(y)))
    fail(structure(x) + " != " + structure(y));
}

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1	// assumes translator 747
2
3	// variable assignments
4	static class Ass {
5	new Map<S, O> map;
6
7	void assign(S var, O value) {
8	O v = map.get(var);
9	if (v == null)
10	map.put(var, value);
11	else if (!v.equals(value))
12	fail("mismatch");
13	}
14	}
15
16	static class Pred {
17	}
18
19	static class Assign extends Pred {
20	S var;
21	O value;
22
23	(S var, O *value) {}
24	}
25
26	static class And extends Pred {
27	new List<Pred> parts;
28
29	*(Pred... parts) {
30	this.parts = new ArrayList<Pred>(Arrays.asList(parts));
31	}
32	}
33
34	static class Or extends Pred {
35	new List<Pred> parts;
36
37	*(Pred... parts) {
38	this.parts = new ArrayList<Pred>(Arrays.asList(parts));
39	}
40	}
41
42	static void eval(Pred p, Ass ass) {
43	if (p instanceof Assign) {
44	Assign a = cast p;
45	ass.assign(a.var, a.value);
46	} else if (p instanceof And) {
47	And a = cast p;
48	for (Pred part : a.parts)
49	eval(part, ass);
50	} else
51	fail(structure(p));
52	}
53
54	static void shouldFail(Pred p) {
55	try {
56	eval(p, new Ass);
57	fail("did not fail");
58	} catch (RuntimeException e) {
59	print("OK (expected fail): " + structure(p));
60	}
61	}
62
63	static <X> List<X> singleton(X x) {
64	new List<X> list;
65	list.add(x);
66	return list;
67	}
68
69	static abstract class Iter {
70	abstract Ass next();
71	}
72
73	static class Singleton extends Iter {
74	Ass value;
75
76	(Ass value) {}
77
78	Ass next() {
79	if (value != null) {
80	Ass v = value; value = null; return v;
81	}
82	return null;
83	}
84	}
85
86	static class OrIterator extends Iter {
87	Or o;
88	int i;
89
90	(Or o) {}
91
92	public Ass next() {
93	if (i >= o.parts.size()) return null;
94	new Ass ass;
95	eval(o.parts.get(i++), ass);
96	return ass;
97	}
98	}
99
100	static Iter multiEval(Pred p) {
101	if (p instanceof Or) {
102	Or o = cast p;
103	return new OrIterator(o);
104	} else {
105	new Ass ass;
106	eval(p, ass);
107	return new Singleton(ass);
108	}
109	}
110
111	p {
112	new Ass ass;
113	eval(new Assign("x", new Integer(1)), ass);
114	print(structure(ass));
115
116	ass = new Ass;
117	eval(new And(
118	new Assign("x", new Integer(1)),
119	new Assign("y", new Integer(2))), ass);
120	print(structure(ass));
121
122	shouldFail(new And(
123	new Assign("x", new Integer(1)),
124	new Assign("x", new Integer(2))));
125
126	// test multiEval
127
128	L<Ass> list = all(multiEval(new Assign("a", new Integer(5))));
129	assertEquals(1, list.size());
130	print(structure(list));
131
132	list = all(multiEval(new Or(
133	new Assign("a", new Integer(5)),
134	new Assign("a", new Integer(7)))));
135	assertEquals(2, list.size());
136	print(structure(list));
137	}
138
139	static L<Ass> all(Iter it) {
140	new L<Ass> l;
141	while (true) {
142	Ass ass = it.next();
143	if (ass != null)
144	l.add(ass);
145	else
146	break;
147	}
148	return l;
149	}
150
151	static void assertEquals(O x, O y) {
152	if (!(x == null ? y == null : x.equals(y)))
153	fail(structure(x) + " != " + structure(y));
154	}

Snippet ID:	#1000773
Snippet name:	Prolog engine (include)
Eternal ID of this version:	#1000773/1
Text MD5:	bf0927083a4a9547006a9177e4a25895
Author:	stefan
Category:
Type:	JavaX fragment (include)
Public (visible to everyone):	Yes
Archived (hidden from active list):	No
Created/modified:	2015-08-26 21:31:42
Source code size:	2947 bytes / 154 lines
Pitched / IR pitched:	No / Yes
Views / Downloads:	622 / 581
Referenced in:	[show references]

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