1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
// -----------------------------------------------------------------------------
//
// Scalax - The Scala Community Library
// Copyright (c) 2005-8 The Scalax Project. All rights reserved.
//
// The primary distribution site is http://scalax.scalaforge.org/
//
// This software is released under the terms of the Revised BSD License.
// There is NO WARRANTY. See the file LICENSE for the full text.
//
// -----------------------------------------------------------------------------
package scala.tools.scalap
package scalax
package rules
/** A Rule is a function from some input to a Result. The result may be:
* <ul>
* <li>Success, with a value of some type and an output that may serve as the input to subsequent rules.</li>
* <li>Failure. A failure may result in some alternative rule being applied.</li>
* <li>Error. No further rules should be attempted.</li>
* </ul>
*
* @author Andrew Foggin
*
* Inspired by the Scala parser combinator.
*/
trait Rule[-In, +Out, +A, +X] extends (In => Result[Out, A, X]) {
val factory : Rules
import factory._
def as(name : String) = ruleWithName(name, this)
def flatMap[Out2, B, X2 >: X](fa2ruleb : A => Out => Result[Out2, B, X2]) = mapResult {
case Success(out, a) => fa2ruleb(a)(out)
case Failure => Failure
case err @ Error(_) => err
}
def map[B](fa2b : A => B) = flatMap { a => out => Success(out, fa2b(a)) }
def filter(f : A => Boolean) = flatMap { a => out => if(f(a)) Success(out, a) else Failure }
def mapResult[Out2, B, Y](f : Result[Out, A, X] => Result[Out2, B, Y]) = rule {
in : In => f(apply(in))
}
def orElse[In2 <: In, Out2 >: Out, A2 >: A, X2 >: X](other : => Rule[In2, Out2, A2, X2]) : Rule[In2, Out2, A2, X2] = new Choice[In2, Out2, A2, X2] {
val factory = Rule.this.factory
lazy val choices = Rule.this :: other :: Nil
}
def orError[In2 <: In] = this orElse error[Any]
def |[In2 <: In, Out2 >: Out, A2 >: A, X2 >: X](other : => Rule[In2, Out2, A2, X2]) = orElse(other)
def ^^[B](fa2b : A => B) = map(fa2b)
def ^^?[B](pf : PartialFunction[A, B]) = filter (pf.isDefinedAt(_)) ^^ pf
def ??(pf : PartialFunction[A, Any]) = filter (pf.isDefinedAt(_))
def -^[B](b : B) = map { any => b }
/** Maps an Error */
def !^[Y](fx2y : X => Y) = mapResult {
case s @ Success(_, _) => s
case Failure => Failure
case Error(x) => Error(fx2y(x))
}
def >>[Out2, B, X2 >: X](fa2ruleb : A => Out => Result[Out2, B, X2]) = flatMap(fa2ruleb)
def >->[Out2, B, X2 >: X](fa2resultb : A => Result[Out2, B, X2]) = flatMap { a => any => fa2resultb(a) }
def >>?[Out2, B, X2 >: X](pf : PartialFunction[A, Rule[Out, Out2, B, X2]]) = filter(pf isDefinedAt _) flatMap pf
def >>&[B, X2 >: X](fa2ruleb : A => Out => Result[Any, B, X2]) = flatMap { a => out => fa2ruleb(a)(out) mapOut { any => out } }
def ~[Out2, B, X2 >: X](next : => Rule[Out, Out2, B, X2]) = for (a <- this; b <- next) yield new ~(a, b)
def ~-[Out2, B, X2 >: X](next : => Rule[Out, Out2, B, X2]) = for (a <- this; b <- next) yield a
def -~[Out2, B, X2 >: X](next : => Rule[Out, Out2, B, X2]) = for (a <- this; b <- next) yield b
def ~++[Out2, B >: A, X2 >: X](next : => Rule[Out, Out2, Seq[B], X2]) = for (a <- this; b <- next) yield a :: b.toList
/** Apply the result of this rule to the function returned by the next rule */
def ~>[Out2, B, X2 >: X](next : => Rule[Out, Out2, A => B, X2]) = for (a <- this; fa2b <- next) yield fa2b(a)
/** Apply the result of this rule to the function returned by the previous rule */
def <~:[InPrev, B, X2 >: X](prev : => Rule[InPrev, In, A => B, X2]) = for (fa2b <- prev; a <- this) yield fa2b(a)
def ~ = for (a <- this; b <- next orError) yield new ~(a, b)
def ~- = for (a <- this; b <- next orError) yield a
def -~ = for (a <- this; b <- next orError) yield b
def -[In2 <: In](exclude : => Rule[In2, Any, Any, Any]) = !exclude -~ this
/** ^~^(f) is equivalent to ^^ { case b1 ~ b2 => f(b1, b2) }
*/
def ^~^[B1, B2, B >: A <% B1 ~ B2, C](f : (B1, B2) => C) = map { a =>
(a : B1 ~ B2) match { case b1 ~ b2 => f(b1, b2) }
}
/** ^~~^(f) is equivalent to ^^ { case b1 ~ b2 ~ b3 => f(b1, b2, b3) }
*/
def ^~~^[B1, B2, B3, B >: A <% B1 ~ B2 ~ B3, C](f : (B1, B2, B3) => C) = map { a =>
(a : B1 ~ B2 ~ B3) match { case b1 ~ b2 ~ b3 => f(b1, b2, b3) }
}
/** ^~~~^(f) is equivalent to ^^ { case b1 ~ b2 ~ b3 ~ b4 => f(b1, b2, b3, b4) }
*/
def ^~~~^[B1, B2, B3, B4, B >: A <% B1 ~ B2 ~ B3 ~ B4, C](f : (B1, B2, B3, B4) => C) = map { a =>
(a : B1 ~ B2 ~ B3 ~ B4) match { case b1 ~ b2 ~ b3 ~ b4 => f(b1, b2, b3, b4) }
}
/** ^~~~~^(f) is equivalent to ^^ { case b1 ~ b2 ~ b3 ~ b4 ~ b5 => f(b1, b2, b3, b4, b5) }
*/
def ^~~~~^[B1, B2, B3, B4, B5, B >: A <% B1 ~ B2 ~ B3 ~ B4 ~ B5, C](f : (B1, B2, B3, B4, B5) => C) = map { a =>
(a : B1 ~ B2 ~ B3 ~ B4 ~ B5) match { case b1 ~ b2 ~ b3 ~ b4 ~ b5 => f(b1, b2, b3, b4, b5) }
}
/** ^~~~~~^(f) is equivalent to ^^ { case b1 ~ b2 ~ b3 ~ b4 ~ b5 ~ b6 => f(b1, b2, b3, b4, b5, b6) }
*/
def ^~~~~~^[B1, B2, B3, B4, B5, B6, B >: A <% B1 ~ B2 ~ B3 ~ B4 ~ B5 ~ B6, C](f : (B1, B2, B3, B4, B5, B6) => C) = map { a =>
(a : B1 ~ B2 ~ B3 ~ B4 ~ B5 ~ B6) match { case b1 ~ b2 ~ b3 ~ b4 ~ b5 ~ b6 => f(b1, b2, b3, b4, b5, b6) }
}
/** ^~~~~~~^(f) is equivalent to ^^ { case b1 ~ b2 ~ b3 ~ b4 ~ b5 ~ b6 => f(b1, b2, b3, b4, b5, b6) }
*/
def ^~~~~~~^[B1, B2, B3, B4, B5, B6, B7, B >: A <% B1 ~ B2 ~ B3 ~ B4 ~ B5 ~ B6 ~ B7, C](f : (B1, B2, B3, B4, B5, B6, B7) => C) = map { a =>
(a : B1 ~ B2 ~ B3 ~ B4 ~ B5 ~ B6 ~ B7) match { case b1 ~ b2 ~ b3 ~ b4 ~ b5 ~ b6 ~b7 => f(b1, b2, b3, b4, b5, b6, b7) }
}
/** >~>(f) is equivalent to >> { case b1 ~ b2 => f(b1, b2) }
*/
def >~>[Out2, B1, B2, B >: A <% B1 ~ B2, C, X2 >: X](f : (B1, B2) => Out => Result[Out2, C, X2]) = flatMap { a =>
(a : B1 ~ B2) match { case b1 ~ b2 => f(b1, b2) }
}
/** ^-^(f) is equivalent to ^^ { b2 => b1 => f(b1, b2) }
*/
def ^-^ [B1, B2 >: A, C](f : (B1, B2) => C) = map { b2 : B2 => b1 : B1 => f(b1, b2) }
/** ^~>~^(f) is equivalent to ^^ { case b2 ~ b3 => b1 => f(b1, b2, b3) }
*/
def ^~>~^ [B1, B2, B3, B >: A <% B2 ~ B3, C](f : (B1, B2, B3) => C) = map { a =>
(a : B2 ~ B3) match { case b2 ~ b3 => b1 : B1 => f(b1, b2, b3) }
}
}
trait Choice[-In, +Out, +A, +X] extends Rule[In, Out, A, X] {
def choices : List[Rule[In, Out, A, X]]
def apply(in : In) = {
def oneOf(list : List[Rule[In, Out, A, X]]) : Result[Out, A, X] = list match {
case Nil => Failure
case first :: rest => first(in) match {
case Failure => oneOf(rest)
case result => result
}
}
oneOf(choices)
}
override def orElse[In2 <: In, Out2 >: Out, A2 >: A, X2 >: X](other : => Rule[In2, Out2, A2, X2]) : Rule[In2, Out2, A2, X2] = new Choice[In2, Out2, A2, X2] {
val factory = Choice.this.factory
lazy val choices = Choice.this.choices ::: other :: Nil
}
}
|
