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author | Adriaan Moors <adriaan.moors@epfl.ch> | 2007-07-18 21:55:59 +0000 |
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committer | Adriaan Moors <adriaan.moors@epfl.ch> | 2007-07-18 21:55:59 +0000 |
commit | 7c574439453b88d328d975845c2e55499b56bf14 (patch) | |
tree | 21a743a0c1b77fb64cb54df2d193f60b95bc3696 /docs/examples/parsing/lambda/TestSyntax.scala | |
parent | bf32e7d4a87b2e0ae000d1fac27ab42a6c57222d (diff) | |
download | scala-7c574439453b88d328d975845c2e55499b56bf14.tar.gz scala-7c574439453b88d328d975845c2e55499b56bf14.tar.bz2 scala-7c574439453b88d328d975845c2e55499b56bf14.zip |
added another example using the combinator pars...
added another example using the combinator parsers, courtesy of Miles
Sabin (slightly simplified/adapted to new combinators)
Diffstat (limited to 'docs/examples/parsing/lambda/TestSyntax.scala')
-rwxr-xr-x | docs/examples/parsing/lambda/TestSyntax.scala | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/docs/examples/parsing/lambda/TestSyntax.scala b/docs/examples/parsing/lambda/TestSyntax.scala new file mode 100755 index 0000000000..531ae4bd54 --- /dev/null +++ b/docs/examples/parsing/lambda/TestSyntax.scala @@ -0,0 +1,86 @@ +package examples.parsing.lambda + +/** + * Parser for an untyped lambda calculus: abstract syntax tree + * + * @author Miles Sabin (adapted slightly by Adriaan Moors) + */ +trait TestSyntax +{ + trait Term + + case class Unit extends Term + { + override def toString = "unit" + } + + case class Lit(n: int) extends Term + { + override def toString = n.toString + } + + case class Bool(b: boolean) extends Term + { + override def toString = b.toString + } + + case class Name(name: String) extends Term + { + override def toString = name + } + + case class Ref(n: Name) extends Term + { + def value = n + } + + case class Lam(n: Name, l: Term) extends Term + { + override def toString = "(\\ "+n+" -> "+l+")" + } + + case class App(t1: Term, t2: Term) extends Term + { + override def toString = "("+t1+" "+t2+")" + } + + case class Let(n: Name, t1: Term, t2: Term) extends Term + { + override def toString = "let "+n+" = "+t1+" in "+t2 + } + + case class If(c: Term, t1: Term, t2: Term) extends Term + { + override def toString = "if "+c+" then "+t1+" else "+t2 + } + + trait PrimTerm extends Term + { + def apply(n: Lit) : Term + } + + case class PrimPlus extends PrimTerm + { + def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n+y.n) } + } + + case class PrimMinus extends PrimTerm + { + def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n-y.n) } + } + + case class PrimMultiply extends PrimTerm + { + def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n*y.n) } + } + + case class PrimDivide extends PrimTerm + { + def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n/y.n) } + } + + case class PrimEquals extends PrimTerm + { + def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Bool(x.n == y.n) } + } +} |