77 lines
3.9 KiB
Scala
77 lines
3.9 KiB
Scala
package xyz.hyperreal.rosettacodeCompiler
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import scala.collection.mutable
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import scala.io.Source
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object ASTInterpreter {
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def fromStdin = fromSource(Source.stdin)
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def fromString(src: String) = fromSource(Source.fromString(src))
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def fromSource(s: Source) = {
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val lines = s.getLines
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def load: Node =
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if (!lines.hasNext)
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TerminalNode
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else
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lines.next.split(" +", 2) match {
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case Array(name, value) => LeafNode(name, value)
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case Array(";") => TerminalNode
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case Array(name) => BranchNode(name, load, load)
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}
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val vars = new mutable.HashMap[String, Any]
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def interpInt(n: Node) = interp(n).asInstanceOf[Int]
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def interpBoolean(n: Node) = interp(n).asInstanceOf[Boolean]
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def interp(n: Node): Any =
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n match {
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case TerminalNode => null
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case LeafNode("Identifier", name) =>
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vars get name match {
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case None =>
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vars(name) = 0
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0
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case Some(v) => v
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}
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case LeafNode("Integer", "'\\n'") => '\n'.toInt
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case LeafNode("Integer", "'\\\\'") => '\\'.toInt
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case LeafNode("Integer", value: String) if value startsWith "'" => value(1).toInt
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case LeafNode("Integer", value: String) => value.toInt
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case LeafNode("String", value: String) => unescape(value.substring(1, value.length - 1))
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case BranchNode("Assign", LeafNode(_, name), exp) => vars(name) = interp(exp)
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case BranchNode("Sequence", l, r) => interp(l); interp(r)
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case BranchNode("Prts" | "Prti", a, _) => print(interp(a))
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case BranchNode("Prtc", a, _) => print(interpInt(a).toChar)
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case BranchNode("Add", l, r) => interpInt(l) + interpInt(r)
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case BranchNode("Subtract", l, r) => interpInt(l) - interpInt(r)
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case BranchNode("Multiply", l, r) => interpInt(l) * interpInt(r)
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case BranchNode("Divide", l, r) => interpInt(l) / interpInt(r)
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case BranchNode("Mod", l, r) => interpInt(l) % interpInt(r)
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case BranchNode("Negate", a, _) => -interpInt(a)
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case BranchNode("Less", l, r) => interpInt(l) < interpInt(r)
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case BranchNode("LessEqual", l, r) => interpInt(l) <= interpInt(r)
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case BranchNode("Greater", l, r) => interpInt(l) > interpInt(r)
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case BranchNode("GreaterEqual", l, r) => interpInt(l) >= interpInt(r)
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case BranchNode("Equal", l, r) => interpInt(l) == interpInt(r)
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case BranchNode("NotEqual", l, r) => interpInt(l) != interpInt(r)
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case BranchNode("And", l, r) => interpBoolean(l) && interpBoolean(r)
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case BranchNode("Or", l, r) => interpBoolean(l) || interpBoolean(r)
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case BranchNode("Not", a, _) => !interpBoolean(a)
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case BranchNode("While", l, r) => while (interpBoolean(l)) interp(r)
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case BranchNode("If", cond, BranchNode("If", yes, no)) => if (interpBoolean(cond)) interp(yes) else interp(no)
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}
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interp(load)
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}
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abstract class Node
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case class BranchNode(name: String, left: Node, right: Node) extends Node
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case class LeafNode(name: String, value: String) extends Node
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case object TerminalNode extends Node
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}
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