Compiler/AST interpreter: Difference between revisions
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=={{header|Scala}}== |
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The complete implementation for the compiler tasks can be found in a GitHub repository at [https://github.com/edadma/rosettacodeCompiler github.com/edadma/rosettacodeCompiler] which includes full unit testing for the samples given in [[Compiler/Sample programs]]. |
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The following code implements as AST interpreter for the output of the [http://rosettacode.org/wiki/Compiler/syntax_analyzer#Scala parser] |
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<lang scala> |
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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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</lang> |
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=={{header|Scheme}}== |
=={{header|Scheme}}== |
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