root/trunk/ProjectFortress/src/com/sun/fortress/scala_src/typechecker/KindEnv.scala @ 3905

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package com.sun.fortress.scala_src.typechecker

import com.sun.fortress.compiler.Types
import com.sun.fortress.nodes._
import scala.collection.immutable.EmptyMap

/**
 * Represents a list of variable name to static parameter bindings for some
 * context. All instances of this class should be created with `KindEnv.make`
 * or with the `extendWith` method.
 */
abstract sealed class KindEnv extends StaticEnv[StaticParam] {
  
  /** My type. */
  type Env = KindEnv
  
  /** My binding type. */
  type EnvBinding = KindBinding

  /** Extend me with the immediate bindings of the given node. */
  def extendWith(node: Any): KindEnv =
    new NestedKindEnv(this, KindEnv.extractEnvBindings(node))

  /**
   * Get the type of the given variable name, if it is bound. The resulting
   * type will only be defined if this name maps to a bool, int, or nat static
   * parameter.
   */
  def getType(x: Name): Option[Type] = lookup(x).flatMap(b =>
    b.value.getKind match {
      case _:KindBool => Some(Types.BOOLEAN)
      case _:KindInt => Some(Types.INT_LITERAL)
      case _:KindNat => Some(Types.INT_LITERAL)
      case _ => None
    })
}

/** The single empty kind environment. */
object EmptyKindEnv extends KindEnv with EmptyStaticEnv[StaticParam]

/**
 * A kind environment with a parent and some explicit bindings.
 * 
 * @param parent A kind environment that this one extends.
 * @param _bindings A collection of all the bindings in this environment.
 */
class NestedKindEnv protected (protected val parent: KindEnv,
                               _bindings: Collection[KindBinding])
    extends KindEnv with NestedStaticEnv[StaticParam] {
    
  /** Internal representation of `bindings` is a map. */
  protected val bindings: Map[Name, KindBinding] =
    new EmptyMap ++ _bindings.map(b => b.name -> b)
}

/** Companion module for KindEnv; contains "static" members. */
object KindEnv extends StaticEnvCompanion[StaticParam] {
  
  /** My type. */
  type Env = KindEnv
  
  /** My binding type. */
  type EnvBinding = KindBinding
  
  /** New kind environment with empty parent and the node's bindings. */
  def make(node: Any): KindEnv =
    new NestedKindEnv(EmptyKindEnv, extractEnvBindings(node))
  
  /** Extract out the bindings in node. */
  protected def extractEnvBindings(node: Any) : Collection[KindBinding] = null
}

/**
 * A binding for a kind environment contains name to static parameter pairs.
 * 
 * @param name The variable name for the binding.
 * @param sparam The static parameter that this name is binding.
 */
case class KindBinding(override val name: Name,
                       sparam: StaticParam)
    extends StaticBinding[StaticParam](name, sparam)