/** Provides classes for generic types and methods. */

import Declaration

/**
 * A generic declaration. Either an unbound generic (`UnboundGeneric`) or a
 * constructed generic (`ConstructedGeneric`).
 */
abstract class Generic extends Declaration, @dotnet_generic { }

/** An unbound generic. */
abstract class UnboundGeneric extends Generic {
  /** Gets the `i`th type parameter, if any. */
  abstract TypeParameter getTypeParameter(int i);

  /** Gets a type parameter. */
  TypeParameter getATypeParameter() { result = getTypeParameter(_) }

  /**
   * Gets one of the constructed versions of this declaration,
   * which has been bound to a specific set of types.
   */
  ConstructedGeneric getAConstructedGeneric() { result.getUnboundGeneric() = this }

  /** Gets the total number of type parameters. */
  int getNumberOfTypeParameters() { result = count(int i | exists(this.getTypeParameter(i))) }
}

/** A constructed generic. */
abstract class ConstructedGeneric extends Generic {
  /** Gets the `i`th type argument, if any. */
  abstract Type getTypeArgument(int i);

  /** Gets a type argument. */
  Type getATypeArgument() { result = getTypeArgument(_) }

  /**
   * Gets the unbound generic declaration from which this declaration was
   * constructed.
   */
  UnboundGeneric getUnboundGeneric() { none() }

  /** Gets the total number of type arguments. */
  int getNumberOfTypeArguments() { result = count(int i | exists(this.getTypeArgument(i))) }
}

/**
 * INTERNAL: Do not use.
 *
 * Constructs the label suffix for a generic method or type.
 */
string getGenericsLabel(Generic g) {
  result = "`" + g.(UnboundGeneric).getNumberOfTypeParameters()
  or
  result = "<" + typeArgs(g) + ">"
}

pragma[noinline]
private string getTypeArgumentLabel(ConstructedGeneric generic, int p) {
  result = generic.getTypeArgument(p).getLabel()
}

language[monotonicAggregates]
pragma[nomagic]
private string typeArgs(ConstructedGeneric generic) {
  result =
    concat(int p |
      p in [0 .. generic.getNumberOfTypeArguments() - 1]
    |
      getTypeArgumentLabel(generic, p), ","
    )
}