/lib/otp.net/Otp/Erlang/List.cs

/*``The contents of this file are subject to the Erlang Public License,

* Version 1.1, (the "License"); you may not use this file except in

* compliance with the License. You should have received a copy of the

* Erlang Public License along with this software. If not, it can be

* retrieved via the world wide web at http://www.erlang.org/.

* 

* Software distributed under the License is distributed on an "AS IS"

* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See

* the License for the specific language governing rights and limitations

* under the License.

* 

* The Initial Developer of the Original Code is Ericsson Utvecklings AB.

* Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings

* AB. All Rights Reserved.''

* 

* Converted from Java to C# by Vlad Dumitrescu (vlad_Dumitrescu@hotmail.com)

* Contribution: Serge Aleynikov (added pattern matching)

*/

namespace Otp.Erlang

{

	using System;

	

	/*

	* Provides a C# representation of Erlang lists. Lists are created

	* from zero or more arbitrary Erlang terms.

	*

	* <p> The arity of the list is the number of elements it contains.

	**/

	[Serializable]

    public class List:Erlang.Object

	{

		private Object[] elems = null;

		

		// todo: use a linked structure to make a proper list with append,

		// car, cdr etc methods. The current representation is essensially the

		// same as for tuples except that empty lists are allowed.

		// private Object car = null;

		// private Object cdr = null;

		// int arity;

		

		/*

		* Create an empty list.

		**/

		public List()

		{

			this.elems = null; // empty list

		}

		

		/*

		* Create a list of characters.

		*

		* @param str the characters from which to create the list.

		*

		public List(System.String str)

		{

    		this.elems = new Object[] { new Erlang.String(str) };

		}

		

		* Create a list containing one element.

		*

		* @param elem the elememet to make the list from.

		*

		public List(Object elem)

		{

			this.elems = new Object[1];

			elems[0] = elem;

		}

        */		

        

		/*

        * Create a list from an array of arbitrary Erlang terms.

		*

		* @param elems the array of terms from which to create the list.

		* @param count the number of terms to insert.

		*/

        public List(Object[] elems): this(elems, 0, elems.Length)

        {

        }



		/*

        * Create a list from an array of arbitrary Erlang terms.

		*

		* @param elems the array of terms from which to create the list.

		* @param start the offset of the first term to insert.

		* @param count the number of terms to insert.

		*/

        public List(Object[] elems, int start, int count)

		{

			if ((elems != null) && (count > 0))

			{

				this.elems = new Object[count];

                Array.Copy(elems, 0, this.elems, start, count);

            }

		}



        /*

        * Create a list from an array of arbitrary Erlang terms.

        *

        * @param elems the array of terms from which to create the list.

        **/

        public List(params System.Object[] elems)

        {

            if ((elems != null) && (elems.Length > 0))

            {

                this.elems = new Object[elems.Length];



                for (int i=0; i < elems.Length; i++) 

                {

                    System.Object o = elems[i];

                    if (o is int) this.elems[i] = new Int((int)o);

                    else if (o is string) this.elems[i] = new String((string)o);

                    else if (o is float) this.elems[i] = new Double((float)o);

                    else if (o is double) this.elems[i] = new Double((double)o);

                    else if (o is Erlang.Object) this.elems[i] = (o as Erlang.Object);

                    //else if (o is BigInteger) this.elems[i] = (BigInteger)o;

                    else if (o is uint) this.elems[i] = new UInt((int)o);

                    else if (o is short) this.elems[i] = new Short((short)o);

                    else if (o is ushort) this.elems[i] = new UShort((short)o);

                    else

                        throw new System.ArgumentException("Unknown type of element[" + i + "]: " + o.GetType().ToString());

                }

            }

        }



        /*

        * Create a list from a stream containing an list encoded in Erlang

        * external format.

        *

        * @param buf the stream containing the encoded list.

        * 

        * @exception DecodeException if the buffer does not

        * contain a valid external representation of an Erlang list.

        **/

		public List(OtpInputStream buf)

		{

			this.elems = null;

			

			int arity = buf.read_list_head();

			

			if (arity > 0)

			{

				this.elems = new Object[arity];

				

				 for (int i = 0; i < arity; i++)

				{

					elems[i] = buf.read_any();

				}

				

				/*discard the terminating nil (empty list) */

				buf.read_nil();

			}

		}

		

		/*

		* Get the arity of the list.

		*

		* @return the number of elements contained in the list.

		**/

		public int arity()

		{

			return (elems == null) ? 0 : elems.Length;

		}

		

		/*

		* Get the specified element from the list.

		*

		* @param i the index of the requested element. List elements are

		* numbered as array elements, starting at 0.

		*

		* @return the requested element, of null if i is not a valid

		* element index.

		**/

		public Object elementAt(int i)

		{

			if ((i >= arity()) || (i < 0))

				return null;

			return elems[i];

		}

		

		/*

		* Get all the elements from the list as an array.

		*

		* @return an array containing all of the list's elements. 

		**/

		public Object[] elements()

		{

			if (arity() == 0)

				return null;

			else

			{

				Object[] res = new Object[arity()];

				Array.Copy(this.elems, 0, res, 0, res.Length);

				return res;

			}

		}



        public Object this[int index]

        {

            get { return elementAt(index); }

            set { this.elems[index] = value; }

        }



        public int Length

        {

            get { return this.elems.Length; }

        }



		/*

		* Get the string representation of the list.

		*

		* @return the string representation of the list.

		**/

		public override System.String ToString()

		{

			System.Text.StringBuilder s = new System.Text.StringBuilder();

			int _arity = arity();

			

			s.Append("[");

			

			 for (int i = 0; i < _arity; i++)

			{

				if (i > 0)

					s.Append(",");

				s.Append(elems[i].ToString());

			}

			

			s.Append("]");

			

			return s.ToString();

		}

		

		/*

		* Convert this list to the equivalent Erlang external

		* representation. Note that this method never encodes lists as

		* strings, even when it is possible to do so.

		*

		* @param buf An output stream to which the encoded list should be

		* written.

		*

		**/

		public override void  encode(OtpOutputStream buf)

		{

			int _arity = arity();

			

			if (_arity > 0)

			{

				buf.write_list_head(_arity);

				

				 for (int i = 0; i < _arity; i++)

				{

					buf.write_any(elems[i]);

				}

			}

			

			buf.write_nil();

		}

		

		/*

		* Determine if two lists are equal. Lists are equal if they have

		* the same arity and all of the elements are equal.

		*

		* @param o the list to compare to.

		*

		* @return true if the lists have the same arity and all the

		* elements are equal.

		**/

		public override bool Equals(System.Object o)

		{

			if (!(o is List))

				return false;

			

			List l = (List) o;

			int a = this.arity();

			

			if (a != l.arity())

				return false;

			

			 for (int i = 0; i < a; i++)

			{

				if (!this.elems[i].Equals(l.elems[i]))

					return false;

				// early exit

			}

			

			return true;

		}



		public override int GetHashCode()

		{

			return 1;

		}



		public override System.Object clone()

		{

			List newList = (List) (base.clone());

			newList.elems = new Object[elems.Length];

			elems.CopyTo(newList.elems, 0);

			return newList;

		}

        

        public override bool subst(ref Erlang.Object a_term, VarBind binding)

        {

            System.Collections.Generic.List<Erlang.Object> result =

                new System.Collections.Generic.List<Erlang.Object>();

            bool changed = false;



            foreach (Erlang.Object term in this.elems)

            {

                Erlang.Object obj = null;

                if (term.subst(ref obj, binding))

                    result.Add(obj);

                else

                {

                    changed = true;

                    result.Add(term);

                }

            }



            if (!changed)

                return false;



            a_term = new Erlang.List(result.ToArray());

            return true;

        }



        public override bool match(Erlang.Object pattern, VarBind binding)

        {

            if (pattern is Erlang.Var)

                pattern.match(this, binding);

            else if (!(pattern is Erlang.List))

                return false;

            Erlang.List tup = pattern as Erlang.List;

            if (arity() != tup.arity())

                return false;

            for (int i = 0; i < arity(); ++i)

                if (!elems[i].match(tup[i], binding))

                    return false;

            return true;

        }

    }

}