/* valabinaryexpression.vala
 *
 * Copyright (C) 2006-2008  Jürg Billeter
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 *
 * Author:
 * 	Jürg Billeter <j@bitron.ch>
 */

using Gee;

/**
 * Represents an expression with two operands in the source code.
 *
 * Supports +, -, *, /, %, <<, >>, <, >, <=, >=, ==, !=, &, |, ^, &&, ||.
 */
public class Vala.BinaryExpression : Expression {
	/**
	 * The binary operator.
	 */
	public BinaryOperator operator { get; set; }
	
	/**
	 * The left operand.
	 */
	public Expression left {
		get {
			return _left;
		}
		set {
			_left = value;
			_left.parent_node = this;
		}
	}
	
	/**
	 * The right operand.
	 */
	public Expression right {
		get {
			return _right;
		}
		set {
			_right = value;
			_right.parent_node = this;
		}
	}
	
	private Expression _left;
	private Expression _right;
	
	/**
	 * Creates a new binary expression.
	 *
	 * @param op     binary operator
	 * @param left   left operand
	 * @param right  right operand
	 * @param source reference to source code
	 * @return       newly created binary expression
	 */
	public BinaryExpression (BinaryOperator op, Expression _left, Expression _right, SourceReference? source = null) {
		operator = op;
		left = _left;
		right = _right;
		source_reference = source;
	}
	
	public override void accept (CodeVisitor visitor) {
		left.accept (visitor);
		right.accept (visitor);			

		visitor.visit_binary_expression (this);

		visitor.visit_expression (this);
	}

	public override void replace_expression (Expression old_node, Expression new_node) {
		if (left == old_node) {
			left = new_node;
		}
		if (right == old_node) {
			right = new_node;
		}
	}

	private string get_operator_string () {
		switch (_operator) {
		case BinaryOperator.PLUS: return "+";
		case BinaryOperator.MINUS: return "-";
		case BinaryOperator.MUL: return "*";
		case BinaryOperator.DIV: return "/";
		case BinaryOperator.MOD: return "%";
		case BinaryOperator.SHIFT_LEFT: return "<<";
		case BinaryOperator.SHIFT_RIGHT: return ">>";
		case BinaryOperator.LESS_THAN: return "<";
		case BinaryOperator.GREATER_THAN: return ">";
		case BinaryOperator.LESS_THAN_OR_EQUAL: return "<=";
		case BinaryOperator.GREATER_THAN_OR_EQUAL: return ">=";
		case BinaryOperator.EQUALITY: return "==";
		case BinaryOperator.INEQUALITY: return "!+";
		case BinaryOperator.BITWISE_AND: return "&";
		case BinaryOperator.BITWISE_OR: return "|";
		case BinaryOperator.BITWISE_XOR: return "^";
		case BinaryOperator.AND: return "&&";
		case BinaryOperator.OR: return "||";
		case BinaryOperator.IN: return "in";
		}

		assert_not_reached ();
	}

	public override string to_string () {
		return _left.to_string () + get_operator_string () + _right.to_string ();
	}

	public override bool is_constant () {
		return left.is_constant () && right.is_constant ();
	}

	public override bool is_pure () {
		return left.is_pure () && right.is_pure ();
	}

	public override bool is_non_null () {
		return left.is_non_null () && right.is_non_null ();
	}

	public override bool check (SemanticAnalyzer analyzer) {
		if (checked) {
			return !error;
		}

		checked = true;

		if (left.error || right.error) {
			/* if there were any errors in inner expressions, skip type check */
			error = true;
			return false;
		}

		if (left.value_type == null) {
			Report.error (left.source_reference, "invalid left operand");
			error = true;
			return false;
		}

		if (operator != BinaryOperator.IN && right.value_type == null) {
			Report.error (right.source_reference, "invalid right operand");
			error = true;
			return false;
		}

		if (left.value_type.data_type == analyzer.string_type.data_type
		    && operator == BinaryOperator.PLUS) {
			// string concatenation

			if (right.value_type == null || right.value_type.data_type != analyzer.string_type.data_type) {
				error = true;
				Report.error (source_reference, "Operands must be strings");
				return false;
			}

			value_type = analyzer.string_type.copy ();
			if (left.is_constant () && right.is_constant ()) {
				value_type.value_owned = false;
			} else {
				value_type.value_owned = true;
			}
		} else if (operator == BinaryOperator.PLUS
			   || operator == BinaryOperator.MINUS
			   || operator == BinaryOperator.MUL
			   || operator == BinaryOperator.DIV) {
			// check for pointer arithmetic
			if (left.value_type is PointerType) {
				var offset_type = right.value_type.data_type as Struct;
				if (offset_type != null && offset_type.is_integer_type ()) {
					if (operator == BinaryOperator.PLUS
					    || operator == BinaryOperator.MINUS) {
						// pointer arithmetic: pointer +/- offset
						value_type = left.value_type.copy ();
					}
				} else if (right.value_type is PointerType) {
					// pointer arithmetic: pointer - pointer
					value_type = analyzer.size_t_type;
				}
			}

			if (value_type == null) {
				value_type = analyzer.get_arithmetic_result_type (left.value_type, right.value_type);
			}

			if (value_type == null) {
				error = true;
				Report.error (source_reference, "Arithmetic operation not supported for types `%s' and `%s'".printf (left.value_type.to_string (), right.value_type.to_string ()));
				return false;
			}
		} else if (operator == BinaryOperator.MOD
			   || operator == BinaryOperator.SHIFT_LEFT
			   || operator == BinaryOperator.SHIFT_RIGHT
			   || operator == BinaryOperator.BITWISE_XOR) {
			value_type = analyzer.get_arithmetic_result_type (left.value_type, right.value_type);

			if (value_type == null) {
				error = true;
				Report.error (source_reference, "Arithmetic operation not supported for types `%s' and `%s'".printf (left.value_type.to_string (), right.value_type.to_string ()));
				return false;
			}
		} else if (operator == BinaryOperator.LESS_THAN
			   || operator == BinaryOperator.GREATER_THAN
			   || operator == BinaryOperator.LESS_THAN_OR_EQUAL
			   || operator == BinaryOperator.GREATER_THAN_OR_EQUAL) {
			if (left.value_type.compatible (analyzer.string_type)
			    && right.value_type.compatible (analyzer.string_type)) {
				// string comparison
				} else if (left.value_type is PointerType && right.value_type is PointerType) {
					// pointer arithmetic
			} else {
				var resulting_type = analyzer.get_arithmetic_result_type (left.value_type, right.value_type);

				if (resulting_type == null) {
					error = true;
					Report.error (source_reference, "Relational operation not supported for types `%s' and `%s'".printf (left.value_type.to_string (), right.value_type.to_string ()));
					return false;
				}
			}

			value_type = analyzer.bool_type;
		} else if (operator == BinaryOperator.EQUALITY
			   || operator == BinaryOperator.INEQUALITY) {
			/* relational operation */

			if (!right.value_type.compatible (left.value_type)
			    && !left.value_type.compatible (right.value_type)) {
				Report.error (source_reference, "Equality operation: `%s' and `%s' are incompatible".printf (right.value_type.to_string (), left.value_type.to_string ()));
				error = true;
				return false;
			}

			if (left.value_type.compatible (analyzer.string_type)
			    && right.value_type.compatible (analyzer.string_type)) {
				// string comparison
			}

			value_type = analyzer.bool_type;
		} else if (operator == BinaryOperator.BITWISE_AND
			   || operator == BinaryOperator.BITWISE_OR) {
			// integer type or flags type

			value_type = left.value_type;
		} else if (operator == BinaryOperator.AND
			   || operator == BinaryOperator.OR) {
			if (!left.value_type.compatible (analyzer.bool_type) || !right.value_type.compatible (analyzer.bool_type)) {
				error = true;
				Report.error (source_reference, "Operands must be boolean");
			}

			value_type = analyzer.bool_type;
		} else if (operator == BinaryOperator.IN) {
			// integer type or flags type or collection/map

			/* handle collections and maps */
			var container_type = right.value_type.data_type;
			
			if ((analyzer.collection_type != null && container_type.is_subtype_of (analyzer.collection_type))
			    || (analyzer.map_type != null && container_type.is_subtype_of (analyzer.map_type))) {
				Symbol contains_sym = null;
				if (container_type.is_subtype_of (analyzer.collection_type)) {
					contains_sym = analyzer.collection_type.scope.lookup ("contains");
				} else if (container_type.is_subtype_of (analyzer.map_type)) {
					contains_sym = analyzer.map_type.scope.lookup ("contains");
				}
				var contains_method = (Method) contains_sym;
				Gee.List<FormalParameter> contains_params = contains_method.get_parameters ();
				Iterator<FormalParameter> contains_params_it = contains_params.iterator ();
				contains_params_it.next ();
				var contains_param = contains_params_it.get ();

				var key_type = analyzer.get_actual_type (right.value_type, contains_method, contains_param.parameter_type, this);
				left.target_type = key_type;
			}
			
			value_type = analyzer.bool_type;
			
		} else {
			assert_not_reached ();
		}

		return !error;
	}
}

public enum Vala.BinaryOperator {
	NONE,
	PLUS,
	MINUS,
	MUL,
	DIV,
	MOD,
	SHIFT_LEFT,
	SHIFT_RIGHT,
	LESS_THAN,
	GREATER_THAN,
	LESS_THAN_OR_EQUAL,
	GREATER_THAN_OR_EQUAL,
	EQUALITY,
	INEQUALITY,
	BITWISE_AND,
	BITWISE_OR,
	BITWISE_XOR,
	AND,
	OR,
	IN
}