path: root/vala/valaforeachstatement.vala

/* valaforeachstatement.vala
 *
 * Copyright (C) 2006-2010  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>
 */


/**
 * Represents a foreach statement in the source code.
 *
 * Foreach statements iterate over the elements of a collection.
 */
public class Vala.ForeachStatement : Block {
	/**
	 * Specifies the element type.
	 */
	public DataType? type_reference {
		get { return _data_type; }
		private set {
			_data_type = value;
			if (_data_type != null) {
				_data_type.parent_node = this;
			}
		}
	}

	/**
	 * Specifies the element variable name.
	 */
	public string variable_name { get; private set; }

	/**
	 * Specifies the container.
	 */
	public Expression collection {
		get {
			return _collection;
		}
		private set {
			_collection = value;
			_collection.parent_node = this;
		}
	}

	/**
	 * Specifies the loop body.
	 */
	public Block body {
		get {
			return _body;
		}
		private set {
			_body = value;
			_body.parent_node = this;
		}
	}

	public bool use_iterator { get; private set; }

	/**
	 * Specifies the declarator for the generated element variable.
	 */
	public LocalVariable element_variable { get; private set; }

	/**
	 * Specifies the declarator for the generated collection variable.
	 */
	public LocalVariable collection_variable { get; private set; }

	/**
	 * Specifies the declarator for the generated iterator variable.
	 */
	public LocalVariable iterator_variable { get; private set; }

	private Expression _collection;
	private Block _body;

	private DataType _data_type;

	/**
	 * Creates a new foreach statement.
	 *
	 * @param type_reference    element type
	 * @param variable_name     element variable name
	 * @param collection        container
	 * @param body              loop body
	 * @param source_reference  reference to source code
	 * @return                  newly created foreach statement
	 */
	public ForeachStatement (DataType? type_reference, string variable_name, Expression collection, Block body, SourceReference? source_reference = null) {
		base (source_reference);
		this.variable_name = variable_name;
		this.collection = collection;
		this.body = body;
		this.type_reference = type_reference;
	}

	public override void accept (CodeVisitor visitor) {
		if (use_iterator) {
			base.accept (visitor);
			return;
		}

		visitor.visit_foreach_statement (this);
	}

	public override void accept_children (CodeVisitor visitor) {
		if (use_iterator) {
			base.accept_children (visitor);
			return;
		}

		collection.accept (visitor);
		visitor.visit_end_full_expression (collection);

		if (type_reference != null) {
			type_reference.accept (visitor);
		}

		body.accept (visitor);
	}

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

	public override void replace_type (DataType old_type, DataType new_type) {
		if (type_reference == old_type) {
			type_reference = new_type;
		}
	}

	public override bool check (CodeContext context) {
		if (checked) {
			return !error;
		}

		checked = true;

		if (type_reference == null) {
			type_reference = new VarType ();
		}

		// analyze collection expression first, used for type inference
		if (!collection.check (context)) {
			// ignore inner error
			error = true;
			return false;
		} else if (collection.value_type == null) {
			Report.error (collection.source_reference, "invalid collection expression");
			error = true;
			return false;
		}

		var collection_type = collection.value_type.copy ();
		collection.target_type = collection_type.copy ();

		if (collection_type is ArrayType) {
			var array_type = (ArrayType) collection_type;

			// can't use inline-allocated array for temporary variable
			array_type.inline_allocated = false;

			return check_without_iterator (context, collection_type, array_type.element_type);
		} else if (context.profile == Profile.GOBJECT && (collection_type.compatible (context.analyzer.glist_type) || collection_type.compatible (context.analyzer.gslist_type))) {
			if (collection_type.get_type_arguments ().size != 1) {
				error = true;
				Report.error (collection.source_reference, "missing type argument for collection");
				return false;
			}

			return check_without_iterator (context, collection_type, collection_type.get_type_arguments ().get (0));
		} else if (context.profile == Profile.GOBJECT && collection_type.compatible (context.analyzer.gvaluearray_type)) {
			return check_without_iterator (context, collection_type, context.analyzer.gvalue_type);
		} else {
			return check_with_iterator (context, collection_type);
		}
	}

	bool check_with_index (CodeContext context, DataType collection_type) {
		var get_method = collection_type.get_member ("get") as Method;
		if (get_method == null) {
			return false;
		}
		unowned List<Parameter> parameters = get_method.get_parameters ();
		if (parameters.size != 1 || !(parameters[0].variable_type is IntegerType)) {
			return false;
		}
		var size_property = collection_type.get_member ("size") as Property;
		if (size_property == null) {
			return false;
		}

		var list_type = collection_type.copy ();
		if (collection.symbol_reference is Variable) {
			list_type.value_owned = false;
		}
		add_statement (new DeclarationStatement (new LocalVariable (list_type, "_%s_list".printf (variable_name), collection, source_reference), source_reference));
		add_statement (new DeclarationStatement (new LocalVariable (null, "_%s_size".printf (variable_name), new MemberAccess (new MemberAccess.simple ("_%s_list".printf (variable_name), source_reference), "size", source_reference), source_reference), source_reference));
		add_statement (new DeclarationStatement (new LocalVariable (null, "_%s_index".printf (variable_name), new UnaryExpression (UnaryOperator.MINUS, new IntegerLiteral ("1", source_reference), source_reference), source_reference), source_reference));
		var next = new UnaryExpression (UnaryOperator.INCREMENT, new MemberAccess.simple ("_%s_index".printf (variable_name), source_reference), source_reference);
		var conditional = new BinaryExpression (BinaryOperator.LESS_THAN, next, new MemberAccess.simple ("_%s_size".printf (variable_name), source_reference), source_reference);
		var loop = new WhileStatement (conditional, body, source_reference);
		add_statement (loop);

		var get_call = new MethodCall (new MemberAccess (new MemberAccess.simple ("_%s_list".printf (variable_name), source_reference), "get", source_reference), source_reference);
		get_call.add_argument (new MemberAccess.simple ("_%s_index".printf (variable_name), source_reference));
		body.insert_statement (0, new DeclarationStatement (new LocalVariable (type_reference, variable_name, get_call, source_reference), source_reference));

		checked = false;
		return base.check (context);
	}

	bool check_with_iterator (CodeContext context, DataType collection_type) {
		use_iterator = true;

		if (check_with_index (context, collection_type)) {
			return true;
		}

		var iterator_method = collection_type.get_member ("iterator") as Method;
		if (iterator_method == null) {
			Report.error (collection.source_reference, "`%s' does not have an `iterator' method", collection_type.to_string ());
			error = true;
			return false;
		}
		if (iterator_method.get_parameters ().size != 0) {
			Report.error (collection.source_reference, "`%s' must not have any parameters", iterator_method.get_full_name ());
			error = true;
			return false;
		}
		var iterator_type = iterator_method.return_type.get_actual_type (collection_type, null, this);
		if (iterator_type is VoidType) {
			Report.error (collection.source_reference, "`%s' must return an iterator", iterator_method.get_full_name ());
			error = true;
			return false;
		}

		var iterator_call = new MethodCall (new MemberAccess (collection, "iterator", source_reference), source_reference);
		add_statement (new DeclarationStatement (new LocalVariable (iterator_type, "_%s_it".printf (variable_name), iterator_call, source_reference), source_reference));

		var next_value_method = iterator_type.get_member ("next_value") as Method;
		var next_method = iterator_type.get_member ("next") as Method;
		if (next_value_method != null) {
			if (next_value_method.get_parameters ().size != 0) {
				Report.error (collection.source_reference, "`%s' must not have any parameters", next_value_method.get_full_name ());
				error = true;
				return false;
			}
			var element_type = next_value_method.return_type.get_actual_type (iterator_type, null, this);
			if (!element_type.nullable) {
				Report.error (collection.source_reference, "return type of `%s' must be nullable", next_value_method.get_full_name ());
				error = true;
				return false;
			}

			if (!analyze_element_type (element_type)) {
				return false;
			}

			add_statement (new DeclarationStatement (new LocalVariable (type_reference, variable_name, null, source_reference), source_reference));

			var next_value_call = new MethodCall (new MemberAccess (new MemberAccess.simple ("_%s_it".printf (variable_name), source_reference), "next_value", source_reference), source_reference);
			var assignment = new Assignment (new MemberAccess (null, variable_name, source_reference), next_value_call, AssignmentOperator.SIMPLE, source_reference);
			var conditional = new BinaryExpression (BinaryOperator.INEQUALITY, assignment, new NullLiteral (source_reference), source_reference);
			var loop = new WhileStatement (conditional, body, source_reference);
			add_statement (loop);
		} else if (next_method != null) {
			if (next_method.get_parameters ().size != 0) {
				Report.error (collection.source_reference, "`%s' must not have any parameters", next_method.get_full_name ());
				error = true;
				return false;
			}
			if (!next_method.return_type.compatible (context.analyzer.bool_type)) {
				Report.error (collection.source_reference, "`%s' must return a boolean value", next_method.get_full_name ());
				error = true;
				return false;
			}
			var get_method = iterator_type.get_member ("get") as Method;
			if (get_method == null) {
				Report.error (collection.source_reference, "`%s' does not have a `get' method", iterator_type.to_string ());
				error = true;
				return false;
			}
			if (get_method.get_parameters ().size != 0) {
				Report.error (collection.source_reference, "`%s' must not have any parameters", get_method.get_full_name ());
				error = true;
				return false;
			}
			var element_type = get_method.return_type.get_actual_type (iterator_type, null, this);
			if (element_type is VoidType) {
				Report.error (collection.source_reference, "`%s' must return an element", get_method.get_full_name ());
				error = true;
				return false;
			}

			if (!analyze_element_type (element_type)) {
				return false;
			}

			var next_call = new MethodCall (new MemberAccess (new MemberAccess.simple ("_%s_it".printf (variable_name), source_reference), "next", source_reference), source_reference);
			var loop = new WhileStatement (next_call, body, source_reference);
			add_statement (loop);

			var get_call = new MethodCall (new MemberAccess (new MemberAccess.simple ("_%s_it".printf (variable_name), source_reference), "get", source_reference), source_reference);
			body.insert_statement (0, new DeclarationStatement (new LocalVariable (type_reference, variable_name, get_call, source_reference), source_reference));
		} else {
			Report.error (collection.source_reference, "`%s' does not have a `next_value' or `next' method", iterator_type.to_string ());
			error = true;
			return false;
		}

		checked = false;
		return base.check (context);
	}

	bool analyze_element_type (DataType element_type) {
		// analyze element type
		if (type_reference is VarType) {
			// var type
			type_reference = element_type.copy ();
			// FIXME Only follows "unowned var" otherwise inherit ownership of element-type
			if (!type_reference.value_owned) {
				type_reference.value_owned = false;
			}
		} else if (!element_type.compatible (type_reference)) {
			error = true;
			Report.error (source_reference, "Foreach: Cannot convert from `%s' to `%s'", element_type.to_string (), type_reference.to_string ());
			return false;
		} else if (element_type.is_disposable () && element_type.value_owned && !type_reference.value_owned) {
			error = true;
			Report.error (source_reference, "Foreach: Invalid assignment from owned expression to unowned variable");
			return false;
		}

		return true;
	}

	bool check_without_iterator (CodeContext context, DataType collection_type, DataType element_type) {
		// analyze element type
		if (type_reference is VarType) {
			// var type
			type_reference = element_type.copy ();
			// FIXME Only follows "unowned var" otherwise inherit ownership of element-type
			if (!type_reference.value_owned) {
				type_reference.value_owned = false;
			}
		} else if (!element_type.compatible (type_reference)) {
			error = true;
			Report.error (source_reference, "Foreach: Cannot convert from `%s' to `%s'", element_type.to_string (), type_reference.to_string ());
			return false;
		}

		element_variable = new LocalVariable (type_reference, variable_name, null, source_reference);

		body.scope.add (variable_name, element_variable);

		body.add_local_variable (element_variable);
		element_variable.active = true;
		element_variable.checked = true;

		// analyze body
		var old_symbol = context.analyzer.current_symbol;
		owner = context.analyzer.current_symbol.scope;
		context.analyzer.current_symbol = this;

		// call add_local_variable to check for shadowed variable
		add_local_variable (element_variable);
		remove_local_variable (element_variable);

		body.check (context);

		foreach (LocalVariable local in get_local_variables ()) {
			local.active = false;
		}

		context.analyzer.current_symbol = old_symbol;

		collection_variable = new LocalVariable (collection_type.copy (), "%s_collection".printf (variable_name));

		add_local_variable (collection_variable);
		collection_variable.active = true;

		return !error;
	}

	public override void get_error_types (Collection<DataType> collection, SourceReference? source_reference = null) {
		if (source_reference == null) {
			source_reference = this.source_reference;
		}
		this.collection.get_error_types (collection, source_reference);
		body.get_error_types (collection, source_reference);
	}

	public override void emit (CodeGenerator codegen) {
		if (use_iterator) {
			base.emit (codegen);
			return;
		}

		collection.emit (codegen);
		codegen.visit_end_full_expression (collection);

		element_variable.active = true;
		collection_variable.active = true;
		if (iterator_variable != null) {
			iterator_variable.active = true;
		}

		codegen.visit_foreach_statement (this);
	}

	public override void get_defined_variables (Collection<Variable> collection) {
		if (element_variable != null) {
			collection.add (element_variable);
		}
	}
}