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/* valawhilestatement.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>
*/
using GLib;
/**
* Represents a while iteration statement in the source code.
*/
public class Vala.WhileStatement : CodeNode, Statement {
/**
* Specifies the loop condition.
*/
public Expression condition {
get {
return _condition;
}
set {
_condition = value;
_condition.parent_node = this;
}
}
/**
* Specifies the loop body.
*/
public Block body {
get {
return _body;
}
set {
_body = value;
_body.parent_node = this;
}
}
private Expression _condition;
private Block _body;
/**
* Creates a new while statement.
*
* @param condition loop condition
* @param body loop body
* @param source_reference reference to source code
* @return newly created while statement
*/
public WhileStatement (Expression condition, Block body, SourceReference? source_reference = null) {
this.body = body;
this.source_reference = source_reference;
this.condition = condition;
}
public override void accept (CodeVisitor visitor) {
visitor.visit_while_statement (this);
}
public override void accept_children (CodeVisitor visitor) {
condition.accept (visitor);
visitor.visit_end_full_expression (condition);
body.accept (visitor);
}
bool always_true (Expression condition) {
var literal = condition as BooleanLiteral;
return (literal != null && literal.value);
}
bool always_false (Expression condition) {
var literal = condition as BooleanLiteral;
return (literal != null && !literal.value);
}
public override void replace_expression (Expression old_node, Expression new_node) {
if (condition == old_node) {
condition = new_node;
}
}
public override bool check (CodeContext context) {
if (checked) {
return !error;
}
checked = true;
// convert to simple loop
if (always_true (condition)) {
// do not generate if block if condition is always true
} else if (always_false (condition)) {
// do not generate if block if condition is always false
body.insert_statement (0, new BreakStatement (condition.source_reference));
} else {
var if_condition = new UnaryExpression (UnaryOperator.LOGICAL_NEGATION, condition, condition.source_reference);
var true_block = new Block (condition.source_reference);
true_block.add_statement (new BreakStatement (condition.source_reference));
var if_stmt = new IfStatement (if_condition, true_block, null, condition.source_reference);
body.insert_statement (0, if_stmt);
}
var loop = new Loop (body, source_reference);
var parent_block = (Block) parent_node;
parent_block.replace_statement (this, loop);
if (!loop.check (context)) {
error = true;
}
return !error;
}
}
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