vala/valadostatement.vala

   1 /* valadostatement.vala
   2  *
   3  * Copyright (C) 2006-2009  Jürg Billeter
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
  18  *
  19  * Author:
  20  *      Jürg Billeter <j@bitron.ch>
  21  */
  22
  23 using GLib;
  24
  25 /**
  26  * Represents a do iteration statement in the source code.
  27  */
  28 public class Vala.DoStatement : CodeNode, Statement {
  29         /**
  30          * Specifies the loop body.
  31          */
  32         public Block body {
  33                 get {
  34                         return _body;
  35                 }
  36                 set {
  37                         _body = value;
  38                         _body.parent_node = this;
  39                 }
  40         }
  41
  42         /**
  43          * Specifies the loop condition.
  44          */
  45         public Expression condition {
  46                 get {
  47                         return _condition;
  48                 }
  49                 set {
  50                         _condition = value;
  51                         _condition.parent_node = this;
  52                 }
  53         }
  54
  55         private Expression _condition;
  56         private Block _body;
  57
  58         /**
  59          * Creates a new do statement.
  60          *
  61          * @param body              loop body
  62          * @param condition         loop condition
  63          * @param source_reference  reference to source code
  64          * @return                  newly created do statement
  65          */
  66         public DoStatement (Block body, Expression condition, SourceReference? source_reference = null) {
  67                 this.condition = condition;
  68                 this.source_reference = source_reference;
  69                 this.body = body;
  70         }
  71
  72         public override void accept (CodeVisitor visitor) {
  73                 visitor.visit_do_statement (this);
  74         }
  75
  76         public override void accept_children (CodeVisitor visitor) {
  77                 body.accept (visitor);
  78
  79                 condition.accept (visitor);
  80
  81                 visitor.visit_end_full_expression (condition);
  82         }
  83
  84         bool always_true (Expression condition) {
  85                 var literal = condition as BooleanLiteral;
  86                 return (literal != null && literal.value);
  87         }
  88
  89         public override bool check (CodeContext context) {
  90                 // convert to simple loop
  91
  92                 // do not generate variable and if block if condition is always true
  93                 if (always_true (condition)) {
  94                         var loop = new Loop (body, source_reference);
  95
  96                         var parent_block = (Block) parent_node;
  97                         parent_block.replace_statement (this, loop);
  98
  99                         return loop.check (context);
 100                 }
 101
 102                 var block = new Block (source_reference);
 103
 104                 var first_local = new LocalVariable (context.analyzer.bool_type.copy (), get_temp_name (), new BooleanLiteral (true, source_reference), source_reference);
 105                 block.add_statement (new DeclarationStatement (first_local, source_reference));
 106
 107                 var if_condition = new UnaryExpression (UnaryOperator.LOGICAL_NEGATION, condition, condition.source_reference);
 108                 var true_block = new Block (condition.source_reference);
 109                 true_block.add_statement (new BreakStatement (condition.source_reference));
 110                 var if_stmt = new IfStatement (if_condition, true_block, null, condition.source_reference);
 111
 112                 var condition_block = new Block (condition.source_reference);
 113                 condition_block.add_statement (if_stmt);
 114
 115                 var first_if = new IfStatement (new UnaryExpression (UnaryOperator.LOGICAL_NEGATION, new MemberAccess.simple (first_local.name, source_reference), source_reference), condition_block, null, source_reference);
 116                 body.insert_statement (0, first_if);
 117                 body.insert_statement (1, new ExpressionStatement (new Assignment (new MemberAccess.simple (first_local.name, source_reference), new BooleanLiteral (false, source_reference), AssignmentOperator.SIMPLE, source_reference), source_reference));
 118
 119                 block.add_statement (new Loop (body, source_reference));
 120
 121                 var parent_block = (Block) parent_node;
 122                 parent_block.replace_statement (this, block);
 123
 124                 return block.check (context);
 125         }
 126 }