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jode/jode/jode/flow/SequentialBlock.java

99 lines
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/* SequentialBlock (c) 1998 Jochen Hoenicke
*
* You may distribute under the terms of the GNU General Public License.
*
* IN NO EVENT SHALL JOCHEN HOENICKE BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
* THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF JOCHEN HOENICKE
* HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* JOCHEN HOENICKE SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
* BASIS, AND JOCHEN HOENICKE HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* $Id$
*/
package jode.flow;
/**
* A sequential block combines exactly two structured blocks to a new
* one. The first sub block mustn't be another sequential block,
* instead the second sub block should be used for this. This
* condition is temporarily violated, while the t1 transformation is
* done.
*/
public class SequentialBlock {
StructuredBlock[] subBlocks;
public SequentialBlock() {
subBlocks = new StructuredBlock[2];
}
public setFirst(StructuredBlock sb) {
subBlocks[0] = sb;
sb.outer = this;
}
public setSecond(StructuredBlock sb) {
subBlocks[1] = sb;
sb.outer = this;
}
/**
* Returns the block where the control will normally flow to, when
* the given sub block is finished (<em>not</em> ignoring the jump
* after this block). (This is overwritten by SequentialBlock and
* SwitchBlock). If this isn't called with a direct sub block,
* the behaviour is undefined, so take care.
* @return null, if the control flows to another FlowBlock. */
StructuredBlock getNextBlock(StructuredBlock subBlock) {
if (subBlock == subBlocks[0])
return subBlocks[1];
return getNextBlock();
}
FlowBlock getNextFlowBlock(StructuredBlock subBlock) {
if (subBlock == subBlocks[0])
return null;
return getNextFlowBlock();
}
/**
* Replaces the given sub block with a new block.
* @param oldBlock the old sub block.
* @param newBlock the new sub block.
* @return false, if oldBlock wasn't a direct sub block.
*/
boolean replaceSubBlock(StructuredBlock oldBlock,
StructuredBlock newBlock) {
for (int i=0; i<2; i++) {
if (subBlocks[i] == oldBlock) {
subBlocks[i] = newBlock;
return true;
}
}
return false;
}
/**
* Returns all sub block of this structured block.
*/
StructuredBlock[] getSubBlocks() {
return subBlocks;
}
/**
* Determines if there is a sub block, that flows through to the end
* of this block. If this returns true, you know that jump is null.
* @return true, if the jump may be safely changed.
*/
public boolean jumpMayBeChanged() {
return (subBlocks[1].jump != null || subBlocks[1].jumpMayBeChanged());
}
}