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139 lines
4.2 KiB
139 lines
4.2 KiB
/* IfThenElseBlock (c) 1998 Jochen Hoenicke
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*
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* You may distribute under the terms of the GNU General Public License.
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*
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* IN NO EVENT SHALL JOCHEN HOENICKE BE LIABLE TO ANY PARTY FOR DIRECT,
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* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
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* THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF JOCHEN HOENICKE
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* HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* JOCHEN HOENICKE SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
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* BASIS, AND JOCHEN HOENICKE HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
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* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* $Id$
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*/
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package jode.flow;
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/**
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* An IfThenElseBlock is the structured block representing an if
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* instruction. The else part may be null.
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*/
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public class IfThenElseBlock extends StructuredBlock {
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/**
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* The condition. Must be of boolean type.
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*/
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Instruction cond;
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/**
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* The then part. This is always a valid block and not null
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*/
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StructuredBlock thenBlock;
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/**
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* The else part, may be null, and mustn't be the then part.
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*/
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StructuredBlock elseBlock;
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/**
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* Creates a new if then else block. The method setThenBlock must
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* be called shortly after the creation.
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*/
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public IfThenElseBlock(Instruction cond) {
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this.cond = cond;
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}
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/**
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* Sets the then block.
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* @param thenBlock the then block, must be non null.
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*/
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public void setThenBlock(StructuredBlock thenBlock) {
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this.thenBlock = thenBlock;
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thenBlock.outer = this;
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}
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/**
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* Sets the else block.
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* @param elseBlock the else block
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*/
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public void setElseBlock(StructuredBlock elseBlock) {
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this.elseBlock = elseBlock;
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elseBlock.outer = this;
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}
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/* The implementation of getNext[Flow]Block is the standard
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* implementation */
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/**
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* Replaces the given sub block with a new block.
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* @param oldBlock the old sub block.
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* @param newBlock the new sub block.
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* @return false, if oldBlock wasn't a direct sub block.
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*/
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boolean replaceSubBlock(StructuredBlock oldBlock,
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StructuredBlock newBlock) {
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if (thenBlock == oldBlock)
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thenBlock = newBlock;
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else if (elseBlock == oldBlock)
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elseBlock = newBlock;
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else
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return false;
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return true;
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}
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/**
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* Print the source code for this structured block. This may be
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* called only once, because it remembers which local variables
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* were declared.
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*/
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public void dumpSource(TabbedPrintWriter writer)
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throws java.io.IOException
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{
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boolean needBrace = ! (thenBlock instanceof InstructionBlock);
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writer.println("if ("+cond.toString()+")"+needBrace?" {":"");
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writer.tab();
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thenBlock.dumpSource(writer);
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writer.untab();
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if (elseBlock != null) {
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writer.print(needBrace?"} ":"");
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needBrace = ! (thenBlock instanceof InstructionBlock);
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writer.println("else"+needBrace?" {":"");
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writer.tab();
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elseBlock.dumpSource(writer);
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writer.untab();
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}
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if (needBrace)
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writer.println("}");
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}
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/**
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* Returns all sub block of this structured block.
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*/
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StructuredBlock[] getSubBlocks() {
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if (elseBlock == null) {
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StructuredBlock result = { thenBlock };
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return result;
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} else {
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StructuredBlock result = { thenBlock, elseBlock };
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return result;
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}
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}
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/**
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* Determines if there is a sub block, that flows through to the end
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* of this block. If this returns true, you know that jump is null.
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* @return true, if the jump may be safely changed.
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*/
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public boolean jumpMayBeChanged() {
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if (thenBlock.jump == null && !thenBlock.jumpMayBeChanged())
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return false;
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if (elseBlock != null && elseBlock.jump == null &&
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!elseBlock.jumpMayBeChanged)
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return false;
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return true;
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}
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}
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