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30 day Evaluation Version distributed via the Maven Jar Repository. Clover is not free. You have 30 days to evaluate it. Please visit http://www.thecortex.net/clover to obtain a licensed version of Clover | |||||||||||||||||||
Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
ExpressionStack.java | 0% | 0% | 0% | 0% |
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/*
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$Id: ExpressionStack.java,v 1.3 2004/04/30 09:57:46 cpoirier Exp $
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Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
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Redistribution and use of this software and associated documentation
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("Software"), with or without modification, are permitted provided
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that the following conditions are met:
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1. Redistributions of source code must retain copyright
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statements and notices. Redistributions must also contain a
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copy of this document.
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2. Redistributions in binary form must reproduce the
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above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other
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materials provided with the distribution.
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3. The name "groovy" must not be used to endorse or promote
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products derived from this Software without prior written
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permission of The Codehaus. For written permission,
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please contact info@codehaus.org.
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4. Products derived from this Software may not be called "groovy"
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nor may "groovy" appear in their names without prior written
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permission of The Codehaus. "groovy" is a registered
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trademark of The Codehaus.
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5. Due credit should be given to The Codehaus -
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http://groovy.codehaus.org/
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THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
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NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.codehaus.groovy.syntax.parser;
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import java.util.ArrayList;
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import org.codehaus.groovy.control.CompilationFailedException;
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import org.codehaus.groovy.syntax.*;
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import org.codehaus.groovy.GroovyBugError;
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/**
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* A combination stack and helper class for parsing groovy expression.
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* <p>
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* Expressions are a little trickier to parse than the statements above.
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* As a result, we are now doing a hybrid LL/LR parse at the expression
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* level.
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*
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* @author <a href="mailto:cpoirier@dreaming.org">Chris Poirier</a>
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*/
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public class ExpressionStack |
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{ |
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private ArrayList stack = new ArrayList(); |
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private Parser parser = null; |
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private int open = 0; |
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ExpressionStack( Parser context ) |
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{ |
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this.parser = context;
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} |
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//---------------------------------------------------------------------------
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// PRIMARY OPERATIONS
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/**
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* Returns true if the stack is empty.
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*/
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boolean isEmpty()
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{ |
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return stack.isEmpty();
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} |
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/**
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* Returns true if the stack is in a state that can be considered
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* a complete expression, provided lookahead is amenable, of course.
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*/
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public boolean isComplete() |
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{ |
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return size() == 1 && topIsAnExpression();
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} |
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/**
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* Returns true if the stack can be completed without further shifts.
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* Used by Parser.la(ExpressionStack) to determine when ambiguous tokens
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* can't be read across a newline. The algorithm will guess true if it
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* isn't sure. If it returns false, you can rely on that analysis.
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*/
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public boolean canComplete() |
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{ |
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//
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// We can immediately return false if there is anything
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// open or if the top is not an expression...
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if( open > 0 || !topIsAnExpression() )
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{ |
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return false; |
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} |
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//
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// If it is complete, it can complete...
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if( size() == 1 )
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{ |
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return true; |
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} |
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//
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// For everything else, we guess true. It is most likely
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// the case, because of the way the parser moves complex
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// stuff off to LL routines and validates the ordering of
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// nodes pushed on the stack, that if the top is an expression,
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// and nothing is "open" (ie. unmatched parenthesis, early
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// stage ternary operators), the stack can be reduced back
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// to the root without further shifts. Our guarantee is
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// that our guess true might be wrong, but that we will only
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// return false when we are sure, so, no harm done...
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return true; |
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} |
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/**
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* Returns the number of elements in the stack.
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*/
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int size()
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{ |
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return stack.size();
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} |
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/**
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* Pushes a node onto the stack.
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*/
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void push( CSTNode node )
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{ |
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if( (node.isA(Types.LEFT_PARENTHESIS) || node.isA(Types.QUESTION)) && node.size() == 1 )
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{ |
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open++; |
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} |
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stack.add( node ); |
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} |
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/**
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* Pops the node from the top of the stack.
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*/
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CSTNode pop() |
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{ |
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CSTNode node = (CSTNode)stack.remove( stack.size() - 1 ); |
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if( (node.isA(Types.LEFT_PARENTHESIS) || node.isA(Types.QUESTION)) && node.size() == 1 )
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{ |
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open--; |
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} |
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return node;
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} |
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/**
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* Returns the top node from the stack without removing it.
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*/
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CSTNode top() |
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{ |
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return top(0);
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} |
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/**
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* Returns some node from the stack. <code>offset</code> is counted
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* from the top of the stack.
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*/
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CSTNode top( int offset )
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{ |
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if( offset < stack.size() )
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{ |
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return (CSTNode)stack.get( stack.size() - 1 - offset );
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} |
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else
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{ |
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return Token.NULL;
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} |
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} |
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//---------------------------------------------------------------------------
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// PARSER OPERATIONS
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/**
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* Shifts some number of (non-newline) tokens from the stream to the top
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* of the stack. They are pushed in order.
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*/
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void shift( int count ) throws SyntaxException, CompilationFailedException |
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{ |
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for( int i = 0; i < count; i++ ) |
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{ |
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push( parser.consume() ); |
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} |
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} |
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/**
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* Shifts a token from the stream to the top of the stack.
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*/
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void shift() throws SyntaxException, CompilationFailedException |
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{ |
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push( parser.consume() ); |
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} |
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/**
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* Performs a reduce by taking some number of <code>CSTNode</code>s
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* from the top of the stack, and making one of them a
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* <code>Reduction</code> with the others as children, then pushes
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* that new node back onto the stack.
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*/
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void reduce( int count, int rootOffset, boolean mark ) |
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{ |
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if( count <= rootOffset || rootOffset < 0 || count > size() )
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{ |
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269 | 0 |
throw new GroovyBugError( "error in call to ExpressionStack.reduce(): count=" + count + ", rootOffset=" + rootOffset ); |
270 |
} |
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CSTNode root = null;
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CSTNode[] children = new CSTNode[count-1];
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275 | 0 |
for( int child = count - 2, element = 0; element < count; element++ ) |
276 |
{ |
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277 | 0 |
if( element == rootOffset )
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{ |
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279 | 0 |
root = pop(); |
280 |
} |
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else
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{ |
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283 | 0 |
children[child--] = pop(); |
284 |
} |
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} |
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287 | 0 |
root = root.asReduction(); |
288 | 0 |
for( int i = 0; i < children.length; i++ ) |
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{ |
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290 | 0 |
root.add( children[i] ); |
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} |
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293 | 0 |
if( mark )
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{ |
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295 | 0 |
root.markAsExpression(); |
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} |
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298 | 0 |
push( root ); |
299 |
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} |
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//---------------------------------------------------------------------------
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// TESTS
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/**
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* Return true if the stack is at the start of an expression. True if
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* either the stack is empty or the top token is a left parenthesis.
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*/
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314 | 0 |
boolean atStartOfExpression()
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{ |
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316 | 0 |
return isEmpty() || (top().isA(Types.LEFT_PARENTHESIS) && !top().hasChildren());
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} |
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/**
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* Returns true if the top element of the stack is an operator.
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*/
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325 | 0 |
boolean topIsAnOperator( )
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{ |
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327 | 0 |
return ExpressionSupport.isAnOperator( top(), false ); |
328 |
} |
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/**
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* Returns true if the element at the specified offset from the top
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* of the stack is an operator.
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*/
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336 |
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337 | 0 |
boolean topIsAnOperator( int offset, boolean unknownReturns ) |
338 |
{ |
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339 | 0 |
return ExpressionSupport.isAnOperator( top(offset), unknownReturns );
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} |
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/**
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* Returns true if the top element of the stack is a modifiable expression.
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*/
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348 | 0 |
boolean topIsAModifiableExpression()
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{ |
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350 | 0 |
return ExpressionSupport.isAModifiableExpression( top() );
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} |
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353 |
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354 |
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/**
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* Returns true if the top element of the stack is an expression.
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*/
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358 |
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359 | 0 |
boolean topIsAnExpression( )
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{ |
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361 | 0 |
return top().isAnExpression();
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} |
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364 |
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//---------------------------------------------------------------------------
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// SUGAR
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368 |
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369 |
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370 |
/**
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371 |
* Shifts if the specified flag is true, reports an error otherwise.
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*/
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373 |
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374 | 0 |
void shiftIf( boolean flag, String error ) throws SyntaxException, CompilationFailedException |
375 |
{ |
|
376 | 0 |
if( flag )
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377 |
{ |
|
378 | 0 |
push( parser.consume() ); |
379 |
} |
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380 |
else
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381 |
{ |
|
382 | 0 |
parser.error( error ); |
383 |
} |
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384 |
} |
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385 |
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386 |
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387 |
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388 |
/**
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389 |
* Shifts unless the specified flag is true, reports an error otherwise.
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390 |
*/
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391 |
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392 | 0 |
void shiftUnless( boolean flag, String error ) throws SyntaxException, CompilationFailedException |
393 |
{ |
|
394 | 0 |
if( flag )
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395 |
{ |
|
396 | 0 |
parser.error( error ); |
397 |
} |
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else
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399 |
{ |
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400 | 0 |
push( parser.consume() ); |
401 |
} |
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} |
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403 |
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404 |
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405 |
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406 |
/**
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407 |
* Shifts if the top of the stack is an expression, reports an error
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* otherwise.
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409 |
*/
|
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410 |
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411 | 0 |
void shiftIfTopIsAnExpression( String error ) throws SyntaxException, CompilationFailedException |
412 |
{ |
|
413 | 0 |
shiftIf( ExpressionSupport.isAnExpression(top(), false), error );
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414 |
} |
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415 |
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416 |
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417 |
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418 |
/**
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419 |
* Shifts if the top of the stack is a operator, reports an
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420 |
* error otherwise.
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*/
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422 |
|
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423 | 0 |
void shiftIfTopIsAnOperator( String error ) throws SyntaxException, CompilationFailedException |
424 |
{ |
|
425 | 0 |
shiftIf( ExpressionSupport.isAnOperator(top(), false), error );
|
426 |
} |
|
427 |
|
|
428 |
|
|
429 |
|
|
430 |
/**
|
|
431 |
* Shifts unless the top of the stack is an expression, reports an
|
|
432 |
* error otherwise.
|
|
433 |
*/
|
|
434 |
|
|
435 | 0 |
void shiftUnlessTopIsAnExpression( String error ) throws SyntaxException, CompilationFailedException |
436 |
{ |
|
437 | 0 |
shiftUnless( ExpressionSupport.isAnExpression(top(), false), error );
|
438 |
} |
|
439 |
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|
440 |
|
|
441 |
|
|
442 |
/**
|
|
443 |
* Shifts unless the top of the stack is an operator, reports an
|
|
444 |
* error otherwise.
|
|
445 |
*/
|
|
446 |
|
|
447 | 0 |
void shiftUnlessTopIsAnOperator( String error ) throws SyntaxException, CompilationFailedException |
448 |
{ |
|
449 | 0 |
shiftUnless( ExpressionSupport.isAnOperator(top(), false), error );
|
450 |
} |
|
451 |
|
|
452 |
|
|
453 |
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|
454 |
|
|
455 |
//---------------------------------------------------------------------------
|
|
456 |
// OUTPUT
|
|
457 |
|
|
458 |
|
|
459 |
/**
|
|
460 |
* Creates a string representation of the stack.
|
|
461 |
*/
|
|
462 |
|
|
463 | 0 |
public String toString( )
|
464 |
{ |
|
465 | 0 |
StringBuffer buffer = new StringBuffer();
|
466 | 0 |
String newline = System.getProperty( "line.separator", "\n" ); |
467 | 0 |
int count = stack.size();
|
468 |
|
|
469 | 0 |
buffer.append( "ExpressionStack with " ).append( size() ).append( " elements" ).append( newline ); |
470 | 0 |
for( int i = count - 1; i >= 0; i-- ) |
471 |
{ |
|
472 | 0 |
buffer.append( top(i).toString() ).append( newline ); |
473 |
} |
|
474 |
|
|
475 | 0 |
return buffer.toString();
|
476 |
} |
|
477 |
|
|
478 |
} |
|
479 |
|
|