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package com.sun.jdo.spi.persistence.support.sqlstore.query.jqlc;
import java.util.*;
import persistence.antlr.ANTLRException;
import persistence.antlr.collections.AST;
import com.sun.enterprise.deployment.interfaces.QueryParser;
import com.sun.jdo.api.persistence.support.JDOFatalInternalException;
import com.sun.jdo.spi.persistence.utility.I18NHelper;
/** Helper class to support parsing of JDOQL parameter declarations.
*
* Created on October 16, 2002
* @author Michael Bouschen
*/
public class JDOQLParameterDeclarationParser
implements QueryParser
{
/**
* I18N support
*/
protected final static ResourceBundle messages = I18NHelper.loadBundle(
JDOQLParameterDeclarationParser.class);
/**
* Returns an iterator over the parameter types of the specified JDOQL
* parameter declartion. The types are represented by their name, thus
* the Iterator's next method returns Strings.
* @param text the JDOQL parameter declaration
* @return an iterator over parameter types
* @exception JDOQueryException indicates a parse error
*/
public Iterator parameterTypeIterator(String text)
{
return new ParameterTypeIterator(parse(text));
}
/**
* Internal method parsing the JDOQL parameter declaration.
* @param text the JDOQL parameter declaration
* @return an AST representing the parameter declarations
*/
private AST parse(String text)
{
if (text == null) {
return null;
}
// return value
AST paramsAST = null;
// error message helper
ErrorMsg errorMsg = new ErrorMsg();
// create parser
JQLParser parser = JQLC.createStringParser(text, errorMsg);
try {
// start parsing
parser.parseParameters();
// get the AST representation
paramsAST = parser.getAST();
}
catch (ANTLRException ex) {
// handle any exceptions thrown by lexer or parser
JQLParser.handleANTLRException(ex, errorMsg);
}
return paramsAST;
}
/**
* Iterator over the parameter types. The next method returns the type
* of the next parameter represented as String.
*/
private static class ParameterTypeIterator
implements Iterator
{
// current parameter declaration node
private AST current;
/**
* The constructor takes the parameter declarations AST. A
* parameter declaration node must have a PARAMETER_DEF node as
* root. The first child is the type, the next child is the name of
* the parameter. All subsequent parameter declarations as siblings
* of the specified ast node.
* @param ast the list of parameter declarations nodes
*/
ParameterTypeIterator(AST ast)
{
current = ast;
}
/**
* Returns <code>true</code> if the iteration has more elements.
* @return <code>true</code> if the iterator has more elements.
*/
public boolean hasNext()
{
return (current != null);
}
/**
* Returns the next element in the iteration. For this Iterator it
* returns the String representation of the type of the next
* parameter declaration.
* @return the type of the next parameter declaration.
* @exception NoSuchElementException iteration has no more elements.
*/
public Object next()
{
// check whether iteration has no more elements
if (current == null)
throw new NoSuchElementException();
// Check whether the current node has the token type
// PARAMETER_DEF => throw exception if not.
if (current.getType() != JQLParser.PARAMETER_DEF)
throw new JDOFatalInternalException(I18NHelper.getMessage(
messages,
"jqlc.jdoqlparameterdeclarationparser.next.wrongtoken", //NOI18N
current.getType()));
// get string repr of parameter type node
String typeRepr = getTypeRepr(current.getFirstChild());
// advance current ast node to next parameter declaration node
current = current.getNextSibling();
return typeRepr;
}
/**
* Not supported.
* @exception UnsupportedOperationException remove is not supported
* by this Iterator
*/
public void remove() { throw new UnsupportedOperationException(); }
/**
* Internal method to calculate the string representation of a type
* node.
* @param ast the type node
* @return the string representation
*/
private String getTypeRepr(AST ast)
{
if (ast == null)
return "";
// Check for DOT nodes #(DOT left right)
// They are represented as left.right
if (ast.getType() == JQLParser.DOT) {
AST left = ast.getFirstChild();
AST right = left.getNextSibling();
return getTypeRepr(left) + "." + getTypeRepr(right);
}
// For all other nodes return the token text
return ast.getText();
}
}
/**
* Method main for testing purposes. Parameter args is expected to a
* an array of parameter declaration String. One parameter declaration
* may declare multiple parameters according to the JDOQL parameter
* declaration syntax. Calling
* java com...jqlc.ParameterDeclarationHelper "int a, String b"
* will print
* <br><code>
* Parameter types for >int a, String b<
* <br>
* int
* <br>
* String</code>
* <br>
*/
public static void main(String[] args)
{
QueryParser helper = new JDOQLParameterDeclarationParser();
for (int i = 0; i < args.length; i++) {
String text = args[i];
System.out.println("Parameter types for >" + text + "<");
for (Iterator types = helper.parameterTypeIterator(text);
types.hasNext();) {
System.out.println(" " + types.next());
}
}
}
}
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