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* Copyright (c) 2011, salesforce.com, inc.
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package com.force.sdk.jpa.query;
import java.util.Map;
import org.datanucleus.query.compiler.JPQLParser;
import org.datanucleus.query.compiler.QueryCompilation;
import org.datanucleus.query.expression.Expression;
import org.datanucleus.query.expression.ExpressionCompiler;
import org.datanucleus.query.node.Node;
import org.datanucleus.query.symbol.SymbolTable;
import org.datanucleus.store.ExecutionContext;
/**
*
* Utility class that compiles JPQL query fragments into query expressions.
* This is mostly intended to take query expressions from annotations and convert them
* into expressions that can be appended to existing queries.
*
* @author Fiaz Hossain
*/
public class JPQLPartialCompiler {
private JPQLParser parser;
private SymbolTable symbolTable;
/**
* Instantiates a JPQLParser and stores the symbol table from the compilation, or
* creates a new one.
*
* @param ec the current execution context
* @param compilation possibly {@code null}, contains components of a query string
* @param options JPQL parser options
* @param params parameters for the parser
*/
public JPQLPartialCompiler(ExecutionContext ec, QueryCompilation compilation, Map options, Map params) {
parser = new JPQLParser(options, params);
this.symbolTable = compilation != null ? compilation.getSymbolTable() : new SymbolTable(ec.getClassLoaderResolver());
}
/**
*
* Adds the proper ordering to the parser and returns the resulting expressions.
*
* @param ordering the orderBy string
* @return an ordered expression array
*/
public Expression[] compileOrdering(String ordering) {
if (ordering == null) {
return null;
}
Node[] node = parser.parseOrder(ordering);
Expression[] expr = new Expression[node.length];
for (int i = 0; i < node.length; i++) {
ExpressionCompiler comp = new ExpressionCompiler();
comp.setSymbolTable(symbolTable);
expr[i] = comp.compileOrderExpression(node[i]);
expr[i].bind(symbolTable);
}
return expr;
}
}