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/*
 * Copyright 2003-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.codehaus.groovy.ast.tools;

import org.codehaus.groovy.ast.expr.ClosureExpression;
import org.codehaus.groovy.control.io.ReaderSource;
/**
 * Handy methods when working with the Closure expressions.
 *
 * @author Hamlet D'Arcy
 * @author Sergei Egorov
 */

public class ClosureUtils {

    /**
     * Converts a ClosureExpression into the String source.
     *
     * @param readerSource a source
     * @param expression a closure. Can't be null
     * @return the source the closure was created from
     * @throws java.lang.IllegalArgumentException when expression is null
     * @throws java.lang.Exception when closure can't be read from source
     */
    public static String convertClosureToSource(ReaderSource readerSource, ClosureExpression expression) throws Exception {
        if (expression == null) throw new IllegalArgumentException("Null: expression");

        StringBuilder result = new StringBuilder();
        for (int x = expression.getLineNumber(); x <= expression.getLastLineNumber(); x++) {
            String line = readerSource.getLine(x, null);
            if (line == null) {
                throw new Exception(
                        "Error calculating source code for expression. Trying to read line " + x + " from " + readerSource.getClass()
                );
            }
            if (x == expression.getLastLineNumber()) {
                line = line.substring(0, expression.getLastColumnNumber() - 1);
            }
            if (x == expression.getLineNumber()) {
                line = line.substring(expression.getColumnNumber() - 1);
            }
            //restoring line breaks is important b/c of lack of semicolons
            result.append(line).append('\n');
        }


        String source = result.toString().trim();
        if (!source.startsWith("{")) {
            throw new Exception("Error converting ClosureExpression into source code. Closures must start with {. Found: " + source);
        }

        return source;
    }
}