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Groovy: A powerful, dynamic language for the JVM
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/*
 * Copyright 2008 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.runtime.powerassert;

import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.stmt.AssertStatement;
import org.codehaus.groovy.control.Janitor;
import org.codehaus.groovy.control.SourceUnit;

import java.util.ArrayList;
import java.util.List;

/**
 * Provides the source text for an assertion statement and translates
 * coordinates in the original source text to coordinates relative to the
 * assertion's (normalized) source text.
 *
 * @author Peter Niederwieser
 */
public class SourceText {
    private final int firstLine;
    private String normalizedText;

    private final List lineOffsets = new ArrayList();
    private final List textOffsets = new ArrayList();

    /**
     * Constructs a SourceText by reading the given assertion's source
     * text from the given source unit.
     *
     * @param stat       an assertion statement
     * @param sourceUnit the source unit containing the assertion statement
     * @param janitor    a Janitor for cleaning up reader sources
     */
    public SourceText(AssertStatement stat, SourceUnit sourceUnit, Janitor janitor) {
        if (!hasPlausibleSourcePosition(stat))
            throw new SourceTextNotAvailableException(stat, sourceUnit, "Invalid source position");

        firstLine = stat.getLineNumber();
        textOffsets.add(0);
        normalizedText = "";

        for (int line = stat.getLineNumber(); line <= stat.getLastLineNumber(); line++) {
            String lineText = sourceUnit.getSample(line, 0, janitor);
            if (lineText == null)
                throw new SourceTextNotAvailableException(stat, sourceUnit, "SourceUnit.getSample() returned null");

            if (line == stat.getLastLineNumber())
                lineText = lineText.substring(0, stat.getLastColumnNumber() - 1);
            if (line == stat.getLineNumber()) {
                lineText = lineText.substring(stat.getColumnNumber() - 1);
                lineOffsets.add(stat.getColumnNumber() - 1);
            } else
                lineOffsets.add(countLeadingWhitespace(lineText));

            lineText = lineText.trim();
            if (line != stat.getLastLineNumber() && lineText.length() > 0)
                lineText += ' ';
            normalizedText += lineText;
            textOffsets.add(normalizedText.length());
        }
    }

    /**
     * Returns the assertion's source text after removing line breaks.
     * Limitation: Line comments within the assertion's source text are not
     * handled.
     *
     * @return the assertion's source text after removing line breaks.
     */
    public String getNormalizedText() {
        return normalizedText;
    }

    /**
     * Returns the column in getNormalizedText() corresponding
     * to the given line and column in the original source text. The
     * first character in the normalized text has column 1.
     *
     * @param line   a line number
     * @param column a column number
     * @return the column in getNormalizedText() corresponding to the given line
     *         and column in the original source text
     */
    public int getNormalizedColumn(int line, int column) {
        int deltaLine = line - firstLine;
        if (deltaLine < 0 || deltaLine >= lineOffsets.size()) // wrong line information
            return -1;
        int deltaColumn = column - lineOffsets.get(deltaLine);
        if (deltaColumn < 0) // wrong column information
            return -1;

        return textOffsets.get(deltaLine) + deltaColumn;
    }

    private boolean hasPlausibleSourcePosition(ASTNode node) {
        return node.getLineNumber() > 0
                && node.getColumnNumber() > 0
                && node.getLastLineNumber() >= node.getLineNumber()
                && node.getLastColumnNumber() >
                (node.getLineNumber() == node.getLastLineNumber() ? node.getColumnNumber() : 0);
    }

    private int countLeadingWhitespace(String lineText) {
        int result = 0;
        while (result < lineText.length() && Character.isWhitespace(lineText.charAt(result)))
            result++;
        return result;
    }
}