org.eclipse.jdt.ls.core.internal.HoverInfoProvider.java Source code

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Here is the source code for org.eclipse.jdt.ls.core.internal.HoverInfoProvider.java

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/*******************************************************************************
 * Copyright (c) 2016-2017 Red Hat Inc. and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Red Hat Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.ls.core.internal;

import java.io.IOException;
import java.io.Reader;
import java.util.stream.Stream;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.jdt.core.IBuffer;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.ILocalVariable;
import org.eclipse.jdt.core.IMember;
import org.eclipse.jdt.core.IPackageFragment;
import org.eclipse.jdt.core.ISourceRange;
import org.eclipse.jdt.core.ITypeParameter;
import org.eclipse.jdt.core.ITypeRoot;
import org.eclipse.jdt.ls.core.internal.hover.JavaElementLabels;
import org.eclipse.jdt.ls.core.internal.javadoc.JavadocContentAccess;

import com.google.common.io.CharStreams;

public class HoverInfoProvider {

    private static final long LABEL_FLAGS = JavaElementLabels.ALL_FULLY_QUALIFIED
            | JavaElementLabels.M_PRE_RETURNTYPE | JavaElementLabels.M_PARAMETER_ANNOTATIONS
            | JavaElementLabels.M_PARAMETER_TYPES | JavaElementLabels.M_PARAMETER_NAMES
            | JavaElementLabels.M_EXCEPTIONS | JavaElementLabels.F_PRE_TYPE_SIGNATURE
            | JavaElementLabels.M_PRE_TYPE_PARAMETERS | JavaElementLabels.T_TYPE_PARAMETERS
            | JavaElementLabels.USE_RESOLVED;

    private static final long LOCAL_VARIABLE_FLAGS = LABEL_FLAGS & ~JavaElementLabels.F_FULLY_QUALIFIED
            | JavaElementLabels.F_POST_QUALIFIED;

    private final ITypeRoot unit;

    public HoverInfoProvider(ITypeRoot aUnit) {
        this.unit = aUnit;
    }

    public String computeHover(int line, int column) {
        try {
            IJavaElement[] elements = JDTUtils.findElementsAtSelection(unit, line, column);
            if (elements == null || elements.length == 0) {
                return null;
            }
            IJavaElement curr = null;
            if (elements.length != 1) {
                // they could be package fragments.
                // We need to select the one that matches the package fragment of the current unit
                IPackageFragment packageFragment = (IPackageFragment) unit.getParent();
                IJavaElement found = Stream.of(elements).filter(e -> e.equals(packageFragment)).findFirst()
                        .orElse(null);
                if (found == null) {
                    // this would be a binary package fragment
                    return computeJavadocHover(elements[0]);
                }
                curr = found;
            } else {
                curr = elements[0];
            }
            return computeJavadocHover(curr);
        } catch (CoreException e) {
            e.printStackTrace();
        }
        return null;
    }

    private String computeJavadocHover(IJavaElement element) throws CoreException {
        IMember member;
        if (element instanceof ILocalVariable) {
            return JavaElementLabels.getElementLabel(element, LOCAL_VARIABLE_FLAGS);
        }
        if (element instanceof ITypeParameter) {
            member = ((ITypeParameter) element).getDeclaringMember();
        } else if (element instanceof IMember) {
            member = (IMember) element;
        } else if (element instanceof IPackageFragment) {
            Reader r = JavadocContentAccess.getHTMLContentReader((IPackageFragment) element, true);
            if (r == null)
                return null;
            return getString(r);
        } else {
            return null;
        }

        IBuffer buf = member.getOpenable().getBuffer();
        if (buf == null) {
            return null; // no source attachment found
        }

        ISourceRange javadocRange = member.getJavadocRange();
        if (javadocRange == null)
            return null;
        Reader r = JavadocContentAccess.getHTMLContentReader(member, true, true);
        if (r == null)
            return null;
        return getString(r);
    }

    /**
     * Gets the reader content as a String
     *
     * @param reader the reader
     * @return the reader content as string
     */
    private static String getString(Reader reader) {
        try {
            return CharStreams.toString(reader);
        } catch (IOException ignored) {
            //meh
        }
        return null;
    }
}