org.eclipse.jdt.bcoview.views.HelpUtils Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2023 Andrey Loskutov and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* Andrey Loskutov - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.bcoview.views;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;
import org.objectweb.asm.util.Printer;
import org.eclipse.jdt.core.dom.AST;
/**
* Fetches latest supported JLS spec and provides help for bytecode opcodes.
*/
public class HelpUtils {
private static final String SPECS_HTML = "https://docs.oracle.com/javase/specs/jvms/se" + AST.getJLSLatest() + "/html/jvms-6.html"; //$NON-NLS-1$ //$NON-NLS-2$
private static String fullSpec;
private static String htmlHead;
private static String checkOpcodeName(String opcodeName) {
opcodeName = opcodeName.toLowerCase();
/*
* we need an additional check for DCONST_1...5, FCONST_1...5 etc case
* to convert it to DCONST_D etc
*/
int sepIndex = opcodeName.indexOf('_');
if (sepIndex > 0) {
if (Character.isDigit(opcodeName.charAt(sepIndex + 1))) {
opcodeName = opcodeName.substring(0, sepIndex);
switch (opcodeName.charAt(0)) {
case 'd':
opcodeName += "_d"; //$NON-NLS-1$
break;
case 'f':
opcodeName += "_f"; //$NON-NLS-1$
break;
case 'l':
opcodeName += "_l"; //$NON-NLS-1$
break;
default:
// ICONST uses "n"
opcodeName += "_n"; //$NON-NLS-1$
break;
}
}
if (opcodeName.startsWith("if_acmp")) { //$NON-NLS-1$
opcodeName = "if_acmp_cond"; //$NON-NLS-1$
} else if (opcodeName.startsWith("if_icmp")) { //$NON-NLS-1$
opcodeName = "if_icmp_cond"; //$NON-NLS-1$
} else if (opcodeName.startsWith("if_")) { //$NON-NLS-1$
opcodeName = "if_cond"; //$NON-NLS-1$
} else if (opcodeName.startsWith("aload_")) { //$NON-NLS-1$
opcodeName = "aload_n"; //$NON-NLS-1$
} else if (opcodeName.startsWith("iconst_")) { //$NON-NLS-1$
opcodeName = "iconst_i"; //$NON-NLS-1$
}
} else if (opcodeName.startsWith("if")) { //$NON-NLS-1$
opcodeName = "if_cond"; //$NON-NLS-1$
}
return opcodeName;
}
private static String getOpcodeName(int opcode) {
if (opcode < 0 || opcode >= Printer.OPCODES.length) {
return null;
}
String opcodeName = Printer.OPCODES[opcode];
if (opcodeName == null) {
return null;
}
return opcodeName;
}
private static URL toUrl(String href) {
try {
return new URL(href);
} catch (MalformedURLException e) {
return null;
}
}
public static URL getHelpIndex() {
return toUrl(SPECS_HTML);
}
private static String readFullSpec() {
// The anchor where the real content starts. We have to ignore content before
// that contains TOC with same anchors we want search later in content
String firstInterestingLine = ""; //$NON-NLS-1$
URL helpResource = toUrl(SPECS_HTML);
StringBuilder sb = new StringBuilder();
boolean foundContentStart = false;
try (BufferedReader in = new BufferedReader(new InputStreamReader(helpResource.openStream(), StandardCharsets.UTF_8))) {
String line;
while ((line = in.readLine()) != null) {
if (!foundContentStart) {
if (line.contains(firstInterestingLine)) {
foundContentStart = true;
// that was enough from head
htmlHead = readHtmlHead(sb.toString());
// from here on we read opcodes
sb = new StringBuilder();
}
}
sb.append(line).append('\n');
}
} catch (IOException e) {
sb.append("Error trying access JVM specification at ").append(SPECS_HTML); //$NON-NLS-1$
sb.append(":"); //$NON-NLS-1$
sb.append(e);
}
return sb.toString();
}
public static StringBuilder getOpcodeHelpFor(int opcode) {
if (fullSpec == null) {
fullSpec = readFullSpec();
}
StringBuilder sb = new StringBuilder();
String opcodeName = getOpcodeName(opcode);
if (opcodeName == null) {
return sb;
}
return getOpcodeHelpFor(opcodeName);
}
public static StringBuilder getOpcodeHelpFor(String opcodeName) {
if (fullSpec == null) {
fullSpec = readFullSpec();
}
StringBuilder sb = new StringBuilder();
if (opcodeName != null) {
opcodeName = checkOpcodeName(opcodeName);
}
sb.append(htmlHead);
// Extract only important part related to the given opcode
String patternStart = "jvms-6.5." + opcodeName + "\""; //$NON-NLS-1$ //$NON-NLS-2$
String patternEnd = ""; //$NON-NLS-1$
try (Scanner in = new Scanner(fullSpec)) {
String line;
boolean foundStart = false;
boolean checkEnd = false;
while (in.hasNextLine()) {
line = in.nextLine();
if (checkEnd && line.contains(patternEnd)) {
break;
}
if (!foundStart && line.contains(patternStart)) {
foundStart = true;
checkEnd = true;
sb.append(startSection);
}
if (foundStart) {
sb.append(line);
}
}
}
// Allow navigation relative to the document
int endHeadIdx = sb.indexOf(""); //$NON-NLS-1$
if (endHeadIdx > 0) {
sb.insert(endHeadIdx, "\n