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Java REPL is a simple Read-Eval-Print-Loop for Java language.
package javarepl;
import com.googlecode.totallylazy.Option;
import com.googlecode.totallylazy.Sequence;
import com.googlecode.totallylazy.Sequences;
import com.googlecode.totallylazy.functions.Function1;
import javarepl.client.EvaluationResult;
import javarepl.client.JavaREPLClient;
import javarepl.completion.CompletionCandidate;
import javarepl.completion.CompletionResult;
import jline.console.ConsoleReader;
import jline.console.CursorBuffer;
import jline.console.completer.CandidateListCompletionHandler;
import jline.console.completer.CompletionHandler;
import jline.console.history.MemoryHistory;
import org.fusesource.jansi.AnsiConsole;
import java.io.IOException;
import java.util.*;
import static com.googlecode.totallylazy.Option.none;
import static com.googlecode.totallylazy.Option.some;
import static com.googlecode.totallylazy.Sequences.sequence;
import static com.googlecode.totallylazy.Strings.replaceAll;
import static com.googlecode.totallylazy.Strings.startsWith;
import static com.googlecode.totallylazy.functions.Callables.compose;
import static com.googlecode.totallylazy.numbers.Numbers.intValue;
import static com.googlecode.totallylazy.numbers.Numbers.valueOf;
import static java.lang.String.format;
import static java.lang.System.getProperty;
import static java.util.Arrays.asList;
import static javarepl.Utils.applicationVersion;
import static javarepl.Utils.randomServerPort;
import static javarepl.completion.CompletionResult.methods.fromJson;
import static javarepl.completion.CompletionResult.methods.toJson;
import static javax.tools.ToolProvider.getSystemJavaCompiler;
public class Main {
private static Option process = none();
private static ResultPrinter console;
public static void main(String... args) throws Exception {
console = new ResultPrinter(printColors(args));
JavaREPLClient client = clientFor(hostname(args), port(args));
ExpressionReader expressionReader = expressionReaderFor(client);
Option expression = none();
Option result = none();
while (expression.isEmpty() || !result.isEmpty()) {
expression = expressionReader.readExpression();
if (!expression.isEmpty()) {
result = client.execute(expression.get());
if (!result.isEmpty())
console.printEvaluationResult(result.get());
}
}
}
private static JavaREPLClient clientFor(Option hostname, Option port) throws Exception {
console.printInfo(format("Welcome to JavaREPL version %s (%s, Java %s)",
applicationVersion(),
getProperty("java.vm.name"),
getProperty("java.version")));
if (hostname.isEmpty() && port.isEmpty()) {
return startNewLocalInstance("localhost", randomServerPort());
} else {
return connectToRemoteInstance(hostname.getOrElse("localhost"), port.getOrElse(randomServerPort()));
}
}
private static JavaREPLClient connectToRemoteInstance(String hostname, Integer port) {
JavaREPLClient replClient = new JavaREPLClient(hostname, port);
if (!replClient.status().isRunning()) {
console.printError("ERROR: Could not connect to remote REPL instance at http://" + hostname + ":" + port);
System.exit(0);
} else {
console.printInfo("Connected to remote instance at http://" + hostname + ":" + port);
}
String remoteInstanceVersion = replClient.version();
if (!remoteInstanceVersion.equals(applicationVersion())) {
console.printError("WARNING: Client version (" + applicationVersion() + ") is different from remote instance version (" + remoteInstanceVersion + ")");
}
return replClient;
}
private static JavaREPLClient startNewLocalInstance(String hostname, Integer port) throws Exception {
if (getSystemJavaCompiler() == null) {
console.printError("\nERROR: Java compiler not found.\n" +
"This can occur when JavaREPL was run with JRE instead of JDK or JDK is not configured correctly.");
System.exit(0);
}
console.printInfo("Type expression to evaluate, \u001B[32m:help\u001B[0m for more options or press \u001B[32mtab\u001B[0m to auto-complete.");
ProcessBuilder builder = new ProcessBuilder("java", "-cp", System.getProperty("java.class.path"), Repl.class.getCanonicalName(), "--port=" + port);
builder.redirectErrorStream(true);
process = some(builder.start());
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
console.printInfo("\nTerminating...");
process.get().destroy();
}
});
JavaREPLClient replClient = new JavaREPLClient(hostname, port);
if (!waitUntilInstanceStarted(replClient)) {
console.printError("\nERROR: Could not start REPL instance at http://" + hostname + ":" + port);
System.exit(0);
}
return replClient;
}
private static boolean waitUntilInstanceStarted(JavaREPLClient client) throws Exception {
for (int i = 0; i < 500; i++) {
Thread.sleep(10);
if (client.status().isRunning())
return true;
}
return false;
}
private static Option port(String[] args) {
return sequence(args).find(startsWith("--port=")).map(compose(replaceAll("--port=", ""), compose(valueOf, intValue)));
}
private static Option hostname(String[] args) {
return sequence(args).find(startsWith("--hostname=")).map(replaceAll("--hostname=", ""));
}
private static Boolean printColors(String[] args) {
return !sequence(args).contains("--noColors");
}
private static ExpressionReader expressionReaderFor(final JavaREPLClient client) throws IOException {
return new ExpressionReader(new Function1, String>() {
private final ConsoleReader consoleReader;
{
consoleReader = new ConsoleReader(System.in, AnsiConsole.out);
consoleReader.setCompletionHandler(new JlineCompletionHandler());
consoleReader.setHistoryEnabled(true);
consoleReader.setExpandEvents(false);
consoleReader.addCompleter(clientCompleter());
}
public String call(Sequence lines) throws Exception {
consoleReader.setPrompt(console.ansiColored(lines.isEmpty() ? "\u001B[1mjava> \u001B[0m" : " \u001B[1m| \u001B[0m"));
consoleReader.setHistory(clientHistory());
return consoleReader.readLine();
}
private MemoryHistory clientHistory() throws Exception {
MemoryHistory history = new MemoryHistory();
for (String historyItem : client.history()) {
history.add(historyItem);
}
return history;
}
private jline.console.completer.Completer clientCompleter() {
return (expression, cursor, candidates) -> {
try {
CompletionResult result = client.completions(expression);
candidates.addAll(asList(toJson(result)));
return result.candidates().isEmpty() ? -1 : result.position();
} catch (Exception e) {
return -1;
}
};
}
});
}
/**
* Copied from JLine sourcecode and heavily modified
* Original sources: https://raw.github.com/jline/jline2/master/src/main/java/jline/console/completer/CandidateListCompletionHandler.java
*/
public static class JlineCompletionHandler implements CompletionHandler {
// TODO: handle quotes and escaped quotes && enable automatic escaping of whitespace
public boolean complete(final ConsoleReader reader, final List candidatesJson, final int pos) throws IOException {
CursorBuffer buf = reader.getCursorBuffer();
CompletionResult completionResult = fromJson(sequence(candidatesJson).head().toString());
Sequence candidatesToPrint = Sequences.empty(String.class);
// if there is only one completion, then fill in the buffer
if (completionResult.candidates().size() == 1) {
CharSequence value = completionResult.candidates().head().value();
// fail if the only candidate is the same as the current buffer
if (value.equals(buf.toString())) {
return false;
}
setBuffer(reader, value, pos);
candidatesToPrint = completionResult.candidates().flatMap(CompletionCandidate::forms);
} else if (completionResult.candidates().size() > 1) {
String value = getUnambiguousCompletions(completionResult.candidates());
setBuffer(reader, value, pos);
candidatesToPrint = completionResult.candidates().map(CompletionCandidate::value);
}
printCandidates(reader, candidatesToPrint.safeCast(CharSequence.class).toList());
// redraw the current console buffer
reader.drawLine();
return true;
}
public static void setBuffer(final ConsoleReader reader, final CharSequence value, final int offset) throws
IOException {
while ((reader.getCursorBuffer().cursor > offset) && reader.backspace()) {
// empty
}
reader.putString(value);
reader.setCursorPosition(offset + value.length());
}
public static void printCandidates(final ConsoleReader reader, Collection candidates) throws
IOException {
Set distinct = new HashSet(candidates);
if (distinct.size() > reader.getAutoprintThreshold()) {
//noinspection StringConcatenation
reader.print(Messages.DISPLAY_CANDIDATES.format(candidates.size()));
reader.flush();
int c;
String noOpt = Messages.DISPLAY_CANDIDATES_NO.format();
String yesOpt = Messages.DISPLAY_CANDIDATES_YES.format();
char[] allowed = {yesOpt.charAt(0), noOpt.charAt(0)};
while ((c = reader.readCharacter(allowed)) != -1) {
String tmp = new String(new char[]{(char) c});
if (noOpt.startsWith(tmp)) {
reader.println();
return;
} else if (yesOpt.startsWith(tmp)) {
break;
} else {
reader.beep();
}
}
}
// copy the values and make them distinct, without otherwise affecting the ordering. Only do it if the sizes differ.
if (distinct.size() != candidates.size()) {
Collection copy = new ArrayList();
for (CharSequence next : candidates) {
if (!copy.contains(next)) {
copy.add(next);
}
}
candidates = copy;
}
reader.println();
reader.printColumns(candidates);
}
/**
* Returns a root that matches all the {@link String} elements of the specified {@link List},
* or null if there are no commonalities. For example, if the list contains
* foobar, foobaz, foobuz, the method will return foob.
*/
private String getUnambiguousCompletions(final Sequence candidates) {
if (candidates == null || candidates.isEmpty()) {
return null;
}
// convert to an array for speed
String[] strings = candidates.map(CompletionCandidate::value).toArray(new String[candidates.size()]);
String first = strings[0];
StringBuilder candidate = new StringBuilder();
for (int i = 0; i < first.length(); i++) {
if (startsWith(first.substring(0, i + 1), strings)) {
candidate.append(first.charAt(i));
} else {
break;
}
}
return candidate.toString();
}
/**
* @return true is all the elements of candidates start with starts
*/
private boolean startsWith(final String starts, final String[] candidates) {
for (String candidate : candidates) {
if (!candidate.startsWith(starts)) {
return false;
}
}
return true;
}
private static enum Messages {
DISPLAY_CANDIDATES,
DISPLAY_CANDIDATES_YES,
DISPLAY_CANDIDATES_NO,;
private static final
ResourceBundle
bundle =
ResourceBundle.getBundle(CandidateListCompletionHandler.class.getName(), Locale.getDefault());
public String format(final Object... args) {
if (bundle == null)
return "";
else
return String.format(bundle.getString(name()), args);
}
}
}
}
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