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package org.graalvm.launcher;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.graalvm.polyglot.Context;
import org.graalvm.polyglot.Engine;
import org.graalvm.polyglot.Language;
import org.graalvm.polyglot.PolyglotException;

public abstract class AbstractLanguageLauncher extends LanguageLauncherBase {

    
This starts the launcher. it should be called from the main method:

public static void main(String[] args) {
    new MyLauncher().launch(args);
}



Params:
  • args – the command line arguments.
/**
     * This starts the launcher. it should be called from the main method:
     *
     * <pre>
     * public static void main(String[] args) {
     *     new MyLauncher().launch(args);
     * }
     * </pre>
     *
     * @param args the command line arguments.
     */
    protected final void launch(String[] args) {
        try {
            try {
                launch(new ArrayList<>(Arrays.asList(args)), null, true);
            } catch (AbortException e) {
                throw e;
            } catch (PolyglotException e) {
                handlePolyglotException(e);
            } catch (Throwable t) {
                throw abort(t);
            }
        } catch (AbortException e) {
            handleAbortException(e);
        }
    }

    protected static final boolean IS_LIBPOLYGLOT = Boolean.getBoolean("graalvm.libpolyglot");

    final void launch(List<String> args, Map<String, String> defaultOptions, boolean doNativeSetup) {
        List<String> originalArgs = Collections.unmodifiableList(new ArrayList<>(args));

        Map<String, String> polyglotOptions = defaultOptions;
        if (polyglotOptions == null) {
            polyglotOptions = new HashMap<>();
        }

        if (isAOT() && doNativeSetup) {
            System.setProperty("org.graalvm.launcher.languageId", getLanguageId());
        }

        List<String> unrecognizedArgs = preprocessArguments(args, polyglotOptions);

        if (isAOT() && doNativeSetup && !IS_LIBPOLYGLOT) {
            assert nativeAccess != null;
            maybeNativeExec(originalArgs, unrecognizedArgs, false);
        }

        parseUnrecognizedOptions(getLanguageId(), polyglotOptions, unrecognizedArgs);

        if (runLauncherAction()) {
            return;
        }

        validateArguments(polyglotOptions);
        argumentsProcessingDone();

        Context.Builder builder;
        if (isPolyglot()) {
            builder = Context.newBuilder().options(polyglotOptions);
        } else {
            builder = Context.newBuilder(getDefaultLanguages()).options(polyglotOptions);
        }

        builder.allowAllAccess(true);
        setupContextBuilder(builder);

        launch(builder);
    }

    
Process command line arguments by either saving the necessary state or adding it to the polyglotOptions. Any unrecognized arguments should be accumulated and returned as a list. VM (--jvm/--native/--polyglot/--vm.*) and polyglot options (--language.option or --option) should be returned as unrecognized arguments to be automatically parsed and validated by Launcher.parsePolyglotOption(String, Map<String,String>, boolean, String). The arguments should not be modified, but doing so also has no effect. polyglotOptions.put() can be used to set launcher-specific default values when they do not match the OptionKey's default. The preprocessArguments implementations can use Engine to inspect the the installed guest languages and 
instruments. But creating a Context or inspecting engine
options is forbidden. 
Params:
  • arguments – the command line arguments that were passed to the launcher.
  • polyglotOptions – a map where polyglot options can be set. These will be used when creating the Engine.
Returns:the list of arguments that were not recognized.
/**
     * Process command line arguments by either saving the necessary state or adding it to the
     * {@code polyglotOptions}. Any unrecognized arguments should be accumulated and returned as a
     * list. VM (--jvm/--native/--polyglot/--vm.*) and polyglot options (--language.option or
     * --option) should be returned as unrecognized arguments to be automatically parsed and
     * validated by {@link Launcher#parsePolyglotOption(String, Map, boolean, String)}.
     *
     * The {@code arguments} should not be modified, but doing so also has no effect.
     *
     * {@code polyglotOptions.put()} can be used to set launcher-specific default values when they
     * do not match the OptionKey's default.
     *
     * The {@code preprocessArguments} implementations can use {@link Engine} to inspect the the
     * installed {@link Engine#getLanguages() guest languages} and {@link Engine#getInstruments()
     * instruments}. But creating a {@link Context} or inspecting {@link Engine#getOptions() engine
     * options} is forbidden.
     *
     * @param arguments the command line arguments that were passed to the launcher.
     * @param polyglotOptions a map where polyglot options can be set. These will be used when
     *            creating the {@link org.graalvm.polyglot.Engine Engine}.
     * @return the list of arguments that were not recognized.
     */
    protected abstract List<String> preprocessArguments(List<String> arguments, Map<String, String> polyglotOptions);

    
Validates arguments after all arguments have been parsed.

Params:
  • polyglotOptions – the options that will be used to create engine.
/**
     * Validates arguments after all arguments have been parsed.
     *
     * @param polyglotOptions the options that will be used to create engine.
     */
    protected void validateArguments(Map<String, String> polyglotOptions) {
        // nothing to validate by default
    }

    
Launch the scripts as required by the arguments received during the previous call to preprocessArguments(List<String>, Map<String,String>). 
Params:
  • contextBuilder – a context builder configured with the proper language and polyglot options.
/**
     * Launch the scripts as required by the arguments received during the previous call to
     * {@link #preprocessArguments(List, Map)}.
     *
     * @param contextBuilder a {@linkplain Context.Builder context builder} configured with the
     *            proper language and polyglot options.
     */
    protected abstract void launch(Context.Builder contextBuilder);

    
Returns the language id of the language launched by this launcher. 
/**
     * Returns the {@linkplain Language#getId() language id} of the language launched by this
     * launcher.
     */
    protected abstract String getLanguageId();

    @Override
    protected void printVersion() {
        printVersion(getTempEngine());
    }

    protected void printVersion(Engine engine) {
        String languageId = getLanguageId();
        Language language = engine.getLanguages().get(languageId);
        if (language == null) {
            throw abort(String.format("Unknown language: '%s'!", languageId));
        }
        String languageImplementationName = language.getImplementationName();
        if (languageImplementationName == null || languageImplementationName.length() == 0) {
            String languageName = language.getName();
            if (languageName == null || languageName.length() == 0) {
                languageName = languageId;
            }
            languageImplementationName = languageName;
        }
        String engineImplementationName = engine.getImplementationName();
        if (isAOT()) {
            engineImplementationName += " Native";
        } else {
            engineImplementationName += " JVM";
        }
        String languageVersion = language.getVersion();
        if (languageVersion.equals(engine.getVersion())) {
            languageVersion = "";
        } else {
            languageVersion += " ";
        }
        System.out.println(String.format("%s %s(%s %s)", languageImplementationName, languageVersion, engineImplementationName, engine.getVersion()));
    }

    protected void runVersionAction(VersionAction action, Engine engine) {
        switch (action) {
            case PrintAndContinue:
                printVersion(engine);
                break;
            case PrintAndExit:
                printVersion(engine);
                throw exit();
        }
    }

    
The return value specifies what languages should be available by default when not using
--polyglot. Note that TruffleLanguage.Registration#dependentLanguages() should be preferred
in most cases.

Returns:an array of required language ids
/**
     * The return value specifies what languages should be available by default when not using
     * --polyglot. Note that TruffleLanguage.Registration#dependentLanguages() should be preferred
     * in most cases.
     *
     * @return an array of required language ids
     */
    protected String[] getDefaultLanguages() {
        return new String[]{getLanguageId()};
    }
}