com.google.inject.internal.util.SourceProvider Maven / Gradle / Ivy

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package com.google.inject.internal.util;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;

import java.util.List;

/**
 * Provides access to the calling line of code.
 */
public final class SourceProvider {

    /**
     * Indicates that the source is unknown.
     */
    public static final Object UNKNOWN_SOURCE = "[unknown source]";
    public static final SourceProvider DEFAULT_INSTANCE
            = new SourceProvider(ImmutableSet.of(SourceProvider.class.getName()));
    private final SourceProvider parent;
    private final ImmutableSet classNamesToSkip;

    private SourceProvider(Iterable classesToSkip) {
        this(null, classesToSkip);
    }

    private SourceProvider(SourceProvider parent, Iterable classesToSkip) {
        this.parent = parent;

        ImmutableSet.Builder classNamesToSkipBuilder = ImmutableSet.builder();
        for (String classToSkip : classesToSkip) {
            if (parent == null || !parent.shouldBeSkipped(classToSkip)) {
                classNamesToSkipBuilder.add(classToSkip);
            }
        }
        this.classNamesToSkip = classNamesToSkipBuilder.build();
    }

    /**
     * Returns the class names as Strings
     */
    private static List asStrings(Class... classes) {
        List strings = Lists.newArrayList();
        for (Class c : classes) {
            strings.add(c.getName());
        }
        return strings;
    }

    /**
     * Returns a new instance that also skips {@code moreClassesToSkip}.
     */
    public SourceProvider plusSkippedClasses(Class... moreClassesToSkip) {
        return new SourceProvider(this, asStrings(moreClassesToSkip));
    }

    /**
     * Returns true if the className should be skipped.
     */
    private boolean shouldBeSkipped(String className) {
        return (parent != null && parent.shouldBeSkipped(className))
                || classNamesToSkip.contains(className);
    }

    /**
     * Returns the calling line of code. The selected line is the nearest to the top of the stack that
     * is not skipped.
     */
    public StackTraceElement get(StackTraceElement[] stackTraceElements) {
        Preconditions.checkNotNull(stackTraceElements, "The stack trace elements cannot be null.");
        for (final StackTraceElement element : stackTraceElements) {
            String className = element.getClassName();

            if (!shouldBeSkipped(className)) {
                return element;
            }
        }
        throw new AssertionError();
    }

    /**
     * Returns the non-skipped module class name.
     */
    public Object getFromClassNames(List moduleClassNames) {
        Preconditions.checkNotNull(moduleClassNames, "The list of module class names cannot be null.");
        for (final String moduleClassName : moduleClassNames) {
            if (!shouldBeSkipped(moduleClassName)) {
                return new StackTraceElement(moduleClassName, "configure", null, -1);
            }
        }
        return UNKNOWN_SOURCE;
    }
}