package org.checkerframework.javacutil;

import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.util.TreePath;
import com.sun.source.util.TreePathScanner;
import javax.lang.model.element.TypeElement;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;

/**
 * Process the types in an AST in a trivial manner, with hooks for derived classes to actually do
 * something.
 */
public abstract class BasicTypeProcessor extends AbstractTypeProcessor {
    /** The source tree that's being scanned. */
    protected @MonotonicNonNull CompilationUnitTree currentRoot;

    /**
     * Create a TreePathScanner at the given root.
     *
     * @param root where to start the tree traversal
     * @return a TreePathScanner at the given root
     */
    protected abstract TreePathScanner<?, ?> createTreePathScanner(CompilationUnitTree root);

    /** Visit the tree path for the type element. */
    @Override
    public void typeProcess(TypeElement e, TreePath p) {
        currentRoot = p.getCompilationUnit();

        TreePathScanner<?, ?> scanner = null;
        try {
            scanner = createTreePathScanner(currentRoot);
            scanner.scan(p, null);
        } catch (Throwable t) {
            System.err.println(
                    "BasicTypeProcessor.typeProcess: unexpected Throwable ("
                            + t.getClass().getSimpleName()
                            + ")  when processing "
                            + currentRoot.getSourceFile().getName()
                            + (t.getMessage() != null ? "; message: " + t.getMessage() : ""));
        }
    }
}
