/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
<<<<<<< Updated upstream
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
=======
 * 
 *     https://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
>>>>>>> Stashed changes
 * limitations under the License.
 */

package org.apache.jdo.tck.util.signature;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
import java.io.PrintWriter;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

/**
 * Tests classes for correct signatures.
 *
 * @author Martin Zaun
 */
public class SignatureVerifier {
  /** The new-line character on this system. */
  protected static final String NL = System.getProperty("line.separator");

  /**
   * All modifiers defined in java.lang.reflect.Modifier. This field is used to filter out
   * vm-specific modifiers such as found in Sun's vm to identify Enum and Annotation.
   */
  protected static final int ALL_MODIFIERS =
      Modifier.ABSTRACT
          | Modifier.FINAL
          | Modifier.INTERFACE
          | Modifier.NATIVE
          | Modifier.PRIVATE
          | Modifier.PROTECTED
          | Modifier.PUBLIC
          | Modifier.STATIC
          | Modifier.STRICT
          | Modifier.SYNCHRONIZED
          | Modifier.TRANSIENT
          | Modifier.VOLATILE;

  /** Pseudo modifier for annotation */
  protected static final int ANNOTATION = 0x2000;

  /** Pseudo modifier for enum */
  protected static final int ENUM = 0x4000;

  /** A writer for standard output. */
  protected final PrintWriter log;

  /** Flag to print error output only. */
  private final boolean quiet;

  /** Flag to also print verbose output. */
  private final boolean verbose;

  /** The parse to be used for parsing signature descriptor files. */
  protected final Parser parser = new Parser();

  /** The classloader to be used for loading types. */
  protected final ClassLoader classLoader;

  /** The currently tested Class. */
  protected Class<?> cls;

  /** All untested, declared members of the current class. */
  protected final Set<Member> members = new HashSet<>();

  /** Collects names of loadable classes. */
  private final Set<String> loading = new TreeSet<>();

  /** Collects names of unloadable classes. */
  private final Set<String> notLoading = new TreeSet<>();

  /** Counts tested features (class, constructor, fields, methods). */
  private int tested;

  /** Counts missing members (constructor, fields, methods). */
  private int missing;

  /** Counts non-matching features (class, constructor, fields, methods). */
  private int mismatch;

  /** Counts matching features (class, constructor, fields, methods). */
  private int matching;

  /** Counts public non-standard members (constructor, fields, methods). */
  private int nonStandard;

  /** Counts other reported problems (e.g., accessing field values). */
  private int otherProblems;

  /**
   * Constructs a test instance.
   *
   * @param loader ClassLoader
   * @param log writer for logging
   * @param quiet quiet option
   * @param verbose verbose option
   */
  public SignatureVerifier(ClassLoader loader, PrintWriter log, boolean quiet, boolean verbose) {
    classLoader = this.getClass().getClassLoader();
    this.log = log;
    this.quiet = quiet;
    this.verbose = (!quiet && verbose);
  }

  /**
   * Constructs a test instance.
   *
   * @param log writer for logging
   * @param quiet quiet option
   * @param verbose verbose option
   */
  public SignatureVerifier(PrintWriter log, boolean quiet, boolean verbose) {
    this(SignatureVerifier.class.getClassLoader(), log, quiet, verbose);
  }

  // ----------------------------------------------------------------------
  // Local Logging Methods
  // ----------------------------------------------------------------------

  /**
   * Prints an error message.
   *
   * @param msg error message
   */
  protected void logError(String msg) {
    log.println(msg);
  }

  /**
   * Prints an info message.
   *
   * @param msg info message
   */
  protected void logInfo(String msg) {
    if (!quiet) {
      log.println(msg);
    }
  }

  /**
   * Prints a verbose message.
   *
   * @param msg verbose message
   */
  protected void logVerbose(String msg) {
    if (verbose) {
      log.println(msg);
    }
  }

  // ----------------------------------------------------------------------
  // Test Methods
  // ----------------------------------------------------------------------

  /**
   * Tests the signature of classes (in the specified classloader) against a list of signature
   * descriptor files; returns with a status code.
   *
   * @param descrFileNames list of signature descriptor file names
   * @return zero if all tests have passed and no problems were detected
   * @throws IOException error reading file
   * @throws ParseException error during parsing
   */
  public int test(List<String> descrFileNames) throws IOException, ParseException {
    // check argument
    if (descrFileNames == null || descrFileNames.isEmpty()) {
      final String m = ("ERROR: No signature descriptor file to parse.");
      logError(m);
      return -1;
    }

    // clear statistics
    loading.clear();
    notLoading.clear();
    tested = 0;
    missing = 0;
    mismatch = 0;
    matching = 0;
    nonStandard = 0;
    otherProblems = 0;

    // process descriptor files
    parser.parse(descrFileNames);
    report();

    // return a positive value in case of any problems
    return (notLoading.size() + missing + mismatch + nonStandard + otherProblems);
  }

  /** Reports the results of the last signature test run. */
  public void report() {
    logInfo("");
    logInfo("Signature Test Results");
    logInfo("======================");
    logInfo("");
    logInfo("    tested features:          " + tested);
    logInfo("");
    logInfo("Successes:");
    logInfo("    matching features:        " + matching);
    logInfo("    loadable classes:         " + loading.size());
    logInfo("");
    logInfo("Failures:");
    logInfo("    missing features:         " + missing);
    logInfo("    non-matching features:    " + mismatch);
    logInfo("    non-standard features:    " + nonStandard);
    logInfo("    unloadable classes:       " + notLoading.size());
    logInfo("    other problems:           " + otherProblems);
    logInfo("");
  }

  // ----------------------------------------------------------------------
  // Test Logic
  // ----------------------------------------------------------------------

  /**
   * Handles class loading problems.
   *
   * @param t Throwable
   */
  protected void handleNotLoading(Throwable t) {
    notLoading.add(t.getMessage().replace('/', '.'));
    final String m = ("--- failed loading class;" + NL + "    caught: " + t);
    logError(m);
  }

  /**
   * Handles missing members.
   *
   * @param msg message
   * @param exp expected
   */
  protected void handleMissing(String msg, String exp) {
    missing++;
    final String m =
        ("--- "
            + msg
            + NL
            + "    expected: "
            + exp
            + NL
            + "    class:    "
            + Formatter.toString(cls));
    logError(m);
  }

  /**
   * Handles non-matching features.
   *
   * @param msg message
   * @param exp expected
   * @param fnd feature
   */
  protected void handleMismatch(String msg, String exp, String fnd) {
    mismatch++;
    final String m =
        ("--- "
            + msg
            + NL
            + "    expected: "
            + exp
            + NL
            + "    found:    "
            + fnd
            + NL
            + "    class:    "
            + Formatter.toString(cls));
    logError(m);
  }

  /**
   * Handles public non-standard features.
   *
   * @param msg message
   * @param fnd feature
   */
  protected void handleNonStandard(String msg, String fnd) {
    nonStandard++;
    final String m =
        ("--- "
            + msg
            + NL
            + "    found:    "
            + fnd
            + NL
            + "    class:    "
            + Formatter.toString(cls));
    logError(m);
  }

  /**
   * Handles other problems.
   *
   * @param msg message
   * @param exp expected
   */
  protected void handleProblem(String msg, String exp) {
    otherProblems++;
    final String m =
        ("--- "
            + msg
            + NL
            + "    expected: "
            + exp
            + NL
            + "    class:    "
            + Formatter.toString(cls));
    logError(m);
  }

  /**
   * Handles a perfect feature match.
   *
   * @param msg message
   * @param fnd feature
   */
  protected void handleMatch(String msg, String fnd) {
    matching++;
    final String m = ("+++ " + msg + fnd);
    logVerbose(m);
  }

  /**
   * Returns the class objects for given (Java) user type names.
   *
   * @param userTypeName user type names
   * @return class objects
   */
  protected Class<?>[] getClasses(String[] userTypeName) {
    @SuppressWarnings("rawtypes")
    final Class<?>[] cls = new Class[userTypeName.length];
    for (int i = userTypeName.length - 1; i >= 0; i--) {
      cls[i] = getClass(userTypeName[i]);
    }
    return cls;
  }

  /**
   * Returns the class object for a given (Java) user type name.
   *
   * @param userTypeName user type name
   * @return class object
   */
  protected Class<?> getClass(String userTypeName) {
    // use helper for retrieving class objects for primitive types
    Class<?> cls = TypeHelper.primitiveClass(userTypeName);
    if (cls != null) {
      return cls;
    }

    // load class
    try {
      final String r = TypeHelper.reflectionTypeName(userTypeName);
      cls = Class.forName(r, false, classLoader);
      loading.add(userTypeName);
    } catch (LinkageError | ClassNotFoundException err) {
      handleNotLoading(err);
    }
    return cls;
  }

  /**
   * Check an expected value expression (the value of a static field or the default value of an
   * annotation method), comparing it to the actual value from the Field or Method object. Only
   * supports primitive, enum, empty array of enum, empty array of annotation, and String.
   *
   * @param value the String form of the value from the signature file
   * @param type the type as declared in the class
   * @param actual the actual value
   * @return the description of the expected value, or null if ok
   * @throws java.lang.NumberFormatException format exception
   */
  protected String checkValue(String value, String type, Object actual)
      throws NumberFormatException {
    // note array type
    boolean isArray = false;
    if (type.endsWith("[]")) {
      isArray = true;
      type = type.substring(0, type.length() - 2);
      // remove { from beginning and } from end
      value = value.substring(1, value.length() - 1);
    }
    // first check primitive type
    final Object exp;
    Class<?> expClass;
    final boolean ok;
    switch (type) {
      case "byte":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(byte.class);
        } else {
          ok = Byte.valueOf(value).equals(actual);
        }
        break;
      case "boolean":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(boolean.class);
        } else {
          ok = Boolean.valueOf(value).equals(actual);
        }
        break;
      case "short":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(short.class);
        } else {
          ok = Short.valueOf(value).equals(actual);
        }
        break;
      case "int":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(int.class);
        } else {
          ok = Integer.valueOf(value).equals(actual);
        }
        break;
      case "long":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(long.class);
        } else {
          ok = Long.valueOf(value).equals(actual);
        }
        break;
      case "float":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(float.class);
        } else {
          ok = Float.valueOf(value).equals(actual);
        }
        break;
      case "double":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(double.class);
        } else {
          ok = Double.valueOf(value).equals(actual);
        }
        break;
      case "char":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(char.class);
        } else {
          ok = Character.valueOf(value.charAt(1)).equals(actual);
        }
        // next check Class
        break;
      case "java.lang.Class":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(Class.class);
        } else {
          // strip ".class" from type name
          int offset = value.indexOf(".class");
          value = value.substring(0, offset);
          ok = getClass(value).equals(actual);
        }
        // next check String
        break;
      case "java.lang.String":
        if (isArray) {
          ok = actual.getClass().getComponentType().equals(String.class);
        } else {
          // cut off '\"' chars at begin and end
          final String s;
          if (value.length() > 1) {
            s = value.substring(1, value.length() - 1);
          } else {
            s = "";
          }
          ok = s.equals(actual);
        }
        // now check non-java.lang annotations and enums
        break;
      default:
        expClass = getClass(type);
        if (isArray) {
          // check if the actual component type is the right class
          // don't check the actual values because only empty arrays
          // are supported.
          ok = actual.getClass().getComponentType().equals(expClass);
        } else if (expClass == null) {
          System.out.println(
              "WARNING : checkValue value="
                  + value
                  + " type="
                  + type
                  + " comes up with null"
                  + " class");
          ok = false;
        } else if (expClass.isAnnotation()) {
          // check whether the type isAssignableFrom the class of the actual value,
          // if type is an annotation. The actual value is a dynamic proxy,
          // so an equals comparison does not work.
          ok = expClass.isAssignableFrom(actual.getClass());
        } else {
          // get the actual value which must be a static class.field
          Object expectedValue = null;
          try {
            // now get actual value
            // separate value name into class and field name
            int lastDot = value.lastIndexOf(".");
            String expectedClassName = value.substring(0, lastDot);
            String expectedFieldName = value.substring(lastDot + 1);
            // get Class object from class name
            Class<?> expectedClass = getClass(expectedClassName);
            if (expectedClass == null) throw new ClassNotFoundException();
            // get Field object from Class and field name
            Field expectedField = expectedClass.getField(expectedFieldName);
            expectedValue = expectedField.get(null);
          } catch (NoSuchFieldException
              | ClassNotFoundException
              | IllegalAccessException
              | IllegalArgumentException
              | SecurityException ex) {
            handleNotLoading(ex);
          }
          ok = expectedValue.equals(actual);
        }
        break;
    }
    // return message if not ok
    if (ok) return null;
    else return value;
  }

  /**
   * Validates a field against a prescribed signature.
   *
   * @param mods modifier
   * @param type type
   * @param name name
   * @param value value
   */
  protected void checkField(int mods, String type, String name, String value) {
    tested++;
    type = TypeHelper.qualifiedUserTypeName(type);

    // get field
    final Field field;
    try {
      field = cls.getDeclaredField(name);
    } catch (NoSuchFieldException ex) {
      handleMissing("missing field: ", Formatter.toString(mods, type, name, value));
      return;
    } catch (LinkageError err) {
      handleNotLoading(err);
      return;
    }

    // check modifiers
    if (cls.isInterface()) {
      // fields interfaces are implicitly public, static, and final
      mods |= Modifier.PUBLIC;
      mods |= Modifier.STATIC;
      mods |= Modifier.FINAL;
    }
    if (mods != convertModifiers(field)) {
      handleMismatch(
          "field declaration: non-matching modifiers;",
          Formatter.toString(mods, type, name, null),
          Formatter.toString(field, null));
    }

    // check type
    if (!TypeHelper.isNameMatch(type, field.getType())) {
      handleMismatch(
          "field declaration: non-matching type;",
          Formatter.toString(mods, type, name, null),
          Formatter.toString(field, null));
    }

    // check field value if any
    Object actualValue = null;
    if (value != null) {
      // only support for public, static, and final fields
      final int m = (Modifier.PUBLIC | Modifier.STATIC | Modifier.FINAL);
      if ((mods & m) == 0) {
        handleProblem(
            "field declaration: ignoring field value " + "definition in descriptor file;",
            Formatter.toString(mods, type, name, value));
      } else {
        // compare field's expected with found value
        try {
          actualValue = field.get(null);
        } catch (IllegalAccessException ex) {
          handleProblem(
              "field declaration: cannot access field " + "value, exception: " + ex + ";",
              Formatter.toString(mods, type, name, value));
        }
        String error = checkValue(value, type, actualValue);
        if (error != null) {
          handleMismatch(
              "field declaration: non-matching values;",
              Formatter.toString(mods, type, name, error),
              Formatter.toString(field, "\"" + actualValue + "\""));
        }
      }
    }

    // field OK
    members.remove(field);
    handleMatch("has field: ", Formatter.toString(field, actualValue));
  }

  /**
   * Validates a constructor against a prescribed signature.
   *
   * @param mods modifier
   * @param params parameters
   * @param excepts excepts
   */
  protected void checkConstructor(int mods, String[] params, String[] excepts) {
    tested++;
    params = TypeHelper.qualifiedUserTypeNames(params);
    excepts = TypeHelper.qualifiedUserTypeNames(excepts);

    // get parameter classes
    final Class<?>[] prms = getClasses(params);
    if (prms == null) {
      return;
    }

    // get constructor
    final Constructor<?> ctor;
    try {
      ctor = cls.getDeclaredConstructor(prms);
    } catch (NoSuchMethodException ex) {
      String name = cls.getName();
      final int i = name.lastIndexOf('.');
      name = (i < 0 ? name : name.substring(i));
      handleMissing("missing constructor: ", Formatter.toString(mods, null, name, params, excepts));
      return;
    } catch (LinkageError err) {
      handleNotLoading(err);
      return;
    }

    // check modifiers
    if (mods != ctor.getModifiers()) {
      handleMismatch(
          "constructor declaration: non-matching modifiers;",
          Formatter.toString(mods, null, cls.getName(), params, excepts),
          Formatter.toString(ctor));
    }

    // check exceptions
    if (!TypeHelper.isNameMatch(excepts, ctor.getExceptionTypes())) {
      handleMismatch(
          "method declaration: non-matching exceptions;",
          Formatter.toString(mods, null, cls.getName(), params, excepts),
          Formatter.toString(ctor));
    }

    // constructor OK
    members.remove(ctor);
    handleMatch("has constructor: ", Formatter.toString(ctor));
  }

  /**
   * Validates a method against a prescribed signature.
   *
   * @param mods modifier
   * @param result result
   * @param name name
   * @param params parameters
   * @param excepts excepts
   * @param value value
   */
  protected void checkMethod(
      int mods, String result, String name, String[] params, String[] excepts, String value) {
    tested++;
    params = TypeHelper.qualifiedUserTypeNames(params);
    excepts = TypeHelper.qualifiedUserTypeNames(excepts);
    result = TypeHelper.qualifiedUserTypeName(result);

    // get parameter classes
    final Class<?>[] prms = getClasses(params);
    if (prms == null) {
      return;
    }

    // get method
    final Method method;
    try {
      method = cls.getDeclaredMethod(name, prms);
    } catch (NoSuchMethodException ex) {
      handleMissing("missing method: ", Formatter.toString(mods, result, name, params, excepts));
      return;
    } catch (LinkageError err) {
      handleNotLoading(err);
      return;
    }

    // check modifiers
    if (cls.isInterface()) {
      // methods in interfaces are implicitly public
      mods |= Modifier.PUBLIC;
    }
    Class<?> resultType = getClass(result);
    if (resultType == null) {
      System.out.println(
          "WARNING : checkMethod "
              + name
              + " result="
              + result
              + " comes up with null resultType!");
    } else if (resultType.isAnnotation()) {
      // add ANNOTATION modifier if the result type is an annotation
      mods |= ANNOTATION;
    }
    if (mods != convertModifiers(method)) {
      handleMismatch(
          "method declaration: non-matching modifiers;",
          Formatter.toString(mods, result, name, params, excepts),
          Formatter.toString(method));
    }

    // check return type
    if (!TypeHelper.isNameMatch(result, method.getReturnType())) {
      handleMismatch(
          "method declaration: non-matching return type",
          Formatter.toString(mods, result, name, params, excepts),
          Formatter.toString(method));
    }

    // check exceptions
    if (!TypeHelper.isNameMatch(excepts, method.getExceptionTypes())) {
      handleMismatch(
          "method declaration: non-matching exceptions;",
          Formatter.toString(mods, result, name, params, excepts),
          Formatter.toString(method));
    }

    // check default value of an annotation element (method)
    if (value != null) {
      Object actualValue = null;
      try {
        actualValue = method.getDefaultValue();
      } catch (Exception ex) {
        handleProblem(
            "method declaration: cannot access default " + "value, exception: " + ex + ";",
            Formatter.toString(mods, result, name, value));
      }
      // check value expected versus actual
      String wrong = checkValue(value, result, actualValue);

      if (wrong != null) {
        handleMismatch(
            "method declaration: non-matching default value;",
            Formatter.toString(mods, result, name + "() default ", wrong),
            Formatter.toString(method));
      }
    }

    // method OK
    members.remove(method);
    handleMatch("has method: ", Formatter.toString(method));
  }

  /**
   * Validates a class declaration against a prescribed signature.
   *
   * @param mods modifier
   * @param name name
   * @param ext ext
   * @param impl implementation
   */
  protected void checkClass(int mods, String name, String[] ext, String[] impl) {
    logVerbose("");
    logVerbose("testing " + Formatter.toString(mods, name, ext, impl));
    tested++;
    ext = TypeHelper.qualifiedUserTypeNames(ext);
    impl = TypeHelper.qualifiedUserTypeNames(impl);

    // get and assign currently processed class
    cls = getClass(name);
    if (cls == null) {
      return; // can't load class
    }

    // collect all declared members of current class
    members.clear();
    try {
      members.addAll(Arrays.asList(cls.getDeclaredFields()));
      members.addAll(Arrays.asList(cls.getDeclaredConstructors()));
      members.addAll(Arrays.asList(cls.getDeclaredMethods()));
    } catch (LinkageError err) {
      handleNotLoading(err);
    }

    // check modifiers
    final boolean isInterface = ((mods & Modifier.INTERFACE) != 0);
    if (isInterface) {
      mods |= Modifier.ABSTRACT;
    }
    if (mods != convertModifiers(cls)) {
      handleMismatch(
          "class declaration: non-matching modifiers;",
          Formatter.toString(mods, name, ext, impl),
          Formatter.toString(cls));
    }

    // check superclass and extended/implemented interfaces
    final Class<?> superclass = cls.getSuperclass();
    final Class<?>[] interfaces = cls.getInterfaces();
    if (isInterface) {
      // assert (impl.length == 0);
      if (!TypeHelper.isNameMatch(ext, interfaces)) {
        handleMismatch(
            "interface declaration: non-matching interfaces;",
            Formatter.toString(mods, name, ext, impl),
            Formatter.toString(cls));
      }
    } else {
      // assert (ext.length <= 1);
      final String s = (ext.length == 0 ? "java.lang.Object" : ext[0]);
      if (!TypeHelper.isNameMatch(s, superclass)) {
        handleMismatch(
            "class declaration: non-matching superclass;",
            Formatter.toString(mods, name, ext, impl),
            Formatter.toString(cls));
      }
      if (!TypeHelper.isNameMatch(impl, interfaces)) {
        handleMismatch(
            "class declaration: non-matching interfaces;",
            Formatter.toString(mods, name, ext, impl),
            Formatter.toString(cls));
      }
    }

    handleMatch("has class: ", Formatter.toString(cls));
  }

  /** Runs checks on a class after its members have been validated. */
  protected void postCheckClass() {
    if (cls == null) {
      return; // nothing to do if class couldn't be loaded
    }

    // check for public non-standard members
    for (final Member m : members) {
      if ((m.getModifiers() & Modifier.PUBLIC) != 0) {
        handleNonStandard("non-standard, public member;", Formatter.toString(m));
      }
    }
  }

  /**
   * Return modifiers for the class, but handling enum and annotation as if they had a special
   * modifier.
   *
   * @param cls the class
   * @return modifiers of the class with extra flags for enum and annotation
   */
  protected int convertModifiers(Class<?> cls) {
    int result = cls.getModifiers();
    // first remove extraneous stuff
    result &= ALL_MODIFIERS;
    // if enum, set pseudo enum flag
    if (cls.isEnum()) result |= ENUM;
    // if annotation, set pseudo annotation flag
    if (cls.isAnnotation()) result |= ANNOTATION;
    return result;
  }

  /**
   * Return modifiers for the method, but handling enum and annotation as if they had a special
   * modifier.
   *
   * @param method the method
   * @return modifiers of the class with extra flags for enum and annotation
   */
  protected int convertModifiers(Method method) {
    int result = method.getModifiers();
    // first remove extraneous stuff
    result &= ALL_MODIFIERS;
    // if enum return type, set pseudo enum flag
    if (method.getReturnType().isEnum()) result |= ENUM;
    // if annotation, set pseudo annotation flag
    if (method.getReturnType().isAnnotation()) result |= ANNOTATION;
    // if return type is an enum class, un-set FINAL modifier in all methods
    // because in Java 5, methods are generated as final; in Java 6, not
    if (method.getDeclaringClass().isEnum()) result &= ~Modifier.FINAL;
    return result;
  }

  /**
   * Return modifiers for the field, but handling enum as if it had a special modifier.
   *
   * @param field the field
   * @return modifiers of the class with extra flag for enum
   */
  protected int convertModifiers(Field field) {
    int result = field.getModifiers();
    // first remove extraneous stuff
    result &= ALL_MODIFIERS;
    // if enum, set pseudo enum flag
    if (field.isEnumConstant()) result |= ENUM;
    return result;
  }

  // ----------------------------------------------------------------------
  // Parser for Signature Descriptor Files
  // ----------------------------------------------------------------------

  /** For parsing of signature descriptor files. */
  protected class Parser {
    /** The current descriptor file being parsed. */
    private File descriptorFile;

    /** The line number reader for the current descriptor file. */
    private LineNumberReader ir;

    /** A look-ahead token to be read next. */
    private String nextToken;

    /**
     * Returns an error message reporting an unexpected end of file.
     *
     * @return message
     */
    protected String msgUnexpectedEOF() {
      return ("unexpected end of file at line: "
          + ir.getLineNumber()
          + ", file: "
          + descriptorFile.getPath());
    }

    /**
     * Returns an error message reporting an unextected token.
     *
     * @param t token
     * @return error message
     */
    protected String msgUnexpectedToken(String t) {
      return ("unexpected token: '"
          + t
          + "'"
          + " in line: "
          + ir.getLineNumber()
          + ", file: "
          + descriptorFile.getPath());
    }

    /**
     * Retrieves the look-ahead token to be parsed next.
     *
     * @return look ahead
     */
    protected String getLookAhead() {
      final String t = nextToken;
      nextToken = null;
      return t;
    }

    /**
     * Sets the look-ahead token to be parsed next.
     *
     * @param t token
     */
    protected void setLookAhead(String t) {
      // assert (nextToken == null);
      nextToken = t;
    }

    /**
     * Skips any "white space" and /* style comments and returns whether there are more characters
     * to be parsed.
     *
     * @return true if there are more characters to be parsed
     * @throws IOException IO error
     */
    protected boolean skip() throws IOException {
      Character c;
      Character cnext;
      // Permitted states are white, commentSlashStar, commentSlashSlash
      String state = "white";
      final Character SLASH = '/';
      final Character STAR = '*';
      while (true) {
        c = peek();
        if (c == null) return false;
        if (state.equals("commentSlashStar") && STAR.equals(c)) {
          cnext = peek();
          if (cnext == null) return false;
          if (SLASH.equals(cnext)) {
            state = "white";
          }
          continue;
        }
        if (state.equals("white")) {
          if (SLASH.equals(c)) {
            cnext = peek();
            if (cnext == null) return false;
            if (STAR.equals(cnext)) {
              state = "commentSlashStar";
              continue;
            }
            if (SLASH.equals(cnext)) {
              state = "commentSlashSlash";
              continue;
            }
          }
          if (!Character.isWhitespace(c)) {
            break;
          }
        }
        if (state.equals("commentSlashSlash")
            && (c == Character.LINE_SEPARATOR || c == '\n' || c == '\r')) {
          state = "white";
          continue;
        }
      }
      ir.reset();
      return true;
    }

    /**
     * Returns next char, or null if there is none
     *
     * @return next char
     * @throws IOException IO error
     */
    protected Character peek() throws IOException {
      ir.mark(1);
      int i;
      if ((i = ir.read()) < 0) {
        return null;
      }
      return Character.valueOf((char) i);
    }

    /**
     * Scans for an (unqualified) identifier.
     *
     * @return <code>null</code> if the next token is not an identifier
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String scanIdentifier() throws IOException, ParseException {
      // parse stored token if any
      String t;
      if ((t = getLookAhead()) != null) {
        if (!Character.isJavaIdentifierStart(t.charAt(0))) {
          setLookAhead(t); // not an identifier
          return null;
        }
        return t;
      }

      // parse first char
      if (!skip()) {
        throw new ParseException(msgUnexpectedEOF(), 0);
      }
      ir.mark(1);
      char c = (char) ir.read();
      if (!Character.isJavaIdentifierStart(c)) {
        ir.reset(); // not start of an identifier
        return null;
      }

      // parse remaining chars
      final StringBuilder sb = new StringBuilder();
      do {
        sb.append(c);
        int i;
        ir.mark(1);
        if ((i = ir.read()) < 0) break;
        c = (char) i;
      } while (Character.isJavaIdentifierPart(c));
      ir.reset(); // not part of an identifier
      return sb.toString();
    }

    /**
     * Scans for a number literal.
     *
     * @return <code>null</code> if the next token is not a number
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String scanNumberLiteral() throws IOException, ParseException {
      // parse stored token if any
      String t;
      if ((t = getLookAhead()) != null) {
        if (!(t.charAt(0) == '-' || Character.isDigit(t.charAt(0)))) {
          setLookAhead(t); // not a number literal
          return null;
        }
        return t;
      }

      // parse first char
      if (!skip()) {
        throw new ParseException(msgUnexpectedEOF(), 0);
      }
      ir.mark(1);
      char c = (char) ir.read();
      if (Character.isDigit(c)) {
      } else if (c == '-') {
        skip();
      } else {
        ir.reset(); // not start of a number
        return null;
      }

      // parse remaining chars
      final StringBuilder sb = new StringBuilder();
      do {
        sb.append(c);
        int i;
        ir.mark(1);
        if ((i = ir.read()) < 0) break;
        c = (char) i;
      } while (Character.isLetterOrDigit(c) || c == '-' || c == '.');
      ir.reset(); // not part of a number
      return sb.toString();
    }

    /**
     * Scans for a character literal.
     *
     * @return <code>null</code> if the next token is not a character
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String scanCharacterLiteral() throws IOException, ParseException {
      // parse stored token if any
      String t;
      if ((t = getLookAhead()) != null) {
        if (t.charAt(0) != '\'') {
          setLookAhead(t); // not a char literal
          return null;
        }
        return t;
      }

      // parse first char
      if (!skip()) {
        throw new ParseException(msgUnexpectedEOF(), 0);
      }
      ir.mark(1);
      char c = (char) ir.read();
      if (c != '\'') {
        ir.reset(); // not start of a char literal
        return null;
      }

      // parse remaining two chars
      final StringBuilder sb = new StringBuilder();
      for (int j = 0; j < 2; j++) {
        sb.append(c);
        int i;
        if ((i = ir.read()) < 0) {
          throw new ParseException(msgUnexpectedEOF(), 0);
        }
        c = (char) i;
      }
      if (c != '\'') {
        throw new ParseException(msgUnexpectedToken(String.valueOf(c)), 0);
      }
      sb.append(c); // keep '\'' part of a char literal
      return sb.toString();
    }

    /**
     * Scans for a string literal.
     *
     * @return <code>null</code> if the next token is not a string
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String scanStringLiteral() throws IOException, ParseException {
      // parse stored token if any
      String t;
      if ((t = getLookAhead()) != null) {
        if (t.charAt(0) != '\"') {
          setLookAhead(t); // not a string literal
          return null;
        }
        return t;
      }

      // parse first char
      if (!skip()) {
        throw new ParseException(msgUnexpectedEOF(), 0);
      }
      ir.mark(1);
      char c = (char) ir.read();
      if (c != '\"') {
        ir.reset(); // not start of a string literal
        return null;
      }

      // parse remaining chars
      final StringBuilder sb = new StringBuilder();
      do {
        sb.append(c);
        int i;
        if ((i = ir.read()) < 0) {
          throw new ParseException(msgUnexpectedEOF(), 0);
        }
        c = (char) i;
      } while (c != '\"'); // not supported: nested '\"' char sequences
      sb.append(c); // keep '\"' part of a string literal
      return sb.toString();
    }

    /**
     * Scans for an array literal. Limitation: only the empty array "{}" can be scanned.
     *
     * @return <code>null</code> if the next token is not an array
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String scanArrayLiteral() throws IOException, ParseException {
      // parse stored token if any
      String t;
      if ((t = getLookAhead()) != null) {
        if (t.charAt(0) != '{' || t.charAt(1) != '}') {
          setLookAhead(t); // not an array literal
          return null;
        }
        return t;
      }

      // parse first char
      if (!skip()) {
        throw new ParseException(msgUnexpectedEOF(), 0);
      }
      ir.mark(1);
      char c = (char) ir.read();
      if (c != '{') {
        ir.reset(); // not start of an array literal
        return null;
      }
      c = (char) ir.read();
      if (c != '}') {
        ir.reset(); // not end of an array literal
        return null;
      }

      return "{}";
    }

    /**
     * Scans for an at-sign
     *
     * @return <code>null</code> if the next token is not an at-sign
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String scanAtSign() throws IOException, ParseException {
      // parse stored token if any
      String t;
      if ((t = getLookAhead()) != null) {
        if (t.charAt(0) != '@') {
          setLookAhead(t); // not an at-sign
          return null;
        }
        return t;
      }

      // parse first char
      if (!skip()) {
        throw new ParseException(msgUnexpectedEOF(), 0);
      }
      ir.mark(1);
      char c = (char) ir.read();
      if (c != '@') {
        ir.reset(); // not an at-sign
        return null;
      }

      return "@";
    }

    /**
     * Returns the next token to be parsed.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String parseToken() throws IOException, ParseException {
      String t;
      if ((t = getLookAhead()) != null) {
      } else if ((t = scanIdentifier()) != null) {
      } else if ((t = scanNumberLiteral()) != null) {
      } else if ((t = scanStringLiteral()) != null) {
      } else if ((t = scanCharacterLiteral()) != null) {
      } else if ((t = scanAtSign()) != null) {
      } else {
        setLookAhead(t); // not an identifier, number, or string
        // next non-white char
        if (!skip()) {
          throw new ParseException(msgUnexpectedEOF(), 0);
        }
        t = String.valueOf((char) ir.read());
      }
      // log.println("parseToken() : '" + t + "'");
      return t;
    }

    /**
     * Parses the next token and validates it against an expected one.
     *
     * @param token the token
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String demandToken(String token) throws IOException, ParseException {
      final String t = parseToken();
      if (!t.equals(token)) {
        throw new ParseException(msgUnexpectedToken(t), 0);
      }
      return t;
    }

    /**
     * Parses a literal.
     *
     * @return <code>null</code> if the next token is not a literal
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String parseLiteral() throws IOException, ParseException {
      String t;
      if ((t = scanNumberLiteral()) != null) {
      } else if ((t = scanStringLiteral()) != null) {
      } else if ((t = scanCharacterLiteral()) != null) {
      } else if ((t = scanArrayLiteral()) != null) {
      }
      // log.println("parseLiteral() : '" + t + "'");
      return t;
    }

    /**
     * Parses the next token and validates that it is a literal.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String demandLiteral() throws IOException, ParseException {
      final String l = parseLiteral();
      if (l == null) {
        throw new ParseException(msgUnexpectedToken(parseToken()), 0);
      }
      return l;
    }

    /**
     * Parses the next token and validates that it is a constant, which is either a literal or a
     * static member.
     *
     * @return the description of the field
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String demandConstant() throws IOException, ParseException {
      final String literal = parseLiteral();
      if (literal != null) {
        return literal;
      }
      final String field = demandIdentifier();
      if (field == null) {
        throw new ParseException(msgUnexpectedToken(parseToken()), 0);
      }
      return field;
    }

    /**
     * Parses an annotation which is an at-sign followed by a fully qualified interface name.
     *
     * @return <code>null</code> if the next token is not an annotation, otherwise return the
     *     annotation type name without the at-sign.
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String parseAnnotation() throws IOException, ParseException {
      String t;
      // parse stored token if any
      if ((t = getLookAhead()) != null) {
        if (t.charAt(0) != '@') {
          setLookAhead(t); // not a annotation
          return null;
        }
      } else if ((t = scanAtSign()) != null) {
      } else {
        return null;
      }

      final String identifier = demandIdentifier();
      if (identifier == null) {
        throw new ParseException(msgUnexpectedToken(parseToken()), 0);
      }

      return identifier;
    }

    /**
     * Parses the default value specification of an annotation element and validates that it is an
     * element value, which is either an annotation or a constant.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String demandElementValue() throws IOException, ParseException {
      final String annotation = parseAnnotation();
      if (annotation != null) {
        return annotation;
      }
      final String constant = demandConstant();
      if (constant == null) {
        throw new ParseException(msgUnexpectedToken(parseToken()), 0);
      }
      return constant;
    }

    /**
     * Parses any available Java modifiers.
     *
     * @return an int value with the parsed modifiers' bit set
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected int parseModifiers() throws IOException, ParseException {
      int m = 0;
      label:
      while (true) {
        // parse known modifiers
        final String t = parseToken();
        switch (t) {
          case "abstract":
            m |= Modifier.ABSTRACT;
            break;
          case "annotation":
            m |= (ANNOTATION + Modifier.ABSTRACT + Modifier.INTERFACE);
            break;
          case "enum":
            m |= ENUM;
            break;
          case "final":
            m |= Modifier.FINAL;
            break;
          case "interface":
            m |= Modifier.INTERFACE;
            break;
          case "native":
            m |= Modifier.NATIVE;
            break;
          case "private":
            m |= Modifier.PRIVATE;
            break;
          case "protected":
            m |= Modifier.PROTECTED;
            break;
          case "public":
            m |= Modifier.PUBLIC;
            break;
          case "static":
            m |= Modifier.STATIC;
            break;
          case "strictfp":
            m |= Modifier.STRICT;
            break;
          case "synchronized":
            m |= Modifier.SYNCHRONIZED;
            break;
          case "transient":
            m |= Modifier.TRANSIENT;
            break;
          case "varargs":
            m |= Modifier.TRANSIENT;
            break;
          case "volatile":
            m |= Modifier.VOLATILE;
            break;
          default:
            setLookAhead(t); // not a modifier

            break label;
        }
      }
      // log.println("parseModifiers() : '" + Modifier.toString(m) + "'");
      return m;
    }

    /**
     * Parses a (qualified) identifier.
     *
     * @return <code>null</code> if the next token is not an identifier
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String parseIdentifier() throws IOException, ParseException {
      String t = scanIdentifier();
      if (t != null) {
        // parse dot-connected identifiers
        final StringBuilder id = new StringBuilder(t);
        String tt = parseToken();
        while (tt.equals(".")) {
          id.append(".");
          tt = parseIdentifier();
          if (tt == null) {
            throw new ParseException(msgUnexpectedToken(tt), 0);
          }
          id.append(tt);
          tt = parseToken();
        }
        setLookAhead(tt); // not a dot token
        t = id.toString();
      }
      // log.println("parseIdentifier() : '" + t + "'");
      return t;
    }

    /**
     * Parses the next token(s) and validates that it is an identifier.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String demandIdentifier() throws IOException, ParseException {
      final String id = parseIdentifier();
      if (id == null) {
        throw new ParseException(msgUnexpectedToken(parseToken()), 0);
      }
      return id;
    }

    /**
     * Parses a comma-separated list of identifiers.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String[] demandIdentifierList() throws IOException, ParseException {
      final List<String> ids = new ArrayList<>();
      ids.add(demandIdentifier());
      String t;
      while ((t = parseToken()).equals(",")) {
        ids.add(demandIdentifier());
      }
      setLookAhead(t); // not an identifier
      return ids.toArray(new String[ids.size()]);
    }

    /**
     * Parses a type expression.
     *
     * @return <code>null</code> if the next token is not a type
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String parseType() throws IOException, ParseException {
      String t = parseIdentifier();
      if (t != null) {
        // parse array dimensions
        final StringBuilder type = new StringBuilder(t);
        while ((t = parseToken()).equals("[")) {
          demandToken("]");
          type.append("[]");
        }
        setLookAhead(t); // not an open bracket token
        t = type.toString();
      }
      // log.println("parseType() : '" + t + "'");
      return t;
    }

    /**
     * Parses the next token and validates that it is a type expression.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String demandType() throws IOException, ParseException {
      final String id = parseType();
      if (id == null) {
        throw new ParseException(msgUnexpectedToken(parseToken()), 0);
      }
      return id;
    }

    /**
     * Parses a comma-separated parameter list.
     *
     * @return never <code>null</code>
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String[] parseParameterList() throws IOException, ParseException {
      final List<String> types = new ArrayList<>();
      String t = parseType();
      if (t != null) {
        types.add(t);
        parseIdentifier(); // optional parameter name
        while ((t = parseToken()).equals(",")) {
          types.add(demandType());
          parseIdentifier(); // optional parameter name
        }
        setLookAhead(t); // not a comma token
      }
      return types.toArray(new String[types.size()]);
    }

    /**
     * Parses a class member declaration and provides the information to a field, constructor, or
     * method handler.
     *
     * @return <code>null</code> if there's no member declaration
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    protected String parseMember() throws IOException, ParseException {
      // parse optional modifiers, type, and member name
      final int mods = parseModifiers();
      final String typeOrName = parseType();
      if (typeOrName == null) {
        if (mods != 0) {
          throw new ParseException(msgUnexpectedEOF(), 0);
        }
        return null; // no member to parse
      }
      final String memberName = parseIdentifier(); // null if constructor

      // parse optional field value or parameter+exception list
      final String value;
      final String[] params;
      final String[] excepts;
      {
        final String tvp = parseToken();
        switch (tvp) {
          case ";":
            value = null;
            params = null;
            excepts = null;
            break;
          case "=":
            // parse field value
            value = demandLiteral();
            demandToken(";");
            params = null;
            excepts = null;
            break;
          case "(":
            // parse optional parameter and exception list
            params = parseParameterList();
            demandToken(")");
            final String tt = parseToken();
            switch (tt) {
              case "throws":
                excepts = demandIdentifierList();
                demandToken(";");
                value = null;
                break;
              case ";":
                excepts = new String[] {};
                value = null;
                break;
              case "default":
                value = demandElementValue();
                demandToken(";");
                excepts = new String[] {};
                break;
              default:
                throw new ParseException(msgUnexpectedToken(tt), 0);
            }
            break;
          default:
            throw new ParseException(msgUnexpectedToken(tvp), 0);
        }
      }

      // verify field, constructor, or method
      String name = memberName;
      if (params == null) {
        checkField(mods, typeOrName, memberName, value);
      } else {
        if (memberName == null) {
          name = typeOrName;
          checkConstructor(mods, params, excepts);
        } else {
          checkMethod(mods, typeOrName, memberName, params, excepts, value);
        }
      }

      // log.println("parseMember() : " + name);
      return name;
    }

    /**
     * Parses a class definition and provides the information to a handler.
     *
     * @return <code>null</code> if there's no class definition
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    @SuppressWarnings("empty-statement")
    protected String parseClass() throws IOException, ParseException {
      // parse optional modifiers, class token, and class name
      if (!skip()) {
        return null; // eof, no class to parse
      }
      final int mods = parseModifiers();
      final String tc = parseToken();
      if (!tc.equals("class")) { // token 'interface' parsed as modifier
        setLookAhead(tc);
      }
      final String name = demandIdentifier();

      // parse optional extends and implements clauses
      final String[] ext;
      final String[] impl;
      {
        String tei = parseToken();
        if (tei.equals("extends")) {
          ext = demandIdentifierList();
          tei = parseToken();
        } else {
          ext = new String[] {};
        }
        if (((mods & Modifier.INTERFACE) == 0) && tei.equals("implements")) {
          impl = demandIdentifierList();
          tei = parseToken();
        } else {
          impl = new String[] {};
        }
        if (!tei.equals("{")) {
          throw new ParseException(msgUnexpectedToken(tei), 0);
        }
      }

      // verify class header
      checkClass(mods, name, ext, impl);

      // process members; empty-statement intentional
      while (parseMember() != null)
        ;
      demandToken("}");

      // verify class
      postCheckClass();

      // log.println("parseClass() : " + name);
      return name;
    }

    /**
     * Parses a list of signature descriptor files and processes the class definitions.
     *
     * @param descrFileNames list of signature descriptor file names
     * @throws IOException IO error
     * @throws ParseException parsing error
     */
    @SuppressWarnings("empty-statement")
    public void parse(List<String> descrFileNames) throws IOException, ParseException {
      for (final String fileName : descrFileNames) {
        logInfo("");
        logInfo("parsing descriptor file: " + fileName);
        try {
          descriptorFile = new File(fileName);
          ir = new LineNumberReader(new FileReader(descriptorFile));
          ir.setLineNumber(1);
          setLookAhead(null);
          // empty-statement intentional
          while (parseClass() != null)
            ;
        } finally {
          descriptorFile = null;
          if (ir != null) {
            ir.close();
          }
          setLookAhead(null);
        }
      }
    }
  }

  // ----------------------------------------------------------------------
  // Stand-Alone Command-Line Interface
  // ----------------------------------------------------------------------

  /** A writer for standard output. */
  protected static final PrintWriter out = new PrintWriter(System.out, true);

  /** Command line arguments */
  public static final List<String> descrFileNames = new ArrayList<>();

  /** Command line option 'quiet'. */
  private static boolean optionQuiet;

  /** Command line option 'verbose'. */
  private static boolean optionVerbose;

  /** Prints the CLI usage. */
  public static void printUsage() {
    out.println();
    out.println("usage: SignatureVerifier [options] arguments");
    out.println("options:");
    out.println("  [-h|--help               print usage and exit]");
    out.println("  [-q|--quiet              only print error messages]");
    out.println("  [-v|--verbose            print verbose messages]");
    out.println("arguments:");
    out.println("  <signature descriptor file>...");
    out.println();
  }

  /**
   * Parses command line arguments.
   *
   * @param args arguments
   * @return status code
   */
  public static int parseArgs(String[] args) {
    out.println("parse main() arguments");

    // parse this class' options and arguments
    for (String arg : args) {
      if (arg == null) {
        continue;
      }
      if (arg.equalsIgnoreCase("-h") || arg.equalsIgnoreCase("--help")) {
        return -1;
      }
      if (arg.equalsIgnoreCase("-v") || arg.equalsIgnoreCase("--verbose")) {
        optionVerbose = true;
        continue;
      }
      if (arg.equalsIgnoreCase("-q") || arg.equalsIgnoreCase("--quiet")) {
        optionQuiet = true;
        continue;
      }
      if (arg.startsWith("-")) {
        out.println("Usage Error: unknown option " + arg);
        return -1;
      }
      // collect argument
      descrFileNames.add(arg);
    }

    // print args
    if (false) {
      out.println("descrFileNames = {");
      for (String descrFileName : descrFileNames) {
        out.println("                     " + descrFileName);
      }
      out.println("                 }");
      out.println("optionQuiet    = " + optionQuiet);
      out.println("optionVerbose  = " + optionVerbose);
    }

    // check args
    if (descrFileNames.isEmpty()) {
      out.println("Usage Error: Missing argument " + "<signature descriptor file>...");
      return -1;
    }
    return 0;
  }

  /**
   * Runs the signature test and exits with a status code.
   *
   * @param args command line arguments
   */
  public static void main(String[] args) {
    out.println("run SignatureVerifier ...");
    if (parseArgs(args) != 0) {
      printUsage();
      out.println("abort.");
      System.exit(-1);
    }

    int status = 0;
    try {
      final SignatureVerifier s = new SignatureVerifier(out, optionQuiet, optionVerbose);
      status = s.test(descrFileNames);
    } catch (IOException ex) {
      out.println("ERROR: exception caught: " + ex);
      // ex.printStackTrace();
      out.println("abort.");
      System.exit(-2);
    } catch (ParseException ex) {
      out.println("ERROR: exception caught: " + ex);
      // ex.printStackTrace();
      out.println("abort.");
      System.exit(-3);
    }

    out.println();
    out.println("done.");
    System.exit(status);
  }
}