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/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.ba.bcp;

import java.util.regex.Pattern;

import javax.annotation.Nullable;

import org.apache.bcel.Const;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InvokeInstruction;

import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.Edge;
import edu.umd.cs.findbugs.ba.Hierarchy;
import edu.umd.cs.findbugs.ba.RepositoryLookupFailureCallback;
import edu.umd.cs.findbugs.ba.vna.ValueNumberFrame;

/**
 * A PatternElement to match a method invocation. Currently, we don't allow
 * variables in this element (for arguments and return value). This would be a
 * good thing to add. We also don't distinguish between invokevirtual,
 * invokeinterface, and invokespecial.
 * 
 * 
 * Invoke objects match by class name, method name, method signature, and
 * mode.
 * 
 * 
 * Names and signatures may be matched in several ways:
 * 
 * By an exact match. This is the default behavior.
 * By a regular expression. If the string provided to the Invoke constructor
 * begins with a "/" character, the rest of the string is treated as a regular
 * expression.
 * As a subclass match. This only applies to class name matches. If the
 * first character of a class name string is "+", then the rest of the string is
 * treated as the name of a base class. Any subclass or subinterface of the
 * named type will be accepted.
 * 
 * 
 * The mode specifies what kind of invocations in the Invoke element
 * matches. It is specified as the bitwise combination of the following values:
 * 
 *  INSTANCE, which matches ordinary instance method invocations
 *  STATIC, which matches static method invocations
 *  CONSTRUCTOR, which matches object constructor invocations
 * 
 * The special mode ORDINARY_METHOD is equivalent to
 * INSTANCE|STATIC. The special mode ANY is equivalent
 * to INSTANCE|STATIC|CONSTRUCTOR.
 *
 * @author David Hovemeyer
 * @see PatternElement
 */
public class Invoke extends PatternElement {

    /**
     * Match ordinary (non-constructor) instance invocations.
     */
    public static final int INSTANCE = 1;

    /**
     * Match static invocations.
     */
    public static final int STATIC = 2;

    /**
     * Match object constructor invocations.
     */
    public static final int CONSTRUCTOR = 4;

    /**
     * Match ordinary methods (everything except constructors).
     */
    public static final int ORDINARY_METHOD = INSTANCE | STATIC;

    /**
     * Match both static and instance invocations.
     */
    public static final int ANY = INSTANCE | STATIC | CONSTRUCTOR;

    private interface StringMatcher {
        public boolean match(String s);
    }

    private static class ExactStringMatcher implements StringMatcher {
        private final String value;

        public ExactStringMatcher(String value) {
            this.value = value;
        }

        @Override
        public boolean match(String s) {
            return s.equals(value);
        }
    }

    private static class RegexpStringMatcher implements StringMatcher {
        private final Pattern pattern;

        public RegexpStringMatcher(String re) {
            pattern = Pattern.compile(re);
        }

        @Override
        public boolean match(String s) {
            return pattern.matcher(s).matches();
        }
    }

    private static class SubclassMatcher implements StringMatcher {
        private final String className;

        public SubclassMatcher(String className) {
            this.className = className;
        }

        @Override
        public boolean match(String s) {
            try {
                return Hierarchy.isSubtype(s, className);
            } catch (ClassNotFoundException e) {
                AnalysisContext.reportMissingClass(e);
                return false;
            }
        }
    }

    private final StringMatcher classNameMatcher;

    private final StringMatcher methodNameMatcher;

    private final StringMatcher methodSigMatcher;

    private final int mode;

    /**
     * Constructor.
     *
     * @param className
     *            the class name of the method; may be specified exactly, as a
     *            regexp, or as a subtype match
     * @param methodName
     *            the name of the method; may be specified exactly or as a
     *            regexp
     * @param methodSig
     *            the signature of the method; may be specified exactly or as a
     *            regexp
     * @param mode
     *            the mode of invocation
     */
    public Invoke(String className, String methodName, String methodSig, int mode,
            @Nullable RepositoryLookupFailureCallback lookupFailureCallback) {
        this.classNameMatcher = createClassMatcher(className);
        this.methodNameMatcher = createMatcher(methodName);
        this.methodSigMatcher = createMatcher(methodSig);
        this.mode = mode;
    }

    private StringMatcher createClassMatcher(String s) {
        return s.startsWith("+") ? new SubclassMatcher(s.substring(1)) : createMatcher(s);
    }

    private StringMatcher createMatcher(String s) {
        return s.startsWith("/") ? (StringMatcher) new RegexpStringMatcher(s.substring(1))
                : (StringMatcher) new ExactStringMatcher(s);
    }

    @Override
    public MatchResult match(InstructionHandle handle, ConstantPoolGen cpg, ValueNumberFrame before, ValueNumberFrame after,
            BindingSet bindingSet) throws DataflowAnalysisException {

        // See if the instruction is an InvokeInstruction
        Instruction ins = handle.getInstruction();
        if (!(ins instanceof InvokeInstruction)) {
            return null;
        }
        InvokeInstruction inv = (InvokeInstruction) ins;

        String methodName = inv.getMethodName(cpg);
        boolean isStatic = inv.getOpcode() == Const.INVOKESTATIC;
        boolean isCtor = Const.CONSTRUCTOR_NAME.equals(methodName);

        int actualMode = 0;

        if (isStatic) {
            actualMode |= STATIC;
        }
        if (isCtor) {
            actualMode |= CONSTRUCTOR;
        }
        if (!isStatic && !isCtor) {
            actualMode |= INSTANCE;
        }

        // Intersection of actual and desired modes must be nonempty.
        if ((actualMode & mode) == 0) {
            return null;
        }

        // Check class name, method name, and method signature.
        if (!methodNameMatcher.match(methodName) || !methodSigMatcher.match(inv.getSignature(cpg))
                || !classNameMatcher.match(inv.getClassName(cpg))) {
            return null;
        }

        // It's a match!
        return new MatchResult(this, bindingSet);

    }

    @Override
    public boolean acceptBranch(Edge edge, InstructionHandle source) {
        return true;
    }

    @Override
    public int minOccur() {
        return 1;
    }

    @Override
    public int maxOccur() {
        return 1;
    }
}