asmcontenthandler.java

asm的源码包 并且包含英文的文档

    /**
     * Constructs a new {@link ASMContentHandler ASMContentHandler} object.
     * 
     * @param os output stream to write generated class.
     * @param computeMax <tt>true</tt> if the maximum stack size and the
     *        maximum number of local variables must be automatically computed.
     *        This value is passed to {@link ClassWriter ClassWriter} instance.
     */
    public ASMContentHandler(final OutputStream os, final boolean computeMax) {
        this.os = os;
        this.computeMax = computeMax;
    }

    /**
     * Returns the bytecode of the class that was build with underneath class
     * writer.
     * 
     * @return the bytecode of the class that was build with underneath class
     *         writer or null if there are no classwriter created.
     */
    public byte[] toByteArray() {
        return cw == null ? null : cw.toByteArray();
    }

    /**
     * Process notification of the start of an XML element being reached.
     * 
     * @param ns - The Namespace URI, or the empty string if the element has no
     *        Namespace URI or if Namespace processing is not being performed.
     * @param lName - The local name (without prefix), or the empty string if
     *        Namespace processing is not being performed.
     * @param qName - The qualified name (with prefix), or the empty string if
     *        qualified names are not available.
     * @param list - The attributes attached to the element. If there are no
     *        attributes, it shall be an empty Attributes object.
     * @exception SAXException if a parsing error is to be reported
     */
    public final void startElement(
        final String ns,
        final String lName,
        final String qName,
        final Attributes list) throws SAXException
    {
        // the actual element name is either in lName or qName, depending
        // on whether the parser is namespace aware
        String name = lName == null || lName.length() == 0 ? qName : lName;

        // Compute the current matching rule
        StringBuffer sb = new StringBuffer(match);
        if (match.length() > 0) {
            sb.append('/');
        }
        sb.append(name);
        match = sb.toString();

        // Fire "begin" events for all relevant rules
        Rule r = (Rule) RULES.match(match);
        if (r != null) {
            r.begin(name, list);
        }
    }

    /**
     * Process notification of the end of an XML element being reached.
     * 
     * @param ns - The Namespace URI, or the empty string if the element has no
     *        Namespace URI or if Namespace processing is not being performed.
     * @param lName - The local name (without prefix), or the empty string if
     *        Namespace processing is not being performed.
     * @param qName - The qualified XML 1.0 name (with prefix), or the empty
     *        string if qualified names are not available.
     * 
     * @exception SAXException if a parsing error is to be reported
     */
    public final void endElement(
        final String ns,
        final String lName,
        final String qName) throws SAXException
    {
        // the actual element name is either in lName or qName, depending
        // on whether the parser is namespace aware
        String name = lName == null || lName.length() == 0 ? qName : lName;

        // Fire "end" events for all relevant rules in reverse order
        Rule r = (Rule) RULES.match(match);
        if (r != null) {
            r.end(name);
        }

        // Recover the previous match expression
        int slash = match.lastIndexOf('/');
        if (slash >= 0) {
            match = match.substring(0, slash);
        } else {
            match = "";
        }
    }

    /**
     * Process notification of the end of a document and write generated
     * bytecode into output stream.
     * 
     * @exception SAXException if parsing or writing error is to be reported.
     */
    public final void endDocument() throws SAXException {
        try {
            os.write(toByteArray());
        } catch (IOException ex) {
            throw new SAXException(ex.toString(), ex);
        }
    }

    /**
     * Return the top object on the stack without removing it. If there are no
     * objects on the stack, return <code>null</code>.
     * 
     * @return the top object on the stack without removing it.
     */
    final Object peek() {
        return stack.size() == 0 ? null : stack.get(stack.size() - 1);
    }

    /**
     * Pop the top object off of the stack, and return it. If there are no
     * objects on the stack, return <code>null</code>.
     * 
     * @return the top object off of the stack.
     */
    final Object pop() {
        return stack.size() == 0 ? null : stack.remove(stack.size() - 1);
    }

    /**
     * Push a new object onto the top of the object stack.
     * 
     * @param object The new object
     */
    final void push(final Object object) {
        stack.add(object);
    }

    private static final class RuleSet {

        private final HashMap rules = new HashMap();

        private final List lpatterns = new ArrayList();

        private final List rpatterns = new ArrayList();

        public void add(final String path, final Object rule) {
            String pattern = path;
            if (path.startsWith("*/")) {
                pattern = path.substring(1);
                lpatterns.add(pattern);
            } else if (path.endsWith("/*")) {
                pattern = path.substring(0, path.length() - 1);
                rpatterns.add(pattern);
            }
            rules.put(pattern, rule);
        }

        public Object match(final String path) {
            if (rules.containsKey(path)) {
                return rules.get(path);
            }

            int n = path.lastIndexOf('/');
            for (Iterator it = lpatterns.iterator(); it.hasNext();) {
                String pattern = (String) it.next();
                if (path.substring(n).endsWith(pattern)) {
                    return rules.get(pattern);
                }
            }

            for (Iterator it = rpatterns.iterator(); it.hasNext();) {
                String pattern = (String) it.next();
                if (path.startsWith(pattern)) {
                    return rules.get(pattern);
                }
            }

            return null;
        }
    }

    /**
     * Rule
     */
    protected abstract class Rule {

        public void begin(final String name, final Attributes attrs)
                throws SAXException
        {
        }

        public void end(final String name) {
        }

        protected final Object getValue(final String desc, final String val)
                throws SAXException
        {
            Object value = null;
            if (val != null) {
                if (desc.equals("Ljava/lang/String;")) {
                    value = decode(val);
                } else if ("Ljava/lang/Integer;".equals(desc)
                        || "I".equals(desc) || "S".equals(desc)
                        || "B".equals(desc) || "C".equals(desc)
                        || desc.equals("Z"))
                {
                    value = new Integer(val);

                } else if ("Ljava/lang/Short;".equals(desc)) {
                    value = new Short(val);

                } else if ("Ljava/lang/Byte;".equals(desc)) {
                    value = new Byte(val);

                } else if ("Ljava/lang/Character;".equals(desc)) {
                    value = new Character(decode(val).charAt(0));

                } else if ("Ljava/lang/Boolean;".equals(desc)) {
                    value = Boolean.valueOf(val);

                    // } else if ("Ljava/lang/Integer;".equals(desc)
                    // || desc.equals("I"))
                    // {
                    // value = new Integer(val);
                    // } else if ("Ljava/lang/Character;".equals(desc)
                    // || desc.equals("C"))
                    // {
                    // value = new Character(decode(val).charAt(0));
                    // } else if ("Ljava/lang/Short;".equals(desc) ||
                    // desc.equals("S"))
                    // {
                    // value = Short.valueOf(val);
                    // } else if ("Ljava/lang/Byte;".equals(desc) ||
                    // desc.equals("B"))
                    // {
                    // value = Byte.valueOf(val);

                } else if ("Ljava/lang/Long;".equals(desc) || desc.equals("J"))
                {
                    value = new Long(val);
                } else if ("Ljava/lang/Float;".equals(desc) || desc.equals("F"))
                {
                    value = new Float(val);
                } else if ("Ljava/lang/Double;".equals(desc)
                        || desc.equals("D"))
                {
                    value = new Double(val);
                } else if (Type.getDescriptor(Type.class).equals(desc)) {
                    value = Type.getType(val);

                    // } else if ("[I".equals(desc)) {
                    // value = new int[0]; // TODO
                    // } else if ("[C".equals(desc)) {
                    // value = new char[0]; // TODO
                    // } else if ("[Z".equals(desc)) {
                    // value = new boolean[0]; // TODO
                    // } else if ("[S".equals(desc)) {
                    // value = new short[0]; // TODO
                    // } else if ("[B".equals(desc)) {
                    // value = new byte[0]; // TODO
                    // } else if ("[J".equals(desc)) {
                    // value = new long[0]; // TODO
                    // } else if ("[F".equals(desc)) {
                    // value = new float[0]; // TODO
                    // } else if ("[D".equals(desc)) {
                    // value = new double[0]; // TODO

                } else {
                    throw new SAXException("Invalid value:" + val + " desc:"
                            + desc + " ctx:" + this);
                }
            }
            return value;
        }

        private final String decode(final String val) throws SAXException {
            StringBuffer sb = new StringBuffer(val.length());
            try {
                int n = 0;
                while (n < val.length()) {
                    char c = val.charAt(n);
                    if (c == '\\') {
                        n++;
                        c = val.charAt(n);
                        if (c == '\\') {
                            sb.append('\\');
                        } else {
                            n++; // skip 'u'
                            sb.append((char) Integer.parseInt(val.substring(n,
                                    n + 4), 16));
                            n += 3;
                        }
                    } else {
                        sb.append(c);
                    }
                    n++;
                }

            } catch (RuntimeException ex) {
                throw new SAXException(ex);
            }
            return sb.toString();
        }

        protected final Label getLabel(final Object label) {
            Label lbl = (Label) labels.get(label);
            if (lbl == null) {
                lbl = new Label();
                labels.put(label, lbl);
            }
            return lbl;
        }

        // TODO verify move to stack
        protected final MethodVisitor getCodeVisitor() {
            return (MethodVisitor) peek();
        }

        protected final int getAccess(final String s) {
            int access = 0;
            if (s.indexOf("public") != -1) {
                access |= Opcodes.ACC_PUBLIC;
            }