xmlprocessor.java

這是一個javascript 的 interpreter是了解 web browser的好材料

    }

    final Node toXml(String defaultNamespaceUri, String xml) throws org.xml.sax.SAXException {
        //    See ECMA357 10.3.1
        DocumentBuilder builder = null;
        try {
            String syntheticXml = "<parent xmlns=\"" + defaultNamespaceUri +
                "\">" + xml + "</parent>";
            builder = getDocumentBuilderFromPool(); 
            Document document = builder.parse( new org.xml.sax.InputSource(new java.io.StringReader(syntheticXml)) );
            if (ignoreProcessingInstructions) {
                java.util.Vector v = new java.util.Vector();
                addProcessingInstructionsTo(v, document);
                for (int i=0; i<v.size(); i++) {
                    Node node = (Node)v.elementAt(i);
                    node.getParentNode().removeChild(node);
                }
            }
            if (ignoreComments) {
                java.util.Vector v = new java.util.Vector();
                addCommentsTo(v, document);
                for (int i=0; i<v.size(); i++) {
                    Node node = (Node)v.elementAt(i);
                    node.getParentNode().removeChild(node);
                }
            }
            if (ignoreWhitespace) {
                //    Apparently JAXP setIgnoringElementContentWhitespace() has a different meaning, it appears from the Javadoc
                //    Refers to element-only content models, which means we would need to have a validating parser and DTD or schema
                //    so that it would know which whitespace to ignore.

                //    Instead we will try to delete it ourselves.
                java.util.Vector v = new java.util.Vector();
                addTextNodesToRemoveAndTrim(v, document);
                for (int i=0; i<v.size(); i++) {
                    Node node = (Node)v.elementAt(i);
                    node.getParentNode().removeChild(node);
                }
            }
            NodeList rv = document.getDocumentElement().getChildNodes();
            if (rv.getLength() > 1) {
                throw ScriptRuntime.constructError("SyntaxError", "XML objects may contain at most one node.");
            } else if (rv.getLength() == 0) {
                Node node = document.createTextNode("");
                return node;
            } else {
                Node node = rv.item(0);
                document.getDocumentElement().removeChild(node);
                return node;
            }
        } catch (java.io.IOException e) {
            throw new RuntimeException("Unreachable.");
        } catch (javax.xml.parsers.ParserConfigurationException e) {
            throw new RuntimeException(e);
        } finally {
            if (builder != null)
                returnDocumentBuilderToPool(builder);
        }
    }

    Document newDocument() {
        DocumentBuilder builder = null;
        try {
            //    TODO    Should this use XML settings?
            builder = getDocumentBuilderFromPool();
            return builder.newDocument();
        } catch (javax.xml.parsers.ParserConfigurationException ex) {
            //    TODO    How to handle these runtime errors?
            throw new RuntimeException(ex);
        } finally {
            if (builder != null)
                returnDocumentBuilderToPool(builder);
        }
    }

    //    TODO    Cannot remember what this is for, so whether it should use settings or not
    private String toString(Node node) {
        javax.xml.transform.dom.DOMSource source = new javax.xml.transform.dom.DOMSource(node);
        java.io.StringWriter writer = new java.io.StringWriter();
        javax.xml.transform.stream.StreamResult result = new javax.xml.transform.stream.StreamResult(writer);
        try {
            javax.xml.transform.Transformer transformer = xform.newTransformer();
            transformer.setOutputProperty(javax.xml.transform.OutputKeys.OMIT_XML_DECLARATION, "yes");
            transformer.setOutputProperty(javax.xml.transform.OutputKeys.INDENT, "no");
            transformer.setOutputProperty(javax.xml.transform.OutputKeys.METHOD, "xml");
            transformer.transform(source, result);
        } catch (javax.xml.transform.TransformerConfigurationException ex) {
            //    TODO    How to handle these runtime errors?
            throw new RuntimeException(ex);
        } catch (javax.xml.transform.TransformerException ex) {
            //    TODO    How to handle these runtime errors?
            throw new RuntimeException(ex);
        }
        return toXmlNewlines(writer.toString());
    }

    String escapeAttributeValue(Object value) {
        String text = ScriptRuntime.toString(value);

        if (text.length() == 0) return "";

        Document dom = newDocument();
        Element e = dom.createElement("a");
        e.setAttribute("b", text);
        String elementText = toString(e);
        int begin = elementText.indexOf('"');
        int end = elementText.lastIndexOf('"');
        return elementText.substring(begin+1,end);
    }

    String escapeTextValue(Object value) {
        if (value instanceof XMLObjectImpl) {
            return ((XMLObjectImpl)value).toXMLString();
        }

        String text = ScriptRuntime.toString(value);

        if (text.length() == 0) return text;

        Document dom = newDocument();
        Element e = dom.createElement("a");
        e.setTextContent(text);
        String elementText = toString(e);

        int begin = elementText.indexOf('>') + 1;
        int end = elementText.lastIndexOf('<');
        return (begin < end) ? elementText.substring(begin, end) : "";
    }

    private String escapeElementValue(String s) {
        //    TODO    Check this
        return escapeTextValue(s);
    }

    private String elementToXmlString(Element element) {
        //    TODO    My goodness ECMA is complicated (see 10.2.1).  We'll try this first.
        Element copy = (Element)element.cloneNode(true);
        if (prettyPrint) {
            beautifyElement(copy, 0);
        }
        return toString(copy);
    }

    final String ecmaToXmlString(Node node) {
        //    See ECMA 357 Section 10.2.1
        StringBuffer s = new StringBuffer();
        int indentLevel = 0;
        if (prettyPrint) {
            for (int i=0; i<indentLevel; i++) {
                s.append(' ');
            }
        }
        if (node instanceof Text) {
            String data = ((Text)node).getData();
            //    TODO Does Java trim() work same as XMLWhitespace?
            String v = (prettyPrint) ? data.trim() : data;
            s.append(escapeElementValue(v));
            return s.toString();
        }
        if (node instanceof Attr) {
            String value = ((Attr)node).getValue();
            s.append(escapeAttributeValue(value));
            return s.toString();
        }
        if (node instanceof Comment) {
            s.append("<!--" + ((Comment)node).getNodeValue() + "-->");
            return s.toString();
        }
        if (node instanceof ProcessingInstruction) {
            ProcessingInstruction pi = (ProcessingInstruction)node;
            s.append("<?" + pi.getTarget() + " " + pi.getData() + "?>");
            return s.toString();
        }
        s.append(elementToXmlString((Element)node));
        return s.toString();
    }

    private void beautifyElement(Element e, int indent) {
        StringBuffer s = new StringBuffer();
        s.append('\n');
        for (int i=0; i<indent; i++) {
            s.append(' ');
        }
        String afterContent = s.toString();
        for (int i=0; i<prettyIndent; i++) {
            s.append(' ');
        }
        String beforeContent = s.toString();

        //    We "mark" all the nodes first; if we tried to do this loop otherwise, it would behave unexpectedly (the inserted nodes
        //    would contribute to the length and it might never terminate).
        java.util.Vector toIndent = new java.util.Vector();
        boolean indentChildren = false;
        for (int i=0; i<e.getChildNodes().getLength(); i++) {
            if (i == 1) indentChildren = true;
            if (e.getChildNodes().item(i) instanceof Text) {
                toIndent.add(e.getChildNodes().item(i));
            } else {
                indentChildren = true;
                toIndent.add(e.getChildNodes().item(i));
            }
        }
        if (indentChildren) {
            for (int i=0; i<toIndent.size(); i++) {
                e.insertBefore( e.getOwnerDocument().createTextNode(beforeContent), (Node)toIndent.elementAt(i) );
            }
        }
        NodeList nodes = e.getChildNodes();
        java.util.Vector v = new java.util.Vector();
        for (int i=0; i<nodes.getLength(); i++) {
            if (nodes.item(i) instanceof Element) {
                v.add( nodes.item(i) );
            }
        }
        for (int i=0; i<v.size(); i++) {
            beautifyElement( (Element)v.elementAt(i), indent + prettyIndent );
        }
        if (indentChildren) {
            e.appendChild( e.getOwnerDocument().createTextNode(afterContent) );
        }
    }
}