/* -*-             c-basic-offset: 4; indent-tabs-mode: nil; -*-  //------100-columns-wide------>|*/
// for license please see accompanying LICENSE.txt file (available also at http://www.xmlpull.org/)

package org.codehaus.plexus.util.xml.pull;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;

Define an interface to serialization of XML Infoset. This interface abstracts away if serialized XML is XML 1.0
compatible text or other formats of XML 1.0 serializations (such as binary XML for example with WBXML).

PLEASE NOTE: This interface will be part of XmlPull 1.2 API. It is included as basis for discussion. It may
change in any way.

Exceptions that may be thrown are: IOException or runtime exception (more runtime exceptions can be thrown but are
not declared and as such have no semantics defined for this interface):

IllegalArgumentException - for almost all methods to signal that argument is illegal
IllegalStateException - to signal that call has good arguments but is not expected here (violation of
contract) and for features/properties when requesting setting unimplemented feature/property
(UnsupportedOperationException would be better but it is not in MIDP)


NOTE: writing CDSECT, ENTITY_REF, IGNORABLE_WHITESPACE, PROCESSING_INSTRUCTION, COMMENT, and DOCDECL in some
implementations may not be supported (for example when serializing to WBXML). In such case IllegalStateException will
be thrown and it is recommended to use an optional feature to signal that implementation is not supporting this kind
of output.
/**
 * Define an interface to serialization of XML Infoset. This interface abstracts away if serialized XML is XML 1.0
 * compatible text or other formats of XML 1.0 serializations (such as binary XML for example with WBXML).
 * <p>
 * <b>PLEASE NOTE:</b> This interface will be part of XmlPull 1.2 API. It is included as basis for discussion. It may
 * change in any way.
 * <p>
 * Exceptions that may be thrown are: IOException or runtime exception (more runtime exceptions can be thrown but are
 * not declared and as such have no semantics defined for this interface):
 * <ul>
 * <li><em>IllegalArgumentException</em> - for almost all methods to signal that argument is illegal
 * <li><em>IllegalStateException</em> - to signal that call has good arguments but is not expected here (violation of
 * contract) and for features/properties when requesting setting unimplemented feature/property
 * (UnsupportedOperationException would be better but it is not in MIDP)
 * </ul>
 * <p>
 * <b>NOTE:</b> writing CDSECT, ENTITY_REF, IGNORABLE_WHITESPACE, PROCESSING_INSTRUCTION, COMMENT, and DOCDECL in some
 * implementations may not be supported (for example when serializing to WBXML). In such case IllegalStateException will
 * be thrown and it is recommended to use an optional feature to signal that implementation is not supporting this kind
 * of output.
 */

public interface XmlSerializer
{

    
Set feature identified by name (recommended to be URI for uniqueness). Some well known optional features are
defined in 
http://www.xmlpull.org/v1/doc/features.html. If feature is not recognized or can not be set then
IllegalStateException MUST be thrown.
Throws:
IllegalStateException – If the feature is not supported or can not be set/**
     * Set feature identified by name (recommended to be URI for uniqueness). Some well known optional features are
     * defined in <a href="http://www.xmlpull.org/v1/doc/features.html">
     * http://www.xmlpull.org/v1/doc/features.html</a>. If feature is not recognized or can not be set then
     * IllegalStateException MUST be thrown.
     *
     * @exception IllegalStateException If the feature is not supported or can not be set
     */
    void setFeature( String name, boolean state )
        throws IllegalArgumentException, IllegalStateException;

    
Return the current value of the feature with given name.

NOTE: unknown properties are always returned as null
Params:
name – The name of feature to be retrieved.
Throws:
IllegalArgumentException – if feature string is null
Returns:
The value of named feature./**
     * Return the current value of the feature with given name.
     * <p>
     * <strong>NOTE:</strong> unknown properties are <strong>always</strong> returned as null
     *
     * @param name The name of feature to be retrieved.
     * @return The value of named feature.
     * @exception IllegalArgumentException if feature string is null
     */
    boolean getFeature( String name );

    
Set the value of a property. (the property name is recommended to be URI for uniqueness). Some well known
optional properties are defined in 
http://www.xmlpull.org/v1/doc/properties.html. If property is not recognized or can not be set then
IllegalStateException MUST be thrown.
Throws:
IllegalStateException – if the property is not supported or can not be set/**
     * Set the value of a property. (the property name is recommended to be URI for uniqueness). Some well known
     * optional properties are defined in <a href="http://www.xmlpull.org/v1/doc/properties.html">
     * http://www.xmlpull.org/v1/doc/properties.html</a>. If property is not recognized or can not be set then
     * IllegalStateException MUST be thrown.
     *
     * @exception IllegalStateException if the property is not supported or can not be set
     */
    void setProperty( String name, Object value )
        throws IllegalArgumentException, IllegalStateException;

    
Look up the value of a property. The property name is any fully-qualified URI. I

NOTE: unknown properties are always returned as null
Params:
name – The name of property to be retrieved.
Returns:
The value of named property./**
     * Look up the value of a property. The property name is any fully-qualified URI. I
     * <p>
     * <strong>NOTE:</strong> unknown properties are <strong>always</strong> returned as null
     *
     * @param name The name of property to be retrieved.
     * @return The value of named property.
     */
    Object getProperty( String name );

    
Set to use binary output stream with given encoding.
/**
     * Set to use binary output stream with given encoding.
     */
    void setOutput( OutputStream os, String encoding )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Set the output to the given writer.

WARNING no information about encoding is available!
/**
     * Set the output to the given writer.
     * <p>
     * <b>WARNING</b> no information about encoding is available!
     */
    void setOutput( Writer writer )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Write <?xml declaration with encoding (if encoding not null) and standalone flag (if standalone not null)
This method can only be called just after setOutput.
/**
     * Write &lt;&#63;xml declaration with encoding (if encoding not null) and standalone flag (if standalone not null)
     * This method can only be called just after setOutput.
     */
    void startDocument( String encoding, Boolean standalone )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Finish writing. All unclosed start tags will be closed and output will be flushed. After calling this method no
more output can be serialized until next call to setOutput()
/**
     * Finish writing. All unclosed start tags will be closed and output will be flushed. After calling this method no
     * more output can be serialized until next call to setOutput()
     */
    void endDocument()
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Binds the given prefix to the given namespace. This call is valid for the next element including child elements.
The prefix and namespace MUST be always declared even if prefix is not used in element (startTag() or
attribute()) - for XML 1.0 it must result in declaring xmlns:prefix='namespace' (or
xmlns:prefix="namespace" depending what character is used to quote attribute value).

NOTE: this method MUST be called directly before startTag() and if anything but startTag() or setPrefix()
is called next there will be exception.

NOTE: prefixes "xml" and "xmlns" are already bound and can not be redefined see:
Namespaces in XML Errata.

NOTE: to set default namespace use as prefix empty string.
Params:
prefix – must be not null (or IllegalArgumentException is thrown)
namespace – must be not null/**
     * Binds the given prefix to the given namespace. This call is valid for the next element including child elements.
     * The prefix and namespace MUST be always declared even if prefix is not used in element (startTag() or
     * attribute()) - for XML 1.0 it must result in declaring <code>xmlns:prefix='namespace'</code> (or
     * <code>xmlns:prefix="namespace"</code> depending what character is used to quote attribute value).
     * <p>
     * <b>NOTE:</b> this method MUST be called directly before startTag() and if anything but startTag() or setPrefix()
     * is called next there will be exception.
     * <p>
     * <b>NOTE:</b> prefixes "xml" and "xmlns" are already bound and can not be redefined see:
     * <a href="http://www.w3.org/XML/xml-names-19990114-errata#NE05">Namespaces in XML Errata</a>.
     * <p>
     * <b>NOTE:</b> to set default namespace use as prefix empty string.
     *
     * @param prefix must be not null (or IllegalArgumentException is thrown)
     * @param namespace must be not null
     */
    void setPrefix( String prefix, String namespace )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Return namespace that corresponds to given prefix If there is no prefix bound to this namespace return null but
if generatePrefix is false then return generated prefix.

NOTE: if the prefix is empty string "" and default namespace is bound to this prefix then empty string
("") is returned.

NOTE: prefixes "xml" and "xmlns" are already bound will have values as defined
Namespaces in XML specification
/**
     * Return namespace that corresponds to given prefix If there is no prefix bound to this namespace return null but
     * if generatePrefix is false then return generated prefix.
     * <p>
     * <b>NOTE:</b> if the prefix is empty string "" and default namespace is bound to this prefix then empty string
     * ("") is returned.
     * <p>
     * <b>NOTE:</b> prefixes "xml" and "xmlns" are already bound will have values as defined
     * <a href="http://www.w3.org/TR/REC-xml-names/">Namespaces in XML specification</a>
     */
    String getPrefix( String namespace, boolean generatePrefix )
        throws IllegalArgumentException;

    
Returns the current depth of the element. Outside the root element, the depth is 0. The depth is incremented by 1
when startTag() is called. The depth is decremented after the call to endTag() event was observed.
<!-- outside -->     0
<root>               1
  sometext                 1
    <foobar>         2
    </foobar>        2
</root>              1
<!-- outside -->     0

/**
     * Returns the current depth of the element. Outside the root element, the depth is 0. The depth is incremented by 1
     * when startTag() is called. The depth is decremented after the call to endTag() event was observed.
     *
     * <pre>
     * &lt;!-- outside --&gt;     0
     * &lt;root&gt;               1
     *   sometext                 1
     *     &lt;foobar&gt;         2
     *     &lt;/foobar&gt;        2
     * &lt;/root&gt;              1
     * &lt;!-- outside --&gt;     0
     * </pre>
     */
    int getDepth();

    
Returns the namespace URI of the current element as set by startTag().

NOTE: that means in particular that:

if there was startTag("", ...) then getNamespace() returns ""
if there was startTag(null, ...) then getNamespace() returns null

Returns:
namespace set by startTag() that is currently in scope/**
     * Returns the namespace URI of the current element as set by startTag().
     * <p>
     * <b>NOTE:</b> that means in particular that:
     * <ul>
     * <li>if there was startTag("", ...) then getNamespace() returns ""
     * <li>if there was startTag(null, ...) then getNamespace() returns null
     * </ul>
     *
     * @return namespace set by startTag() that is currently in scope
     */
    String getNamespace();

    
Returns the name of the current element as set by startTag(). It can only be null before first call to startTag()
or when last endTag() is called to close first startTag().
Returns:
namespace set by startTag() that is currently in scope/**
     * Returns the name of the current element as set by startTag(). It can only be null before first call to startTag()
     * or when last endTag() is called to close first startTag().
     *
     * @return namespace set by startTag() that is currently in scope
     */
    String getName();

    
Writes a start tag with the given namespace and name. If there is no prefix defined for the given namespace, a
prefix will be defined automatically. The explicit prefixes for namespaces can be established by calling
setPrefix() immediately before this method. If namespace is null no namespace prefix is printed but just name. If
namespace is empty string then serializer will make sure that default empty namespace is declared (in XML 1.0
xmlns='') or throw IllegalStateException if default namespace is already bound to non-empty string.
/**
     * Writes a start tag with the given namespace and name. If there is no prefix defined for the given namespace, a
     * prefix will be defined automatically. The explicit prefixes for namespaces can be established by calling
     * setPrefix() immediately before this method. If namespace is null no namespace prefix is printed but just name. If
     * namespace is empty string then serializer will make sure that default empty namespace is declared (in XML 1.0
     * xmlns='') or throw IllegalStateException if default namespace is already bound to non-empty string.
     */
    XmlSerializer startTag( String namespace, String name )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Write an attribute. Calls to attribute() MUST follow a call to startTag() immediately. If there is no prefix
defined for the given namespace, a prefix will be defined automatically. If namespace is null or empty string no
namespace prefix is printed but just name.
/**
     * Write an attribute. Calls to attribute() MUST follow a call to startTag() immediately. If there is no prefix
     * defined for the given namespace, a prefix will be defined automatically. If namespace is null or empty string no
     * namespace prefix is printed but just name.
     */
    XmlSerializer attribute( String namespace, String name, String value )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Write end tag. Repetition of namespace and name is just for avoiding errors.

Background: in kXML endTag had no arguments, and non matching tags were very difficult to find... If
namespace is null no namespace prefix is printed but just name. If namespace is empty string then serializer will
make sure that default empty namespace is declared (in XML 1.0 xmlns='').
/**
     * Write end tag. Repetition of namespace and name is just for avoiding errors.
     * <p>
     * <b>Background:</b> in kXML endTag had no arguments, and non matching tags were very difficult to find... If
     * namespace is null no namespace prefix is printed but just name. If namespace is empty string then serializer will
     * make sure that default empty namespace is declared (in XML 1.0 xmlns='').
     */
    XmlSerializer endTag( String namespace, String name )
        throws IOException, IllegalArgumentException, IllegalStateException;

    // /**
    // * Writes a start tag with the given namespace and name.
    // * <br />If there is no prefix defined (prefix == null) for the given namespace,
    // * a prefix will be defined automatically.
    // * <br />If explicit prefixes is passed (prefix != null) then it will be used
    // *and namespace declared if not already declared or
    // * throw IllegalStateException the same prefix was already set on this
    // * element (setPrefix()) and was bound to different namespace.
    // * <br />If namespace is null then prefix must be null too or IllegalStateException is thrown.
    // * <br />If namespace is null then no namespace prefix is printed but just name.
    // * <br />If namespace is empty string then serializer will make sure that
    // * default empty namespace is declared (in XML 1.0 xmlns='')
    // * or throw IllegalStateException if default namespace is already bound
    // * to non-empty string.
    // */
    // XmlSerializer startTag (String prefix, String namespace, String name)
    // throws IOException, IllegalArgumentException, IllegalStateException;
    //
    // /**
    // * Write an attribute. Calls to attribute() MUST follow a call to
    // * startTag() immediately.
    // * <br />If there is no prefix defined (prefix == null) for the given namespace,
    // * a prefix will be defined automatically.
    // * <br />If explicit prefixes is passed (prefix != null) then it will be used
    // * and namespace declared if not already declared or
    // * throw IllegalStateException the same prefix was already set on this
    // * element (setPrefix()) and was bound to different namespace.
    // * <br />If namespace is null then prefix must be null too or IllegalStateException is thrown.
    // * <br />If namespace is null then no namespace prefix is printed but just name.
    // * <br />If namespace is empty string then serializer will make sure that
    // * default empty namespace is declared (in XML 1.0 xmlns='')
    // * or throw IllegalStateException if default namespace is already bound
    // * to non-empty string.
    // */
    // XmlSerializer attribute (String prefix, String namespace, String name, String value)
    // throws IOException, IllegalArgumentException, IllegalStateException;
    //
    // /**
    // * Write end tag. Repetition of namespace, prefix, and name is just for avoiding errors.
    // * <br />If namespace or name arguments are different from corresponding startTag call
    // * then IllegalArgumentException is thrown, if prefix argument is not null and is different
    // * from corresponding starTag then IllegalArgumentException is thrown.
    // * <br />If namespace is null then prefix must be null too or IllegalStateException is thrown.
    // * <br />If namespace is null then no namespace prefix is printed but just name.
    // * <br />If namespace is empty string then serializer will make sure that
    // * default empty namespace is declared (in XML 1.0 xmlns='').
    // * <p><b>Background:</b> in kXML endTag had no arguments, and non matching tags were
    // * very difficult to find...</p>
    // */
    // ALEK: This is really optional as prefix in end tag MUST correspond to start tag but good for error checking
    // XmlSerializer endTag (String prefix, String namespace, String name)
    // throws IOException, IllegalArgumentException, IllegalStateException;

    
Writes text, where special XML chars are escaped automatically
/**
     * Writes text, where special XML chars are escaped automatically
     */
    XmlSerializer text( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Writes text, where special XML chars are escaped automatically
/**
     * Writes text, where special XML chars are escaped automatically
     */
    XmlSerializer text( char[] buf, int start, int len )
        throws IOException, IllegalArgumentException, IllegalStateException;

    void cdsect( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    void entityRef( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    void processingInstruction( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    void comment( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    void docdecl( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    void ignorableWhitespace( String text )
        throws IOException, IllegalArgumentException, IllegalStateException;

    
Write all pending output to the stream. If method startTag() or attribute() was called then start tag is closed
(final >) before flush() is called on underlying output stream.

NOTE: if there is need to close start tag (so no more attribute() calls are allowed) but without flushing
output call method text() with empty string (text("")).
/**
     * Write all pending output to the stream. If method startTag() or attribute() was called then start tag is closed
     * (final &gt;) before flush() is called on underlying output stream.
     * <p>
     * <b>NOTE:</b> if there is need to close start tag (so no more attribute() calls are allowed) but without flushing
     * output call method text() with empty string (text("")).
     */
    void flush()
        throws IOException;

}