include/apr_xml.h

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Apache" and "Apache Software Foundation" must
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 *
 * 5. Products derived from this software may not be called "Apache",
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 *
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
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 * information on the Apache Software Foundation, please see
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 */

#ifndef UTIL_XML_H
#define UTIL_XML_H

#ifdef __cplusplus
extern "C" {
#endif

#include "httpd.h"
#include "apr_lib.h"

/**
 * @package Apache XML library
 */

/* -------------------------------------------------------------------- */

/* ### these will need to move at some point to a more logical spot */

/* simple strutures to keep a linked list of pieces of text */
typedef struct ap_text ap_text;

/** Structure to keep a linked list of pieces of text */
struct ap_text {
    /** The current piece of text */
    const char *text;
    /** a pointer to the next piece of text 
     *  @defvar ap_text *next */
    struct ap_text *next;
};

typedef struct ap_text_header ap_text_header;

/** A list of pieces of text */
struct ap_text_header {
    /** The first piece of text in the list */
    ap_text *first;
    /** The last piece of text in the list */
    ap_text *last;
};

/**
 * Append a piece of text to the end of a list
 * @param p The pool to allocate out of
 * @param hdr The text header to append to
 * @param text The new text to append
 * @deffunc void ap_text_append(apr_pool_t *p, ap_text_header *hdr, const char *text)
 */
AP_DECLARE(void) ap_text_append(apr_pool_t *p, ap_text_header *hdr,
                                const char *text);


/* --------------------------------------------------------------------
**
** XML PARSING
*/

/*
** Qualified namespace values
**
** AP_XML_NS_DAV_ID
**    We always insert the "DAV:" namespace URI at the head of the
**    namespace array. This means that it will always be at ID==0,
**    making it much easier to test for.
**
** AP_XML_NS_NONE
**    This special ID is used for two situations:
**
**    1) The namespace prefix begins with "xml" (and we do not know
**       what it means). Namespace prefixes with "xml" (any case) as
**       their first three characters are reserved by the XML Namespaces
**       specification for future use. mod_dav will pass these through
**       unchanged. When this identifier is used, the prefix is LEFT in
**       the element/attribute name. Downstream processing should not
**       prepend another prefix.
**
**    2) The element/attribute does not have a namespace.
**
**       a) No prefix was used, and a default namespace has not been
**          defined.
**       b) No prefix was used, and the default namespace was specified
**          to mean "no namespace". This is done with a namespace
**          declaration of:  xmlns=""
**          (this declaration is typically used to override a previous
**          specification for the default namespace)
**
**       In these cases, we need to record that the elem/attr has no
**       namespace so that we will not attempt to prepend a prefix.
**       All namespaces that are used will have a prefix assigned to
**       them -- mod_dav will never set or use the default namespace
**       when generating XML. This means that "no prefix" will always
**       mean "no namespace".
**
**    In both cases, the XML generation will avoid prepending a prefix.
**    For the first case, this means the original prefix/name will be
**    inserted into the output stream. For the latter case, it means
**    the name will have no prefix, and since we never define a default
**    namespace, this means it will have no namespace.
**
** Note: currently, mod_dav understands the "xmlns" prefix and the
**     "xml:lang" attribute. These are handled specially (they aren't
**     left within the XML tree), so the AP_XML_NS_NONE value won't ever
**     really apply to these values.
*/
#define AP_XML_NS_DAV_ID	0	/* namespace ID for "DAV:" */
#define AP_XML_NS_NONE		-10	/* no namespace for this elem/attr */

#define AP_XML_NS_ERROR_BASE	-100	/* used only during processing */
#define AP_XML_NS_IS_ERROR(e)	((e) <= AP_XML_NS_ERROR_BASE)


typedef struct ap_xml_attr ap_xml_attr;
typedef struct ap_xml_elem ap_xml_elem;
typedef struct ap_xml_doc ap_xml_doc;

/** ap_xml_attr: holds a parsed XML attribute */
struct ap_xml_attr {
    /** attribute name */
    const char *name;
    /** index into namespace array */
    int ns;

    /** attribute value */
    const char *value;

    /** next attribute
     *  @defvar ap_xml_attr *next */
    struct ap_xml_attr *next;
};

/** ap_xml_elem: holds a parsed XML element */
struct ap_xml_elem {
    /** element name */
    const char *name;
    /** index into namespace array */
    int ns;
    /** xml:lang for attrs/contents */
    const char *lang;

    /** cdata right after start tag */
    ap_text_header first_cdata;
    /** cdata after MY end tag */
    ap_text_header following_cdata;

    /** parent element 
     *  @defvar ap_xml_elem *parent */
    struct ap_xml_elem *parent;	
    /** next (sibling) element 
     *  @defvar ap_xml_elem *next */
    struct ap_xml_elem *next;	
    /** first child element 
     *  @defvar ap_xml_elem *first_child */
    struct ap_xml_elem *first_child;
    /** first attribute 
     *  @defvar ap_xml_attr *attr */
    struct ap_xml_attr *attr;		

    /* used only during parsing */
    /** last child element 
     *  @defvar ap_xml_elem *last_child */
    struct ap_xml_elem *last_child;
    /** namespaces scoped by this elem 
     *  @defvar ap_xml_ns_scope *ns_scope */
    struct ap_xml_ns_scope *ns_scope;

    /* used by modules during request processing */
    /** Place for modules to store private data */
    void *private;
};

#define AP_XML_ELEM_IS_EMPTY(e)	((e)->first_child == NULL && \
				 (e)->first_cdata.first == NULL)

/** ap_xml_doc: holds a parsed XML document */
struct ap_xml_doc {
    /** root element */
    ap_xml_elem *root;	
    /** array of namespaces used */
    apr_array_header_t *namespaces;
};

/**
 * Get XML post data and parse it
 * @param r The current request
 * @param pdoc The XML post data
 * @return HTTP status code
 * @deffunc int ap_xml_parse_input(request_rec *r, ap_xml_doc **pdoc)
 */
AP_DECLARE(int) ap_xml_parse_input(request_rec *r, ap_xml_doc **pdoc);


/**
 * Converts an XML element tree to flat text 
 * @param p The pool to allocate out of
 * @param elem The XML element to convert
 * @param style How to covert the XML.  One of:
 * <PRE>
 *     AP_XML_X2T_FULL                start tag, contents, end tag 
 *     AP_XML_X2T_INNER               contents only 
 *     AP_XML_X2T_LANG_INNER          xml:lang + inner contents 
 *     AP_XML_X2T_FULL_NS_LANG        FULL + ns defns + xml:lang 
 * </PRE>
 * @param namespaces The namespace of the current XML element
 * @param ns_map Namespace mapping
 * @param pbuf Buffer to put the converted text into
 * @param psize Size of the converted text
 * @deffunc void ap_xml_to_text(apr_pool_t *p, const ap_xml_elem *elem, int style, apr_array_header_t *namespaces, int *ns_map, const char **pbuf, size_t *psize);
 */
AP_DECLARE(void) ap_xml_to_text(apr_pool_t *p, const ap_xml_elem *elem,
				int style, apr_array_header_t *namespaces,
				int *ns_map, const char **pbuf,
                                apr_size_t *psize);

/* style argument values: */
#define AP_XML_X2T_FULL		0	/* start tag, contents, end tag */
#define AP_XML_X2T_INNER 	1	/* contents only */
#define AP_XML_X2T_LANG_INNER	2	/* xml:lang + inner contents */
#define AP_XML_X2T_FULL_NS_LANG	3	/* FULL + ns defns + xml:lang */

/**
 * empty XML element
 * @param p The pool to allocate out of
 * @param elem The XML element to empty
 * @return the string that was stored in the XML element
 * @deffunc const char *ap_xml_empty_elem(apr_pool_t *p, const ap_xml_elem *elem)
 */
AP_DECLARE(const char *) ap_xml_empty_elem(apr_pool_t *p,
                                           const ap_xml_elem *elem);

/**
 * quote an XML string
 * Replace '<', '>', and '&' with '&lt;', '&gt;', and '&amp;'.
 * @param p The pool to allocate out of
 * @param s The string to quote
 * @param quotes If quotes is true, then replace '"' with '&quot;'.
 * @return The quoted string
 * @deffunc const char *ap_xml_quote_string(apr_pool_t *p, const char *s, int quotes)
 */
AP_DECLARE(const char *) ap_xml_quote_string(apr_pool_t *p, const char *s,
                                             int quotes);

/**
 * Quote an XML element
 * @param p The pool to allocate out of
 * @param elem The element to quote
 * @deffunc void ap_xml_quote_elem(apr_pool_t *p, ap_xml_elem *elem)
 */
AP_DECLARE(void) ap_xml_quote_elem(apr_pool_t *p, ap_xml_elem *elem);

/* manage an array of unique URIs: ap_xml_insert_uri() and AP_XML_URI_ITEM() */

/**
 * return the URI's (existing) index, or insert it and return a new index 
 * @param uri_array array to insert into
 * @param uri The uri to insert
 * @return int The uri's index
 * @deffunc int ap_xml_insert_uri(apr_array_header_t *uri_array, const char *uri)
 */
AP_DECLARE(int) ap_xml_insert_uri(apr_array_header_t *uri_array,
                                  const char *uri);
#define AP_XML_GET_URI_ITEM(ary, i)    (((const char * const *)(ary)->elts)[i])

#ifdef __cplusplus
}
#endif

#endif /* UTIL_XML_H */