xpointer.c

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/*
 * xpointer.c : Code to handle XML Pointer
 *
 * Base implementation was made accordingly to
 * W3C Candidate Recommendation 7 June 2000
 * http://www.w3.org/TR/2000/CR-xptr-20000607
 *
 * Added support for the element() scheme described in:
 * W3C Proposed Recommendation 13 November 2002
 * http://www.w3.org/TR/2002/PR-xptr-element-20021113/  
 *
 * See Copyright for the status of this software.
 *
 * [e-mail]
 */

#define IN_LIBXML
#include "libxml.h"

/*
 * TODO: better handling of error cases, the full expression should
 *       be parsed beforehand instead of a progressive evaluation
 * TODO: Access into entities references are not supported now ...
 *       need a start to be able to pop out of entities refs since
 *       parent is the endity declaration, not the ref.
 */

#include <string.h>
#include <libxml/xpointer.h>
#include <libxml/xmlmemory.h>
#include <libxml/parserInternals.h>
#include <libxml/uri.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/xmlerror.h>
#include <libxml/globals.h>

#ifdef LIBXML_XPTR_ENABLED

/* Add support of the xmlns() xpointer scheme to initialize the namespaces */
#define XPTR_XMLNS_SCHEME

/* #define DEBUG_RANGES */
#ifdef DEBUG_RANGES
#ifdef LIBXML_DEBUG_ENABLED
#include <libxml/debugXML.h>
#endif
#endif

#define TODO 								\
    xmlGenericError(xmlGenericErrorContext,				\
	    "Unimplemented block at %s:%d\n",				\
            __FILE__, __LINE__);

#define STRANGE 							\
    xmlGenericError(xmlGenericErrorContext,				\
	    "Internal error at %s:%d\n",				\
            __FILE__, __LINE__);

/************************************************************************
 *									*
 * 		Some factorized error routines				*
 *									*
 ************************************************************************/

/**
 * xmlXPtrErrMemory:
 * @extra:  extra informations
 *
 * Handle a redefinition of attribute error
 */
static void
xmlXPtrErrMemory(const char *extra)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_XPOINTER,
		    XML_ERR_NO_MEMORY, XML_ERR_ERROR, NULL, 0, extra,
		    NULL, NULL, 0, 0,
		    "Memory allocation failed : %s\n", extra);
}

/**
 * xmlXPtrErr:
 * @ctxt:  an XPTR evaluation context
 * @extra:  extra informations
 *
 * Handle a redefinition of attribute error
 */
static void
xmlXPtrErr(xmlXPathParserContextPtr ctxt, int error,
           const char * msg, const xmlChar *extra)
{
    if (ctxt != NULL)
        ctxt->error = error;
    if ((ctxt == NULL) || (ctxt->context == NULL)) {
	__xmlRaiseError(NULL, NULL, NULL,
			NULL, NULL, XML_FROM_XPOINTER, error,
			XML_ERR_ERROR, NULL, 0,
			(const char *) extra, NULL, NULL, 0, 0,
			msg, extra);
	return;
    }
    ctxt->context->lastError.domain = XML_FROM_XPOINTER;
    ctxt->context->lastError.code = error;
    ctxt->context->lastError.level = XML_ERR_ERROR;
    ctxt->context->lastError.str1 = (char *) xmlStrdup(ctxt->base);
    ctxt->context->lastError.int1 = ctxt->cur - ctxt->base;
    ctxt->context->lastError.node = ctxt->context->debugNode;
    if (ctxt->context->error != NULL) {
	ctxt->context->error(ctxt->context->userData,
	                     &ctxt->context->lastError);
    } else {
	__xmlRaiseError(NULL, NULL, NULL,
			NULL, ctxt->context->debugNode, XML_FROM_XPOINTER,
			error, XML_ERR_ERROR, NULL, 0,
			(const char *) extra, (const char *) ctxt->base, NULL,
			ctxt->cur - ctxt->base, 0,
			msg, extra);
    }
}

/************************************************************************
 *									*
 *		A few helper functions for child sequences		*
 *									*
 ************************************************************************/
/* xmlXPtrAdvanceNode is a private function, but used by xinclude.c */
xmlNodePtr xmlXPtrAdvanceNode(xmlNodePtr cur, int *level);
/**
 * xmlXPtrGetArity:
 * @cur:  the node
 *
 * Returns the number of child for an element, -1 in case of error
 */
static int
xmlXPtrGetArity(xmlNodePtr cur) {
    int i;
    if (cur == NULL) 
	return(-1);
    cur = cur->children;
    for (i = 0;cur != NULL;cur = cur->next) {
	if ((cur->type == XML_ELEMENT_NODE) ||
	    (cur->type == XML_DOCUMENT_NODE) ||
	    (cur->type == XML_HTML_DOCUMENT_NODE)) {
	    i++;
	}
    }
    return(i);
}

/**
 * xmlXPtrGetIndex:
 * @cur:  the node
 *
 * Returns the index of the node in its parent children list, -1
 *         in case of error
 */
static int
xmlXPtrGetIndex(xmlNodePtr cur) {
    int i;
    if (cur == NULL) 
	return(-1);
    for (i = 1;cur != NULL;cur = cur->prev) {
	if ((cur->type == XML_ELEMENT_NODE) ||
	    (cur->type == XML_DOCUMENT_NODE) ||
	    (cur->type == XML_HTML_DOCUMENT_NODE)) {
	    i++;
	}
    }
    return(i);
}

/**
 * xmlXPtrGetNthChild:
 * @cur:  the node
 * @no:  the child number
 *
 * Returns the @no'th element child of @cur or NULL
 */
static xmlNodePtr
xmlXPtrGetNthChild(xmlNodePtr cur, int no) {
    int i;
    if (cur == NULL) 
	return(cur);
    cur = cur->children;
    for (i = 0;i <= no;cur = cur->next) {
	if (cur == NULL) 
	    return(cur);
	if ((cur->type == XML_ELEMENT_NODE) ||
	    (cur->type == XML_DOCUMENT_NODE) ||
	    (cur->type == XML_HTML_DOCUMENT_NODE)) {
	    i++;
	    if (i == no)
		break;
	}
    }
    return(cur);
}

/************************************************************************
 *									*
 *		Handling of XPointer specific types			*
 *									*
 ************************************************************************/

/**
 * xmlXPtrCmpPoints:
 * @node1:  the first node
 * @index1:  the first index
 * @node2:  the second node
 * @index2:  the second index
 *
 * Compare two points w.r.t document order
 *
 * Returns -2 in case of error 1 if first point < second point, 0 if
 *         that's the same point, -1 otherwise
 */
static int
xmlXPtrCmpPoints(xmlNodePtr node1, int index1, xmlNodePtr node2, int index2) {
    if ((node1 == NULL) || (node2 == NULL))
	return(-2);
    /*
     * a couple of optimizations which will avoid computations in most cases
     */
    if (node1 == node2) {
	if (index1 < index2)
	    return(1);
	if (index1 > index2)
	    return(-1);
	return(0);
    }
    return(xmlXPathCmpNodes(node1, node2));
}

/**
 * xmlXPtrNewPoint:
 * @node:  the xmlNodePtr
 * @indx:  the indx within the node
 *
 * Create a new xmlXPathObjectPtr of type point
 *
 * Returns the newly created object.
 */
static xmlXPathObjectPtr
xmlXPtrNewPoint(xmlNodePtr node, int indx) {
    xmlXPathObjectPtr ret;

    if (node == NULL)
	return(NULL);
    if (indx < 0)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPtrErrMemory("allocating point");
	return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
    ret->type = XPATH_POINT;
    ret->user = (void *) node;
    ret->index = indx;
    return(ret);
}

/**
 * xmlXPtrRangeCheckOrder:
 * @range:  an object range
 *
 * Make sure the points in the range are in the right order
 */
static void
xmlXPtrRangeCheckOrder(xmlXPathObjectPtr range) {
    int tmp;
    xmlNodePtr tmp2;
    if (range == NULL)
	return;
    if (range->type != XPATH_RANGE)
	return;
    if (range->user2 == NULL)
	return;
    tmp = xmlXPtrCmpPoints(range->user, range->index,
	                     range->user2, range->index2);
    if (tmp == -1) {
	tmp2 = range->user;
	range->user = range->user2;
	range->user2 = tmp2;
	tmp = range->index;
	range->index = range->index2;
	range->index2 = tmp;
    }
}

/**
 * xmlXPtrRangesEqual:
 * @range1:  the first range
 * @range2:  the second range
 *
 * Compare two ranges
 *
 * Returns 1 if equal, 0 otherwise
 */
static int
xmlXPtrRangesEqual(xmlXPathObjectPtr range1, xmlXPathObjectPtr range2) {
    if (range1 == range2)
	return(1);
    if ((range1 == NULL) || (range2 == NULL))
	return(0);
    if (range1->type != range2->type)
	return(0);
    if (range1->type != XPATH_RANGE)
	return(0);
    if (range1->user != range2->user)
	return(0);
    if (range1->index != range2->index)
	return(0);
    if (range1->user2 != range2->user2)
	return(0);
    if (range1->index2 != range2->index2)
	return(0);
    return(1);
}

/**
 * xmlXPtrNewRange:
 * @start:  the starting node
 * @startindex:  the start index
 * @end:  the ending point
 * @endindex:  the ending index
 *
 * Create a new xmlXPathObjectPtr of type range
 *
 * Returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPtrNewRange(xmlNodePtr start, int startindex,
	        xmlNodePtr end, int endindex) {
    xmlXPathObjectPtr ret;

    if (start == NULL)
	return(NULL);
    if (end == NULL)
	return(NULL);
    if (startindex < 0)
	return(NULL);
    if (endindex < 0)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPtrErrMemory("allocating range");
	return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
    ret->type = XPATH_RANGE;
    ret->user = start;
    ret->index = startindex;
    ret->user2 = end;
    ret->index2 = endindex;
    xmlXPtrRangeCheckOrder(ret);
    return(ret);
}

/**
 * xmlXPtrNewRangePoints:
 * @start:  the starting point
 * @end:  the ending point
 *
 * Create a new xmlXPathObjectPtr of type range using 2 Points
 *
 * Returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPtrNewRangePoints(xmlXPathObjectPtr start, xmlXPathObjectPtr end) {
    xmlXPathObjectPtr ret;

    if (start == NULL)
	return(NULL);
    if (end == NULL)
	return(NULL);
    if (start->type != XPATH_POINT)
	return(NULL);
    if (end->type != XPATH_POINT)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPtrErrMemory("allocating range");
	return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
    ret->type = XPATH_RANGE;
    ret->user = start->user;
    ret->index = start->index;
    ret->user2 = end->user;
    ret->index2 = end->index;
    xmlXPtrRangeCheckOrder(ret);
    return(ret);
}

/**
 * xmlXPtrNewRangePointNode:
 * @start:  the starting point
 * @end:  the ending node
 *
 * Create a new xmlXPathObjectPtr of type range from a point to a node
 *
 * Returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPtrNewRangePointNode(xmlXPathObjectPtr start, xmlNodePtr end) {
    xmlXPathObjectPtr ret;

    if (start == NULL)
	return(NULL);
    if (end == NULL)
	return(NULL);
    if (start->type != XPATH_POINT)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPtrErrMemory("allocating range");
	return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
    ret->type = XPATH_RANGE;
    ret->user = start->user;
    ret->index = start->index;
    ret->user2 = end;
    ret->index2 = -1;
    xmlXPtrRangeCheckOrder(ret);
    return(ret);
}

/**
 * xmlXPtrNewRangeNodePoint:
 * @start:  the starting node
 * @end:  the ending point
 *
 * Create a new xmlXPathObjectPtr of type range from a node to a point
 *
 * Returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPtrNewRangeNodePoint(xmlNodePtr start, xmlXPathObjectPtr end) {
    xmlXPathObjectPtr ret;

    if (start == NULL)
	return(NULL);
    if (end == NULL)
	return(NULL);
    if (start->type != XPATH_POINT)
	return(NULL);
    if (end->type != XPATH_POINT)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPtrErrMemory("allocating range");
	return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
    ret->type = XPATH_RANGE;
    ret->user = start;
    ret->index = -1;
    ret->user2 = end->user;
    ret->index2 = end->index;
    xmlXPtrRangeCheckOrder(ret);
    return(ret);
}

/**
 * xmlXPtrNewRangeNodes:
 * @start:  the starting node
 * @end:  the ending node
 *
 * Create a new xmlXPathObjectPtr of type range using 2 nodes
 *
 * Returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPtrNewRangeNodes(xmlNodePtr start, xmlNodePtr end) {
    xmlXPathObjectPtr ret;

    if (start == NULL)
	return(NULL);
    if (end == NULL)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPtrErrMemory("allocating range");
	return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));