xpointer.c

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    if (CUR != '(')
	XP_ERROR(XPATH_EXPR_ERROR);
    NEXT;
    level = 1;

    len = xmlStrlen(ctxt->cur);
    len++;
    buffer = (xmlChar *) xmlMallocAtomic(len * sizeof (xmlChar));
    if (buffer == NULL) {
        xmlXPtrErrMemory("allocating buffer");
	return;
    }

    cur = buffer;
    while (CUR != 0) {
	if (CUR == ')') {
	    level--;
	    if (level == 0) {
		NEXT;
		break;
	    }
	    *cur++ = CUR;
	} else if (CUR == '(') {
	    level++;
	    *cur++ = CUR;
	} else if (CUR == '^') {
	    NEXT;
	    if ((CUR == ')') || (CUR == '(') || (CUR == '^')) {
		*cur++ = CUR;
	    } else {
		*cur++ = '^';
		*cur++ = CUR;
	    }
	} else {
	    *cur++ = CUR;
	}
	NEXT;
    }
    *cur = 0;

    if ((level != 0) && (CUR == 0)) {
	xmlFree(buffer);
	XP_ERROR(XPTR_SYNTAX_ERROR);
    }

    if (xmlStrEqual(name, (xmlChar *) "xpointer")) {
	const xmlChar *left = CUR_PTR;

	CUR_PTR = buffer;
	/*
	 * To evaluate an xpointer scheme element (4.3) we need:
	 *   context initialized to the root
	 *   context position initalized to 1
	 *   context size initialized to 1
	 */
	ctxt->context->node = (xmlNodePtr)ctxt->context->doc;
	ctxt->context->proximityPosition = 1;
	ctxt->context->contextSize = 1;
	xmlXPathEvalExpr(ctxt);
	CUR_PTR=left;
    } else if (xmlStrEqual(name, (xmlChar *) "element")) {
	const xmlChar *left = CUR_PTR;
	xmlChar *name2;

	CUR_PTR = buffer;
	if (buffer[0] == '/') {
	    xmlXPathRoot(ctxt);
	    xmlXPtrEvalChildSeq(ctxt, NULL);
	} else {
	    name2 = xmlXPathParseName(ctxt);
	    if (name2 == NULL) {
		CUR_PTR = left;
		xmlFree(buffer);
		XP_ERROR(XPATH_EXPR_ERROR);
	    }
	    xmlXPtrEvalChildSeq(ctxt, name2);
	}
	CUR_PTR = left;
#ifdef XPTR_XMLNS_SCHEME
    } else if (xmlStrEqual(name, (xmlChar *) "xmlns")) {
	const xmlChar *left = CUR_PTR;
	xmlChar *prefix;
	xmlChar *URI;
	xmlURIPtr value;

	CUR_PTR = buffer;
        prefix = xmlXPathParseNCName(ctxt);
	if (prefix == NULL) {
	    xmlFree(buffer);
	    xmlFree(name);
	    XP_ERROR(XPTR_SYNTAX_ERROR);
	}
	SKIP_BLANKS;
	if (CUR != '=') {
	    xmlFree(prefix);
	    xmlFree(buffer);
	    xmlFree(name);
	    XP_ERROR(XPTR_SYNTAX_ERROR);
	}
	NEXT;
	SKIP_BLANKS;
	/* @@ check escaping in the XPointer WD */

	value = xmlParseURI((const char *)ctxt->cur);
	if (value == NULL) {
	    xmlFree(prefix);
	    xmlFree(buffer);
	    xmlFree(name);
	    XP_ERROR(XPTR_SYNTAX_ERROR);
	}
	URI = xmlSaveUri(value);
	xmlFreeURI(value);
	if (URI == NULL) {
	    xmlFree(prefix);
	    xmlFree(buffer);
	    xmlFree(name);
	    XP_ERROR(XPATH_MEMORY_ERROR);
	}
	
	xmlXPathRegisterNs(ctxt->context, prefix, URI);
	CUR_PTR = left;
	xmlFree(URI);
	xmlFree(prefix);
#endif /* XPTR_XMLNS_SCHEME */
    } else {
        xmlXPtrErr(ctxt, XML_XPTR_UNKNOWN_SCHEME,
		   "unsupported scheme '%s'\n", name);
    }
    xmlFree(buffer);
    xmlFree(name);
}

/**
 * xmlXPtrEvalFullXPtr:
 * @ctxt:  the XPointer Parser context
 * @name:  the preparsed Scheme for the first XPtrPart
 *
 * FullXPtr ::= XPtrPart (S? XPtrPart)*
 *
 * As the specs says:
 * -----------
 * When multiple XPtrParts are provided, they must be evaluated in
 * left-to-right order. If evaluation of one part fails, the nexti
 * is evaluated. The following conditions cause XPointer part failure:
 *
 * - An unknown scheme
 * - A scheme that does not locate any sub-resource present in the resource
 * - A scheme that is not applicable to the media type of the resource
 *
 * The XPointer application must consume a failed XPointer part and
 * attempt to evaluate the next one, if any. The result of the first
 * XPointer part whose evaluation succeeds is taken to be the fragment
 * located by the XPointer as a whole. If all the parts fail, the result
 * for the XPointer as a whole is a sub-resource error.
 * -----------
 *
 * Parse and evaluate a Full XPtr i.e. possibly a cascade of XPath based
 * expressions or other schemes.
 */
static void
xmlXPtrEvalFullXPtr(xmlXPathParserContextPtr ctxt, xmlChar *name) {
    if (name == NULL)
    name = xmlXPathParseName(ctxt);
    if (name == NULL)
	XP_ERROR(XPATH_EXPR_ERROR);
    while (name != NULL) {
	xmlXPtrEvalXPtrPart(ctxt, name);

	/* in case of syntax error, break here */
	if (ctxt->error != XPATH_EXPRESSION_OK)
	    return;

	/*
	 * If the returned value is a non-empty nodeset
	 * or location set, return here.
	 */
	if (ctxt->value != NULL) {
	    xmlXPathObjectPtr obj = ctxt->value;

	    switch (obj->type) {
		case XPATH_LOCATIONSET: {
		    xmlLocationSetPtr loc = ctxt->value->user;
		    if ((loc != NULL) && (loc->locNr > 0))
			return;
		    break;
		}
		case XPATH_NODESET: {
		    xmlNodeSetPtr loc = ctxt->value->nodesetval;
		    if ((loc != NULL) && (loc->nodeNr > 0))
			return;
		    break;
		}
		default:
		    break;
	    }

	    /*
	     * Evaluating to improper values is equivalent to
	     * a sub-resource error, clean-up the stack
	     */
	    do {
		obj = valuePop(ctxt);
		if (obj != NULL) {
		    xmlXPathFreeObject(obj);
		}
	    } while (obj != NULL);
	}

	/*
	 * Is there another XPointer part.
	 */
	SKIP_BLANKS;
	name = xmlXPathParseName(ctxt);
    }
}

/**
 * xmlXPtrEvalChildSeq:
 * @ctxt:  the XPointer Parser context
 * @name:  a possible ID name of the child sequence
 *
 *  ChildSeq ::= '/1' ('/' [0-9]*)*
 *             | Name ('/' [0-9]*)+
 *
 * Parse and evaluate a Child Sequence. This routine also handle the
 * case of a Bare Name used to get a document ID.
 */
static void
xmlXPtrEvalChildSeq(xmlXPathParserContextPtr ctxt, xmlChar *name) {
    /*
     * XPointer don't allow by syntax to address in mutirooted trees
     * this might prove useful in some cases, warn about it.
     */
    if ((name == NULL) && (CUR == '/') && (NXT(1) != '1')) {
        xmlXPtrErr(ctxt, XML_XPTR_CHILDSEQ_START,
		   "warning: ChildSeq not starting by /1\n", NULL);
    }

    if (name != NULL) {
	valuePush(ctxt, xmlXPathNewString(name));
	xmlFree(name);
	xmlXPathIdFunction(ctxt, 1);
	CHECK_ERROR;
    }

    while (CUR == '/') {
	int child = 0;
	NEXT;
        
	while ((CUR >= '0') && (CUR <= '9')) {
	    child = child * 10 + (CUR - '0');
	    NEXT;
	}
	xmlXPtrGetChildNo(ctxt, child);
    }
}


/**
 * xmlXPtrEvalXPointer:
 * @ctxt:  the XPointer Parser context
 *
 *  XPointer ::= Name
 *             | ChildSeq
 *             | FullXPtr
 *
 * Parse and evaluate an XPointer
 */
static void
xmlXPtrEvalXPointer(xmlXPathParserContextPtr ctxt) {
    if (ctxt->valueTab == NULL) {
	/* Allocate the value stack */
	ctxt->valueTab = (xmlXPathObjectPtr *) 
			 xmlMalloc(10 * sizeof(xmlXPathObjectPtr));
	if (ctxt->valueTab == NULL) {
	    xmlXPtrErrMemory("allocating evaluation context");
	    return;
	}
	ctxt->valueNr = 0;
	ctxt->valueMax = 10;
	ctxt->value = NULL;
    }
    SKIP_BLANKS;
    if (CUR == '/') {
	xmlXPathRoot(ctxt);
        xmlXPtrEvalChildSeq(ctxt, NULL);
    } else {
	xmlChar *name;

	name = xmlXPathParseName(ctxt);
	if (name == NULL)
	    XP_ERROR(XPATH_EXPR_ERROR);
	if (CUR == '(') {
	    xmlXPtrEvalFullXPtr(ctxt, name);
	    /* Short evaluation */
	    return;
	} else {
	    /* this handle both Bare Names and Child Sequences */
	    xmlXPtrEvalChildSeq(ctxt, name);
	}
    }
    SKIP_BLANKS;
    if (CUR != 0)
	XP_ERROR(XPATH_EXPR_ERROR);
}


/************************************************************************
 *									*
 *			General routines				*
 *									*
 ************************************************************************/

void xmlXPtrStringRangeFunction(xmlXPathParserContextPtr ctxt, int nargs);
void xmlXPtrStartPointFunction(xmlXPathParserContextPtr ctxt, int nargs);
void xmlXPtrEndPointFunction(xmlXPathParserContextPtr ctxt, int nargs);
void xmlXPtrHereFunction(xmlXPathParserContextPtr ctxt, int nargs);
void xmlXPtrOriginFunction(xmlXPathParserContextPtr ctxt, int nargs);
void xmlXPtrRangeInsideFunction(xmlXPathParserContextPtr ctxt, int nargs);
void xmlXPtrRangeFunction(xmlXPathParserContextPtr ctxt, int nargs);

/**
 * xmlXPtrNewContext:
 * @doc:  the XML document
 * @here:  the node that directly contains the XPointer being evaluated or NULL
 * @origin:  the element from which a user or program initiated traversal of
 *           the link, or NULL.
 *
 * Create a new XPointer context
 *
 * Returns the xmlXPathContext just allocated.
 */
xmlXPathContextPtr
xmlXPtrNewContext(xmlDocPtr doc, xmlNodePtr here, xmlNodePtr origin) {
    xmlXPathContextPtr ret;

    ret = xmlXPathNewContext(doc);
    if (ret == NULL)
	return(ret);
    ret->xptr = 1;
    ret->here = here;
    ret->origin = origin;

    xmlXPathRegisterFunc(ret, (xmlChar *)"range-to",
	                 xmlXPtrRangeToFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)"range",
	                 xmlXPtrRangeFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)"range-inside",
	                 xmlXPtrRangeInsideFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)"string-range",
	                 xmlXPtrStringRangeFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)"start-point",
	                 xmlXPtrStartPointFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)"end-point",
	                 xmlXPtrEndPointFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)"here",
	                 xmlXPtrHereFunction);
    xmlXPathRegisterFunc(ret, (xmlChar *)" origin",
	                 xmlXPtrOriginFunction);

    return(ret);
}

/**
 * xmlXPtrEval:
 * @str:  the XPointer expression
 * @ctx:  the XPointer context
 *
 * Evaluate the XPath Location Path in the given context.
 *
 * Returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
 *         the caller has to free the object.
 */
xmlXPathObjectPtr
xmlXPtrEval(const xmlChar *str, xmlXPathContextPtr ctx) {
    xmlXPathParserContextPtr ctxt;
    xmlXPathObjectPtr res = NULL, tmp;
    xmlXPathObjectPtr init = NULL;
    int stack = 0;

    xmlXPathInit();

    if ((ctx == NULL) || (str == NULL))
	return(NULL);

    ctxt = xmlXPathNewParserContext(str, ctx);
    ctxt->xptr = 1;
    xmlXPtrEvalXPointer(ctxt);

    if ((ctxt->value != NULL) &&
	(ctxt->value->type != XPATH_NODESET) &&
	(ctxt->value->type != XPATH_LOCATIONSET)) {
        xmlXPtrErr(ctxt, XML_XPTR_EVAL_FAILED,
		"xmlXPtrEval: evaluation failed to return a node set\n",
		   NULL);
    } else {
	res = valuePop(ctxt);
    }

    do {
        tmp = valuePop(ctxt);
	if (tmp != NULL) {
	    if (tmp != init) {
		if (tmp->type == XPATH_NODESET) {
		    /*
		     * Evaluation may push a root nodeset which is unused
		     */
		    xmlNodeSetPtr set; 
		    set = tmp->nodesetval;
		    if ((set->nodeNr != 1) ||
			(set->nodeTab[0] != (xmlNodePtr) ctx->doc))
			stack++;
		} else
		    stack++;    
	    }
	    xmlXPathFreeObject(tmp);
        }
    } while (tmp != NULL);
    if (stack != 0) {
        xmlXPtrErr(ctxt, XML_XPTR_EXTRA_OBJECTS,
		   "xmlXPtrEval: object(s) left on the eval stack\n",
		   NULL);
    }
    if (ctxt->error != XPATH_EXPRESSION_OK) {
	xmlXPathFreeObject(res);
	res = NULL;
    }
        
    xmlXPathFreeParserContext(ctxt);
    return(res);
}

/**
 * xmlXPtrBuildRangeNodeList:
 * @range:  a range object
 *
 * Build a node list tree copy of the range
 *
 * Returns an xmlNodePtr list or NULL.
 *         the caller has to free the node tree.
 */
static xmlNodePtr
xmlXPtrBuildRangeNodeList(xmlXPathObjectPtr range) {
    /* pointers to generated nodes */
    xmlNodePtr list = NULL, last = NULL, parent = NULL, tmp;
    /* pointers to traversal nodes */
    xmlNodePtr start, cur, end;
    int index1, index2;

    if (range == NULL)
	return(NULL);
    if (range->type != XPATH_RANGE)
	return(NULL);
    start = (xmlNodePtr) range->user;

    if (start == NULL)
	return(NULL);
    end = range->user2;
    if (end == NULL)
	return(xmlCopyNode(start, 1));

    cur = start;
    index1 = range->index;
    index2 = range->index2;
    while (cur != NULL) {
	if (cur == end) {
	    if (cur->type == XML_TEXT_NODE) {
		const xmlChar *content = cur->content;
		int len;

		if (content == NULL) {
		    tmp = xmlNewTextLen(NULL, 0);
		} else {
		    len = index2;
		    if ((cur == start) && (index1 > 1)) {
			content += (index1 - 1);
			len -= (index1 - 1);
			index1 = 0;
		    } else {
			len = index2;
		    }
		    tmp = xmlNewTextLen(content, len);
		}
		/* single sub text node selection */
		if (list == NULL)
		    return(tmp);
		/* prune and return full set */
		if (last != NULL)
		    xmlAddNextSibling(last, tmp);
		else 
		    xmlAddChild(parent, tmp);
		return(list);
	    } else {
		tmp = xmlCopyNode(cur, 0);