root/third_party/libxslt/libexslt/functions.c

DEFINITIONS

1. exsltFuncRegisterFunc
2. exsltFuncRegisterImportFunc
3. exsltFuncInit
4. exsltFuncShutdown
5. exsltFuncStyleInit
6. exsltFuncStyleShutdown
7. exsltFuncNewFunctionData
8. exsltFreeFuncResultPreComp
9. exsltFuncFunctionFunction
10. exsltFuncFunctionComp
11. exsltFuncResultComp
12. exsltFuncResultElem
13. exsltFuncRegister

#define IN_LIBEXSLT
#include "libexslt/libexslt.h"

#if defined(WIN32) && !defined (__CYGWIN__) && (!__MINGW32__)
#include <win32config.h>
#else
#include "config.h"
#endif

#include <string.h>

#include <libxml/tree.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/hash.h>
#include <libxml/debugXML.h>

#include <libxslt/xsltutils.h>
#include <libxslt/variables.h>
#include <libxslt/xsltInternals.h>
#include <libxslt/extensions.h>
#include <libxslt/transform.h>
#include <libxslt/imports.h>

#include "exslt.h"

typedef struct _exsltFuncFunctionData exsltFuncFunctionData;
struct _exsltFuncFunctionData {
    int nargs;                  /* number of arguments to the function */
    xmlNodePtr content;         /* the func:fuction template content */
};

typedef struct _exsltFuncData exsltFuncData;
struct _exsltFuncData {
    xmlHashTablePtr funcs;      /* pointer to the stylesheet module data */
    xmlXPathObjectPtr result;   /* returned by func:result */
    int error;                  /* did an error occur? */
    xmlDocPtr RVT;   /* result tree fragment */
};

typedef struct _exsltFuncResultPreComp exsltFuncResultPreComp;
struct _exsltFuncResultPreComp {
    xsltElemPreComp comp;
    xmlXPathCompExprPtr select;
    xmlNsPtr *nsList;
    int nsNr;
};

/* Used for callback function in exsltInitFunc */
typedef struct _exsltFuncImportRegData exsltFuncImportRegData;
struct _exsltFuncImportRegData {
    xsltTransformContextPtr ctxt;
    xmlHashTablePtr hash;
};

static void exsltFuncFunctionFunction (xmlXPathParserContextPtr ctxt,
                                       int nargs);
static exsltFuncFunctionData *exsltFuncNewFunctionData(void);

#define MAX_FUNC_RECURSION 1000

/*static const xmlChar *exsltResultDataID = (const xmlChar *) "EXSLT Result";*/

/**
 * exsltFuncRegisterFunc:
 * @func:  the #exsltFuncFunctionData for the function
 * @ctxt:  an XSLT transformation context
 * @URI:  the function namespace URI
 * @name: the function name
 *
 * Registers a function declared by a func:function element
 */
static void
exsltFuncRegisterFunc (exsltFuncFunctionData *data,
                       xsltTransformContextPtr ctxt,
                       const xmlChar *URI, const xmlChar *name,
                       ATTRIBUTE_UNUSED const xmlChar *ignored) {
    if ((data == NULL) || (ctxt == NULL) || (URI == NULL) || (name == NULL))
        return;

    xsltGenericDebug(xsltGenericDebugContext,
                     "exsltFuncRegisterFunc: register {%s}%s\n",
                     URI, name);
    xsltRegisterExtFunction(ctxt, name, URI,
                            exsltFuncFunctionFunction);
}

/*
 * exsltFuncRegisterImportFunc
 * @data:    the exsltFuncFunctionData for the function
 * @ch:      structure containing context and hash table
 * @URI:     the function namespace URI
 * @name:    the function name
 *
 * Checks if imported function is already registered in top-level
 * stylesheet.  If not, copies function data and registers function
 */
static void
exsltFuncRegisterImportFunc (exsltFuncFunctionData *data,
                             exsltFuncImportRegData *ch,
                             const xmlChar *URI, const xmlChar *name,
                             ATTRIBUTE_UNUSED const xmlChar *ignored) {
    exsltFuncFunctionData *func=NULL;

    if ((data == NULL) || (ch == NULL) || (URI == NULL) || (name == NULL))
            return;

    if (ch->ctxt == NULL || ch->hash == NULL)
        return;

    /* Check if already present */
    func = (exsltFuncFunctionData*)xmlHashLookup2(ch->hash, URI, name);
    if (func == NULL) {         /* Not yet present - copy it in */
        func = exsltFuncNewFunctionData();
        memcpy(func, data, sizeof(exsltFuncFunctionData));
        if (xmlHashAddEntry2(ch->hash, URI, name, func) < 0) {
            xsltGenericError(xsltGenericErrorContext,
                    "Failed to register function {%s}%s\n",
                    URI, name);
        } else {                /* Do the registration */
            xsltGenericDebug(xsltGenericDebugContext,
                    "exsltFuncRegisterImportFunc: register {%s}%s\n",
                    URI, name);
            xsltRegisterExtFunction(ch->ctxt, name, URI,
                    exsltFuncFunctionFunction);
        }
    }
}

/**
 * exsltFuncInit:
 * @ctxt: an XSLT transformation context
 * @URI: the namespace URI for the extension
 *
 * Initializes the EXSLT - Functions module.
 * Called at transformation-time; merges all
 * functions declared in the import tree taking
 * import precedence into account, i.e. overriding
 * functions with lower import precedence.
 *
 * Returns the data for this transformation
 */
static exsltFuncData *
exsltFuncInit (xsltTransformContextPtr ctxt, const xmlChar *URI) {
    exsltFuncData *ret;
    xsltStylesheetPtr tmp;
    exsltFuncImportRegData ch;
    xmlHashTablePtr hash;
    
    ret = (exsltFuncData *) xmlMalloc (sizeof(exsltFuncData));
    if (ret == NULL) {
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncInit: not enough memory\n");
        return(NULL);
    }
    memset(ret, 0, sizeof(exsltFuncData));

    ret->result = NULL;
    ret->error = 0;

    ch.hash = (xmlHashTablePtr) xsltStyleGetExtData(ctxt->style, URI);
    ret->funcs = ch.hash;
    xmlHashScanFull(ch.hash, (xmlHashScannerFull) exsltFuncRegisterFunc, ctxt);
    tmp = ctxt->style;
    ch.ctxt = ctxt;
    while ((tmp=xsltNextImport(tmp))!=NULL) {
        hash = xsltGetExtInfo(tmp, URI);
        if (hash != NULL) {
            xmlHashScanFull(hash, 
                    (xmlHashScannerFull) exsltFuncRegisterImportFunc, &ch);
        }
    }

    return(ret);
}

/**
 * exsltFuncShutdown:
 * @ctxt: an XSLT transformation context
 * @URI: the namespace URI for the extension
 * @data: the module data to free up
 *  
 * Shutdown the EXSLT - Functions module
 * Called at transformation-time.
 */
static void
exsltFuncShutdown (xsltTransformContextPtr ctxt ATTRIBUTE_UNUSED,
                   const xmlChar *URI ATTRIBUTE_UNUSED,
                   exsltFuncData *data) {
    if (data->result != NULL)
        xmlXPathFreeObject(data->result);
    xmlFree(data);
}

/**
 * exsltFuncStyleInit:
 * @style: an XSLT stylesheet
 * @URI: the namespace URI for the extension
 *
 * Allocates the stylesheet data for EXSLT - Function
 * Called at compile-time.
 *
 * Returns the allocated data
 */
static xmlHashTablePtr
exsltFuncStyleInit (xsltStylesheetPtr style ATTRIBUTE_UNUSED,
                    const xmlChar *URI ATTRIBUTE_UNUSED) {
    return xmlHashCreate(1);
}

/**
 * exsltFuncStyleShutdown:
 * @style: an XSLT stylesheet
 * @URI: the namespace URI for the extension
 * @data: the stylesheet data to free up 
 *
 * Shutdown the EXSLT - Function module
 * Called at compile-time.
 */
static void
exsltFuncStyleShutdown (xsltStylesheetPtr style ATTRIBUTE_UNUSED,
                        const xmlChar *URI ATTRIBUTE_UNUSED,
                        xmlHashTablePtr data) {
    xmlHashFree(data, (xmlHashDeallocator) xmlFree);
}

/**
 * exsltFuncNewFunctionData:
 *
 * Allocates an #exslFuncFunctionData object
 *
 * Returns the new structure
 */
static exsltFuncFunctionData *
exsltFuncNewFunctionData (void) {
    exsltFuncFunctionData *ret;

    ret = (exsltFuncFunctionData *) xmlMalloc (sizeof(exsltFuncFunctionData));
    if (ret == NULL) {
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncNewFunctionData: not enough memory\n");
        return (NULL);
    }
    memset(ret, 0, sizeof(exsltFuncFunctionData));

    ret->nargs = 0;
    ret->content = NULL;

    return(ret);
}

/**
 * exsltFreeFuncResultPreComp:
 * @comp:  the #exsltFuncResultPreComp to free up
 *
 * Deallocates an #exsltFuncResultPreComp
 */
static void
exsltFreeFuncResultPreComp (exsltFuncResultPreComp *comp) {
    if (comp == NULL)
        return;

    if (comp->select != NULL)
        xmlXPathFreeCompExpr (comp->select);
    if (comp->nsList != NULL)
        xmlFree(comp->nsList);
    xmlFree(comp);
}

/**
 * exsltFuncFunctionFunction:
 * @ctxt:  an XPath parser context
 * @nargs:  the number of arguments
 *
 * Evaluates the func:function element that defines the called function.
 */
static void
exsltFuncFunctionFunction (xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr oldResult, ret;
    exsltFuncData *data;
    exsltFuncFunctionData *func;
    xmlNodePtr paramNode, oldInsert, fake;
    int oldBase;
    xsltStackElemPtr params = NULL, param;
    xsltTransformContextPtr tctxt = xsltXPathGetTransformContext(ctxt);
    int i, notSet;
    struct objChain {
        struct objChain *next;
        xmlXPathObjectPtr obj;
    };
    struct objChain     *savedObjChain = NULL, *savedObj;

    /*
     * retrieve func:function template
     */
    data = (exsltFuncData *) xsltGetExtData (tctxt,
                                             EXSLT_FUNCTIONS_NAMESPACE);
    oldResult = data->result;
    data->result = NULL;

    func = (exsltFuncFunctionData*) xmlHashLookup2 (data->funcs,
                                                    ctxt->context->functionURI,
                                                    ctxt->context->function);

    /*
     * params handling
     */
    if (nargs > func->nargs) {
        xsltGenericError(xsltGenericErrorContext,
                         "{%s}%s: called with too many arguments\n",
                         ctxt->context->functionURI, ctxt->context->function);
        ctxt->error = XPATH_INVALID_ARITY;
        return;
    }
    if (func->content != NULL) {
        paramNode = func->content->prev;
    }
    else
        paramNode = NULL;
    if ((paramNode == NULL) && (func->nargs != 0)) {
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncFunctionFunction: nargs != 0 and "
                         "param == NULL\n");
        return;
    }
    if (tctxt->funcLevel > MAX_FUNC_RECURSION) {
        xsltGenericError(xsltGenericErrorContext,
                         "{%s}%s: detected a recursion\n",
                         ctxt->context->functionURI, ctxt->context->function);
        ctxt->error = XPATH_MEMORY_ERROR;
        return;
    }
    tctxt->funcLevel++;

    /*
     * We have a problem with the evaluation of function parameters.
     * The original library code did not evaluate XPath expressions until
     * the last moment.  After version 1.1.17 of the libxslt, the logic
     * of other parts of the library was changed, and the evaluation of
     * XPath expressions within parameters now takes place as soon as the
     * parameter is parsed/evaluated (xsltParseStylesheetCallerParam).
     * This means that the parameters need to be evaluated in lexical
     * order (since a variable is "in scope" as soon as it is declared).
     * However, on entry to this routine, the values (from the caller) are
     * in reverse order (held on the XPath context variable stack).  To
     * accomplish what is required, I have added code to pop the XPath
     * objects off of the stack at the beginning and save them, then use
     * them (in the reverse order) as the params are evaluated.  This
     * requires an xmlMalloc/xmlFree for each param set by the caller,
     * which is not very nice.  There is probably a much better solution
     * (like change other code to delay the evaluation).
     */
    /* 
     * In order to give the function params and variables a new 'scope'
     * we change varsBase in the context.
     */
    oldBase = tctxt->varsBase;
    tctxt->varsBase = tctxt->varsNr;
    /* If there are any parameters */
    if (paramNode != NULL) {
        /* Fetch the stored argument values from the caller */
        for (i = 0; i < nargs; i++) {
            savedObj = xmlMalloc(sizeof(struct objChain));
            savedObj->next = savedObjChain;
            savedObj->obj = valuePop(ctxt);
            savedObjChain = savedObj;
        }

        /*
         * Prepare to process params in reverse order.  First, go to
         * the beginning of the param chain.
         */
        for (i = 1; i <= func->nargs; i++) {
            if (paramNode->prev == NULL)
                break;
            paramNode = paramNode->prev;
        }
        /*
         * i has total # params found, nargs is number which are present
         * as arguments from the caller
         * Calculate the number of un-set parameters
         */
        notSet = func->nargs - nargs;
        for (; i > 0; i--) {
            param = xsltParseStylesheetCallerParam (tctxt, paramNode);
            if (i > notSet) {   /* if parameter value set */
                param->computed = 1;
                if (param->value != NULL)
                    xmlXPathFreeObject(param->value);
                savedObj = savedObjChain;       /* get next val from chain */
                param->value = savedObj->obj;
                savedObjChain = savedObjChain->next;
                xmlFree(savedObj);
            }
            xsltLocalVariablePush(tctxt, param, -1);
            param->next = params;
            params = param;
            paramNode = paramNode->next;
        }
    }
    /*
     * actual processing
     */
    fake = xmlNewDocNode(tctxt->output, NULL,
                         (const xmlChar *)"fake", NULL);
    oldInsert = tctxt->insert;
    tctxt->insert = fake;
    xsltApplyOneTemplate (tctxt, xmlXPathGetContextNode(ctxt),
                          func->content, NULL, NULL);
    xsltLocalVariablePop(tctxt, tctxt->varsBase, -2);
    tctxt->insert = oldInsert;
    tctxt->varsBase = oldBase;  /* restore original scope */
    if (params != NULL)
        xsltFreeStackElemList(params);    

    if (data->error != 0)
        goto error;

    if (data->result != NULL) {
        ret = data->result;
    } else
        ret = xmlXPathNewCString("");

    data->result = oldResult;

    /*
     * It is an error if the instantiation of the template results in
     * the generation of result nodes.
     */
    if (fake->children != NULL) {
#ifdef LIBXML_DEBUG_ENABLED
        xmlDebugDumpNode (stderr, fake, 1);
#endif
        xsltGenericError(xsltGenericErrorContext,
                         "{%s}%s: cannot write to result tree while "
                         "executing a function\n",
                         ctxt->context->functionURI, ctxt->context->function);
        xmlFreeNode(fake);
        goto error;
    }
    xmlFreeNode(fake);
    valuePush(ctxt, ret);

error:
    /*
    * IMPORTANT: This enables previously tree fragments marked as
    * being results of a function, to be garbage-collected after
    * the calling process exits.
    */
    xsltExtensionInstructionResultFinalize(tctxt);
    tctxt->funcLevel--;
}


static void
exsltFuncFunctionComp (xsltStylesheetPtr style, xmlNodePtr inst) {
    xmlChar *name, *prefix;
    xmlNsPtr ns;
    xmlHashTablePtr data;
    exsltFuncFunctionData *func;

    if ((style == NULL) || (inst == NULL))
        return;


    {
        xmlChar *qname;

        qname = xmlGetProp(inst, (const xmlChar *) "name");
        name = xmlSplitQName2 (qname, &prefix);
        xmlFree(qname);
    }
    if ((name == NULL) || (prefix == NULL)) {
        xsltGenericError(xsltGenericErrorContext,
                         "func:function: not a QName\n");
        if (name != NULL)
            xmlFree(name);
        return;
    }
    /* namespace lookup */
    ns = xmlSearchNs (inst->doc, inst, prefix);
    if (ns == NULL) {
        xsltGenericError(xsltGenericErrorContext,
                         "func:function: undeclared prefix %s\n",
                         prefix);
        xmlFree(name);
        xmlFree(prefix);
        return;
    }
    xmlFree(prefix);

    /*
     * Create function data
     */
    func = exsltFuncNewFunctionData();
    func->content = inst->children;
    while (IS_XSLT_ELEM(func->content) &&
           IS_XSLT_NAME(func->content, "param")) {
        func->content = func->content->next;
        func->nargs++;
    }

    xsltParseTemplateContent(style, inst);

    /*
     * Register the function data such that it can be retrieved
     * by exslFuncFunctionFunction
     */
#ifdef XSLT_REFACTORED
    /*
    * Ensure that the hash table will be stored in the *current*
    * stylesheet level in order to correctly evaluate the
    * import precedence.
    */
    data = (xmlHashTablePtr)
        xsltStyleStylesheetLevelGetExtData(style,
            EXSLT_FUNCTIONS_NAMESPACE);
#else
    data = (xmlHashTablePtr)
        xsltStyleGetExtData (style, EXSLT_FUNCTIONS_NAMESPACE);
#endif
    if (data == NULL) {
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncFunctionComp: no stylesheet data\n");
        xmlFree(name);
        return;
    }

    if (xmlHashAddEntry2 (data, ns->href, name, func) < 0) {
        xsltTransformError(NULL, style, inst,
            "Failed to register function {%s}%s\n",
                         ns->href, name);
        style->errors++;
    } else {
        xsltGenericDebug(xsltGenericDebugContext,
                         "exsltFuncFunctionComp: register {%s}%s\n",
                         ns->href, name);
    }
    xmlFree(name);
}

static xsltElemPreCompPtr
exsltFuncResultComp (xsltStylesheetPtr style, xmlNodePtr inst,
                     xsltTransformFunction function) {
    xmlNodePtr test;
    xmlChar *sel;
    exsltFuncResultPreComp *ret;

    /*
     * "Validity" checking
     */
    /* it is an error to have any following sibling elements aside
     * from the xsl:fallback element.
     */
    for (test = inst->next; test != NULL; test = test->next) {
        if (test->type != XML_ELEMENT_NODE)
            continue;
        if (IS_XSLT_ELEM(test) && IS_XSLT_NAME(test, "fallback"))
            continue;
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncResultElem: only xsl:fallback is "
                         "allowed to follow func:result\n");
        return (NULL);
    }
    /* it is an error for a func:result element to not be a descendant
     * of func:function.
     * it is an error if a func:result occurs within a func:result
     * element.
     * it is an error if instanciating the content of a variable
     * binding element (i.e. xsl:variable, xsl:param) results in the 
     * instanciation of a func:result element.
     */
    for (test = inst->parent; test != NULL; test = test->parent) {
        if (IS_XSLT_ELEM(test) &&
            IS_XSLT_NAME(test, "stylesheet")) {
            xsltGenericError(xsltGenericErrorContext,
                             "func:result element not a descendant "
                             "of a func:function\n");
            return (NULL);
        }
        if ((test->ns != NULL) &&
            (xmlStrEqual(test->ns->href, EXSLT_FUNCTIONS_NAMESPACE))) {
            if (xmlStrEqual(test->name, (const xmlChar *) "function")) {
                break;
            }
            if (xmlStrEqual(test->name, (const xmlChar *) "result")) {
                xsltGenericError(xsltGenericErrorContext,
                                 "func:result element not allowed within"
                                 " another func:result element\n");
                return (NULL);
            }
        }
        if (IS_XSLT_ELEM(test) &&
            (IS_XSLT_NAME(test, "variable") ||
             IS_XSLT_NAME(test, "param"))) {
            xsltGenericError(xsltGenericErrorContext,
                             "func:result element not allowed within"
                             " a variable binding element\n");
            return (NULL);
        }
    }

    /*
     * Precomputation
     */
    ret = (exsltFuncResultPreComp *)
        xmlMalloc (sizeof(exsltFuncResultPreComp));
    if (ret == NULL) {
        xsltPrintErrorContext(NULL, NULL, NULL);
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncResultComp : malloc failed\n");
        return (NULL);
    }
    memset(ret, 0, sizeof(exsltFuncResultPreComp));

    xsltInitElemPreComp ((xsltElemPreCompPtr) ret, style, inst, function,
                 (xsltElemPreCompDeallocator) exsltFreeFuncResultPreComp);
    ret->select = NULL;

    /*
     * Precompute the select attribute
     */
    sel = xmlGetNsProp(inst, (const xmlChar *) "select", NULL);
    if (sel != NULL) {
        ret->select = xmlXPathCompile (sel);
        xmlFree(sel);
    }
    /*
     * Precompute the namespace list
     */
    ret->nsList = xmlGetNsList(inst->doc, inst);
    if (ret->nsList != NULL) {
        int i = 0;
        while (ret->nsList[i] != NULL)
            i++;
        ret->nsNr = i;
    }
    return ((xsltElemPreCompPtr) ret);
}

static void
exsltFuncResultElem (xsltTransformContextPtr ctxt,
                     xmlNodePtr node ATTRIBUTE_UNUSED, xmlNodePtr inst,
                     exsltFuncResultPreComp *comp) {
    exsltFuncData *data;
    xmlXPathObjectPtr ret;
    

    /* It is an error if instantiating the content of the
     * func:function element results in the instantiation of more than
     * one func:result elements.
     */
    data = (exsltFuncData *) xsltGetExtData (ctxt, EXSLT_FUNCTIONS_NAMESPACE);
    if (data == NULL) {
        xsltGenericError(xsltGenericErrorContext,
                         "exsltFuncReturnElem: data == NULL\n");
        return;
    }
    if (data->result != NULL) {
        xsltGenericError(xsltGenericErrorContext,
                         "func:result already instanciated\n");
        data->error = 1;
        return;
    }
    /*
     * Processing
     */
    if (comp->select != NULL) {
        xmlNsPtr *oldXPNsList;
        int oldXPNsNr;
        xmlNodePtr oldXPContextNode;
        /* If the func:result element has a select attribute, then the
         * value of the attribute must be an expression and the
         * returned value is the object that results from evaluating
         * the expression. In this case, the content must be empty.
         */
        if (inst->children != NULL) {
            xsltGenericError(xsltGenericErrorContext,
                             "func:result content must be empty if"
                             " the function has a select attribute\n");
            data->error = 1;
            return;
        }
        oldXPNsList = ctxt->xpathCtxt->namespaces;
        oldXPNsNr = ctxt->xpathCtxt->nsNr;
        oldXPContextNode = ctxt->xpathCtxt->node;

        ctxt->xpathCtxt->namespaces = comp->nsList;
        ctxt->xpathCtxt->nsNr = comp->nsNr;

        ret = xmlXPathCompiledEval(comp->select, ctxt->xpathCtxt);

        ctxt->xpathCtxt->node = oldXPContextNode;
        ctxt->xpathCtxt->nsNr = oldXPNsNr;
        ctxt->xpathCtxt->namespaces = oldXPNsList;

        if (ret == NULL) {
            xsltGenericError(xsltGenericErrorContext,
                             "exsltFuncResultElem: ret == NULL\n");
            return;
        }
        /*
        * Mark it as a function result in order to avoid garbage
        * collecting of tree fragments before the function exits.
        */
        xsltExtensionInstructionResultRegister(ctxt, ret);
    } else if (inst->children != NULL) {
        /* If the func:result element does not have a select attribute
         * and has non-empty content (i.e. the func:result element has
         * one or more child nodes), then the content of the
         * func:result element specifies the value.
         */
        xmlNodePtr oldInsert;
        xmlDocPtr container;

        container = xsltCreateRVT(ctxt);
        if (container == NULL) {
            xsltGenericError(xsltGenericErrorContext,
                             "exsltFuncResultElem: out of memory\n");
            data->error = 1;
            return;
        }
        xsltRegisterLocalRVT(ctxt, container);  

        oldInsert = ctxt->insert;
        ctxt->insert = (xmlNodePtr) container;
        xsltApplyOneTemplate (ctxt, ctxt->xpathCtxt->node,
                              inst->children, NULL, NULL);
        ctxt->insert = oldInsert;

        ret = xmlXPathNewValueTree((xmlNodePtr) container);
        if (ret == NULL) {
            xsltGenericError(xsltGenericErrorContext,
                             "exsltFuncResultElem: ret == NULL\n");
            data->error = 1;
        } else {
            ret->boolval = 0; /* Freeing is not handled there anymore */
            /*
            * Mark it as a function result in order to avoid garbage
            * collecting of tree fragments before the function exits.
            */
            xsltExtensionInstructionResultRegister(ctxt, ret);
        }
    } else {
        /* If the func:result element has empty content and does not
         * have a select attribute, then the returned value is an
         * empty string.
         */
        ret = xmlXPathNewCString("");
    }
    data->result = ret;
}

/**
 * exsltFuncRegister:
 *
 * Registers the EXSLT - Functions module
 */
void
exsltFuncRegister (void) {
    xsltRegisterExtModuleFull (EXSLT_FUNCTIONS_NAMESPACE,
                       (xsltExtInitFunction) exsltFuncInit,
                       (xsltExtShutdownFunction) exsltFuncShutdown,
                       (xsltStyleExtInitFunction) exsltFuncStyleInit,
                       (xsltStyleExtShutdownFunction) exsltFuncStyleShutdown);

    xsltRegisterExtModuleTopLevel ((const xmlChar *) "function",
                                   EXSLT_FUNCTIONS_NAMESPACE,
                                   exsltFuncFunctionComp);
    xsltRegisterExtModuleElement ((const xmlChar *) "result",
                          EXSLT_FUNCTIONS_NAMESPACE,
                          (xsltPreComputeFunction)exsltFuncResultComp,
                          (xsltTransformFunction) exsltFuncResultElem);
}