schematron.c

/*
 * schematron.c : implementation of the Schematron schema validity checking
 *
 * See Copyright for the status of this software.
 *
 * Daniel Veillard <daniel@veillard.com>
 */

/*
 * TODO:
 * + double check the semantic, especially
 *        - multiple rules applying in a single pattern/node
 *        - the semantic of libxml2 patterns vs. XSLT production referenced
 *          by the spec.
 * + export of results in SVRL
 * + full parsing and coverage of the spec, conformance of the input to the
 *   spec
 * + divergences between the draft and the ISO proposed standard :-(
 * + hook and test include
 * + try and compare with the XSLT version
 */

#define IN_LIBXML
#include "libxml.h"

#ifdef LIBXML_SCHEMATRON_ENABLED

#include <string.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <libxml/uri.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/pattern.h>
#include <libxml/schematron.h>

#define SCHEMATRON_PARSE_OPTIONS XML_PARSE_NOENT

#define SCT_OLD_NS BAD_CAST "http://www.ascc.net/xml/schematron"

#define XML_SCHEMATRON_NS BAD_CAST "http://purl.oclc.org/dsdl/schematron"


static const xmlChar *xmlSchematronNs = XML_SCHEMATRON_NS;
static const xmlChar *xmlOldSchematronNs = SCT_OLD_NS;

#define IS_SCHEMATRON(node, elem)                                       \
   ((node != NULL) && (node->type == XML_ELEMENT_NODE ) &&              \
    (node->ns != NULL) &&                                               \
    (xmlStrEqual(node->name, (const xmlChar *) elem)) &&                \
    ((xmlStrEqual(node->ns->href, xmlSchematronNs)) ||                  \
     (xmlStrEqual(node->ns->href, xmlOldSchematronNs))))

#define NEXT_SCHEMATRON(node)                                           \
   while (node != NULL) {                                               \
       if ((node->type == XML_ELEMENT_NODE ) && (node->ns != NULL) &&   \
           ((xmlStrEqual(node->ns->href, xmlSchematronNs)) ||           \
            (xmlStrEqual(node->ns->href, xmlOldSchematronNs))))         \
           break;                                                       \
       node = node->next;                                               \
   }

/**
 * TODO:
 *
 * macro to flag unimplemented blocks
 */
#define TODO                                                            \
    xmlGenericError(xmlGenericErrorContext,                             \
            "Unimplemented block at %s:%d\n",                           \
            __FILE__, __LINE__);

typedef enum {
    XML_SCHEMATRON_ASSERT=1,
    XML_SCHEMATRON_REPORT=2
} xmlSchematronTestType;

/**
 * _xmlSchematronLet:
 *
 * A Schematron let variable
 */
typedef struct _xmlSchematronLet xmlSchematronLet;
typedef xmlSchematronLet *xmlSchematronLetPtr;
struct _xmlSchematronLet {
    xmlSchematronLetPtr next; /* the next let variable in the list */
    xmlChar *name;            /* the name of the variable */
    xmlXPathCompExprPtr comp; /* the compiled expression */
};

/**
 * _xmlSchematronTest:
 *
 * A Schematrons test, either an assert or a report
 */
typedef struct _xmlSchematronTest xmlSchematronTest;
typedef xmlSchematronTest *xmlSchematronTestPtr;
struct _xmlSchematronTest {
    xmlSchematronTestPtr next;  /* the next test in the list */
    xmlSchematronTestType type; /* the test type */
    xmlNodePtr node;            /* the node in the tree */
    xmlChar *test;              /* the expression to test */
    xmlXPathCompExprPtr comp;   /* the compiled expression */
    xmlChar *report;            /* the message to report */
};

/**
 * _xmlSchematronRule:
 *
 * A Schematrons rule
 */
typedef struct _xmlSchematronRule xmlSchematronRule;
typedef xmlSchematronRule *xmlSchematronRulePtr;
struct _xmlSchematronRule {
    xmlSchematronRulePtr next;  /* the next rule in the list */
    xmlSchematronRulePtr patnext;/* the next rule in the pattern list */
    xmlNodePtr node;            /* the node in the tree */
    xmlChar *context;           /* the context evaluation rule */
    xmlSchematronTestPtr tests; /* the list of tests */
    xmlPatternPtr pattern;      /* the compiled pattern associated */
    xmlChar *report;            /* the message to report */
    xmlSchematronLetPtr lets;   /* the list of let variables */
};

/**
 * _xmlSchematronPattern:
 *
 * A Schematrons pattern
 */
typedef struct _xmlSchematronPattern xmlSchematronPattern;
typedef xmlSchematronPattern *xmlSchematronPatternPtr;
struct _xmlSchematronPattern {
    xmlSchematronPatternPtr next;/* the next pattern in the list */
    xmlSchematronRulePtr rules; /* the list of rules */
    xmlChar *name;              /* the name of the pattern */
};

/**
 * _xmlSchematron:
 *
 * A Schematrons definition
 */
struct _xmlSchematron {
    const xmlChar *name;        /* schema name */
    int preserve;               /* was the document passed by the user */
    xmlDocPtr doc;              /* pointer to the parsed document */
    int flags;                  /* specific to this schematron */

    void *_private;             /* unused by the library */
    xmlDictPtr dict;            /* the dictionary used internally */

    const xmlChar *title;       /* the title if any */

    int nbNs;                   /* the number of namespaces */

    int nbPattern;              /* the number of patterns */
    xmlSchematronPatternPtr patterns;/* the patterns found */
    xmlSchematronRulePtr rules; /* the rules gathered */
    int nbNamespaces;           /* number of namespaces in the array */
    int maxNamespaces;          /* size of the array */
    const xmlChar **namespaces; /* the array of namespaces */
};

/**
 * xmlSchematronValidCtxt:
 *
 * A Schematrons validation context
 */
struct _xmlSchematronValidCtxt {
    int type;
    int flags;                  /* an or of xmlSchematronValidOptions */

    xmlDictPtr dict;
    int nberrors;
    int err;

    xmlSchematronPtr schema;
    xmlXPathContextPtr xctxt;

    FILE *outputFile;           /* if using XML_SCHEMATRON_OUT_FILE */
    xmlBufferPtr outputBuffer;  /* if using XML_SCHEMATRON_OUT_BUFFER */
#ifdef LIBXML_OUTPUT_ENABLED
    xmlOutputWriteCallback iowrite; /* if using XML_SCHEMATRON_OUT_IO */
    xmlOutputCloseCallback  ioclose;
#endif
    void *ioctx;

    /* error reporting data */
    void *userData;                      /* user specific data block */
    xmlSchematronValidityErrorFunc error;/* the callback in case of errors */
    xmlSchematronValidityWarningFunc warning;/* callback in case of warning */
    xmlStructuredErrorFunc serror;       /* the structured function */
};

struct _xmlSchematronParserCtxt {
    int type;
    const xmlChar *URL;
    xmlDocPtr doc;
    int preserve;               /* Whether the doc should be freed  */
    const char *buffer;
    int size;

    xmlDictPtr dict;            /* dictionary for interned string names */

    int nberrors;
    int err;
    xmlXPathContextPtr xctxt;   /* the XPath context used for compilation */
    xmlSchematronPtr schema;

    int nbNamespaces;           /* number of namespaces in the array */
    int maxNamespaces;          /* size of the array */
    const xmlChar **namespaces; /* the array of namespaces */

    int nbIncludes;             /* number of includes in the array */
    int maxIncludes;            /* size of the array */
    xmlNodePtr *includes;       /* the array of includes */

    /* error reporting data */
    void *userData;                      /* user specific data block */
    xmlSchematronValidityErrorFunc error;/* the callback in case of errors */
    xmlSchematronValidityWarningFunc warning;/* callback in case of warning */
    xmlStructuredErrorFunc serror;       /* the structured function */
};

#define XML_STRON_CTXT_PARSER 1
#define XML_STRON_CTXT_VALIDATOR 2

/************************************************************************
 *                                                                      *
 *                      Error reporting                                 *
 *                                                                      *
 ************************************************************************/

/**
 * xmlSchematronPErrMemory:
 * @node: a context node
 * @extra:  extra information
 *
 * Handle an out of memory condition
 */
static void
xmlSchematronPErrMemory(xmlSchematronParserCtxtPtr ctxt,
                        const char *extra, xmlNodePtr node)
{
    if (ctxt != NULL)
        ctxt->nberrors++;
    __xmlSimpleError(XML_FROM_SCHEMASP, XML_ERR_NO_MEMORY, node, NULL,
                     extra);
}

/**
 * xmlSchematronPErr:
 * @ctxt: the parsing context
 * @node: the context node
 * @error: the error code
 * @msg: the error message
 * @str1: extra data
 * @str2: extra data
 *
 * Handle a parser error
 */
static void LIBXML_ATTR_FORMAT(4,0)
xmlSchematronPErr(xmlSchematronParserCtxtPtr ctxt, xmlNodePtr node, int error,
              const char *msg, const xmlChar * str1, const xmlChar * str2)
{
    xmlGenericErrorFunc channel = NULL;
    xmlStructuredErrorFunc schannel = NULL;
    void *data = NULL;

    if (ctxt != NULL) {
        ctxt->nberrors++;
        channel = ctxt->error;
        data = ctxt->userData;
        schannel = ctxt->serror;
    }
    __xmlRaiseError(schannel, channel, data, ctxt, node, XML_FROM_SCHEMASP,
                    error, XML_ERR_ERROR, NULL, 0,
                    (const char *) str1, (const char *) str2, NULL, 0, 0,
                    msg, str1, str2);
}

/**
 * xmlSchematronVTypeErrMemory:
 * @node: a context node
 * @extra:  extra information
 *
 * Handle an out of memory condition
 */
static void
xmlSchematronVErrMemory(xmlSchematronValidCtxtPtr ctxt,
                        const char *extra, xmlNodePtr node)
{
    if (ctxt != NULL) {
        ctxt->nberrors++;
        ctxt->err = XML_SCHEMAV_INTERNAL;
    }
    __xmlSimpleError(XML_FROM_SCHEMASV, XML_ERR_NO_MEMORY, node, NULL,
                     extra);
}

/************************************************************************
 *                                                                      *
 *              Parsing and compilation of the Schematrontrons          *
 *                                                                      *
 ************************************************************************/

/**
 * xmlSchematronAddTest:
 * @ctxt: the schema parsing context
 * @type:  the type of test
 * @rule:  the parent rule
 * @node:  the node hosting the test
 * @test: the associated test
 * @report: the associated report string
 *
 * Add a test to a schematron
 *
 * Returns the new pointer or NULL in case of error
 */
static xmlSchematronTestPtr
xmlSchematronAddTest(xmlSchematronParserCtxtPtr ctxt,
                     xmlSchematronTestType type,
                     xmlSchematronRulePtr rule,
                     xmlNodePtr node, xmlChar *test, xmlChar *report)
{
    xmlSchematronTestPtr ret;
    xmlXPathCompExprPtr comp;

    if ((ctxt == NULL) || (rule == NULL) || (node == NULL) ||
        (test == NULL))
        return(NULL);

    /*
     * try first to compile the test expression
     */
    comp = xmlXPathCtxtCompile(ctxt->xctxt, test);
    if (comp == NULL) {
        xmlSchematronPErr(ctxt, node,
            XML_SCHEMAP_NOROOT,
            "Failed to compile test expression %s",
            test, NULL);
        return(NULL);
    }

    ret = (xmlSchematronTestPtr) xmlMalloc(sizeof(xmlSchematronTest));
    if (ret == NULL) {
        xmlSchematronPErrMemory(ctxt, "allocating schema test", node);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematronTest));
    ret->type = type;
    ret->node = node;
    ret->test = test;
    ret->comp = comp;
    ret->report = report;
    ret->next = NULL;
    if (rule->tests == NULL) {
        rule->tests = ret;
    } else {
        xmlSchematronTestPtr prev = rule->tests;

        while (prev->next != NULL)
             prev = prev->next;
        prev->next = ret;
    }
    return (ret);
}

/**
 * xmlSchematronFreeTests:
 * @tests:  a list of tests
 *
 * Free a list of tests.
 */
static void
xmlSchematronFreeTests(xmlSchematronTestPtr tests) {
    xmlSchematronTestPtr next;

    while (tests != NULL) {
        next = tests->next;
        if (tests->test != NULL)
            xmlFree(tests->test);
        if (tests->comp != NULL)
            xmlXPathFreeCompExpr(tests->comp);
        if (tests->report != NULL)
            xmlFree(tests->report);
        xmlFree(tests);
        tests = next;
    }
}

/**
 * xmlSchematronFreeLets:
 * @lets:  a list of let variables
 *
 * Free a list of let variables.
 */
static void
xmlSchematronFreeLets(xmlSchematronLetPtr lets) {
    xmlSchematronLetPtr next;

    while (lets != NULL) {
        next = lets->next;
        if (lets->name != NULL)
            xmlFree(lets->name);
        if (lets->comp != NULL)
            xmlXPathFreeCompExpr(lets->comp);
        xmlFree(lets);
        lets = next;
    }
}

/**
 * xmlSchematronAddRule:
 * @ctxt: the schema parsing context
 * @schema:  a schema structure
 * @node:  the node hosting the rule
 * @context: the associated context string
 * @report: the associated report string
 *
 * Add a rule to a schematron
 *
 * Returns the new pointer or NULL in case of error
 */
static xmlSchematronRulePtr
xmlSchematronAddRule(xmlSchematronParserCtxtPtr ctxt, xmlSchematronPtr schema,
                     xmlSchematronPatternPtr pat, xmlNodePtr node,
                     xmlChar *context, xmlChar *report)
{
    xmlSchematronRulePtr ret;
    xmlPatternPtr pattern;

    if ((ctxt == NULL) || (schema == NULL) || (node == NULL) ||
        (context == NULL))
        return(NULL);

    /*
     * Try first to compile the pattern
     */
    pattern = xmlPatterncompile(context, ctxt->dict, XML_PATTERN_XPATH,
                                ctxt->namespaces);
    if (pattern == NULL) {
        xmlSchematronPErr(ctxt, node,
            XML_SCHEMAP_NOROOT,
            "Failed to compile context expression %s",
            context, NULL);
    }

    ret = (xmlSchematronRulePtr) xmlMalloc(sizeof(xmlSchematronRule));
    if (ret == NULL) {
        xmlSchematronPErrMemory(ctxt, "allocating schema rule", node);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematronRule));
    ret->node = node;
    ret->context = context;
    ret->pattern = pattern;
    ret->report = report;
    ret->next = NULL;
    ret->lets = NULL;
    if (schema->rules == NULL) {
        schema->rules = ret;
    } else {
        xmlSchematronRulePtr prev = schema->rules;

        while (prev->next != NULL)
             prev = prev->next;
        prev->next = ret;
    }
    ret->patnext = NULL;
    if (pat->rules == NULL) {
        pat->rules = ret;
    } else {
        xmlSchematronRulePtr prev = pat->rules;

        while (prev->patnext != NULL)
             prev = prev->patnext;
        prev->patnext = ret;
    }
    return (ret);
}

/**
 * xmlSchematronFreeRules:
 * @rules:  a list of rules
 *
 * Free a list of rules.
 */
static void
xmlSchematronFreeRules(xmlSchematronRulePtr rules) {
    xmlSchematronRulePtr next;

    while (rules != NULL) {
        next = rules->next;
        if (rules->tests)
            xmlSchematronFreeTests(rules->tests);
        if (rules->context != NULL)
            xmlFree(rules->context);
        if (rules->pattern)
            xmlFreePattern(rules->pattern);
        if (rules->report != NULL)
            xmlFree(rules->report);
        if (rules->lets != NULL)
            xmlSchematronFreeLets(rules->lets);
        xmlFree(rules);
        rules = next;
    }
}

/**
 * xmlSchematronAddPattern:
 * @ctxt: the schema parsing context
 * @schema:  a schema structure
 * @node:  the node hosting the pattern
 * @id: the id or name of the pattern
 *
 * Add a pattern to a schematron
 *
 * Returns the new pointer or NULL in case of error
 */
static xmlSchematronPatternPtr
xmlSchematronAddPattern(xmlSchematronParserCtxtPtr ctxt,
                     xmlSchematronPtr schema, xmlNodePtr node, xmlChar *name)
{
    xmlSchematronPatternPtr ret;

    if ((ctxt == NULL) || (schema == NULL) || (node == NULL) || (name == NULL))
        return(NULL);

    ret = (xmlSchematronPatternPtr) xmlMalloc(sizeof(xmlSchematronPattern));
    if (ret == NULL) {
        xmlSchematronPErrMemory(ctxt, "allocating schema pattern", node);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematronPattern));
    ret->name = name;
    ret->next = NULL;
    if (schema->patterns == NULL) {
        schema->patterns = ret;
    } else {
        xmlSchematronPatternPtr prev = schema->patterns;

        while (prev->next != NULL)
             prev = prev->next;
        prev->next = ret;
    }
    return (ret);
}

/**
 * xmlSchematronFreePatterns:
 * @patterns:  a list of patterns
 *
 * Free a list of patterns.
 */
static void
xmlSchematronFreePatterns(xmlSchematronPatternPtr patterns) {
    xmlSchematronPatternPtr next;

    while (patterns != NULL) {
        next = patterns->next;
        if (patterns->name != NULL)
            xmlFree(patterns->name);
        xmlFree(patterns);
        patterns = next;
    }
}

/**
 * xmlSchematronNewSchematron:
 * @ctxt:  a schema validation context
 *
 * Allocate a new Schematron structure.
 *
 * Returns the newly allocated structure or NULL in case or error
 */
static xmlSchematronPtr
xmlSchematronNewSchematron(xmlSchematronParserCtxtPtr ctxt)
{
    xmlSchematronPtr ret;

    ret = (xmlSchematronPtr) xmlMalloc(sizeof(xmlSchematron));
    if (ret == NULL) {
        xmlSchematronPErrMemory(ctxt, "allocating schema", NULL);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematron));
    ret->dict = ctxt->dict;
    xmlDictReference(ret->dict);

    return (ret);
}

/**
 * xmlSchematronFree:
 * @schema:  a schema structure
 *
 * Deallocate a Schematron structure.
 */
void
xmlSchematronFree(xmlSchematronPtr schema)
{
    if (schema == NULL)
        return;

    if ((schema->doc != NULL) && (!(schema->preserve)))
        xmlFreeDoc(schema->doc);

    if (schema->namespaces != NULL)
        xmlFree((char **) schema->namespaces);

    xmlSchematronFreeRules(schema->rules);
    xmlSchematronFreePatterns(schema->patterns);
    xmlDictFree(schema->dict);
    xmlFree(schema);
}

/**
 * xmlSchematronNewParserCtxt:
 * @URL:  the location of the schema
 *
 * Create an XML Schematrons parse context for that file/resource expected
 * to contain an XML Schematrons file.
 *
 * Returns the parser context or NULL in case of error
 */
xmlSchematronParserCtxtPtr
xmlSchematronNewParserCtxt(const char *URL)
{
    xmlSchematronParserCtxtPtr ret;

    if (URL == NULL)
        return (NULL);

    ret =
        (xmlSchematronParserCtxtPtr)
        xmlMalloc(sizeof(xmlSchematronParserCtxt));
    if (ret == NULL) {
        xmlSchematronPErrMemory(NULL, "allocating schema parser context",
                                NULL);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematronParserCtxt));
    ret->type = XML_STRON_CTXT_PARSER;
    ret->dict = xmlDictCreate();
    ret->URL = xmlDictLookup(ret->dict, (const xmlChar *) URL, -1);
    ret->includes = NULL;
    ret->xctxt = xmlXPathNewContext(NULL);
    if (ret->xctxt == NULL) {
        xmlSchematronPErrMemory(NULL, "allocating schema parser XPath context",
                                NULL);
        xmlSchematronFreeParserCtxt(ret);
        return (NULL);
    }
    ret->xctxt->flags = XML_XPATH_CHECKNS;
    return (ret);
}

/**
 * xmlSchematronNewMemParserCtxt:
 * @buffer:  a pointer to a char array containing the schemas
 * @size:  the size of the array
 *
 * Create an XML Schematrons parse context for that memory buffer expected
 * to contain an XML Schematrons file.
 *
 * Returns the parser context or NULL in case of error
 */
xmlSchematronParserCtxtPtr
xmlSchematronNewMemParserCtxt(const char *buffer, int size)
{
    xmlSchematronParserCtxtPtr ret;

    if ((buffer == NULL) || (size <= 0))
        return (NULL);

    ret =
        (xmlSchematronParserCtxtPtr)
        xmlMalloc(sizeof(xmlSchematronParserCtxt));
    if (ret == NULL) {
        xmlSchematronPErrMemory(NULL, "allocating schema parser context",
                                NULL);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematronParserCtxt));
    ret->buffer = buffer;
    ret->size = size;
    ret->dict = xmlDictCreate();
    ret->xctxt = xmlXPathNewContext(NULL);
    if (ret->xctxt == NULL) {
        xmlSchematronPErrMemory(NULL, "allocating schema parser XPath context",
                                NULL);
        xmlSchematronFreeParserCtxt(ret);
        return (NULL);
    }
    return (ret);
}

/**
 * xmlSchematronNewDocParserCtxt:
 * @doc:  a preparsed document tree
 *
 * Create an XML Schematrons parse context for that document.
 * NB. The document may be modified during the parsing process.
 *
 * Returns the parser context or NULL in case of error
 */
xmlSchematronParserCtxtPtr
xmlSchematronNewDocParserCtxt(xmlDocPtr doc)
{
    xmlSchematronParserCtxtPtr ret;

    if (doc == NULL)
        return (NULL);

    ret =
        (xmlSchematronParserCtxtPtr)
        xmlMalloc(sizeof(xmlSchematronParserCtxt));
    if (ret == NULL) {
        xmlSchematronPErrMemory(NULL, "allocating schema parser context",
                                NULL);
        return (NULL);
    }
    memset(ret, 0, sizeof(xmlSchematronParserCtxt));
    ret->doc = doc;
    ret->dict = xmlDictCreate();
    /* The application has responsibility for the document */
    ret->preserve = 1;
    ret->xctxt = xmlXPathNewContext(doc);
    if (ret->xctxt == NULL) {
        xmlSchematronPErrMemory(NULL, "allocating schema parser XPath context",
                                NULL);
        xmlSchematronFreeParserCtxt(ret);
        return (NULL);
    }

    return (ret);
}

/**
 * xmlSchematronFreeParserCtxt:
 * @ctxt:  the schema parser context
 *
 * Free the resources associated to the schema parser context
 */
void
xmlSchematronFreeParserCtxt(xmlSchematronParserCtxtPtr ctxt)
{
    if (ctxt == NULL)
        return;
    if (ctxt->doc != NULL && !ctxt->preserve)
        xmlFreeDoc(ctxt->doc);
    if (ctxt->xctxt != NULL) {
        xmlXPathFreeContext(ctxt->xctxt);
    }
    if (ctxt->namespaces != NULL)
        xmlFree((char **) ctxt->namespaces);
    xmlDictFree(ctxt->dict);
    xmlFree(ctxt);
}

#if 0
/**
 * xmlSchematronPushInclude:
 * @ctxt:  the schema parser context
 * @doc:  the included document
 * @cur:  the current include node
 *
 * Add an included document
 */
static void
xmlSchematronPushInclude(xmlSchematronParserCtxtPtr ctxt,
                        xmlDocPtr doc, xmlNodePtr cur)
{
    if (ctxt->includes == NULL) {
        ctxt->maxIncludes = 10;
        ctxt->includes = (xmlNodePtr *)
            xmlMalloc(ctxt->maxIncludes * 2 * sizeof(xmlNodePtr));
        if (ctxt->includes == NULL) {
            xmlSchematronPErrMemory(NULL, "allocating parser includes",
                                    NULL);
            return;
        }
        ctxt->nbIncludes = 0;
    } else if (ctxt->nbIncludes + 2 >= ctxt->maxIncludes) {
        xmlNodePtr *tmp;

        tmp = (xmlNodePtr *)
            xmlRealloc(ctxt->includes, ctxt->maxIncludes * 4 *
                       sizeof(xmlNodePtr));
        if (tmp == NULL) {
            xmlSchematronPErrMemory(NULL, "allocating parser includes",
                                    NULL);
            return;
        }
        ctxt->includes = tmp;
        ctxt->maxIncludes *= 2;
    }
    ctxt->includes[2 * ctxt->nbIncludes] = cur;
    ctxt->includes[2 * ctxt->nbIncludes + 1] = (xmlNodePtr) doc;
    ctxt->nbIncludes++;
}

/**
 * xmlSchematronPopInclude:
 * @ctxt:  the schema parser context
 *
 * Pop an include level. The included document is being freed
 *
 * Returns the node immediately following the include or NULL if the
 *         include list was empty.
 */
static xmlNodePtr
xmlSchematronPopInclude(xmlSchematronParserCtxtPtr ctxt)
{
    xmlDocPtr doc;
    xmlNodePtr ret;

    if (ctxt->nbIncludes <= 0)
        return(NULL);
    ctxt->nbIncludes--;
    doc = (xmlDocPtr) ctxt->includes[2 * ctxt->nbIncludes + 1];
    ret = ctxt->includes[2 * ctxt->nbIncludes];
    xmlFreeDoc(doc);
    if (ret != NULL)
        ret = ret->next;
    if (ret == NULL)
        return(xmlSchematronPopInclude(ctxt));
    return(ret);
}
#endif

/**
 * xmlSchematronAddNamespace:
 * @ctxt:  the schema parser context
 * @prefix:  the namespace prefix
 * @ns:  the namespace name
 *
 * Add a namespace definition in the context
 */
static void
xmlSchematronAddNamespace(xmlSchematronParserCtxtPtr ctxt,
                          const xmlChar *prefix, const xmlChar *ns)
{
    if (ctxt->namespaces == NULL) {
        ctxt->maxNamespaces = 10;
        ctxt->namespaces = (const xmlChar **)
            xmlMalloc(ctxt->maxNamespaces * 2 * sizeof(const xmlChar *));
        if (ctxt->namespaces == NULL) {
            xmlSchematronPErrMemory(NULL, "allocating parser namespaces",
                                    NULL);
            return;
        }
        ctxt->nbNamespaces = 0;
    } else if (ctxt->nbNamespaces + 2 >= ctxt->maxNamespaces) {
        const xmlChar **tmp;

        tmp = (const xmlChar **)
            xmlRealloc((xmlChar **) ctxt->namespaces, ctxt->maxNamespaces * 4 *
                       sizeof(const xmlChar *));
        if (tmp == NULL) {
            xmlSchematronPErrMemory(NULL, "allocating parser namespaces",
                                    NULL);
            return;
        }
        ctxt->namespaces = tmp;
        ctxt->maxNamespaces *= 2;
    }
    ctxt->namespaces[2 * ctxt->nbNamespaces] =
        xmlDictLookup(ctxt->dict, ns, -1);
    ctxt->namespaces[2 * ctxt->nbNamespaces + 1] =
        xmlDictLookup(ctxt->dict, prefix, -1);
    ctxt->nbNamespaces++;
    ctxt->namespaces[2 * ctxt->nbNamespaces] = NULL;
    ctxt->namespaces[2 * ctxt->nbNamespaces + 1] = NULL;

}

/**
 * xmlSchematronParseTestReportMsg:
 * @ctxt:  the schema parser context
 * @con:  the assert or report node
 *
 * Format the message content of the assert or report test
 */
static void
xmlSchematronParseTestReportMsg(xmlSchematronParserCtxtPtr ctxt, xmlNodePtr con)
{
    xmlNodePtr child;
    xmlXPathCompExprPtr comp;

    child = con->children;
    while (child != NULL) {
        if ((child->type == XML_TEXT_NODE) ||
            (child->type == XML_CDATA_SECTION_NODE))
            /* Do Nothing */
            {}
        else if (IS_SCHEMATRON(child, "name")) {
            /* Do Nothing */
        } else if (IS_SCHEMATRON(child, "value-of")) {
            xmlChar *select;

            select = xmlGetNoNsProp(child, BAD_CAST "select");

            if (select == NULL) {
                xmlSchematronPErr(ctxt, child,
                                  XML_SCHEMAV_ATTRINVALID,
                                  "value-of has no select attribute",
                                  NULL, NULL);
            } else {
                /*
                 * try first to compile the test expression
                 */
                comp = xmlXPathCtxtCompile(ctxt->xctxt, select);
                if (comp == NULL) {
                    xmlSchematronPErr(ctxt, child,
                                      XML_SCHEMAV_ATTRINVALID,
                                      "Failed to compile select expression %s",
                                      select, NULL);
                }
                xmlXPathFreeCompExpr(comp);
            }
            xmlFree(select);
        }
        child = child->next;
        continue;
    }
}

/**
 * xmlSchematronParseRule:
 * @ctxt:  a schema validation context
 * @rule:  the rule node
 *
 * parse a rule element
 */
static void
xmlSchematronParseRule(xmlSchematronParserCtxtPtr ctxt,
                       xmlSchematronPatternPtr pattern,
                       xmlNodePtr rule)
{
    xmlNodePtr cur;
    int nbChecks = 0;
    xmlChar *test;
    xmlChar *context;
    xmlChar *report;
    xmlChar *name;
    xmlChar *value;
    xmlSchematronRulePtr ruleptr;
    xmlSchematronTestPtr testptr;

    if ((ctxt == NULL) || (rule == NULL)) return;

    context = xmlGetNoNsProp(rule, BAD_CAST "context");
    if (context == NULL) {
        xmlSchematronPErr(ctxt, rule,
            XML_SCHEMAP_NOROOT,
            "rule has no context attribute",
            NULL, NULL);
        return;
    } else if (context[0] == 0) {
        xmlSchematronPErr(ctxt, rule,
            XML_SCHEMAP_NOROOT,
            "rule has an empty context attribute",
            NULL, NULL);
        xmlFree(context);
        return;
    } else {
        ruleptr = xmlSchematronAddRule(ctxt, ctxt->schema, pattern,
                                       rule, context, NULL);
        if (ruleptr == NULL) {
            xmlFree(context);
            return;
        }
    }

    cur = rule->children;
    NEXT_SCHEMATRON(cur);
    while (cur != NULL) {
        if (IS_SCHEMATRON(cur, "let")) {
            xmlXPathCompExprPtr var_comp;
            xmlSchematronLetPtr let;

            name = xmlGetNoNsProp(cur, BAD_CAST "name");
            if (name == NULL) {
                xmlSchematronPErr(ctxt, cur,
                                  XML_SCHEMAP_NOROOT,
                                  "let has no name attribute",
                                  NULL, NULL);
                return;
            } else if (name[0] == 0) {
                xmlSchematronPErr(ctxt, cur,
                                  XML_SCHEMAP_NOROOT,
                                  "let has an empty name attribute",
                                  NULL, NULL);
                xmlFree(name);
                return;
            }
            value = xmlGetNoNsProp(cur, BAD_CAST "value");
            if (value == NULL) {