pattern.c

/*
 * pattern.c: Implemetation of selectors for nodes
 *
 * Reference:
 *   http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/
 *   to some extent 
 *   http://www.w3.org/TR/1999/REC-xml-19991116
 *
 * See Copyright for the status of this software.
 *
 * daniel@veillard.com
 */

/*
 * TODO:
 * - compilation flags to check for specific syntaxes
 *   using flags of xmlPatterncompile()
 * - making clear how pattern starting with / or . need to be handled,
 *   currently push(NULL, NULL) means a reset of the streaming context
 *   and indicating we are on / (the document node), probably need
 *   something similar for .
 * - xmlPatterncompile support of namespaces arguments, I'm not sure
 *   it's implemented and definitely not tested
 * - handling of disjunction "pattern1 | pattern2" mean needed to build
 *   and check a list internally
 * - get rid of the "compile" starting with lowercase
 * - get rid of the Strdup/Strndup in case of dictionary
 */

#define IN_LIBXML
#include "libxml.h"

#include <string.h>
#include <libxml/xmlmemory.h>
#include <libxml/tree.h>
#include <libxml/hash.h>
#include <libxml/dict.h>
#include <libxml/xmlerror.h>
#include <libxml/parserInternals.h>
#include <libxml/pattern.h>

#ifdef LIBXML_PATTERN_ENABLED

/* #define DEBUG_STREAMING */

#define ERROR(a, b, c, d)
#define ERROR5(a, b, c, d, e)

#define XML_STREAM_STEP_DESC	1
#define XML_STREAM_STEP_FINAL	2
#define XML_STREAM_STEP_ROOT	4

typedef struct _xmlStreamStep xmlStreamStep;
typedef xmlStreamStep *xmlStreamStepPtr;
struct _xmlStreamStep {
    int flags;			/* properties of that step */
    const xmlChar *name;	/* first string value if NULL accept all */
    const xmlChar *ns;		/* second string value */
};

typedef struct _xmlStreamComp xmlStreamComp;
typedef xmlStreamComp *xmlStreamCompPtr;
struct _xmlStreamComp {
    xmlDict *dict;		/* the dictionnary if any */
    int nbStep;			/* number of steps in the automata */
    int maxStep;		/* allocated number of steps */
    xmlStreamStepPtr steps;	/* the array of steps */
};

struct _xmlStreamCtxt {
    xmlStreamCompPtr comp;	/* the compiled stream */
    int nbState;		/* number of state in the automata */
    int maxState;		/* allocated number of state */
    int level;			/* how deep are we ? */
    int *states;		/* the array of step indexes */
};

static void xmlFreeStreamComp(xmlStreamCompPtr comp);

/*
 * Types are private:
 */

typedef enum {
    XML_OP_END=0,
    XML_OP_ROOT,
    XML_OP_ELEM,
    XML_OP_CHILD,
    XML_OP_ATTR,
    XML_OP_PARENT,
    XML_OP_ANCESTOR,
    XML_OP_NS,
    XML_OP_ALL
} xmlPatOp;


typedef struct _xmlStepState xmlStepState;
typedef xmlStepState *xmlStepStatePtr;
struct _xmlStepState {
    int step;
    xmlNodePtr node;
};

typedef struct _xmlStepStates xmlStepStates;
typedef xmlStepStates *xmlStepStatesPtr;
struct _xmlStepStates {
    int nbstates;
    int maxstates;
    xmlStepStatePtr states;
};

typedef struct _xmlStepOp xmlStepOp;
typedef xmlStepOp *xmlStepOpPtr;
struct _xmlStepOp {
    xmlPatOp op;
    const xmlChar *value;
    const xmlChar *value2;
};

struct _xmlPattern {
    void *data;    		/* the associated template */
    xmlDictPtr dict;		/* the optional dictionnary */
    struct _xmlPattern *next;	/* siblings */
    const xmlChar *pattern;	/* the pattern */

    int nbStep;
    int maxStep;
    xmlStepOpPtr steps;        /* ops for computation */
    xmlStreamCompPtr stream;	/* the streaming data if any */
};

typedef struct _xmlPatParserContext xmlPatParserContext;
typedef xmlPatParserContext *xmlPatParserContextPtr;
struct _xmlPatParserContext {
    const xmlChar *cur;			/* the current char being parsed */
    const xmlChar *base;		/* the full expression */
    int	           error;		/* error code */
    xmlDictPtr     dict;		/* the dictionnary if any */
    xmlPatternPtr  comp;		/* the result */
    xmlNodePtr     elem;		/* the current node if any */    
    const xmlChar **namespaces;		/* the namespaces definitions */
    int   nb_namespaces;		/* the number of namespaces */
};

/************************************************************************
 * 									*
 * 			Type functions 					*
 * 									*
 ************************************************************************/

/**
 * xmlNewPattern:
 *
 * Create a new XSLT Pattern
 *
 * Returns the newly allocated xmlPatternPtr or NULL in case of error
 */
static xmlPatternPtr
xmlNewPattern(void) {
    xmlPatternPtr cur;

    cur = (xmlPatternPtr) xmlMalloc(sizeof(xmlPattern));
    if (cur == NULL) {
	ERROR(NULL, NULL, NULL,
		"xmlNewPattern : malloc failed\n");
	return(NULL);
    }
    memset(cur, 0, sizeof(xmlPattern));
    cur->maxStep = 10;
    cur->steps = (xmlStepOpPtr) xmlMalloc(cur->maxStep * sizeof(xmlStepOp));
    if (cur->steps == NULL) {
        xmlFree(cur);
	ERROR(NULL, NULL, NULL,
		"xmlNewPattern : malloc failed\n");
	return(NULL);
    }
    return(cur);
}

/**
 * xmlFreePattern:
 * @comp:  an XSLT comp
 *
 * Free up the memory allocated by @comp
 */
void
xmlFreePattern(xmlPatternPtr comp) {
    xmlStepOpPtr op;
    int i;

    if (comp == NULL)
	return;
    if (comp->stream != NULL)
        xmlFreeStreamComp(comp->stream);
    if (comp->pattern != NULL)
	xmlFree((xmlChar *)comp->pattern);
    if (comp->steps != NULL) {
        if (comp->dict == NULL) {
	    for (i = 0;i < comp->nbStep;i++) {
		op = &comp->steps[i];
		if (op->value != NULL)
		    xmlFree((xmlChar *) op->value);
		if (op->value2 != NULL)
		    xmlFree((xmlChar *) op->value2);
	    }
	}
	xmlFree(comp->steps);
    }
    if (comp->dict != NULL)
        xmlDictFree(comp->dict);

    memset(comp, -1, sizeof(xmlPattern));
    xmlFree(comp);
}

/**
 * xmlFreePatternList:
 * @comp:  an XSLT comp list
 *
 * Free up the memory allocated by all the elements of @comp
 */
void
xmlFreePatternList(xmlPatternPtr comp) {
    xmlPatternPtr cur;

    while (comp != NULL) {
	cur = comp;
	comp = comp->next;
	xmlFreePattern(cur);
    }
}

/**
 * xmlNewPatParserContext:
 * @pattern:  the pattern context
 * @dict:  the inherited dictionnary or NULL
 * @namespaces: the prefix definitions, array of [URI, prefix] terminated
 *              with [NULL, NULL] or NULL if no namespace is used
 *
 * Create a new XML pattern parser context
 *
 * Returns the newly allocated xmlPatParserContextPtr or NULL in case of error
 */
static xmlPatParserContextPtr
xmlNewPatParserContext(const xmlChar *pattern, xmlDictPtr dict,
                       const xmlChar **namespaces) {
    xmlPatParserContextPtr cur;

    if (pattern == NULL)
        return(NULL);

    cur = (xmlPatParserContextPtr) xmlMalloc(sizeof(xmlPatParserContext));
    if (cur == NULL) {
	ERROR(NULL, NULL, NULL,
		"xmlNewPatParserContext : malloc failed\n");
	return(NULL);
    }
    memset(cur, 0, sizeof(xmlPatParserContext));
    cur->dict = dict;
    cur->cur = pattern;
    cur->base = pattern;
    if (namespaces != NULL) {
        int i;
	for (i = 0;namespaces[2 * i] != NULL;i++);
        cur->nb_namespaces = i;
    } else {
        cur->nb_namespaces = 0;
    }
    cur->namespaces = namespaces;
    return(cur);
}

/**
 * xmlFreePatParserContext:
 * @ctxt:  an XSLT parser context
 *
 * Free up the memory allocated by @ctxt
 */
static void
xmlFreePatParserContext(xmlPatParserContextPtr ctxt) {
    if (ctxt == NULL)
	return;
    memset(ctxt, -1, sizeof(xmlPatParserContext));
    xmlFree(ctxt);
}

/**
 * xmlPatternAdd:
 * @comp:  the compiled match expression
 * @op:  an op
 * @value:  the first value
 * @value2:  the second value
 *
 * Add an step to an XSLT Compiled Match
 *
 * Returns -1 in case of failure, 0 otherwise.
 */
static int
xmlPatternAdd(xmlPatParserContextPtr ctxt ATTRIBUTE_UNUSED,
                xmlPatternPtr comp,
                xmlPatOp op, xmlChar * value, xmlChar * value2)
{
    if (comp->nbStep >= comp->maxStep) {
        xmlStepOpPtr temp;
	temp = (xmlStepOpPtr) xmlRealloc(comp->steps, comp->maxStep * 2 *
	                                 sizeof(xmlStepOp));
        if (temp == NULL) {
	    ERROR(ctxt, NULL, NULL,
			     "xmlPatternAdd: realloc failed\n");
	    return (-1);
	}
	comp->steps = temp;
	comp->maxStep *= 2;
    }
    comp->steps[comp->nbStep].op = op;
    comp->steps[comp->nbStep].value = value;
    comp->steps[comp->nbStep].value2 = value2;
    comp->nbStep++;
    return (0);
}

#if 0
/**
 * xsltSwapTopPattern:
 * @comp:  the compiled match expression
 *
 * reverse the two top steps.
 */
static void
xsltSwapTopPattern(xmlPatternPtr comp) {
    int i;
    int j = comp->nbStep - 1;

    if (j > 0) {
	register const xmlChar *tmp;
	register xmlPatOp op;
	i = j - 1;
	tmp = comp->steps[i].value;
	comp->steps[i].value = comp->steps[j].value;
	comp->steps[j].value = tmp;
	tmp = comp->steps[i].value2;
	comp->steps[i].value2 = comp->steps[j].value2;
	comp->steps[j].value2 = tmp;
	op = comp->steps[i].op;
	comp->steps[i].op = comp->steps[j].op;
	comp->steps[j].op = op;
    }
}
#endif

/**
 * xmlReversePattern:
 * @comp:  the compiled match expression
 *
 * reverse all the stack of expressions
 *
 * returns 0 in case of success and -1 in case of error.
 */
static int
xmlReversePattern(xmlPatternPtr comp) {
    int i = 0;
    int j = comp->nbStep - 1;

    if (comp->nbStep >= comp->maxStep) {
        xmlStepOpPtr temp;
	temp = (xmlStepOpPtr) xmlRealloc(comp->steps, comp->maxStep * 2 *
	                                 sizeof(xmlStepOp));
        if (temp == NULL) {
	    ERROR(ctxt, NULL, NULL,
			     "xmlReversePattern: realloc failed\n");
	    return (-1);
	}
	comp->steps = temp;
	comp->maxStep *= 2;
    }
    while (j > i) {
	register const xmlChar *tmp;
	register xmlPatOp op;
	tmp = comp->steps[i].value;
	comp->steps[i].value = comp->steps[j].value;
	comp->steps[j].value = tmp;
	tmp = comp->steps[i].value2;
	comp->steps[i].value2 = comp->steps[j].value2;
	comp->steps[j].value2 = tmp;
	op = comp->steps[i].op;
	comp->steps[i].op = comp->steps[j].op;
	comp->steps[j].op = op;
	j--;
	i++;
    }
    comp->steps[comp->nbStep].value = NULL;
    comp->steps[comp->nbStep].value2 = NULL;
    comp->steps[comp->nbStep++].op = XML_OP_END;
    return(0);
}

/************************************************************************
 * 									*
 * 		The interpreter for the precompiled patterns		*
 * 									*
 ************************************************************************/

static int
xmlPatPushState(xmlStepStates *states, int step, xmlNodePtr node) {
    if ((states->states == NULL) || (states->maxstates <= 0)) {
        states->maxstates = 4;
	states->nbstates = 0;
	states->states = xmlMalloc(4 * sizeof(xmlStepState));
    }
    else if (states->maxstates <= states->nbstates) {
        xmlStepState *tmp;

	tmp = (xmlStepStatePtr) xmlRealloc(states->states,
			       2 * states->maxstates * sizeof(xmlStepState));
	if (tmp == NULL)
	    return(-1);
	states->states = tmp;
	states->maxstates *= 2;
    }
    states->states[states->nbstates].step = step;
    states->states[states->nbstates++].node = node;
#if 0
    fprintf(stderr, "Push: %d, %s\n", step, node->name);
#endif
    return(0);
}

/**
 * xmlPatMatch:
 * @comp: the precompiled pattern
 * @node: a node
 *
 * Test wether the node matches the pattern
 *
 * Returns 1 if it matches, 0 if it doesn't and -1 in case of failure
 */
static int
xmlPatMatch(xmlPatternPtr comp, xmlNodePtr node) {
    int i;
    xmlStepOpPtr step;
    xmlStepStates states = {0, 0, NULL}; /* // may require backtrack */

    if ((comp == NULL) || (node == NULL)) return(-1);
    i = 0;
restart:
    for (;i < comp->nbStep;i++) {
	step = &comp->steps[i];
	switch (step->op) {
            case XML_OP_END:
		goto found;
            case XML_OP_ROOT:
		if (node->type == XML_NAMESPACE_DECL)
		    goto rollback;
		node = node->parent;
		if ((node->type == XML_DOCUMENT_NODE) ||
#ifdef LIBXML_DOCB_ENABLED
		    (node->type == XML_DOCB_DOCUMENT_NODE) ||
#endif
		    (node->type == XML_HTML_DOCUMENT_NODE))
		    continue;
		goto rollback;
            case XML_OP_ELEM:
		if (node->type != XML_ELEMENT_NODE)
		    goto rollback;
		if (step->value == NULL)
		    continue;
		if (step->value[0] != node->name[0])
		    goto rollback;
		if (!xmlStrEqual(step->value, node->name))
		    goto rollback;

		/* Namespace test */
		if (node->ns == NULL) {
		    if (step->value2 != NULL)
			goto rollback;
		} else if (node->ns->href != NULL) {
		    if (step->value2 == NULL)
			goto rollback;
		    if (!xmlStrEqual(step->value2, node->ns->href))
			goto rollback;
		}
		continue;
            case XML_OP_CHILD: {
		xmlNodePtr lst;

		if ((node->type != XML_ELEMENT_NODE) &&
		    (node->type != XML_DOCUMENT_NODE) &&
#ifdef LIBXML_DOCB_ENABLED
		    (node->type != XML_DOCB_DOCUMENT_NODE) &&
#endif
		    (node->type != XML_HTML_DOCUMENT_NODE))
		    goto rollback;

		lst = node->children;

		if (step->value != NULL) {
		    while (lst != NULL) {
			if ((lst->type == XML_ELEMENT_NODE) &&
			    (step->value[0] == lst->name[0]) &&
			    (xmlStrEqual(step->value, lst->name)))
			    break;
			lst = lst->next;
		    }
		    if (lst != NULL)
			continue;
		}
		goto rollback;
	    }
            case XML_OP_ATTR:
		if (node->type != XML_ATTRIBUTE_NODE)
		    goto rollback;
		if (step->value != NULL) {
		    if (step->value[0] != node->name[0])
			goto rollback;
		    if (!xmlStrEqual(step->value, node->name))
			goto rollback;
		}
		/* Namespace test */
		if (node->ns == NULL) {
		    if (step->value2 != NULL)
			goto rollback;
		} else if (step->value2 != NULL) {
		    if (!xmlStrEqual(step->value2, node->ns->href))
			goto rollback;
		}
		continue;
            case XML_OP_PARENT:
		if ((node->type == XML_DOCUMENT_NODE) ||
		    (node->type == XML_HTML_DOCUMENT_NODE) ||
#ifdef LIBXML_DOCB_ENABLED
		    (node->type == XML_DOCB_DOCUMENT_NODE) ||
#endif
		    (node->type == XML_NAMESPACE_DECL))
		    goto rollback;
		node = node->parent;
		if (node == NULL)
		    goto rollback;
		if (step->value == NULL)
		    continue;
		if (step->value[0] != node->name[0])
		    goto rollback;
		if (!xmlStrEqual(step->value, node->name))
		    goto rollback;
		/* Namespace test */
		if (node->ns == NULL) {
		    if (step->value2 != NULL)
			goto rollback;
		} else if (node->ns->href != NULL) {
		    if (step->value2 == NULL)
			goto rollback;
		    if (!xmlStrEqual(step->value2, node->ns->href))
			goto rollback;
		}
		continue;
            case XML_OP_ANCESTOR:
		/* TODO: implement coalescing of ANCESTOR/NODE ops */
		if (step->value == NULL) {
		    i++;
		    step = &comp->steps[i];
		    if (step->op == XML_OP_ROOT)
			goto found;
		    if (step->op != XML_OP_ELEM)
			goto rollback;
		    if (step->value == NULL)
			return(-1);
		}
		if (node == NULL)
		    goto rollback;
		if ((node->type == XML_DOCUMENT_NODE) ||
		    (node->type == XML_HTML_DOCUMENT_NODE) ||
#ifdef LIBXML_DOCB_ENABLED
		    (node->type == XML_DOCB_DOCUMENT_NODE) ||
#endif
		    (node->type == XML_NAMESPACE_DECL))
		    goto rollback;
		node = node->parent;
		while (node != NULL) {
		    if (node == NULL)
			goto rollback;
		    if ((node->type == XML_ELEMENT_NODE) &&
			(step->value[0] == node->name[0]) &&
			(xmlStrEqual(step->value, node->name))) {
			/* Namespace test */
			if (node->ns == NULL) {
			    if (step->value2 == NULL)
				break;
			} else if (node->ns->href != NULL) {
			    if ((step->value2 != NULL) &&
			        (xmlStrEqual(step->value2, node->ns->href)))
				break;
			}
		    }
		    node = node->parent;
		}
		if (node == NULL)
		    goto rollback;
		/*
		 * prepare a potential rollback from here
		 * for ancestors of that node.
		 */
		if (step->op == XML_OP_ANCESTOR)
		    xmlPatPushState(&states, i, node);
		else
		    xmlPatPushState(&states, i - 1, node);
		continue;
            case XML_OP_NS:
		if (node->type != XML_ELEMENT_NODE)
		    goto rollback;
		if (node->ns == NULL) {
		    if (step->value != NULL)
			goto rollback;
		} else if (node->ns->href != NULL) {
		    if (step->value == NULL)
			goto rollback;
		    if (!xmlStrEqual(step->value, node->ns->href))
			goto rollback;
		}
		break;
            case XML_OP_ALL:
		if (node->type != XML_ELEMENT_NODE)
		    goto rollback;
		break;
	}
    }
found:
    if (states.states != NULL) {
        /* Free the rollback states */
	xmlFree(states.states);
    }
    return(1);
rollback:
    /* got an error try to rollback */
    if (states.states == NULL)
	return(0);
    if (states.nbstates <= 0) {
	xmlFree(states.states);
	return(0);
    }
    states.nbstates--;
    i = states.states[states.nbstates].step;
    node = states.states[states.nbstates].node;
#if 0
    fprintf(stderr, "Pop: %d, %s\n", i, node->name);
#endif
    goto restart;
}

/************************************************************************
 *									*
 *			Dedicated parser for templates			*
 *									*
 ************************************************************************/

#define TODO 								\
    xmlGenericError(xmlGenericErrorContext,				\
	    "Unimplemented block at %s:%d\n",				\
            __FILE__, __LINE__);
#define CUR (*ctxt->cur)
#define SKIP(val) ctxt->cur += (val)
#define NXT(val) ctxt->cur[(val)]
#define CUR_PTR ctxt->cur

#define SKIP_BLANKS 							\
    while (IS_BLANK_CH(CUR)) NEXT

#define CURRENT (*ctxt->cur)
#define NEXT ((*ctxt->cur) ?  ctxt->cur++: ctxt->cur)


#define PUSH(op, val, val2) 						\
    if (xmlPatternAdd(ctxt, ctxt->comp, (op), (val), (val2))) goto error;

#define XSLT_ERROR(X)							\
    { xsltError(ctxt, __FILE__, __LINE__, X);			\
      ctxt->error = (X); return; }

#define XSLT_ERROR0(X)							\
    { xsltError(ctxt, __FILE__, __LINE__, X);			\
      ctxt->error = (X); return(0); }

#if 0
/**
 * xmlPatScanLiteral:
 * @ctxt:  the XPath Parser context
 *
 * Parse an XPath Litteral:
 *
 * [29] Literal ::= '"' [^"]* '"'
 *                | "'" [^']* "'"
 *
 * Returns the Literal parsed or NULL
 */

static xmlChar *
xmlPatScanLiteral(xmlPatParserContextPtr ctxt) {
    const xmlChar *q, *cur;
    xmlChar *ret = NULL;
    int val, len;

    SKIP_BLANKS;
    if (CUR == '"') {
        NEXT;
	cur = q = CUR_PTR;
	val = xmlStringCurrentChar(NULL, cur, &len);
	while ((IS_CHAR(val)) && (val != '"')) {
	    cur += len;
	    val = xmlStringCurrentChar(NULL, cur, &len);
	}
	if (!IS_CHAR(val)) {
	    ctxt->error = 1;
	    return(NULL);
	} else {
	    ret = xmlStrndup(q, cur - q);
        }
	cur += len;
	CUR_PTR = cur;
    } else if (CUR == '\'') {
        NEXT;
	cur = q = CUR_PTR;
	val = xmlStringCurrentChar(NULL, cur, &len);
	while ((IS_CHAR(val)) && (val != '\'')) {
	    cur += len;
	    val = xmlStringCurrentChar(NULL, cur, &len);
	}
	if (!IS_CHAR(val)) {
	    ctxt->error = 1;
	    return(NULL);
	} else {
	    ret = xmlStrndup(q, cur - q);
        }
	cur += len;
	CUR_PTR = cur;
    } else {
	/* XP_ERROR(XPATH_START_LITERAL_ERROR); */
	ctxt->error = 1;
	return(NULL);
    }
    return(ret);
}
#endif

/**
 * xmlPatScanName:
 * @ctxt:  the XPath Parser context
 *
 * [4] NameChar ::= Letter | Digit | '.' | '-' | '_' | 
 *                  CombiningChar | Extender
 *
 * [5] Name ::= (Letter | '_' | ':') (NameChar)*
 *
 * [6] Names ::= Name (S Name)*
 *
 * Returns the Name parsed or NULL
 */

static xmlChar *
xmlPatScanName(xmlPatParserContextPtr ctxt) {
    const xmlChar *q, *cur;
    xmlChar *ret = NULL;
    int val, len;

    SKIP_BLANKS;

    cur = q = CUR_PTR;
    val = xmlStringCurrentChar(NULL, cur, &len);
    if (!IS_LETTER(val) && (val != '_') && (val != ':'))
	return(NULL);

    while ((IS_LETTER(val)) || (IS_DIGIT(val)) ||
           (val == '.') || (val == '-') ||
	   (val == '_') || 
	   (IS_COMBINING(val)) ||
	   (IS_EXTENDER(val))) {
	cur += len;
	val = xmlStringCurrentChar(NULL, cur, &len);
    }
    ret = xmlStrndup(q, cur - q);
    CUR_PTR = cur;
    return(ret);
}

/**
 * xmlPatScanNCName:
 * @ctxt:  the XPath Parser context
 *
 * Parses a non qualified name
 *
 * Returns the Name parsed or NULL
 */

static xmlChar *
xmlPatScanNCName(xmlPatParserContextPtr ctxt) {
    const xmlChar *q, *cur;
    xmlChar *ret = NULL;
    int val, len;

    SKIP_BLANKS;

    cur = q = CUR_PTR;
    val = xmlStringCurrentChar(NULL, cur, &len);
    if (!IS_LETTER(val) && (val != '_'))
	return(NULL);

    while ((IS_LETTER(val)) || (IS_DIGIT(val)) ||
           (val == '.') || (val == '-') ||
	   (val == '_') ||
	   (IS_COMBINING(val)) ||
	   (IS_EXTENDER(val))) {
	cur += len;
	val = xmlStringCurrentChar(NULL, cur, &len);
    }
    ret = xmlStrndup(q, cur - q);
    CUR_PTR = cur;
    return(ret);
}

#if 0
/**
 * xmlPatScanQName:
 * @ctxt:  the XPath Parser context
 * @prefix:  the place to store the prefix
 *
 * Parse a qualified name
 *
 * Returns the Name parsed or NULL
 */

static xmlChar *
xmlPatScanQName(xmlPatParserContextPtr ctxt, xmlChar **prefix) {
    xmlChar *ret = NULL;

    *prefix = NULL;
    ret = xmlPatScanNCName(ctxt);
    if (CUR == ':') {
        *prefix = ret;
	NEXT;
	ret = xmlPatScanNCName(ctxt);
    }
    return(ret);
}
#endif

/**
 * xmlCompileStepPattern:
 * @ctxt:  the compilation context
 *
 * Compile the Step Pattern and generates a precompiled
 * form suitable for fast matching.
 *
 * [3]    Step    ::=    '.' | NameTest
 * [4]    NameTest    ::=    QName | '*' | NCName ':' '*' 
 */

static void
xmlCompileStepPattern(xmlPatParserContextPtr ctxt) {
    xmlChar *token = NULL;
    xmlChar *name = NULL;
    const xmlChar *URI = NULL;
    xmlChar *URL = NULL;

    SKIP_BLANKS;
    if (CUR == '.') {
	NEXT;
	PUSH(XML_OP_ELEM, NULL, NULL);
	return;
    }
    name = xmlPatScanNCName(ctxt);
    if (name == NULL) {
	if (CUR == '*') {
	    NEXT;
	    PUSH(XML_OP_ALL, NULL, NULL);
	    return;
	} else {
	    ERROR(NULL, NULL, NULL,
		    "xmlCompileStepPattern : Name expected\n");
	    ctxt->error = 1;
	    return;
	}
    }
    SKIP_BLANKS;
    if (CUR == ':') {
	NEXT;
	if (CUR != ':') {
	    xmlChar *prefix = name;
	    xmlNsPtr ns;
	    int i;

	    /*
	     * This is a namespace match
	     */
	    token = xmlPatScanName(ctxt);
	    for (i = 0;i < ctxt->nb_namespaces;i++) {
	        if (xmlStrEqual(ctxt->namespaces[2 * i + 1], prefix)) {
		    URL = xmlStrdup(ctxt->namespaces[2 * i + 1]);
		    break;
		}
	    }
	    if (i >= ctxt->nb_namespaces) {
		ERROR5(NULL, NULL, NULL,
	    "xmlCompileStepPattern : no namespace bound to prefix %s\n",
				 prefix);
		ctxt->error = 1;
		goto error;
	    } else {
		URL = xmlStrdup(ns->href);
	    }
	    xmlFree(prefix);
	    if (token == NULL) {
		if (CUR == '*') {
		    NEXT;
		    PUSH(XML_OP_NS, URL, NULL);
		} else {
		    ERROR(NULL, NULL, NULL,
			    "xmlCompileStepPattern : Name expected\n");
		    ctxt->error = 1;
		    goto error;
		}
	    } else {
		PUSH(XML_OP_ELEM, token, URL);
	    }
	} else {
	    NEXT;
	    if (xmlStrEqual(token, (const xmlChar *) "child")) {
		xmlFree(token);
		token = xmlPatScanName(ctxt);
		if (token == NULL) {
	            if (CUR == '*') {
            	        NEXT;
	                PUSH(XML_OP_ALL, token, NULL);
	                return;
	            } else {
		        ERROR(NULL, NULL, NULL,
			    "xmlCompileStepPattern : QName expected\n");
		        ctxt->error = 1;
		        goto error;
		    }
		}
		TODO
		/* URI = xsltGetQNameURI(ctxt->elem, &token); */
		if (token == NULL) {
		    ctxt->error = 1;
		    goto error;
		} else {
		    name = xmlStrdup(token);
		    if (URI != NULL)
			URL = xmlStrdup(URI);
		}
		PUSH(XML_OP_CHILD, name, URL);
	    } else if (xmlStrEqual(token, (const xmlChar *) "attribute")) {
		xmlFree(token);
		token = xmlPatScanName(ctxt);
		if (token == NULL) {
		    ERROR(NULL, NULL, NULL,
			    "xmlCompileStepPattern : QName expected\n");
		    ctxt->error = 1;
		    goto error;
		}
		TODO
		/* URI = xsltGetQNameURI(ctxt->elem, &token); */
		if (token == NULL) {
		    ctxt->error = 1;
		    goto error;
		} else {
		    name = xmlStrdup(token);
		    if (URI != NULL)
			URL = xmlStrdup(URI);
		}
		PUSH(XML_OP_ATTR, name, URL);
	    } else {
		ERROR(NULL, NULL, NULL,
		    "xmlCompileStepPattern : 'child' or 'attribute' expected\n");
		ctxt->error = 1;
		goto error;
	    }
	    xmlFree(token);
	}
    } else if (CUR == '*') {
	NEXT;
	PUSH(XML_OP_ALL, token, NULL);
    } else {
	if (name == NULL) {
	    ctxt->error = 1;
	    goto error;
	}
	PUSH(XML_OP_ELEM, name, NULL);
    }
    return;
error:
    if (token != NULL)
	xmlFree(token);
    if (name != NULL)
	xmlFree(name);
}

/**
 * xmlCompilePathPattern:
 * @ctxt:  the compilation context
 *
 * Compile the Path Pattern and generates a precompiled
 * form suitable for fast matching.
 *
 * [5]    Path    ::=    ('.//')? ( Step '/' )* ( Step | '@' NameTest ) 
 */
static void
xmlCompilePathPattern(xmlPatParserContextPtr ctxt) {
    SKIP_BLANKS;
    if ((CUR == '/') && (NXT(1) == '/')) {
	/*
	 * since we reverse the query
	 * a leading // can be safely ignored
	 */
	NEXT;
	NEXT;
    } else if ((CUR == '.') && (NXT(1) == '/') && (NXT(2) == '/')) {
	/*
	 * a leading .// can be safely ignored
	 */
	NEXT;
	NEXT;
	NEXT;
    }
    if (CUR == '@') {
	TODO
    } else {
        if (CUR == '/') {
	    PUSH(XML_OP_ROOT, NULL, NULL);
	    NEXT;
	}
	xmlCompileStepPattern(ctxt);
	SKIP_BLANKS;
	while (CUR == '/') {
	    if ((CUR == '/') && (NXT(1) == '/')) {
	        PUSH(XML_OP_ANCESTOR, NULL, NULL);
		NEXT;
		NEXT;
		SKIP_BLANKS;
		xmlCompileStepPattern(ctxt);
	    } else {
	        PUSH(XML_OP_PARENT, NULL, NULL);
		NEXT;
		SKIP_BLANKS;
		if ((CUR != 0) || (CUR == '|')) {
		    xmlCompileStepPattern(ctxt);
		}
	    }
	}
    }
error:
    return;
}

/************************************************************************
 *									*
 *			The streaming code				*
 *									*
 ************************************************************************/

#ifdef DEBUG_STREAMING
static void
xmlDebugStreamComp(xmlStreamCompPtr stream) {
    int i;

    if (stream == NULL) {
        printf("Stream: NULL\n");
	return;
    }
    printf("Stream: %d steps\n", stream->nbStep);
    for (i = 0;i < stream->nbStep;i++) {
	if (stream->steps[i].ns != NULL) {
	    printf("{%s}", stream->steps[i].ns);
	}
        if (stream->steps[i].name == NULL) {
	    printf("* ");
	} else {
	    printf("%s ", stream->steps[i].name);
	}
	if (stream->steps[i].flags & XML_STREAM_STEP_ROOT)
	    printf("root ");
	if (stream->steps[i].flags & XML_STREAM_STEP_DESC)
	    printf("// ");
	if (stream->steps[i].flags & XML_STREAM_STEP_FINAL)
	    printf("final ");
	printf("\n");
    }
}
static void
xmlDebugStreamCtxt(xmlStreamCtxtPtr ctxt, int match) {
    int i;

    if (ctxt == NULL) {
        printf("Stream: NULL\n");
	return;
    }
    printf("Stream: level %d, %d states: ", ctxt->level, ctxt->nbState);
    if (match)
        printf("matches\n");
    else
        printf("\n");
    for (i = 0;i < ctxt->nbState;i++) {
        if (ctxt->states[2 * i] < 0)
	    printf(" %d: free\n", i);
	else {
	    printf(" %d: step %d, level %d", i, ctxt->states[2 * i],
	           ctxt->states[(2 * i) + 1]);
            if (ctxt->comp->steps[ctxt->states[2 * i]].flags &
	        XML_STREAM_STEP_DESC)
	        printf(" //\n");
	    else
	        printf("\n");
	}
    }
}
#endif
/**
 * xmlNewStreamComp:
 * @size: the number of expected steps
 *
 * build a new compiled pattern for streaming
 *
 * Returns the new structure or NULL in case of error.
 */
static xmlStreamCompPtr
xmlNewStreamComp(int size) {
    xmlStreamCompPtr cur;

    if (size < 4)
        size  = 4;

    cur = (xmlStreamCompPtr) xmlMalloc(sizeof(xmlStreamComp));
    if (cur == NULL) {
	ERROR(NULL, NULL, NULL,
		"xmlNewStreamComp: malloc failed\n");
	return(NULL);
    }
    memset(cur, 0, sizeof(xmlStreamComp));
    cur->steps = (xmlStreamStepPtr) xmlMalloc(size * sizeof(xmlStreamStep));
    if (cur->steps == NULL) {
	xmlFree(cur);
	ERROR(NULL, NULL, NULL,
	      "xmlNewStreamComp: malloc failed\n");
	return(NULL);
    }
    cur->nbStep = 0;
    cur->maxStep = size;
    return(cur);
}

/**
 * xmlFreeStreamComp:
 * @comp: the compiled pattern for streaming
 *
 * Free the compiled pattern for streaming
 */
static void
xmlFreeStreamComp(xmlStreamCompPtr comp) {
    if (comp != NULL) {
        if (comp->steps != NULL)
	    xmlFree(comp->steps);
	if (comp->dict != NULL)
	    xmlDictFree(comp->dict);
        xmlFree(comp);
    }
}

/**
 * xmlStreamCompAddStep:
 * @comp: the compiled pattern for streaming
 * @name: the first string, the name, or NULL for *
 * @ns: the second step, the namespace name
 * @flags: the flags for that step
 *
 * Add a new step to the compiled pattern
 *
 * Returns -1 in case of error or the step index if successful
 */
static int
xmlStreamCompAddStep(xmlStreamCompPtr comp, const xmlChar *name,
                     const xmlChar *ns, int flags) {
    xmlStreamStepPtr cur;

    if (comp->nbStep >= comp->maxStep) {
	cur = (xmlStreamStepPtr) xmlRealloc(comp->steps,
				 comp->maxStep * 2 * sizeof(xmlStreamStep));
	if (cur == NULL) {
	    ERROR(NULL, NULL, NULL,
		  "xmlNewStreamComp: malloc failed\n");
	    return(-1);
	}
	comp->steps = cur;
        comp->maxStep *= 2;
    }
    cur = &comp->steps[comp->nbStep++];
    cur->flags = flags;
    cur->name = name;
    cur->ns = ns;
    return(comp->nbStep - 1);
}

/**
 * xmlStreamCompile:
 * @comp: the precompiled pattern
 * 
 * Tries to stream compile a pattern
 *
 * Returns -1 in case of failure and 0 in case of success.
 */
static int
xmlStreamCompile(xmlPatternPtr comp) {
    xmlStreamCompPtr stream;
    int i, s = 0, root = 0, desc = 0;

    if ((comp == NULL) || (comp->steps == NULL))
        return(-1);
    stream = xmlNewStreamComp((comp->nbStep / 2) + 1);
    if (stream == NULL)
        return(-1);
    if (comp->dict != NULL) {
        stream->dict = comp->dict;
	xmlDictReference(stream->dict);
    }
    for (i = 0;i < comp->nbStep;i++) {
        switch (comp->steps[i].op) {
	    case XML_OP_END:
	        break;
	    case XML_OP_ROOT:
	        if (i != 0)
		    goto error;
		root = 1;
		break;
	    case XML_OP_CHILD:
	    case XML_OP_ATTR:
	    case XML_OP_NS:
	        goto error;
	    case XML_OP_ELEM:
	        s = xmlStreamCompAddStep(stream, comp->steps[i].value,
		                         comp->steps[i].value2, desc);
		desc = 0;
		if (s < 0)
		    goto error;
		break;
	    case XML_OP_ALL:
	        s = xmlStreamCompAddStep(stream, NULL, NULL, desc);
		desc = 0;
		if (s < 0)
		    goto error;
		break;
	    case XML_OP_PARENT:
	        break;
	    case XML_OP_ANCESTOR:
	        desc = XML_STREAM_STEP_DESC;
		break;
	}
    }
    stream->steps[s].flags |= XML_STREAM_STEP_FINAL;
    if (root)
	stream->steps[0].flags |= XML_STREAM_STEP_ROOT;
#ifdef DEBUG_STREAMING
    xmlDebugStreamComp(stream);
#endif
    comp->stream = stream;
    return(0);
error:
    xmlFreeStreamComp(stream);
    return(0);
}

/**
 * xmlNewStreamCtxt:
 * @size: the number of expected states
 *
 * build a new stream context
 *
 * Returns the new structure or NULL in case of error.
 */
static xmlStreamCtxtPtr
xmlNewStreamCtxt(xmlStreamCompPtr stream) {
    xmlStreamCtxtPtr cur;

    cur = (xmlStreamCtxtPtr) xmlMalloc(sizeof(xmlStreamCtxt));
    if (cur == NULL) {
	ERROR(NULL, NULL, NULL,
		"xmlNewStreamCtxt: malloc failed\n");
	return(NULL);
    }
    memset(cur, 0, sizeof(xmlStreamCtxt));
    cur->states = (int *) xmlMalloc(4 * 2 * sizeof(int));
    if (cur->states == NULL) {
	xmlFree(cur);
	ERROR(NULL, NULL, NULL,
	      "xmlNewStreamCtxt: malloc failed\n");
	return(NULL);
    }
    cur->nbState = 0;
    cur->maxState = 4;
    cur->level = 0;
    cur->comp = stream;
    return(cur);
}

/**
 * xmlFreeStreamCtxt:
 * @stream: the stream context
 *
 * Free the stream context
 */
void
xmlFreeStreamCtxt(xmlStreamCtxtPtr stream) {
    if (stream != NULL) {
        if (stream->states != NULL)
	    xmlFree(stream->states);
        xmlFree(stream);
    }
}

/**
 * xmlStreamCtxtAddState:
 * @comp: the stream context
 * @idx: the step index for that streaming state
 *
 * Add a new state to the stream context
 *
 * Returns -1 in case of error or the state index if successful
 */
static int
xmlStreamCtxtAddState(xmlStreamCtxtPtr comp, int idx, int level) {
    int i;
    for (i = 0;i < comp->nbState;i++) {
        if (comp->states[2 * i] < 0) {
	    comp->states[2 * i] = idx;
	    comp->states[2 * i + 1] = level;
	    return(i);
	}
    }
    if (comp->nbState >= comp->maxState) {
        int *cur;

	cur = (int *) xmlRealloc(comp->states,
				 comp->maxState * 4 * sizeof(int));
	if (cur == NULL) {
	    ERROR(NULL, NULL, NULL,
		  "xmlNewStreamCtxt: malloc failed\n");
	    return(-1);
	}
	comp->states = cur;
        comp->maxState *= 2;
    }
    comp->states[2 * comp->nbState] = idx;
    comp->states[2 * comp->nbState++ + 1] = level;
    return(comp->nbState - 1);
}

/**
 * xmlStreamPush:
 * @stream: the stream context
 * @name: the current name
 * @ns: the namespace name
 *
 * push new data onto the stream. NOTE: if the call xmlPatterncompile()
 * indicated a dictionnary, then strings for name and ns will be expected
 * to come from the dictionary.
 * Both @name and @ns being NULL means the / i.e. the root of the document.
 * This can also act as a reset.
 *
 * Returns: -1 in case of error, 1 if the current state in the stream is a
 *    match and 0 otherwise.
 */
int
xmlStreamPush(xmlStreamCtxtPtr stream,
              const xmlChar *name, const xmlChar *ns) {
    int ret = 0, tmp, i, m, match, step, desc, final;
    xmlStreamCompPtr comp;

    if ((stream == NULL) || (stream->nbState < 0))
        return(-1);
    comp = stream->comp;
    if ((name == NULL) && (ns == NULL)) {
        stream->nbState = 0;
	stream->level = 0;
	if (comp->steps[0].flags & XML_STREAM_STEP_ROOT) {
	    tmp = xmlStreamCtxtAddState(stream, 0, 0);
	    if (tmp < 0)
	        return(-1);
	    if (comp->steps[tmp].flags & XML_STREAM_STEP_FINAL)
		return(1);
	}
	return(0);
    }
    /*
     * Check evolution of existing states
     */
    m = stream->nbState;
    for (i = 0;i < m;i++) {
        match = 0;
	step = stream->states[2 * i];
	/* dead states */
	if (step < 0) continue;
	/* skip new states just added */
	if (stream->states[(2 * i) + 1] > stream->level) continue;
	/* skip continuations */
	desc = comp->steps[step].flags & XML_STREAM_STEP_DESC;
	if ((stream->states[(2 * i) + 1] < stream->level) && (!desc))continue;

	/* discard old states */
	/* something needed about old level discarded */

        if (comp->dict) {
	    if (comp->steps[step].name == NULL) {
	        if (comp->steps[step].ns == NULL)
		    match = 1;
		else
		    match = (comp->steps[step].ns == ns);
	    } else {
		match = ((comp->steps[step].name == name) &&
			 (comp->steps[step].ns == ns));
	    }
	} else {
	    if (comp->steps[step].name == NULL) {
	        if (comp->steps[step].ns == NULL)
		    match = 1;
		else
		    match = xmlStrEqual(comp->steps[step].ns, ns);
	    } else {
		match = ((xmlStrEqual(comp->steps[step].name, name)) &&
			 (xmlStrEqual(comp->steps[step].ns, ns)));
	    }
	}
	if (match) {
	    final = comp->steps[step].flags & XML_STREAM_STEP_FINAL;
	    if (desc) {
		if (final) {
		    ret = 1;
		} else {
		    /* descending match create a new state */
		    xmlStreamCtxtAddState(stream, step + 1, stream->level + 1);
		}
	    } else {
		if (final) {
		    ret = 1;
#if 0
		    stream->states[2 * i] = -1;
#endif
		} else {
#if 0
		    stream->states[2 * i] = step + 1;
		    stream->states[2 * i + 1] = stream->level + 1;
#endif
		    xmlStreamCtxtAddState(stream, step + 1, stream->level + 1);
		}
	    }
#if 0
	} else if (!desc) {
	    /* didn't match, discard */
	    stream->states[2 * i] = -1;
#endif
	}
    }

    /*
     * Check creating a new state.
     */
    stream->level++;
    if (!(comp->steps[0].flags & XML_STREAM_STEP_ROOT)) {
        match = 0;
        if (comp->dict) {
	    if (comp->steps[0].name == NULL) {
	        if (comp->steps[0].ns == NULL)
		    match = 1;
		else
		    match = (comp->steps[0].ns == ns);
	    } else {
		match = ((comp->steps[0].name == name) &&
			 (comp->steps[0].ns == ns));
	    }
	} else {
	    if (comp->steps[0].name == NULL) {
	        if (comp->steps[0].ns == NULL)
		    match = 1;
		else
		    match = xmlStrEqual(comp->steps[0].ns, ns);
	    } else {
		match = ((xmlStrEqual(comp->steps[0].name, name)) &&
			 (xmlStrEqual(comp->steps[0].ns, ns)));
	    }
	}
	if (match) {
	    if (comp->steps[0].flags & XML_STREAM_STEP_FINAL)
	        ret = 1;
            else
	        xmlStreamCtxtAddState(stream, 1, stream->level);
	}
    }
    
#ifdef DEBUG_STREAMING
    xmlDebugStreamCtxt(stream, ret);
#endif
    return(ret);
}

/**
 * xmlStreamPop:
 * @stream: the stream context
 *
 * push one level from the stream.
 *
 * Returns: -1 in case of error, 0 otherwise.
 */
int
xmlStreamPop(xmlStreamCtxtPtr stream) {
    int i, m;

    if (stream == NULL)
        return(-1);
    stream->level--;
    if (stream->level < 0)
        return(-1);
    
    /*
     * Check evolution of existing states
     */
    m = stream->nbState;
    for (i = 0;i < m;i++) {
	if (stream->states[(2 * i)] < 0) break;
	/* discard obsoleted states */
	if (stream->states[(2 * i) + 1] > stream->level)
	    stream->states[(2 * i)] = -1;
    }
    return(0);
}

/************************************************************************
 *									*
 *			The public interfaces				*
 *									*
 ************************************************************************/

/**
 * xmlPatterncompile:
 * @pattern: the pattern to compile
 * @dict: an optional dictionnary for interned strings
 * @flags: compilation flags, undefined yet
 * @namespaces: the prefix definitions, array of [URI, prefix] or NULL
 *
 * Compile a pattern.
 *
 * Returns the compiled for of the pattern or NULL in case of error
 */
xmlPatternPtr
xmlPatterncompile(const xmlChar *pattern, xmlDict *dict,
                  int flags ATTRIBUTE_UNUSED,
                  const xmlChar **namespaces) {
    xmlPatternPtr ret = NULL;
    xmlPatParserContextPtr ctxt = NULL;

    ctxt = xmlNewPatParserContext(pattern, dict, namespaces);
    if (ctxt == NULL) goto error;
    ret = xmlNewPattern();
    if (ret == NULL) goto error;
    ctxt->comp = ret;

    xmlCompilePathPattern(ctxt);
    xmlFreePatParserContext(ctxt);

    xmlStreamCompile(ret);
    if (xmlReversePattern(ret) < 0)
        goto error;
    return(ret);
error:
    if (ctxt != NULL) xmlFreePatParserContext(ctxt);
    if (ret != NULL) xmlFreePattern(ret);
    return(NULL);
}

/**
 * xmlPatternMatch:
 * @comp: the precompiled pattern
 * @node: a node
 *
 * Test wether the node matches the pattern
 *
 * Returns 1 if it matches, 0 if it doesn't and -1 in case of failure
 */
int
xmlPatternMatch(xmlPatternPtr comp, xmlNodePtr node)
{
    if ((comp == NULL) || (node == NULL))
        return(-1);
    return(xmlPatMatch(comp, node));
}

/**
 * xmlPatternGetStreamCtxt:
 * @comp: the precompiled pattern
 *
 * Get a streaming context for that pattern
 * Use xmlFreeStreamCtxt to free the context.
 *
 * Returns a pointer to the context or NULL in case of failure
 */
xmlStreamCtxtPtr
xmlPatternGetStreamCtxt(xmlPatternPtr comp)
{
    if ((comp == NULL) || (comp->stream == NULL))
        return(NULL);
    return(xmlNewStreamCtxt(comp->stream));
}

#endif /* LIBXML_PATTERN_ENABLED */