xpath.h

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/*
 * Summary: XML Path Language implementation
 * Description: API for the XML Path Language implementation
 *
 * XML Path Language implementation
 * XPath is a language for addressing parts of an XML document,
 * designed to be used by both XSLT and XPointer
 *     http://www.w3.org/TR/xpath
 *
 * Implements
 * W3C Recommendation 16 November 1999
 *     http://www.w3.org/TR/1999/REC-xpath-19991116
 *
 * Copy: See Copyright for the status of this software.
 *
 * Author: Daniel Veillard
 */

#ifndef __XML_XPATH_H__
#define __XML_XPATH_H__

#include <libxml/xmlversion.h>

#ifdef LIBXML_XPATH_ENABLED

#include <libxml/xmlerror.h>
#include <libxml/tree.h>
#include <libxml/hash.h>
#endif /* LIBXML_XPATH_ENABLED */

#if defined(LIBXML_XPATH_ENABLED) || defined(LIBXML_SCHEMAS_ENABLED)
#ifdef __cplusplus
extern "C" {
#endif
#endif /* LIBXML_XPATH_ENABLED or LIBXML_SCHEMAS_ENABLED */
	
#ifdef LIBXML_XPATH_ENABLED
typedef struct _xmlXPathContext xmlXPathContext;
typedef xmlXPathContext *xmlXPathContextPtr;
typedef struct _xmlXPathParserContext xmlXPathParserContext;
typedef xmlXPathParserContext *xmlXPathParserContextPtr;

/**
 * The set of XPath error codes.
 */

typedef enum {
    XPATH_EXPRESSION_OK = 0,
    XPATH_NUMBER_ERROR,
    XPATH_UNFINISHED_LITERAL_ERROR,
    XPATH_START_LITERAL_ERROR,
    XPATH_VARIABLE_REF_ERROR,
    XPATH_UNDEF_VARIABLE_ERROR,
    XPATH_INVALID_PREDICATE_ERROR,
    XPATH_EXPR_ERROR,
    XPATH_UNCLOSED_ERROR,
    XPATH_UNKNOWN_FUNC_ERROR,
    XPATH_INVALID_OPERAND,
    XPATH_INVALID_TYPE,
    XPATH_INVALID_ARITY,
    XPATH_INVALID_CTXT_SIZE,
    XPATH_INVALID_CTXT_POSITION,
    XPATH_MEMORY_ERROR,
    XPTR_SYNTAX_ERROR,
    XPTR_RESOURCE_ERROR,
    XPTR_SUB_RESOURCE_ERROR,
    XPATH_UNDEF_PREFIX_ERROR,
    XPATH_ENCODING_ERROR,
    XPATH_INVALID_CHAR_ERROR,
    XPATH_INVALID_CTXT
} xmlXPathError;

/*
 * A node-set (an unordered collection of nodes without duplicates).
 */
typedef struct _xmlNodeSet xmlNodeSet;
typedef xmlNodeSet *xmlNodeSetPtr;
struct _xmlNodeSet {
    int nodeNr;			/* number of nodes in the set */
    int nodeMax;		/* size of the array as allocated */
    xmlNodePtr *nodeTab;	/* array of nodes in no particular order */
    /* @@ with_ns to check wether namespace nodes should be looked at @@ */
};

/*
 * An expression is evaluated to yield an object, which
 * has one of the following four basic types:
 *   - node-set
 *   - boolean
 *   - number
 *   - string
 *
 * @@ XPointer will add more types !
 */

typedef enum {
    XPATH_UNDEFINED = 0,
    XPATH_NODESET = 1,
    XPATH_BOOLEAN = 2,
    XPATH_NUMBER = 3,
    XPATH_STRING = 4,
    XPATH_POINT = 5,
    XPATH_RANGE = 6,
    XPATH_LOCATIONSET = 7,
    XPATH_USERS = 8,
    XPATH_XSLT_TREE = 9  /* An XSLT value tree, non modifiable */
} xmlXPathObjectType;

typedef struct _xmlXPathObject xmlXPathObject;
typedef xmlXPathObject *xmlXPathObjectPtr;
struct _xmlXPathObject {
    xmlXPathObjectType type;
    xmlNodeSetPtr nodesetval;
    int boolval;
    double floatval;
    xmlChar *stringval;
    void *user;
    int index;
    void *user2;
    int index2;
};

/**
 * xmlXPathConvertFunc:
 * @obj:  an XPath object
 * @type:  the number of the target type
 *
 * A conversion function is associated to a type and used to cast
 * the new type to primitive values.
 *
 * Returns -1 in case of error, 0 otherwise
 */
typedef int (*xmlXPathConvertFunc) (xmlXPathObjectPtr obj, int type);

/*
 * Extra type: a name and a conversion function.
 */

typedef struct _xmlXPathType xmlXPathType;
typedef xmlXPathType *xmlXPathTypePtr;
struct _xmlXPathType {
    const xmlChar         *name;		/* the type name */
    xmlXPathConvertFunc func;		/* the conversion function */
};

/*
 * Extra variable: a name and a value.
 */

typedef struct _xmlXPathVariable xmlXPathVariable;
typedef xmlXPathVariable *xmlXPathVariablePtr;
struct _xmlXPathVariable {
    const xmlChar       *name;		/* the variable name */
    xmlXPathObjectPtr value;		/* the value */
};

/**
 * xmlXPathEvalFunc:
 * @ctxt: an XPath parser context
 * @nargs: the number of arguments passed to the function
 *
 * An XPath evaluation function, the parameters are on the XPath context stack.
 */

typedef void (*xmlXPathEvalFunc)(xmlXPathParserContextPtr ctxt,
	                         int nargs);

/*
 * Extra function: a name and a evaluation function.
 */

typedef struct _xmlXPathFunct xmlXPathFunct;
typedef xmlXPathFunct *xmlXPathFuncPtr;
struct _xmlXPathFunct {
    const xmlChar      *name;		/* the function name */
    xmlXPathEvalFunc func;		/* the evaluation function */
};

/**
 * xmlXPathAxisFunc:
 * @ctxt:  the XPath interpreter context
 * @cur:  the previous node being explored on that axis
 *
 * An axis traversal function. To traverse an axis, the engine calls
 * the first time with cur == NULL and repeat until the function returns
 * NULL indicating the end of the axis traversal.
 *
 * Returns the next node in that axis or NULL if at the end of the axis.
 */

typedef xmlXPathObjectPtr (*xmlXPathAxisFunc) (xmlXPathParserContextPtr ctxt,
				 xmlXPathObjectPtr cur);

/*
 * Extra axis: a name and an axis function.
 */

typedef struct _xmlXPathAxis xmlXPathAxis;
typedef xmlXPathAxis *xmlXPathAxisPtr;
struct _xmlXPathAxis {
    const xmlChar      *name;		/* the axis name */
    xmlXPathAxisFunc func;		/* the search function */
};

/**
 * xmlXPathFunction:
 * @ctxt:  the XPath interprestation context
 * @nargs:  the number of arguments
 *
 * An XPath function.
 * The arguments (if any) are popped out from the context stack
 * and the result is pushed on the stack.
 */

typedef void (*xmlXPathFunction) (xmlXPathParserContextPtr ctxt, int nargs);

/*
 * Function and Variable Lookup.
 */

/**
 * xmlXPathVariableLookupFunc:
 * @ctxt:  an XPath context
 * @name:  name of the variable
 * @ns_uri:  the namespace name hosting this variable
 *
 * Prototype for callbacks used to plug variable lookup in the XPath
 * engine.
 *
 * Returns the XPath object value or NULL if not found.
 */
typedef xmlXPathObjectPtr (*xmlXPathVariableLookupFunc) (void *ctxt,
                                         const xmlChar *name,
                                         const xmlChar *ns_uri);

/**
 * xmlXPathFuncLookupFunc:
 * @ctxt:  an XPath context
 * @name:  name of the function
 * @ns_uri:  the namespace name hosting this function
 *
 * Prototype for callbacks used to plug function lookup in the XPath
 * engine.
 *
 * Returns the XPath function or NULL if not found.
 */
typedef xmlXPathFunction (*xmlXPathFuncLookupFunc) (void *ctxt,
					 const xmlChar *name,
					 const xmlChar *ns_uri);

/**
 * xmlXPathContext:
 *
 * Expression evaluation occurs with respect to a context.
 * he context consists of:
 *    - a node (the context node) 
 *    - a node list (the context node list)