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/*
* xpath.c: interface for XML Path Language implementation
*
* Reference: W3C Working Draft 5 July 1999
* http://www.w3.org/Style/XSL/Group/1999/07/xpath-19990705.html
*
* See COPYRIGHT for the status of this software
*
* Author: Daniel.Veillard@w3.org
*/
#ifndef __XML_XPATH_H__
#define __XML_XPATH_H__
#include "tree.h"
typedef struct xmlXPathParserContext *xmlXPathParserContextPtr;
/*
* A node-set (an unordered collection of nodes without duplicates)
*/
typedef struct xmlNodeSet {
int nodeNr; /* # of node in the set */
int nodeMax; /* allocated space */
xmlNodePtr *nodeTab; /* array of nodes in no particular order */
} xmlNodeSet, *xmlNodeSetPtr;
/*
* An expression is evaluated to yield an object, which
* has one of the following four basic types:
* - node-set
* - boolean
* - number
* - string
*/
#define XPATH_UNDEFINED 0
#define XPATH_NODESET 1
#define XPATH_BOOLEAN 2
#define XPATH_NUMBER 3
#define XPATH_STRING 4
#define XPATH_USERS 5
typedef struct xmlXPathObject {
int type;
xmlNodeSetPtr nodesetval;
int boolval;
double floatval;
CHAR *stringval;
void *user;
} xmlXPathObject, *xmlXPathObjectPtr;
/*
* A conversion function is associated to a type and used to cast
* the new type to primitive values.
*/
typedef int (*xmlXPathConvertFunc) (xmlXPathObjectPtr obj, int type);
/*
* Extra type: a name and a conversion function.
*/
typedef struct xmlXPathType {
const CHAR *name; /* the type name */
xmlXPathConvertFunc func; /* the conversion function */
} xmlXPathType, *xmlXPathTypePtr;
/*
* Extra variable: a name and a value.
*/
typedef struct xmlXPathVariable {
const CHAR *name; /* the variable name */
xmlXPathObjectPtr value; /* the value */
} xmlXPathVariable, *xmlXPathVariablePtr;
/*
* an evaluation function, the parameters are on the context stack
*/
typedef void (*xmlXPathEvalFunc)(xmlXPathParserContextPtr ctxt, int nargs);
/*
* Extra function: a name and a evaluation function.
*/
typedef struct xmlXPathFunct {
const CHAR *name; /* the function name */
xmlXPathEvalFunc func; /* the evaluation function */
} xmlXPathFunc, *xmlXPathFuncPtr;
/*
* 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.
*/
typedef xmlXPathObjectPtr (*xmlXPathAxisFunc) (xmlXPathParserContextPtr ctxt,
xmlXPathObjectPtr cur);
/*
* Extra axis: a name and an axis function.
*/
typedef struct xmlXPathAxis {
const CHAR *name; /* the axis name */
xmlXPathAxisFunc func; /* the search function */
} xmlXPathAxis, *xmlXPathAxisPtr;
/*
* Expression evaluation occurs with respect to a context.
* he context consists of:
* - a node (the context node)
* - a node list (the context node list)
* - a set of variable bindings
* - a function library
* - the set of namespace declarations in scope for the expression
*/
typedef struct xmlXPathContext {
xmlDocPtr doc; /* The current document */
xmlNodePtr node; /* The current node */
xmlNodeSetPtr nodelist; /* The current node list */
int nb_variables; /* number of defined variables */
int max_variables; /* max number of variables */
xmlXPathVariablePtr *variables; /* Array of defined variables */
int nb_types; /* number of defined types */
int max_types; /* max number of types */
xmlXPathTypePtr *types; /* Array of defined types */
int nb_funcs; /* number of defined funcs */
int max_funcs; /* max number of funcs */
xmlXPathFuncPtr *funcs; /* Array of defined funcs */
int nb_axis; /* number of defined axis */
int max_axis; /* max number of axis */
xmlXPathAxisPtr *axis; /* Array of defined axis */
/* Namespace traversal should be implemented with user */
xmlNsPtr *namespaces; /* The namespaces lookup */
int nsNr; /* the current Namespace index */
void *user; /* user defined extra info */
} xmlXPathContext, *xmlXPathContextPtr;
/*
* An XPath parser context, it contains pure parsing informations,
* an xmlXPathContext, and the stack of objects.
*/
typedef struct xmlXPathParserContext {
const CHAR *cur; /* the current char being parsed */
const CHAR *base; /* the full expression */
int error; /* error code */
xmlXPathContextPtr context; /* the evaluation context */
xmlXPathObjectPtr value; /* the current value */
int valueNr; /* number of values stacked */
int valueMax; /* max number of values stacked */
xmlXPathObjectPtr *valueTab; /* stack of values */
} xmlXPathParserContext;
/*
* An XPath function
* The arguments (if any) are popped out of the context stack
* and the result is pushed on the stack.
*/
typedef void (*xmlXPathFunction) (xmlXPathParserContextPtr ctxt, int nargs);
/************************************************************************
* *
* Public API *
* *
************************************************************************/
/**
* Registering extensions to the expression language
*/
/* TODO */ int xmlXPathRegisterType (xmlXPathContextPtr ctxt,
const CHAR *name,
xmlXPathConvertFunc f);
/* TODO */ int xmlXPathRegisterAxis (xmlXPathContextPtr ctxt,
const CHAR *name,
xmlXPathAxisFunc f);
/* TODO */ int xmlXPathRegisterFunc (xmlXPathContextPtr ctxt,
const CHAR *name,
xmlXPathFunction f);
/* TODO */ int xmlXPathRegisterVariable (xmlXPathContextPtr ctxt,
const CHAR *name,
xmlXPathObject value);
/**
* Evaluation functions.
*/
xmlXPathContextPtr xmlXPathNewContext (xmlDocPtr doc);
void xmlXPathFreeContext (xmlXPathContextPtr ctxt);
xmlXPathObjectPtr xmlXPathEval (const CHAR *str,
xmlXPathContextPtr ctxt);
void xmlXPathFreeObject (xmlXPathObjectPtr obj);
xmlXPathObjectPtr xmlXPathEvalExpression (const CHAR *str,
xmlXPathContextPtr ctxt);
#endif /* ! __XML_XPATH_H__ */
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