xpath.h revision dbfd641b78b5a98e790459e13d126e2784a7adeb 
1/*
2 * xpath.c: interface for XML Path Language implementation
3 *
4 * Reference: W3C Working Draft 5 July 1999
5 *            http://www.w3.org/Style/XSL/Group/1999/07/xpath-19990705.html
6 *
7 * See COPYRIGHT for the status of this software
8 *
9 * Author: Daniel.Veillard@w3.org
10 */
11
12#ifndef __XML_XPATH_H__
13#define __XML_XPATH_H__
14
15#include "tree.h"
16
17#ifdef __cplusplus
18extern "C" {
19#endif
20
21typedef struct xmlXPathParserContext *xmlXPathParserContextPtr;
22
23/*
24 * A node-set (an unordered collection of nodes without duplicates)
25 */
26typedef struct xmlNodeSet {
27    int nodeNr;			/* # of node in the set */
28    int nodeMax;		/* allocated space */
29    xmlNodePtr *nodeTab;	/* array of nodes in no particular order */
30} xmlNodeSet, *xmlNodeSetPtr;
31
32/*
33 * An expression is evaluated to yield an object, which
34 * has one of the following four basic types:
35 *   - node-set
36 *   - boolean
37 *   - number
38 *   - string
39 */
40
41#define XPATH_UNDEFINED	0
42#define XPATH_NODESET	1
43#define XPATH_BOOLEAN	2
44#define XPATH_NUMBER	3
45#define XPATH_STRING	4
46#define XPATH_USERS	5
47
48typedef struct xmlXPathObject {
49    int type;
50    xmlNodeSetPtr nodesetval;
51    int boolval;
52    double floatval;
53    xmlChar *stringval;
54    void *user;
55} xmlXPathObject, *xmlXPathObjectPtr;
56
57/*
58 * A conversion function is associated to a type and used to cast
59 * the new type to primitive values.
60 */
61typedef int (*xmlXPathConvertFunc) (xmlXPathObjectPtr obj, int type);
62
63/*
64 * Extra type: a name and a conversion function.
65 */
66
67typedef struct xmlXPathType {
68    const xmlChar         *name;		/* the type name */
69    xmlXPathConvertFunc func;		/* the conversion function */
70} xmlXPathType, *xmlXPathTypePtr;
71
72/*
73 * Extra variable: a name and a value.
74 */
75
76typedef struct xmlXPathVariable {
77    const xmlChar       *name;		/* the variable name */
78    xmlXPathObjectPtr value;		/* the value */
79} xmlXPathVariable, *xmlXPathVariablePtr;
80
81/*
82 * an evaluation function, the parameters are on the context stack
83 */
84
85typedef void (*xmlXPathEvalFunc)(xmlXPathParserContextPtr ctxt, int nargs);
86
87/*
88 * Extra function: a name and a evaluation function.
89 */
90
91typedef struct xmlXPathFunct {
92    const xmlChar      *name;		/* the function name */
93    xmlXPathEvalFunc func;		/* the evaluation function */
94} xmlXPathFunc, *xmlXPathFuncPtr;
95
96/*
97 * An axis traversal function. To traverse an axis, the engine calls
98 * the first time with cur == NULL and repeat until the function returns
99 * NULL indicating the end of the axis traversal.
100 */
101
102typedef xmlXPathObjectPtr (*xmlXPathAxisFunc)	(xmlXPathParserContextPtr ctxt,
103						 xmlXPathObjectPtr cur);
104
105/*
106 * Extra axis: a name and an axis function.
107 */
108
109typedef struct xmlXPathAxis {
110    const xmlChar      *name;		/* the axis name */
111    xmlXPathAxisFunc func;		/* the search function */
112} xmlXPathAxis, *xmlXPathAxisPtr;
113
114/*
115 * Expression evaluation occurs with respect to a context.
116 * he context consists of:
117 *    - a node (the context node)
118 *    - a node list (the context node list)
119 *    - a set of variable bindings
120 *    - a function library
121 *    - the set of namespace declarations in scope for the expression
122 */
123
124typedef struct xmlXPathContext {
125    xmlDocPtr doc;			/* The current document */
126    xmlNodePtr node;			/* The current node */
127    xmlNodeSetPtr nodelist;		/* The current node list */
128
129    int nb_variables;			/* number of defined variables */
130    int max_variables;			/* max number of variables */
131    xmlXPathVariablePtr *variables;	/* Array of defined variables */
132
133    int nb_types;			/* number of defined types */
134    int max_types;			/* max number of types */
135    xmlXPathTypePtr *types;		/* Array of defined types */
136
137    int nb_funcs;			/* number of defined funcs */
138    int max_funcs;			/* max number of funcs */
139    xmlXPathFuncPtr *funcs;		/* Array of defined funcs */
140
141    int nb_axis;			/* number of defined axis */
142    int max_axis;			/* max number of axis */
143    xmlXPathAxisPtr *axis;		/* Array of defined axis */
144
145    /* Namespace traversal should be implemented with user */
146    xmlNsPtr *namespaces;		/* The namespaces lookup */
147    int nsNr;				/* the current Namespace index */
148    void *user;				/* user defined extra info */
149} xmlXPathContext, *xmlXPathContextPtr;
150
151/*
152 * An XPath parser context, it contains pure parsing informations,
153 * an xmlXPathContext, and the stack of objects.
154 */
155typedef struct xmlXPathParserContext {
156    const xmlChar *cur;			/* the current char being parsed */
157    const xmlChar *base;			/* the full expression */
158
159    int error;				/* error code */
160
161    xmlXPathContextPtr  context;	/* the evaluation context */
162    xmlXPathObjectPtr     value;	/* the current value */
163    int                 valueNr;	/* number of values stacked */
164    int                valueMax;	/* max number of values stacked */
165    xmlXPathObjectPtr *valueTab;	/* stack of values */
166} xmlXPathParserContext;
167
168/*
169 * An XPath function
170 * The arguments (if any) are popped out of the context stack
171 * and the result is pushed on the stack.
172 */
173
174typedef void (*xmlXPathFunction) (xmlXPathParserContextPtr ctxt, int nargs);
175
176/************************************************************************
177 *									*
178 *			Public API					*
179 *									*
180 ************************************************************************/
181
182/**
183 * Registering extensions to the expression language
184 */
185/* TODO */ int	   xmlXPathRegisterType		(xmlXPathContextPtr ctxt,
186						 const xmlChar *name,
187                                                 xmlXPathConvertFunc f);
188/* TODO */ int	   xmlXPathRegisterAxis		(xmlXPathContextPtr ctxt,
189						 const xmlChar *name,
190						 xmlXPathAxisFunc f);
191/* TODO */ int	   xmlXPathRegisterFunc		(xmlXPathContextPtr ctxt,
192						 const xmlChar *name,
193						 xmlXPathFunction f);
194/* TODO */ int	   xmlXPathRegisterVariable	(xmlXPathContextPtr ctxt,
195						 const xmlChar *name,
196						 xmlXPathObject value);
197
198/**
199 * Evaluation functions.
200 */
201xmlXPathContextPtr xmlXPathNewContext		(xmlDocPtr doc);
202void		   xmlXPathFreeContext		(xmlXPathContextPtr ctxt);
203xmlXPathObjectPtr  xmlXPathEval			(const xmlChar *str,
204						 xmlXPathContextPtr ctxt);
205void		   xmlXPathFreeObject		(xmlXPathObjectPtr obj);
206xmlXPathObjectPtr  xmlXPathEvalExpression	(const xmlChar *str,
207						 xmlXPathContextPtr ctxt);
208xmlNodeSetPtr	   xmlXPathNodeSetCreate	(xmlNodePtr val);
209void		   xmlXPathFreeNodeSetList	(xmlXPathObjectPtr obj);
210void		   xmlXPathFreeNodeSet		(xmlNodeSetPtr obj);
211
212#ifdef __cplusplus
213}
214#endif
215#endif /* ! __XML_XPATH_H__ */
216