xpath

Name

xpath -- 

Synopsis



struct      xmlXPathContext;
typedef     xmlXPathContextPtr;
struct      xmlXPathParserContext;
typedef     xmlXPathParserContextPtr;
enum        xmlXPathError;
struct      xmlNodeSet;
typedef     xmlNodeSetPtr;
enum        xmlXPathObjectType;
struct      xmlXPathObject;
typedef     xmlXPathObjectPtr;
int         (*xmlXPathConvertFunc)          (xmlXPathObjectPtr obj,
                                             int type);
struct      xmlXPathType;
typedef     xmlXPathTypePtr;
struct      xmlXPathVariable;
typedef     xmlXPathVariablePtr;
void        (*xmlXPathEvalFunc)             (xmlXPathParserContextPtr ctxt,
                                             int nargs);
struct      xmlXPathFunct;
typedef     xmlXPathFuncPtr;
xmlXPathObjectPtr (*xmlXPathAxisFunc)       (xmlXPathParserContextPtr ctxt,
                                             xmlXPathObjectPtr cur);
struct      xmlXPathAxis;
typedef     xmlXPathAxisPtr;
struct      xmlXPathCompExpr;
typedef     xmlXPathCompExprPtr;
void        (*xmlXPathFunction)             (xmlXPathParserContextPtr ctxt,
                                             int nargs);
int         xmlXPathIsNaN                   (double val);
int         xmlXPathIsInf                   (double val);
#define     xmlXPathNodeSetGetLength        (ns)
#define     xmlXPathNodeSetItem             (ns, index)
#define     xmlXPathNodeSetIsEmpty          (ns)
void        xmlXPathFreeObject              (xmlXPathObjectPtr obj);
xmlNodeSetPtr xmlXPathNodeSetCreate         (xmlNodePtr val);
void        xmlXPathFreeNodeSetList         (xmlXPathObjectPtr obj);
void        xmlXPathFreeNodeSet             (xmlNodeSetPtr obj);
xmlXPathObjectPtr xmlXPathObjectCopy        (xmlXPathObjectPtr val);
int         xmlXPathCmpNodes                (xmlNodePtr node1,
                                             xmlNodePtr node2);
int         xmlXPathCastNumberToBoolean     (double val);
int         xmlXPathCastStringToBoolean     (const xmlChar *val);
int         xmlXPathCastNodeSetToBoolean    (xmlNodeSetPtr ns);
int         xmlXPathCastToBoolean           (xmlXPathObjectPtr val);
double      xmlXPathCastBooleanToNumber     (int val);
double      xmlXPathCastStringToNumber      (const xmlChar *val);
double      xmlXPathCastNodeToNumber        (xmlNodePtr node);
double      xmlXPathCastNodeSetToNumber     (xmlNodeSetPtr ns);
double      xmlXPathCastToNumber            (xmlXPathObjectPtr val);
xmlChar*    xmlXPathCastBooleanToString     (int val);
xmlChar*    xmlXPathCastNumberToString      (double val);
xmlChar*    xmlXPathCastNodeToString        (xmlNodePtr node);
xmlChar*    xmlXPathCastNodeSetToString     (xmlNodeSetPtr ns);
xmlChar*    xmlXPathCastToString            (xmlXPathObjectPtr val);
xmlXPathObjectPtr xmlXPathConvertBoolean    (xmlXPathObjectPtr val);
xmlXPathObjectPtr xmlXPathConvertNumber     (xmlXPathObjectPtr val);
xmlXPathObjectPtr xmlXPathConvertString     (xmlXPathObjectPtr val);
void        xmlXPathInit                    (void);
xmlXPathContextPtr xmlXPathNewContext       (xmlDocPtr doc);
void        xmlXPathFreeContext             (xmlXPathContextPtr ctxt);
xmlXPathObjectPtr xmlXPathEval              (const xmlChar *str,
                                             xmlXPathContextPtr ctx);
xmlXPathObjectPtr xmlXPathEvalExpression    (const xmlChar *str,
                                             xmlXPathContextPtr ctxt);
int         xmlXPathEvalPredicate           (xmlXPathContextPtr ctxt,
                                             xmlXPathObjectPtr res);
xmlXPathCompExprPtr xmlXPathCompile         (const xmlChar *str);
xmlXPathObjectPtr xmlXPathCompiledEval      (xmlXPathCompExprPtr comp,
                                             xmlXPathContextPtr ctx);
void        xmlXPathFreeCompExpr            (xmlXPathCompExprPtr comp);

Description

Details

struct xmlXPathContext

struct xmlXPathContext {
    xmlDocPtr doc;			/* The current document */
    xmlNodePtr node;			/* The current node */

    int nb_variables_unused;		/* unused (hash table) */
    int max_variables_unused;		/* unused (hash table) */
    xmlHashTablePtr varHash;		/* Hash table 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_unused;		/* unused (hash table) */
    int max_funcs_unused;		/* unused (hash table) */
    xmlHashTablePtr funcHash;		/* Hash table of defined funcs */

    int nb_axis;			/* number of defined axis */
    int max_axis;			/* max number of axis */
    xmlXPathAxisPtr axis;		/* Array of defined axis */

    /* the namespace nodes of the context node */
    xmlNsPtr *namespaces;		/* Array of namespaces */
    int nsNr;				/* number of namespace in scope */
    void *user;				/* function to free */

    /* extra variables */
    int contextSize;			/* the context size */
    int proximityPosition;		/* the proximity position */

    /* extra stuff for XPointer */
    int xptr;				/* it this an XPointer context */
    xmlNodePtr here;			/* for here() */
    xmlNodePtr origin;			/* for origin() */

    /* the set of namespace declarations in scope for the expression */
    xmlHashTablePtr nsHash;		/* The namespaces hash table */
    void *varLookupFunc;		/* variable lookup func */
    void *varLookupData;		/* variable lookup data */

    /* Possibility to link in an extra item */
    void *extra;                        /* needed for XSLT */

    /* The function name and URI when calling a function */
    const xmlChar *function;
    const xmlChar *functionURI;

    /* function lookup function and data */
    void *funcLookupFunc;		/* function lookup func */
    void *funcLookupData;		/* function lookup data */

    /* temporary namespace lists kept for walking the namespace axis */
    xmlNsPtr *tmpNsList;		/* Array of namespaces */
    int tmpNsNr;			/* number of namespace in scope */
};

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 Following the switch to hash tables, this need to be trimmed up at the next binary incompatible release.


xmlXPathContextPtr

typedef xmlXPathContext *xmlXPathContextPtr;


struct xmlXPathParserContext

struct xmlXPathParserContext {
    const xmlChar *cur;			/* the current char being parsed */
    const xmlChar *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 */

    xmlXPathCompExprPtr comp;		/* the precompiled expression */
    int xptr;				/* it this an XPointer expression */
    xmlNodePtr         ancestor;	/* used for walking preceding axis */
};

An XPath parser context. It contains pure parsing informations, an xmlXPathContext, and the stack of objects.


xmlXPathParserContextPtr

typedef xmlXPathParserContext *xmlXPathParserContextPtr;


enum xmlXPathError

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
} xmlXPathError;


struct xmlNodeSet

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 @@ */
};


xmlNodeSetPtr

typedef xmlNodeSet *xmlNodeSetPtr;


enum xmlXPathObjectType

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;


struct xmlXPathObject

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


xmlXPathObjectPtr

typedef xmlXPathObject *xmlXPathObjectPtr;


xmlXPathConvertFunc ()

int         (*xmlXPathConvertFunc)          (xmlXPathObjectPtr obj,
                                             int type);

A conversion function is associated to a type and used to cast the new type to primitive values.

obj : an XPath object
type : the number of the target type
Returns :-1 in case of error, 0 otherwise


struct xmlXPathType

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


xmlXPathTypePtr

typedef xmlXPathType *xmlXPathTypePtr;


struct xmlXPathVariable

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


xmlXPathVariablePtr

typedef xmlXPathVariable *xmlXPathVariablePtr;


xmlXPathEvalFunc ()

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

An XPath evaluation function, the parameters are on the XPath context stack.

ctxt : an XPath parser context
nargs : the number of arguments passed to the function


struct xmlXPathFunct

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


xmlXPathFuncPtr

typedef xmlXPathFunct *xmlXPathFuncPtr;


xmlXPathAxisFunc ()

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

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.

ctxt : the XPath interpreter context
cur : the previous node being explored on that axis
Returns :the next node in that axis or NULL if at the end of the axis.


struct xmlXPathAxis

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


xmlXPathAxisPtr

typedef xmlXPathAxis *xmlXPathAxisPtr;


struct xmlXPathCompExpr

struct xmlXPathCompExpr;

[14] Expr ::= OrExpr [21] OrExpr ::= AndExpr | OrExpr 'or' AndExpr

Parse and compile an expression


xmlXPathCompExprPtr

typedef xmlXPathCompExpr *xmlXPathCompExprPtr;


xmlXPathFunction ()

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

An XPath function. The arguments (if any) are popped out from the context stack and the result is pushed on the stack.

ctxt : the XPath interprestation context
nargs : the number of arguments


xmlXPathIsNaN ()

int         xmlXPathIsNaN                   (double val);

Provides a portable isnan() function to detect whether a double is a NotaNumber. Based on trio code http://sourceforge.net/projects/ctrio/

val : a double value
Returns :1 if the value is a NaN, 0 otherwise


xmlXPathIsInf ()

int         xmlXPathIsInf                   (double val);

Provides a portable isinf() function to detect whether a double is a +Infinite or -Infinite. Based on trio code http://sourceforge.net/projects/ctrio/

val : a double value
Returns :1 vi the value is +Infinite, -1 if -Infinite, 0 otherwise


xmlXPathNodeSetGetLength()

#define xmlXPathNodeSetGetLength(ns) ((ns) ? (ns)->nodeNr : 0)

Implement a functionality similar to the DOM NodeList.length.

ns : a node-set


xmlXPathNodeSetItem()

#define     xmlXPathNodeSetItem(ns, index)

Implements a functionality similar to the DOM NodeList.item().

ns : a node-set
index : index of a node in the set


xmlXPathNodeSetIsEmpty()

#define     xmlXPathNodeSetIsEmpty(ns)

Checks whether ns is empty or not.

ns : a node-set


xmlXPathFreeObject ()

void        xmlXPathFreeObject              (xmlXPathObjectPtr obj);

Free up an xmlXPathObjectPtr object.

obj : the object to free


xmlXPathNodeSetCreate ()

xmlNodeSetPtr xmlXPathNodeSetCreate         (xmlNodePtr val);

Create a new xmlNodeSetPtr of type double and of value val

val : an initial xmlNodePtr, or NULL
Returns :the newly created object.


xmlXPathFreeNodeSetList ()

void        xmlXPathFreeNodeSetList         (xmlXPathObjectPtr obj);

Free up the xmlXPathObjectPtr obj but don't deallocate the objects in the list contrary to xmlXPathFreeObject().

obj : an existing NodeSetList object


xmlXPathFreeNodeSet ()

void        xmlXPathFreeNodeSet             (xmlNodeSetPtr obj);

Free the NodeSet compound (not the actual nodes !).

obj : the xmlNodeSetPtr to free


xmlXPathObjectCopy ()

xmlXPathObjectPtr xmlXPathObjectCopy        (xmlXPathObjectPtr val);

allocate a new copy of a given object

val : the original object
Returns :the newly created object.


xmlXPathCmpNodes ()

int         xmlXPathCmpNodes                (xmlNodePtr node1,
                                             xmlNodePtr node2);

Compare two nodes w.r.t document order

node1 : the first node
node2 : the second node
Returns :-2 in case of error 1 if first point < second point, 0 if that's the same node, -1 otherwise


xmlXPathCastNumberToBoolean ()

int         xmlXPathCastNumberToBoolean     (double val);

Converts a number to its boolean value

val : a number
Returns :the boolean value


xmlXPathCastStringToBoolean ()

int         xmlXPathCastStringToBoolean     (const xmlChar *val);

Converts a string to its boolean value

val : a string
Returns :the boolean value


xmlXPathCastNodeSetToBoolean ()

int         xmlXPathCastNodeSetToBoolean    (xmlNodeSetPtr ns);

Converts a node-set to its boolean value

ns : a node-set
Returns :the boolean value


xmlXPathCastToBoolean ()

int         xmlXPathCastToBoolean           (xmlXPathObjectPtr val);

Converts an XPath object to its boolean value

val : an XPath object
Returns :the boolean value


xmlXPathCastBooleanToNumber ()

double      xmlXPathCastBooleanToNumber     (int val);

Converts a boolean to its number value

val : a boolean
Returns :the number value


xmlXPathCastStringToNumber ()

double      xmlXPathCastStringToNumber      (const xmlChar *val);

Converts a string to its number value

val : a string
Returns :the number value


xmlXPathCastNodeToNumber ()

double      xmlXPathCastNodeToNumber        (xmlNodePtr node);

Converts a node to its number value

node : a node
Returns :the number value


xmlXPathCastNodeSetToNumber ()

double      xmlXPathCastNodeSetToNumber     (xmlNodeSetPtr ns);

Converts a node-set to its number value

ns : a node-set
Returns :the number value


xmlXPathCastToNumber ()

double      xmlXPathCastToNumber            (xmlXPathObjectPtr val);

Converts an XPath object to its number value

val : an XPath object
Returns :the number value


xmlXPathCastBooleanToString ()

xmlChar*    xmlXPathCastBooleanToString     (int val);

Converts a boolean to its string value.

val : a boolean
Returns :a newly allocated string.


xmlXPathCastNumberToString ()

xmlChar*    xmlXPathCastNumberToString      (double val);

Converts a number to its string value.

val : a number
Returns :a newly allocated string.


xmlXPathCastNodeToString ()

xmlChar*    xmlXPathCastNodeToString        (xmlNodePtr node);

Converts a node to its string value.

node : a node
Returns :a newly allocated string.


xmlXPathCastNodeSetToString ()

xmlChar*    xmlXPathCastNodeSetToString     (xmlNodeSetPtr ns);

Converts a node-set to its string value.

ns : a node-set
Returns :a newly allocated string.


xmlXPathCastToString ()

xmlChar*    xmlXPathCastToString            (xmlXPathObjectPtr val);

Converts an existing object to its string() equivalent

val : an XPath object
Returns :the string value of the object, NULL in case of error. A new string is allocated only if needed (val isn't a string object).


xmlXPathConvertBoolean ()

xmlXPathObjectPtr xmlXPathConvertBoolean    (xmlXPathObjectPtr val);

Converts an existing object to its boolean() equivalent

val : an XPath object
Returns :the new object, the old one is freed (or the operation is done directly on val)


xmlXPathConvertNumber ()

xmlXPathObjectPtr xmlXPathConvertNumber     (xmlXPathObjectPtr val);

Converts an existing object to its number() equivalent

val : an XPath object
Returns :the new object, the old one is freed (or the operation is done directly on val)


xmlXPathConvertString ()

xmlXPathObjectPtr xmlXPathConvertString     (xmlXPathObjectPtr val);

Converts an existing object to its string() equivalent

val : an XPath object
Returns :the new object, the old one is freed (or the operation is done directly on val)


xmlXPathInit ()

void        xmlXPathInit                    (void);

Initialize the XPath environment


xmlXPathNewContext ()

xmlXPathContextPtr xmlXPathNewContext       (xmlDocPtr doc);

Create a new xmlXPathContext

doc : the XML document
Returns :the xmlXPathContext just allocated. The caller will need to free it.


xmlXPathFreeContext ()

void        xmlXPathFreeContext             (xmlXPathContextPtr ctxt);

Free up an xmlXPathContext

ctxt : the context to free


xmlXPathEval ()

xmlXPathObjectPtr xmlXPathEval              (const xmlChar *str,
                                             xmlXPathContextPtr ctx);

Evaluate the XPath Location Path in the given context.

str : the XPath expression
ctx : the XPath context
Returns :the xmlXPathObjectPtr resulting from the evaluation or NULL. the caller has to free the object.


xmlXPathEvalExpression ()

xmlXPathObjectPtr xmlXPathEvalExpression    (const xmlChar *str,
                                             xmlXPathContextPtr ctxt);

Evaluate the XPath expression in the given context.

str : the XPath expression
ctxt : the XPath context
Returns :the xmlXPathObjectPtr resulting from the evaluation or NULL. the caller has to free the object.


xmlXPathEvalPredicate ()

int         xmlXPathEvalPredicate           (xmlXPathContextPtr ctxt,
                                             xmlXPathObjectPtr res);

Evaluate a predicate result for the current node. A PredicateExpr is evaluated by evaluating the Expr and converting the result to a boolean. If the result is a number, the result will be converted to true if the number is equal to the position of the context node in the context node list (as returned by the position function) and will be converted to false otherwise; if the result is not a number, then the result will be converted as if by a call to the boolean function.

ctxt : the XPath context
res : the Predicate Expression evaluation result
Returns :1 if predicate is true, 0 otherwise


xmlXPathCompile ()

xmlXPathCompExprPtr xmlXPathCompile         (const xmlChar *str);

Compile an XPath expression

str : the XPath expression
Returns :the xmlXPathObjectPtr resulting from the evaluation or NULL. the caller has to free the object.


xmlXPathCompiledEval ()

xmlXPathObjectPtr xmlXPathCompiledEval      (xmlXPathCompExprPtr comp,
                                             xmlXPathContextPtr ctx);

Evaluate the Precompiled XPath expression in the given context.

comp : the compiled XPath expression
ctx : the XPath context
Returns :the xmlXPathObjectPtr resulting from the evaluation or NULL. the caller has to free the object.


xmlXPathFreeCompExpr ()

void        xmlXPathFreeCompExpr            (xmlXPathCompExprPtr comp);

Free up the memory allocated by comp

comp : an XPATH comp