Class: LibXML::XML::XPath::Context
- Inherits:
-
Object
- Object
- LibXML::XML::XPath::Context
- Defined in:
- ext/libxml/ruby_xml_xpath_context.c,
ext/libxml/ruby_xml_xpath_context.c
Overview
The XML::XPath::Context class is used to evaluate XPath expressions. Generally, you should not directly use this class, but instead use the XML::Document#find and XML::Node#find methods.
doc = XML::Document.string('<header>content</header>')
context = XPath::Context.new(doc)
context.node = doc.root
context.register_namespaces_from_node(doc.root)
nodes = context.find('/header')
Instance Method Summary collapse
-
#disable_cache ⇒ Object
Disables an XPath::Context’s built-in cache.
-
#doc ⇒ Object
Obtain the XML::Document this node belongs to.
-
#enable_cache(size = nil) ⇒ Object
Enables an XPath::Context’s built-in cache.
-
#find("xpath") ⇒ true|false|number|string|XML::XPath::Object
Executes the provided xpath function.
-
#XPath::Context.new(doc) ⇒ XPath::Context
constructor
Creates a new XPath context for the specified document.
-
#node=(node) ⇒ Object
Set the current node used by the XPath engine.
-
#register_namespace(prefix, uri) ⇒ Object
Register the specified namespace URI with the specified prefix in this context.
-
#register_namespaces(["prefix: uri"]) ⇒ self
Register the specified namespaces in this context.
-
#register_namespaces_from_node(node) ⇒ self
Helper method to read in namespaces defined on a node.
Constructor Details
#XPath::Context.new(doc) ⇒ XPath::Context
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 58
static VALUE rxml_xpath_context_initialize(VALUE self, VALUE document)
{
xmlDocPtr xdoc;
if (rb_obj_is_kind_of(document, cXMLDocument) != Qtrue)
{
rb_raise(rb_eTypeError, "Supplied argument must be a document or node.");
}
Data_Get_Struct(document, xmlDoc, xdoc);
DATA_PTR(self) = xmlXPathNewContext(xdoc);
return self;
}
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Instance Method Details
#disable_cache ⇒ Object
Disables an XPath::Context’s built-in cache.
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 334
static VALUE
rxml_xpath_context_disable_cache(VALUE self)
{
xmlXPathContextPtr xctxt;
Data_Get_Struct(self, xmlXPathContext, xctxt);
if (xmlXPathContextSetCache(xctxt, 0, 0, 0) == -1)
rxml_raise(xmlGetLastError());
return self;
}
|
#doc ⇒ Object
Obtain the XML::Document this node belongs to.
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 79
static VALUE rxml_xpath_context_doc(VALUE self)
{
xmlDocPtr xdoc = NULL;
xmlXPathContextPtr ctxt;
Data_Get_Struct(self, xmlXPathContext, ctxt);
xdoc = ctxt->doc;
return rxml_document_wrap(xdoc);
}
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#enable_cache(size = nil) ⇒ Object
Enables an XPath::Context’s built-in cache. If the cache is enabled then XPath objects will be cached internally for reuse. The size parameter controls sets the maximum number of XPath objects that will be cached per XPath object type (node-set, string, number, boolean, and misc objects). Set size to nil to use the default cache size of 100.
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 308
static VALUE
rxml_xpath_context_enable_cache(int argc, VALUE *argv, VALUE self)
{
xmlXPathContextPtr xctxt;
VALUE size;
int value = -1;
Data_Get_Struct(self, xmlXPathContext, xctxt);
if (rb_scan_args(argc, argv, "01", &size) == 1)
{
value = NUM2INT(size);
}
if (xmlXPathContextSetCache(xctxt, 1, value, 0) == -1)
rxml_raise(xmlGetLastError());
return self;
}
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#find("xpath") ⇒ true|false|number|string|XML::XPath::Object
Executes the provided xpath function. The result depends on the execution of the xpath statement. It may be true, false, a number, a string or a node set.
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 269
static VALUE rxml_xpath_context_find(VALUE self, VALUE xpath_expr)
{
xmlXPathContextPtr xctxt;
xmlXPathObjectPtr xobject;
xmlXPathCompExprPtr xcompexpr;
Data_Get_Struct(self, xmlXPathContext, xctxt);
if (TYPE(xpath_expr) == T_STRING)
{
VALUE expression = rb_check_string_type(xpath_expr);
xobject = xmlXPathEval((xmlChar*) StringValueCStr(expression), xctxt);
}
else if (rb_obj_is_kind_of(xpath_expr, cXMLXPathExpression))
{
Data_Get_Struct(xpath_expr, xmlXPathCompExpr, xcompexpr);
xobject = xmlXPathCompiledEval(xcompexpr, xctxt);
}
else
{
rb_raise(rb_eTypeError,
"Argument should be an instance of a String or XPath::Expression");
}
return rxml_xpath_to_value(xctxt, xobject);
}
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#node=(node) ⇒ Object
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 250
static VALUE rxml_xpath_context_node_set(VALUE self, VALUE node)
{
xmlXPathContextPtr xctxt;
xmlNodePtr xnode;
Data_Get_Struct(self, xmlXPathContext, xctxt);
Data_Get_Struct(node, xmlNode, xnode);
xctxt->node = xnode;
return node;
}
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#register_namespace(prefix, uri) ⇒ Object
Register the specified namespace URI with the specified prefix in this context.
context.register_namespace('xi', 'http://www.w3.org/2001/XInclude')
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 98
static VALUE rxml_xpath_context_register_namespace(VALUE self, VALUE prefix, VALUE uri)
{
xmlXPathContextPtr ctxt;
Data_Get_Struct(self, xmlXPathContext, ctxt);
/* Prefix could be a symbol. */
prefix = rb_obj_as_string(prefix);
if (xmlXPathRegisterNs(ctxt, (xmlChar*) StringValuePtr(prefix),
(xmlChar*) StringValuePtr(uri)) == 0)
{
return (Qtrue);
}
else
{
/* Should raise an exception, IMHO (whose?, why shouldnt it? -danj)*/
rb_warning("register namespace failed");
return (Qfalse);
}
}
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#register_namespaces(["prefix: uri"]) ⇒ self
Register the specified namespaces in this context. There are three different forms that libxml accepts. These include a string, an array of strings, or a hash table:
context.register_namespaces('xi:http://www.w3.org/2001/XInclude')
context.register_namespaces(['xlink:http://www.w3.org/1999/xlink',
'xi:http://www.w3.org/2001/XInclude')
context.register_namespaces('xlink' => 'http://www.w3.org/1999/xlink',
'xi' => 'http://www.w3.org/2001/XInclude')
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 196
static VALUE rxml_xpath_context_register_namespaces(VALUE self, VALUE nslist)
{
char *cp;
long i;
VALUE rprefix, ruri;
xmlXPathContextPtr xctxt;
Data_Get_Struct(self, xmlXPathContext, xctxt);
/* Need to loop through the 2nd argument and iterate through the
* list of namespaces that we want to allow */
switch (TYPE(nslist))
{
case T_STRING:
cp = strchr(StringValuePtr(nslist), (int) ':');
if (cp == NULL)
{
rprefix = nslist;
ruri = Qnil;
}
else
{
rprefix = rb_str_new(StringValuePtr(nslist), (long) ((intptr_t) cp - (intptr_t)StringValuePtr(nslist)));
ruri = rxml_new_cstr((const xmlChar*)&cp[1], xctxt->doc->encoding);
}
/* Should test the results of this */
rxml_xpath_context_register_namespace(self, rprefix, ruri);
break;
case T_ARRAY:
for (i = 0; i < RARRAY_LEN(nslist); i++)
{
rxml_xpath_context_register_namespaces(self, RARRAY_PTR(nslist)[i]);
}
break;
case T_HASH:
rb_hash_foreach(nslist, iterate_ns_hash, self);
break;
default:
rb_raise(
rb_eArgError,
"Invalid argument type, only accept string, array of strings, or an array of arrays");
}
return self;
}
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#register_namespaces_from_node(node) ⇒ self
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# File 'ext/libxml/ruby_xml_xpath_context.c', line 128
static VALUE rxml_xpath_context_register_namespaces_from_node(VALUE self,
VALUE node)
{
xmlXPathContextPtr xctxt;
xmlNodePtr xnode;
xmlNsPtr *xnsArr;
Data_Get_Struct(self, xmlXPathContext, xctxt);
if (rb_obj_is_kind_of(node, cXMLDocument) == Qtrue)
{
xmlDocPtr xdoc;
Data_Get_Struct(node, xmlDoc, xdoc);
xnode = xmlDocGetRootElement(xdoc);
}
else if (rb_obj_is_kind_of(node, cXMLNode) == Qtrue)
{
Data_Get_Struct(node, xmlNode, xnode);
}
else
{
rb_raise(rb_eTypeError, "The first argument must be a document or node.");
}
xnsArr = xmlGetNsList(xnode->doc, xnode);
if (xnsArr)
{
xmlNsPtr xns = *xnsArr;
while (xns)
{
/* If there is no prefix, then this is the default namespace.
Skip it for now. */
if (xns->prefix)
{
VALUE prefix = rxml_new_cstr(xns->prefix, xctxt->doc->encoding);
VALUE uri = rxml_new_cstr(xns->href, xctxt->doc->encoding);
rxml_xpath_context_register_namespace(self, prefix, uri);
}
xns = xns->next;
}
xmlFree(xnsArr);
}
return self;
}
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