BDB::XML::Context

The context within which a query is performed against a Container.

The context within which a query is performed against a Container is complex enough to warrent an encapsulating class. This context includes a namespace mapping, variable bindings, and flags that determine how the query result set should be determined and returned to the caller.

The XPath syntax permits expressions to refer to namespace prefixes, but not to define them. The Context class provides a number of namespace management methods so that the caller may manage the namespace prefix to URI mapping.

The XPath syntax also permits expressions to refer to variables, but not to define them. The Context class provides a number of methods so that the caller may manage the variable to value bindings.

Class Methods

allocate

Allocate a new Context object

Methods

self[variable]

Get the value bound to a variable

self[variable] = value

Bind a value to a variable

clear_namespaces

clear

Delete all the namespace prefix mappings

del_namespace(name)

Delete the namespace URI for a particular prefix

evaltype

Return the evaluation type

evaltype=(type)

Set the evaluation type

get_namespace(name)

namespace[name]

Get the namespace URI that a namespace prefix maps onto

initialize(returntype = nil, evaluation = nil)

Initialize the object with the optional evaluation type BDB::XML::Context::Lazy or BDB::XML::Context::Eager and return type BDB::XML::Context::Documents, BDB::XML::Context::Values or BDB::XML::Context::Candidates

metadata

with_metadata

return true if the metadata is added to the document

metadata=(with)

with_metadata=(with)

The with parameter specifies whether or not to add the document metadata prior to the query.

returntype

Return the return type

returntype=(type)

Set the return type

namespace[name]=(uri)

set_namespace(name, uri)

Define a namespace prefix, providing the URI that it maps onto

If uri is nil delete the namespace