diff -r 000000000000 -r 02cd6b52f378 dummy_foundation/lib/XML/XQL/Query.pod --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/dummy_foundation/lib/XML/XQL/Query.pod Thu May 28 10:10:03 2009 +0100 @@ -0,0 +1,155 @@ +=head1 NAME + +XML::XQL::Query - Creates an XQL query evaluater from a XQL expression + +=head1 SYNOPSIS + + use XML::XQL; + + $parser = new XML::DOM::Parser; + $doc = $parser->parsefile ("file.xml"); + + # Return all elements with tagName='title' under the root element 'book' + $query = new XML::XQL::Query (Expr => "book/title"); + @result = $query->solve ($doc); + + # Or (to save some typing) + @result = XML::XQL::solve ("book/title", $doc); + +=head1 DESCRIPTION + +To perform XQL queries on an XML::DOM document (or, in the future, on other XML +storage structures), you first have to create an XML::XQL::Query object and +pass it a valid XQL query expression. You can then perform queries on one or +more documents by calling the solve() method. + +=head1 XML::XQL::Query constructor + +Usage, e.g: + + $query = new XML::XQL::Query( + Expr => "book/author", + Func => [ myfunc => \&my_func, # define 2 functions + myfunc2 => \&my_func2 ], + FuncArgCount => [ myfunc2 => [2, -1] ], # myfunc2 has 2 or more args + AllowedOutSideSubquery => [ myfunc => 1 ], + ConstFunc => [ myfunc2 => 1], + CompareOper => [ mycmp => \&mycmp ], # define comparison operator + q => "str"); # use str// as string delim + +=over 4 + +=item Expr => STRING + +The query expression to be evaluated. + +=item NodeQuery => BOOLEAN + +If set to 1, the query is a I as opposed to a +I (which is the default.) +A node query is a query that is only capable of returning Nodes. +A full query is capable of returning Node values and non-Node values. +Non-Node values include XML Primitives, element type names, namespace URI's, +concatenated text nodes, and node type names. The distinction is significant +because node queries may appear as XSL match and select patterns, while full +queries have use in other applications. +The difference between the two forms of queries is trivial and exists only as +constraints on the syntax of node queries. +Node queries may contain nested full queries. + +=item Func => [ FUNCNAME => FUNCREF, ...] + +Defines one or more functions. FUNCNAME is the name as used in the query +expression. FUNCREF can be either a function reference like \&my_func or +an anonymous sub. +See also: defineFunction + +=item Method => [ FUNCNAME => FUNCREF, ...] + +Defines one or more methods. FUNCNAME is the name as used in the query +expression. FUNCREF can be either a function reference like \&my_func or +an anonymous sub. +See also: defineMethod + +=item FuncArgCount => [ FUNCNAME => ARGCOUNT, ...] + +Defines the number of arguments for one or more functions or methods. +FUNCNAME is the name as used in the query expression. +See also: defineFunction and defineMethod + +=item AllowedOutsideSubquery => [ FUNCNAME => BOOLEAN, ...] + +Defines whether the specified function or method is allowed outside +subqueries. FUNCNAME is the name as used in the query expression. +See also: defineFunction and defineMethod + +=item ConstFunc => [ FUNCNAME => BOOLEAN, ...] + +Defines whether the function (not method!) is a "constant" function. +FUNCNAME is the name as used in the query expression. +See L for a definition of "constant" +See also: defineFunction and defineMethod + +=item CompareOper => [ OPERNAME => FUNCREF, ...] + +Defines the comparison operator with the specified OPERNAME, e.g. if +OPERNAME is "contains", you can use "$contains$" in the query. +See also: defineComparisonOperators + +=item q => TOKEN + +Defines the q// token. See also: defineTokenQ + +=item qq => TOKEN + +Defines the qq// token. See also: defineTokenQQ + +=item Error => FUNCREF + +Defines the function that is called when errors occur during parsing the +query expression. The default function prints an error message to STDERR. + +=item Debug => FLAGS + +Sets the debug level for the Yapp parser that parses the query expression. +Default value is 0 (don't print anything). The maximum value is 0x17, which +prints a lot of stuff. See the Parse::Yapp manpage for the meaning of the +individual bits. + +=item Reserved hash keys + +Users may add their own (key, value) pairs to the Query constructor. +Beware that the key 'Tree' is used internally. + +=back + +=head1 XML::XQL::Query methods + +=over 4 + +=item solve (INPUT_LIST...) + +Note that solve takes a list of nodes which are assumed to be in document order +and must belong to the same document. E.g: + + $query = new XML::XQL::Query (Expr => "doc//book"); + @result = $query->solve ($doc); + @result2 = $query->solve ($node1, $node2, $node3); + +=back + +The following functions are also available at the query level, i.e. when called +on a Query object they only affect this Query and no others: + + defineFunction, defineMethod, defineComparisonOperators, + defineTokenQ, defineTokenQQ + +See L for details. +Another way to define these features for a particular Query is by passing the +appropriate values to the XML::XQL::Query constructor. + +=head1 SEE ALSO + +L for general information about the XML::XQL module + +L which describes the XQL syntax