packer-cn/vendor/gopkg.in/xmlpath.v2/doc.go

76 lines
3.1 KiB
Go

// Package xmlpath implements a strict subset of the XPath specification for the Go language.
//
// The XPath specification is available at:
//
// http://www.w3.org/TR/xpath
//
// Path expressions supported by this package are in the following format,
// with all components being optional:
//
// /axis-name::node-test[predicate]/axis-name::node-test[predicate]
//
// At the moment, xmlpath is compatible with the XPath specification
// to the following extent:
//
// - All axes are supported ("child", "following-sibling", etc)
// - All abbreviated forms are supported (".", "//", etc)
// - All node types except for namespace are supported
// - Predicates may be [N], [path], [not(path)], [path=literal] or [contains(path, literal)]
// - Predicates may be joined with "or", "and", and parenthesis
// - Richer expressions and namespaces are not supported
//
// For example, assuming the following document:
//
// <library>
// <!-- Great book. -->
// <book id="b0836217462" available="true">
// <isbn>0836217462</isbn>
// <title lang="en">Being a Dog Is a Full-Time Job</title>
// <quote>I'd dog paddle the deepest ocean.</quote>
// <author id="CMS">
// <?echo "go rocks"?>
// <name>Charles M Schulz</name>
// <born>1922-11-26</born>
// <dead>2000-02-12</dead>
// </author>
// <character id="PP">
// <name>Peppermint Patty</name>
// <born>1966-08-22</born>
// <qualification>bold, brash and tomboyish</qualification>
// </character>
// <character id="Snoopy">
// <name>Snoopy</name>
// <born>1950-10-04</born>
// <qualification>extroverted beagle</qualification>
// </character>
// </book>
// </library>
//
// The following examples are valid path expressions, and the first
// match has the indicated value:
//
// /library/book/isbn => "0836217462"
// library/*/isbn => "0836217462"
// /library/book/../book/./isbn => "0836217462"
// /library/book/character[2]/name => "Snoopy"
// /library/book/character[born='1950-10-04']/name => "Snoopy"
// /library/book//node()[@id='PP']/name => "Peppermint Patty"
// //book[author/@id='CMS']/title => "Being a Dog Is a Full-Time Job",
// /library/book/preceding::comment() => " Great book. "
// //*[contains(born,'1922')]/name => "Charles M Schulz"
// //*[@id='PP' or @id='Snoopy']/born => {"1966-08-22", "1950-10-04"}
//
// To run an expression, compile it, and then apply the compiled path to any
// number of context nodes, from one or more parsed xml documents:
//
// path := xmlpath.MustCompile("/library/book/isbn")
// root, err := xmlpath.Parse(file)
// if err != nil {
// log.Fatal(err)
// }
// if value, ok := path.String(root); ok {
// fmt.Println("Found:", value)
// }
//
package xmlpath