xmlpath · pkg.go.dev

Documentation

Overview ¶

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 are restricted to [N], [path], and [path=literal] forms
- Only a single predicate is supported per path step
- 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. "

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)
}

Index ¶

type Iter
- func (iter *Iter) Next() bool
- func (iter *Iter) Node() *Node
type Node
- func (node *Node) Bytes() []byte
- func (node *Node) String() string
type Path
- func Compile(path string) (*Path, error)
- func MustCompile(path string) *Path

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

This section is empty.

Types ¶

type Iter ¶

type Iter struct {
	// contains filtered or unexported fields
}

Iter iterates over node sets.

func (*Iter) Next ¶

func (iter *Iter) Next() bool

Next iterates to the next node in the set, if any, and returns whether there is a node available.

func (*Iter) Node ¶

func (iter *Iter) Node() *Node

Node returns the current node. Must only be called after Iter.Next returns true.

type Node ¶

type Node struct {
	// contains filtered or unexported fields
}

Node is an item in an xml tree that was compiled to be processed via xml paths. A node may represent:

- An element in the xml document (<body>)
- An attribute of an element in the xml document (href="...")
- A comment in the xml document (<!--...-->)
- A processing instruction in the xml document (<?...?>)
- Some text within the xml document

func Parse ¶

func Parse(r io.Reader) (*Node, error)

Parse reads an xml document from r, parses it, and returns its root node.

func ParseDecoder ¶

func ParseDecoder(d *xml.Decoder) (*Node, error)

ParseDecoder parses the xml document being decoded by d and returns its root node.

func ParseHTML ¶

func ParseHTML(r io.Reader) (*Node, error)

ParseHTML reads an HTML-like document from r, parses it, and returns its root node.

func (*Node) Bytes ¶

func (node *Node) Bytes() []byte

Bytes returns the string value of node as a byte slice. See Node.String for a description of what the string value of a node is.

func (*Node) String ¶

func (node *Node) String() string

String returns the string value of node.

The string value of a node is:

- For element nodes, the concatenation of all text nodes within the element.
- For text nodes, the text itself.
- For attribute nodes, the attribute value.
- For comment nodes, the text within the comment delimiters.
- For processing instruction nodes, the content of the instruction.

type Path ¶

type Path struct {
	// contains filtered or unexported fields
}

Path is a compiled path that can be applied to a context node to obtain a matching node set. A single Path can be applied concurrently to any number of context nodes.

func Compile ¶

func Compile(path string) (*Path, error)

Compile returns the compiled path.

func MustCompile ¶

func MustCompile(path string) *Path

MustCompile returns the compiled path, and panics if there are any errors.

func (*Path) Bytes ¶

func (p *Path) Bytes(node *Node) (b []byte, ok bool)

Bytes returns as a byte slice the string value of the first node matched by p on the given context.

See the documentation of Node.String.

func (*Path) Exists ¶

func (p *Path) Exists(context *Node) bool

Exists returns whether any nodes match p on the given context.

func (*Path) Iter ¶

func (p *Path) Iter(context *Node) *Iter

Iter returns an iterator that goes over the list of nodes that p matches on the given context.

func (*Path) String ¶

func (p *Path) String(context *Node) (s string, ok bool)

String returns the string value of the first node matched by p on the given context.

See the documentation of Node.String.

Source Files

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