terraform/vendor/github.com/antchfx/xpath/README.md

3.8 KiB

XPath

GoDoc Coverage Status Build Status Go Report Card

XPath is Go package provides selecting nodes from XML, HTML or other documents using XPath expression.

XQuery : lets you extract data from HTML/XML documents using XPath package.

Features

The basic XPath patterns.

The basic XPath patterns cover 90% of the cases that most stylesheets will need.

  • node : Selects all child elements with nodeName of node.

  • * : Selects all child elements.

  • @attr : Selects the attribute attr.

  • @* : Selects all attributes.

  • node() : Matches an org.w3c.dom.Node.

  • text() : Matches a org.w3c.dom.Text node.

  • comment() : Matches a comment.

  • . : Selects the current node.

  • .. : Selects the parent of current node.

  • / : Selects the document node.

  • a[expr] : Select only those nodes matching a which also satisfy the expression expr.

  • a[n] : Selects the nth matching node matching a When a filter's expression is a number, XPath selects based on position.

  • a/b : For each node matching a, add the nodes matching b to the result.

  • a//b : For each node matching a, add the descendant nodes matching b to the result.

  • //b : Returns elements in the entire document matching b.

  • a|b : All nodes matching a or b.

Node Axes

  • child::* : The child axis selects children of the current node.

  • descendant::* : The descendant axis selects descendants of the current node. It is equivalent to '//'.

  • descendant-or-self::* : Selects descendants including the current node.

  • attribute::* : Selects attributes of the current element. It is equivalent to @*

  • following-sibling::* : Selects nodes after the current node.

  • preceding-sibling::* : Selects nodes before the current node.

  • following::* : Selects the first matching node following in document order, excluding descendants.

  • preceding::* : Selects the first matching node preceding in document order, excluding ancestors.

  • parent::* : Selects the parent if it matches. The '..' pattern from the core is equivalent to 'parent::node()'.

  • ancestor::* : Selects matching ancestors.

  • ancestor-or-self::* : Selects ancestors including the current node.

  • self::* : Selects the current node. '.' is equivalent to 'self::node()'.

Expressions

The gxpath supported three types: number, boolean, string.

  • path : Selects nodes based on the path.

  • a = b : Standard comparisons.

    • a = b True if a equals b.
    • a != b True if a is not equal to b.
    • a < b True if a is less than b.
    • a <= b True if a is less than or equal to b.
    • a > b True if a is greater than b.
    • a >= b True if a is greater than or equal to b.
  • a + b : Arithmetic expressions.

    • - a Unary minus
    • a + b Add
    • a - b Substract
    • a * b Multiply
    • a div b Divide
    • a mod b Floating point mod, like Java.
  • (expr) : Parenthesized expressions.

  • fun(arg1, ..., argn) : Function calls.

    • position()
    • last()
    • count( node-set )
    • name()
    • starts-with( string, string )
    • normalize-space( string )
    • substring( string , start [, length] )
    • not( expression )
    • string-length( [string] )
    • contains( string, string )
    • sum( node-set )
    • concat( string1 , string2 [, stringn]* )
  • a or b : Boolean or.

  • a and b : Boolean and.