119 lines
3.8 KiB
Markdown
119 lines
3.8 KiB
Markdown
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XPath
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====
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[](https://godoc.org/github.com/antchfx/xpath)
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[](https://coveralls.io/github/antchfx/xpath?branch=master)
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[](https://travis-ci.org/antchfx/xpath)
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[](https://goreportcard.com/report/github.com/antchfx/xpath)
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XPath is Go package provides selecting nodes from XML, HTML or other documents using XPath expression.
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[XQuery](https://github.com/antchfx/xquery) : lets you extract data from HTML/XML documents using XPath package.
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### Features
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#### The basic XPath patterns.
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> The basic XPath patterns cover 90% of the cases that most stylesheets will need.
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- `node` : Selects all child elements with nodeName of node.
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- `*` : Selects all child elements.
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- `@attr` : Selects the attribute attr.
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- `@*` : Selects all attributes.
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- `node()` : Matches an org.w3c.dom.Node.
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- `text()` : Matches a org.w3c.dom.Text node.
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- `comment()` : Matches a comment.
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- `.` : Selects the current node.
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- `..` : Selects the parent of current node.
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- `/` : Selects the document node.
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- `a[expr]` : Select only those nodes matching a which also satisfy the expression expr.
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- `a[n]` : Selects the nth matching node matching a When a filter's expression is a number, XPath selects based on position.
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- `a/b` : For each node matching a, add the nodes matching b to the result.
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- `a//b` : For each node matching a, add the descendant nodes matching b to the result.
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- `//b` : Returns elements in the entire document matching b.
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- `a|b` : All nodes matching a or b.
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#### Node Axes
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- `child::*` : The child axis selects children of the current node.
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- `descendant::*` : The descendant axis selects descendants of the current node. It is equivalent to '//'.
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- `descendant-or-self::*` : Selects descendants including the current node.
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- `attribute::*` : Selects attributes of the current element. It is equivalent to @*
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- `following-sibling::*` : Selects nodes after the current node.
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- `preceding-sibling::*` : Selects nodes before the current node.
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- `following::*` : Selects the first matching node following in document order, excluding descendants.
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- `preceding::*` : Selects the first matching node preceding in document order, excluding ancestors.
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- `parent::*` : Selects the parent if it matches. The '..' pattern from the core is equivalent to 'parent::node()'.
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- `ancestor::*` : Selects matching ancestors.
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- `ancestor-or-self::*` : Selects ancestors including the current node.
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- `self::*` : Selects the current node. '.' is equivalent to 'self::node()'.
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#### Expressions
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The gxpath supported three types: number, boolean, string.
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- `path` : Selects nodes based on the path.
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- `a = b` : Standard comparisons.
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* a = b True if a equals b.
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* a != b True if a is not equal to b.
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* a < b True if a is less than b.
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* a <= b True if a is less than or equal to b.
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* a > b True if a is greater than b.
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* a >= b True if a is greater than or equal to b.
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- `a + b` : Arithmetic expressions.
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* `- a` Unary minus
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* a + b Add
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* a - b Substract
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* a * b Multiply
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* a div b Divide
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* a mod b Floating point mod, like Java.
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- `(expr)` : Parenthesized expressions.
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- `fun(arg1, ..., argn)` : Function calls.
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* position()
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* last()
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* count( node-set )
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* name()
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* starts-with( string, string )
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* normalize-space( string )
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* substring( string , start [, length] )
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* not( expression )
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* string-length( [string] )
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* contains( string, string )
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* sum( node-set )
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* concat( string1 , string2 [, stringn]* )
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- `a or b` : Boolean or.
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- `a and b` : Boolean and.
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