XPath
====
[](https://godoc.org/github.com/antchfx/xpath)
[](https://coveralls.io/github/antchfx/xpath?branch=master)
[](https://travis-ci.org/antchfx/xpath)
[](https://goreportcard.com/report/github.com/antchfx/xpath)
XPath is Go package provides selecting nodes from XML, HTML or other documents using XPath expression.
Implementation
===
- [htmlquery](https://github.com/antchfx/htmlquery) - an XPath query package for HTML document
- [xmlquery](https://github.com/antchfx/xmlquery) - an XPath query package for XML document.
- [jsonquery](https://github.com/antchfx/jsonquery) - an XPath query package for JSON document
Supported 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, union operation(not boolean or).
- `(a, b, c)` : Evaluates each of its operands and concatenates the resulting sequences, in order, into a single result sequence
#### 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.
- `a or b` : Boolean `or` operation.
- `a and b` : Boolean `and` operation.
- `(expr)` : Parenthesized expressions.
- `fun(arg1, ..., argn)` : Function calls:
| Function | Supported |
| --- | --- |
`boolean()`| ✓ |
`ceiling()`| ✓ |
`choose()`| ✗ |
`concat()`| ✓ |
`contains()`| ✓ |
`count()`| ✓ |
`current()`| ✗ |
`document()`| ✗ |
`element-available()`| ✗ |
`ends-with()`| ✓ |
`false()`| ✓ |
`floor()`| ✓ |
`format-number()`| ✗ |
`function-available()`| ✗ |
`generate-id()`| ✗ |
`id()`| ✗ |
`key()`| ✗ |
`lang()`| ✗ |
`last()`| ✓ |
`local-name()`| ✓ |
`name()`| ✓ |
`namespace-uri()`| ✓ |
`normalize-space()`| ✓ |
`not()`| ✓ |
`number()`| ✓ |
`position()`| ✓ |
`replace()`| ✓ |
`reverse()`| ✓ |
`round()`| ✓ |
`starts-with()`| ✓ |
`string()`| ✓ |
`string-length()`| ✓ |
`substring()`| ✓ |
`substring-after()`| ✓ |
`substring-before()`| ✓ |
`sum()`| ✓ |
`system-property()`| ✗ |
`translate()`| ✓ |
`true()`| ✓ |
`unparsed-entity-url()` | ✗ |
Changelogs
===
2019-03-19
- optimize XPath `|` operation performance. [#33](https://github.com/antchfx/xpath/issues/33). Tips: suggest split into multiple subquery if you have a lot of `|` operations.
2019-01-29
- improvement `normalize-space` function. [#32](https://github.com/antchfx/xpath/issues/32)
2018-12-07
- supports XPath 2.0 Sequence expressions. [#30](https://github.com/antchfx/xpath/pull/30) by [@minherz](https://github.com/minherz).