168 lines
6.0 KiB
Markdown
168 lines
6.0 KiB
Markdown
# XPath
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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://github.com/antchfx/xpath/actions/workflows/testing.yml)
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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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# Implementation
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- [htmlquery](https://github.com/antchfx/htmlquery) - an XPath query package for HTML document
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- [xmlquery](https://github.com/antchfx/xmlquery) - an XPath query package for XML document.
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- [jsonquery](https://github.com/antchfx/jsonquery) - an XPath query package for JSON document
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# Supported 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, union operation(not boolean or).
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- `(a, b, c)` : Evaluates each of its operands and concatenates the resulting sequences, in order, into a single result sequence
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- `(a/b)` : Selects all matches nodes as grouping set.
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#### Node Axes
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- `child::*` : The child axis selects children of the current node.
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- `child::node()`: Selects all the children of the context node.
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- `child::text()`: Selects all text node children of the context 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` : Addition
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- `a - b` : Subtraction
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- `a * b` : Multiplication
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- `a div b` : Division
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- `a mod b` : Modulus (division remainder)
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- `a or b` : Boolean `or` operation.
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- `a and b` : Boolean `and` operation.
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- `(expr)` : Parenthesized expressions.
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- `fun(arg1, ..., argn)` : Function calls:
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| Function | Supported |
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| ----------------------- | --------- |
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| `boolean()` | ✓ |
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| `ceiling()` | ✓ |
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| `choose()` | ✗ |
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| `concat()` | ✓ |
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| `contains()` | ✓ |
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| `count()` | ✓ |
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| `current()` | ✗ |
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| `document()` | ✗ |
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| `element-available()` | ✗ |
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| `ends-with()` | ✓ |
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| `false()` | ✓ |
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| `floor()` | ✓ |
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| `format-number()` | ✗ |
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| `function-available()` | ✗ |
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| `generate-id()` | ✗ |
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| `id()` | ✗ |
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| `key()` | ✗ |
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| `lang()` | ✗ |
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| `last()` | ✓ |
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| `local-name()` | ✓ |
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| `lower-case()`[^1] | ✓ |
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| `matches()` | ✓ |
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| `name()` | ✓ |
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| `namespace-uri()` | ✓ |
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| `normalize-space()` | ✓ |
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| `not()` | ✓ |
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| `number()` | ✓ |
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| `position()` | ✓ |
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| `replace()` | ✓ |
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| `reverse()` | ✓ |
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| `round()` | ✓ |
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| `starts-with()` | ✓ |
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| `string()` | ✓ |
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| `string-join()`[^1] | ✓ |
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| `string-length()` | ✓ |
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| `substring()` | ✓ |
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| `substring-after()` | ✓ |
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| `substring-before()` | ✓ |
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| `sum()` | ✓ |
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| `system-property()` | ✗ |
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| `translate()` | ✓ |
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| `true()` | ✓ |
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| `unparsed-entity-url()` | ✗ |
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[^1]: XPath-2.0 expression
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