xpath2

XPath implementation in Crystal xpath xpath2 crystal-shard xpath-api
0.1.0 Latest release released

Crystal XPath2

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Crystal XPath2 Shard provide XPath implementation in Pure Crystal. Performs the compilation of XPath expression and provides mechanism to select/evaluate nodes from HTML or other documents using XPath expression

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 node Name 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

Shard supports 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() | ✗ |

Installation

  1. Add the dependency to your shard.yml:

    dependencies:
      html:
        github: naqvis/crystal-xpath2
    
  2. Run shards install

Usage

refer to spec for usage examples or refer to Crystal HTML5 and JSON XPath for implementation details.

Development

To run all tests:

crystal spec

Contributing

  1. Fork it (https://github.com/naqvis/crystal-xpath2/fork)
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

Contributors

xpath2:
  github: naqvis/crystal-xpath2
  version: ~> 0.1.0
License MIT
Crystal 0.34.0

Authors

Dependencies 1

  • fnv
    {'github' => 'naqvis/crystal-fnv'}

Development Dependencies 0

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