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

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

• 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()".

Shard supports three types: number, boolean, string.

• path : Selects nodes based on the path.

• a = b : Standard comparisons.

  • a= btrue if a equals b.
  • a!= btrue if a is not equal to b.
  • a< btrue if a is less than b.
  • a<= btrue if a is less than or equal to b.
  • a> btrue if a is greater than b.
  • a>= btrue if a is greater than or equal to b.

• a + b : Arithmetic expressions.

  • - aUnary minus
  • a+ bAdd
  • a- bSubstract
  • a* bMultiply
  • adiv bDivide
  • amod bFloating point mod, like Java.

• a or b : Booleanor operation.

• a and b : Booleanand operation.

• (expr) : Parenthesized expressions.

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

1. Add the dependency to yourshard.yml:

   dependencies:xpath2:github:naqvis/crystal-xpath2

2. Runshards install

refer tospec for usage examples or refer toCrystal HTML5 andJSON XPath for implementation details.

To run all tests:

crystal spec

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

• Ali Naqvi - creator and maintainer