Enum xrust::evaluate::Constructor

pub enum Constructor<'a> {
    Literal(Value),
    LiteralElement(String, String, String, Vec<Constructor<'a>>),
    ContextItem,
    Or(Vec<Vec<Constructor<'a>>>),
    And(Vec<Vec<Constructor<'a>>>),
    Root,
    Path(Vec<Vec<Constructor<'a>>>),
    Step(NodeMatch, Vec<Vec<Constructor<'a>>>),
    GeneralComparison(Operator, Vec<Vec<Constructor<'a>>>),
    ValueComparison(Operator, Vec<Vec<Constructor<'a>>>),
    Concat(Vec<Vec<Constructor<'a>>>),
    Range(Vec<Vec<Constructor<'a>>>),
    Arithmetic(Vec<ArithmeticOperand<'a>>),
    FunctionCall(Function<'a>, Vec<Vec<Constructor<'a>>>),
    VariableDeclaration(String, Vec<Constructor<'a>>),
    VariableReference(String),
    Loop(Vec<Constructor<'a>>, Vec<Constructor<'a>>),
    Switch(Vec<Vec<Constructor<'a>>>, Vec<Constructor<'a>>),
    ApplyTemplates(Vec<Constructor<'a>>),
    NotImplemented(&'static str),
}

Specifies how a sequence is to be constructed.

These are usually included in a Vector, where each Constructor builds an item. If the constructor results in a singleton, then it becomes an item in the Sequence, otherwise the sequence is unpacked into the parent Sequence.

Variants

Literal(Value)

A literal, atomic value

LiteralElement(String, String, String, Vec<Constructor<'a>>)

A literal element. This will become a node in the result tree. TODO: this may be merged with the Literal option in a later version. Arguments are: element name, prefix, namespace and content

ContextItem

The context item from the dynamic context

Or(Vec<Vec<Constructor<'a>>>)

Logical OR. Each element of the outer vector is an operand.

And(Vec<Vec<Constructor<'a>>>)

Logical AND. Each element of the outer vector is an operand.

Root

Root node of the context item

Path(Vec<Vec<Constructor<'a>>>)

A path in a tree of nodes. Each element of the outer vector is a step in the path. The result of each step becomes the new context for the next step.

Step(NodeMatch, Vec<Vec<Constructor<'a>>>)

A step in a path. The second argument is zero or more predicates. Each item in the result sequence is evaluated against each predicate as a boolean. If the predicate evaluates to true it is kept, otherwise it is discarded.

GeneralComparison(Operator, Vec<Vec<Constructor<'a>>>)

XPath general comparison. Each element of the outer vector is a comparator. If the comparator is a sequence then each item is compared.

ValueComparison(Operator, Vec<Vec<Constructor<'a>>>)

XPath value comparison. Compares single items.

Concat(Vec<Vec<Constructor<'a>>>)

Concatentate string values

Range(Vec<Vec<Constructor<'a>>>)

Construct a range of integers

Arithmetic(Vec<ArithmeticOperand<'a>>)

Perform addition, subtraction, multiply, divide

FunctionCall(Function<'a>, Vec<Vec<Constructor<'a>>>)

Call a function

VariableDeclaration(String, Vec<Constructor<'a>>)

Declare a variable. The variable will be available for subsequent constructors

VariableReference(String)

Reference a variable.

Loop(Vec<Constructor<'a>>, Vec<Constructor<'a>>)

Repeating constructor (i.e. ‘for’). The first argument declares variables. The second argument is the body of the loop.

Switch(Vec<Vec<Constructor<'a>>>, Vec<Constructor<'a>>)

Selects an arm to evaluate. The first argument is pairs of (test,body) clauses. The second argument is the otherwise clause

ApplyTemplates(Vec<Constructor<'a>>)

Find a matching template and evaluate its sequence constructor. The argument is the select attribute.

NotImplemented(&'static str)

Something that is not yet implemented

Trait Implementations

impl<'a> Clone for Constructor<'a>

fn clone(&self) -> Constructor<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.