class Prism::MatchRequiredNode - Documentation for Ruby 4.1
Description: class Prism::MatchRequiredNode: Represents the use of the `=>` operator.
Keywords: ruby,class,Prism::MatchRequiredNode

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# class Prism::MatchRequiredNode

Represents the use of the `=>` operator.

    foo => bar
    ^^^^^^^^^^

### Public Class Methods

new (source, node_id, location, flags, value, pattern, operator_loc)
Source

    # File lib/prism/node.rb, line 21613
    def initialize(source, node_id, location, flags, value, pattern, operator_loc)
      @source = source
      @node_id = node_id
      @location = location
      @flags = flags
      @value = value
      @pattern = pattern
      @operator_loc = operator_loc
    end

Initialize a new `MatchRequiredNode` node.

### Public Instance Methods

pattern → Node
Source

    # File lib/prism/node.rb, line 21772
    def pattern
      @pattern
    end

Represents the right-hand side of the operator. The type of the node depends on the expression.

Anything that looks like a local variable name (including `_`) will result in a `LocalVariableTargetNode`.

    foo => a # This is equivalent to writing `a = foo`
           ^

Using an explicit `Array` or combining expressions with `,` will result in a `ArrayPatternNode`. This can be preceded by a constant.

    foo => [a]
           ^^^

    foo => a, b
           ^^^^

    foo => Bar[a, b]
           ^^^^^^^^^

If the array pattern contains at least two wildcard matches, a `FindPatternNode` is created instead.

    foo => *, 1, *a
           ^^^^^

Using an explicit `Hash` or a constant with square brackets and hash keys in the square brackets will result in a `HashPatternNode`.

    foo => { a: 1, b: }

    foo => Bar[a: 1, b:]

    foo => Bar[**]

To use any variable that needs run time evaluation, pinning is required. This results in a `PinnedVariableNode`

    foo => ^a
           ^^

Similar, any expression can be used with pinning. This results in a `PinnedExpressionNode`.

    foo => ^(a + 1)

Anything else will result in the regular node for that expression, for example a `ConstantReadNode`.

    foo => CONST

value → Node
Source

    # File lib/prism/node.rb, line 21720
    def value
      @value
    end

Represents the left-hand side of the operator.

    foo => bar
    ^^^

## Locations

### Public Instance Methods

operator_loc → Location
Source

    # File lib/prism/node.rb, line 21786
    def operator_loc
      location = @operator_loc
      return location if location.is_a?(Location)
      @operator_loc = Location.new(source, location >> 32, location & 0xFFFFFFFF)
    end

The `Location` of the operator.

    foo => bar
        ^^

## Node Interface

These methods are present on all subclasses of `Node`. Read the node interface docs for more information.

### Public Class Methods

type ()
Source

    # File lib/prism/node.rb, line 21700
    def self.type
      :match_required_node
    end

See `Node.type`.

### Public Instance Methods

accept (visitor)
Source

    # File lib/prism/node.rb, line 21637
    def accept(visitor)
      visitor.visit_match_required_node(self)
    end

See `Node.accept`.

child_nodes ()
Source

    # File lib/prism/node.rb, line 21644
    def child_nodes
      [value, pattern]
    end

See `Node.child_nodes`.

Also aliased as: deconstruct
comment_targets ()
Source

    # File lib/prism/node.rb, line 21669
    def comment_targets
      [value, pattern, operator_loc] #: Array[Prism::node | Location]
    end

See `Node.comment_targets`.

compact_child_nodes ()
Source

    # File lib/prism/node.rb, line 21662
    def compact_child_nodes
      [value, pattern]
    end

See `Node.compact_child_nodes`.

copy(**fields) → MatchRequiredNode
Source

    # File lib/prism/node.rb, line 21679
    def copy(node_id: self.node_id, location: self.location, flags: self.flags, value: self.value, pattern: self.pattern, operator_loc: self.operator_loc)
      MatchRequiredNode.new(source, node_id, location, flags, value, pattern, operator_loc)
    end

Creates a copy of self with the given fields, using self as the template.

deconstruct ()
Alias for: child_nodes
each_child_node () { |value| ... }
Source

    # File lib/prism/node.rb, line 21652
    def each_child_node(&blk)
      return to_enum(:each_child_node) unless block_given?

      yield value
      yield pattern
    end

See `Node.each_child_node`.

type ()
Source

    # File lib/prism/node.rb, line 21693
    def type
      :match_required_node
    end

See `Node#type`.

## Repository

Methods related to `Relocation`.

### Public Instance Methods

save_operator_loc (repository)
Source

    # File lib/prism/node.rb, line 21797
    def save_operator_loc(repository)
      repository.enter(node_id, :operator_loc)
    end

Save the `operator_loc` location using the given saved source so that it can be retrieved later.

## Slicing

### Public Instance Methods

operator → String
Source

    # File lib/prism/node.rb, line 21809
    def operator
      operator_loc.slice
    end

Slice the location of `operator_loc` from the source.