# class Prism::CaseNode

Represents the use of a case statement.

    case true
    when false
    end
    ^^^^^^^^^^

### Attributes

case_keyword_loc[R]

attr_reader `case_keyword_loc`: `Location`

conditions[R]

attr_reader conditions: Array

consequent[R]

attr_reader consequent: `ElseNode`?

end_keyword_loc[R]

attr_reader `end_keyword_loc`: `Location`

predicate[R]

attr_reader predicate: `Node`?

### Public Class Methods

new(predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location) click to toggle source

def initialize: (predicate: `Node`?, conditions: Array, consequent: `ElseNode`?, `case_keyword_loc`: `Location`, `end_keyword_loc`: `Location`, location: `Location`) -> void

    # File lib/prism/node.rb, line 3084
    def initialize(predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location)
      @predicate = predicate
      @conditions = conditions
      @consequent = consequent
      @case_keyword_loc = case_keyword_loc
      @end_keyword_loc = end_keyword_loc
      @location = location
    end

type() click to toggle source

Similar to `type`, this method returns a symbol that you can use for splitting on the type of the node without having to do a long === chain. Note that like `type`, it will still be slower than using == for a single class, but should be faster in a case statement or an array comparison.

def self.type: () -> `Symbol`

    # File lib/prism/node.rb, line 3192
    def self.type
      :case_node
    end

### Public Instance Methods

accept(visitor) click to toggle source

def accept: (visitor: `Visitor`) -> void

    # File lib/prism/node.rb, line 3094
    def accept(visitor)
      visitor.visit_case_node(self)
    end

case_keyword() click to toggle source

def `case_keyword`: () -> `String`

    # File lib/prism/node.rb, line 3138
    def case_keyword
      case_keyword_loc.slice
    end

child_nodes() click to toggle source

def `child_nodes`: () -> Array[nil | Node]

    # File lib/prism/node.rb, line 3099
    def child_nodes
      [predicate, *conditions, consequent]
    end

Also aliased as: deconstruct
comment_targets() click to toggle source

def `comment_targets`: () -> Array[Node | Location]

    # File lib/prism/node.rb, line 3113
    def comment_targets
      [*predicate, *conditions, *consequent, case_keyword_loc, end_keyword_loc]
    end

compact_child_nodes() click to toggle source

def `compact_child_nodes`: () -> Array

    # File lib/prism/node.rb, line 3104
    def compact_child_nodes
      compact = []
      compact << predicate if predicate
      compact.concat(conditions)
      compact << consequent if consequent
      compact
    end

copy(**params) click to toggle source

def copy: (**params) -> `CaseNode`

    # File lib/prism/node.rb, line 3118
    def copy(**params)
      CaseNode.new(
        params.fetch(:predicate) { predicate },
        params.fetch(:conditions) { conditions },
        params.fetch(:consequent) { consequent },
        params.fetch(:case_keyword_loc) { case_keyword_loc },
        params.fetch(:end_keyword_loc) { end_keyword_loc },
        params.fetch(:location) { location },
      )
    end

deconstruct()

def deconstruct: () -> Array[nil | Node]

Alias for: child_nodes
deconstruct_keys(keys) click to toggle source

def `deconstruct_keys`: (keys: Array) -> Hash[Symbol, nil | `Node` | Array | `String` | `Token` | Array | Location]

    # File lib/prism/node.rb, line 3133
    def deconstruct_keys(keys)
      { predicate: predicate, conditions: conditions, consequent: consequent, case_keyword_loc: case_keyword_loc, end_keyword_loc: end_keyword_loc, location: location }
    end

end_keyword() click to toggle source

def `end_keyword`: () -> `String`

    # File lib/prism/node.rb, line 3143
    def end_keyword
      end_keyword_loc.slice
    end

inspect(inspector = NodeInspector.new) click to toggle source

def inspect(inspector: NodeInspector) -> `String`

    # File lib/prism/node.rb, line 3148
    def inspect(inspector = NodeInspector.new)
      inspector << inspector.header(self)
      if (predicate = self.predicate).nil?
        inspector << "├── predicate: ∅\n"
      else
        inspector << "├── predicate:\n"
        inspector << predicate.inspect(inspector.child_inspector("│   ")).delete_prefix(inspector.prefix)
      end
      inspector << "├── conditions: #{inspector.list("#{inspector.prefix}│   ", conditions)}"
      if (consequent = self.consequent).nil?
        inspector << "├── consequent: ∅\n"
      else
        inspector << "├── consequent:\n"
        inspector << consequent.inspect(inspector.child_inspector("│   ")).delete_prefix(inspector.prefix)
      end
      inspector << "├── case_keyword_loc: #{inspector.location(case_keyword_loc)}\n"
      inspector << "└── end_keyword_loc: #{inspector.location(end_keyword_loc)}\n"
      inspector.to_str
    end

type() click to toggle source

Sometimes you want to check an instance of a node against a list of classes to see what kind of behavior to perform. Usually this is done by calling ‘[cls1, cls2].include?(node.class)` or putting the node into a case statement and doing `case node; when cls1; when cls2; end`. Both of these approaches are relatively slow because of the constant lookups, method calls, and/or array allocations.

Instead, you can call `type`, which will return to you a symbol that you can use for comparison. This is faster than the other approaches because it uses a single integer comparison, but also because if you’re on CRuby you can take advantage of the fact that case statements with all symbol keys will use a jump table.

def type: () -> `Symbol`

    # File lib/prism/node.rb, line 3182
    def type
      :case_node
    end