# class Prism::Node

This represents a node in the tree. It is the parent class of all of the various node types.

### Attributes

flags [R]

An bitset of flags for this node. There are certain flags that are common for all nodes, and then some nodes have specific flags.

node_id [R]

A unique identifier for this node. This is used in a very specific use case where you want to keep around a reference to a node without having to keep around the syntax tree in memory. This unique identifier will be consistent across multiple parses of the same source code.

source [R]

A pointer to the source that this node was created from.

### Public Class Methods

fields ()
Source

    # File lib/prism/node.rb, line 242
    def self.fields
      # This method should only be called on subclasses of Node, not Node
      # itself.
      raise NoMethodError, "undefined method `fields' for #{inspect}" if self == Node

      Reflection.fields_for(self)
    end

Returns a list of the fields that exist for this node class. Fields describe the structure of the node. This kind of reflection is useful for things like recursively visiting each node and field in the tree.

### Public Instance Methods

breadth_first_search () { |node| ... }
Source

    # File lib/prism/node.rb, line 228
    def breadth_first_search(&block)
      queue = [self] #: Array[Prism::node]

      while (node = queue.shift)
        return node if yield node
        queue.concat(node.compact_child_nodes)
      end

      nil
    end

Returns the first node that matches the given block when visited in a depth-first search. This is useful for finding a node that matches a particular condition.

    node.breadth_first_search { |node| node.node_id == node_id }

cached_end_code_units_column (cache)
Source

    # File lib/prism/node.rb, line 115
    def cached_end_code_units_column(cache)
      location.cached_end_code_units_column(cache)
    end

Delegates to the `cached_end_code_units_column` of the associated location object.

cached_end_code_units_offset (cache)
Source

    # File lib/prism/node.rb, line 83
    def cached_end_code_units_offset(cache)
      location.cached_end_code_units_offset(cache)
    end

Delegates to the `cached_end_code_units_offset` of the associated location object.

cached_start_code_units_column (cache)
Source

    # File lib/prism/node.rb, line 109
    def cached_start_code_units_column(cache)
      location.cached_start_code_units_column(cache)
    end

Delegates to the `cached_start_code_units_column` of the associated location object.

cached_start_code_units_offset (cache)
Source

    # File lib/prism/node.rb, line 77
    def cached_start_code_units_offset(cache)
      location.cached_start_code_units_offset(cache)
    end

Delegates to the `cached_start_code_units_offset` of the associated location object.

comments ()
Source

    # File lib/prism/node.rb, line 130
    def comments
      location.comments
    end

Delegates to the comments of the associated location object.

end_character_column ()
Source

    # File lib/prism/node.rb, line 103
    def end_character_column
      location.end_character_column
    end

Delegates to the `end_character_column` of the associated location object.

end_character_offset ()
Source

    # File lib/prism/node.rb, line 71
    def end_character_offset
      location.end_character_offset
    end

Delegates to the `end_character_offset` of the associated location object.

end_column ()
Source

    # File lib/prism/node.rb, line 93
    def end_column
      location.end_column
    end

Delegates to the `end_column` of the associated location object.

end_line ()
Source

    # File lib/prism/node.rb, line 47
    def end_line
      location.end_line
    end

Delegates to the `end_line` of the associated location object.

end_offset ()
Source

    # File lib/prism/node.rb, line 60
    def end_offset
      location = @location
      location.is_a?(Location) ? location.end_offset : ((location >> 32) + (location & 0xFFFFFFFF))
    end

The end offset of the node in the source. This method is effectively a delegate method to the location object.

leading_comments ()
Source

    # File lib/prism/node.rb, line 120
    def leading_comments
      location.leading_comments
    end

Delegates to the `leading_comments` of the associated location object.

location ()
Source

    # File lib/prism/node.rb, line 30
    def location
      location = @location
      return location if location.is_a?(Location)
      @location = Location.new(source, location >> 32, location & 0xFFFFFFFF)
    end

A `Location` instance that represents the location of this node in the source.

newline? ()
Source

    # File lib/prism/node.rb, line 161
    def newline?
      flags.anybits?(NodeFlags::NEWLINE)
    end

Returns true if the node has the newline flag set.

pretty_print (q)
Source

    # File lib/prism/node.rb, line 172
    def pretty_print(q)
      q.seplist(inspect.chomp.each_line, -> { q.breakable }) do |line|
        q.text(line.chomp)
      end
      q.current_group.break
    end

Similar to inspect, but respects the current level of indentation given by the pretty print object.

save (repository)
Source

    # File lib/prism/node.rb, line 24
    def save(repository)
      repository.enter(node_id, :itself)
    end

Save this node using a saved source so that it can be retrieved later.

save_location (repository)
Source

    # File lib/prism/node.rb, line 37
    def save_location(repository)
      repository.enter(node_id, :location)
    end

Save the location using a saved source so that it can be retrieved later.

script_lines ()

An alias for `source_lines`, used to mimic the API from `RubyVM::AbstractSyntaxTree` to make it easier to migrate.

Alias for: source_lines
slice ()
Source

    # File lib/prism/node.rb, line 144
    def slice
      location.slice
    end

Slice the location of the node from the source.

slice_lines ()
Source

    # File lib/prism/node.rb, line 151
    def slice_lines
      location.slice_lines
    end

Slice the location of the node from the source, starting at the beginning of the line that the location starts on, ending at the end of the line that the location ends on.

source_lines ()
Source

    # File lib/prism/node.rb, line 135
    def source_lines
      location.source_lines
    end

Returns all of the lines of the source code associated with this node.

Also aliased as: script_lines
start_character_column ()
Source

    # File lib/prism/node.rb, line 98
    def start_character_column
      location.start_character_column
    end

Delegates to the `start_character_column` of the associated location object.

start_character_offset ()
Source

    # File lib/prism/node.rb, line 66
    def start_character_offset
      location.start_character_offset
    end

Delegates to the `start_character_offset` of the associated location object.

start_column ()
Source

    # File lib/prism/node.rb, line 88
    def start_column
      location.start_column
    end

Delegates to the `start_column` of the associated location object.

start_line ()
Source

    # File lib/prism/node.rb, line 42
    def start_line
      location.start_line
    end

Delegates to the `start_line` of the associated location object.

start_offset ()
Source

    # File lib/prism/node.rb, line 53
    def start_offset
      location = @location
      location.is_a?(Location) ? location.start_offset : location >> 32
    end

The start offset of the node in the source. This method is effectively a delegate method to the location object.

static_literal? ()
Source

    # File lib/prism/node.rb, line 166
    def static_literal?
      flags.anybits?(NodeFlags::STATIC_LITERAL)
    end

Returns true if the node has the static literal flag set.

to_dot ()
Source

    # File lib/prism/node.rb, line 180
    def to_dot
      # @type self: node
      DotVisitor.new.tap { |visitor| accept(visitor) }.to_dot
    end

Convert this node into a graphviz dot graph string.

trailing_comments ()
Source

    # File lib/prism/node.rb, line 125
    def trailing_comments
      location.trailing_comments
    end

Delegates to the `trailing_comments` of the associated location object.

tunnel (line, column)
Source

    # File lib/prism/node.rb, line 191
    def tunnel(line, column)
      queue = [self] #: Array[Prism::node]
      result = [] #: Array[Prism::node]

      while (node = queue.shift)
        result << node

        node.compact_child_nodes.each do |child_node|
          child_location = child_node.location

          start_line = child_location.start_line
          end_line = child_location.end_line

          if start_line == end_line
            if line == start_line && column >= child_location.start_column && column < child_location.end_column
              queue << child_node
              break
            end
          elsif (line == start_line && column >= child_location.start_column) || (line == end_line && column < child_location.end_column)
            queue << child_node
            break
          elsif line > start_line && line < end_line
            queue << child_node
            break
          end
        end
      end

      result
    end

Returns a list of nodes that are descendants of this node that contain the given line and column. This is useful for locating a node that is selected based on the line and column of the source code.

Important to note is that the column given to this method should be in bytes, as opposed to characters or code units.

## Node interface

↑ top

### Public Class Methods

type ()
Source

    # File lib/prism/node.rb, line 307
    def self.type
      raise NoMethodError, "undefined method `type' for #{inspect}"
    end

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.

### Public Instance Methods

accept (visitor)
Source

    # File lib/prism/node.rb, line 258
    def accept(visitor)
      raise NoMethodError, "undefined method `accept' for #{inspect}"
    end

Accepts a visitor and calls back into the specialized visit function.

child_nodes ()
Source

    # File lib/prism/node.rb, line 264
    def child_nodes
      raise NoMethodError, "undefined method `child_nodes' for #{inspect}"
    end

Returns an array of child nodes, including ‘nil`s in the place of optional nodes that were not present.

Also aliased as: deconstruct
comment_targets ()
Source

    # File lib/prism/node.rb, line 278
    def comment_targets
      raise NoMethodError, "undefined method `comment_targets' for #{inspect}"
    end

Returns an array of child nodes and locations that could potentially have comments attached to them.

compact_child_nodes ()
Source

    # File lib/prism/node.rb, line 272
    def compact_child_nodes
      raise NoMethodError, "undefined method `compact_child_nodes' for #{inspect}"
    end

Returns an array of child nodes, excluding any ‘nil`s in the place of optional nodes that were not present.

deconstruct ()
Alias for: child_nodes
inspect ()
Source

    # File lib/prism/node.rb, line 283
    def inspect
      raise NoMethodError, "undefined method `inspect' for #{inspect}"
    end

Returns a string representation of the node.

type ()
Source

    # File lib/prism/node.rb, line 299
    def type
      raise NoMethodError, "undefined method `type' for #{inspect}"
    end

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.