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() click to toggle source

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.

# File 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

Public Instance Methods

breadth_first_search() { |node| ... } click to toggle source

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 }

# File 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

cached_end_code_units_column(cache) click to toggle source

Delegates to the cached_end_code_units_column of the associated location object.

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

cached_end_code_units_offset(cache) click to toggle source

Delegates to the cached_end_code_units_offset of the associated location object.

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

cached_start_code_units_column(cache) click to toggle source

Delegates to the cached_start_code_units_column of the associated location object.

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

cached_start_code_units_offset(cache) click to toggle source

Delegates to the cached_start_code_units_offset of the associated location object.

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

comments() click to toggle source

Delegates to the comments of the associated location object.

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

end_character_column() click to toggle source

Delegates to the end_character_column of the associated location object.

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

end_character_offset() click to toggle source

Delegates to the end_character_offset of the associated location object.

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

end_column() click to toggle source

Delegates to the end_column of the associated location object.

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

end_line() click to toggle source

Delegates to the end_line of the associated location object.

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

end_offset() click to toggle source

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

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

leading_comments() click to toggle source

Delegates to the leading_comments of the associated location object.

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

location() click to toggle source

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

# File 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

newline?() click to toggle source

Returns true if the node has the newline flag set.

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

pretty_print(q) click to toggle source

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

# File 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

save(repository) click to toggle source

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

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

save_location(repository) click to toggle source

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

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

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() click to toggle source

Slice the location of the node from the source.

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

slice_lines() click to toggle source

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.

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

source_lines() click to toggle source

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

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

Also aliased as: script_lines

start_character_column() click to toggle source

Delegates to the start_character_column of the associated location object.

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

start_character_offset() click to toggle source

Delegates to the start_character_offset of the associated location object.

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

start_column() click to toggle source

Delegates to the start_column of the associated location object.

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

start_line() click to toggle source

Delegates to the start_line of the associated location object.

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

start_offset() click to toggle source

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

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

static_literal?() click to toggle source

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

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

to_dot() click to toggle source

Convert this node into a graphviz dot graph string.

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

trailing_comments() click to toggle source

Delegates to the trailing_comments of the associated location object.

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

tunnel(line, column) click to toggle source

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.

# File 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

Node interface

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Public Class Methods

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.

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

Public Instance Methods

accept(visitor) click to toggle source

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

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

child_nodes() click to toggle source

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

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

Also aliased as: deconstruct

comment_targets() click to toggle source

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

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

compact_child_nodes() click to toggle source

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

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

deconstruct()

Alias for: child_nodes

inspect() click to toggle source

Returns a string representation of the node.

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

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