class Prism::Node
This represents a node in the tree. It is the parent class of all of the various node types.
Attributes
An bitset of flags for this node. There are certain flags that are common for all nodes, and then some nodes have specific flags.
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.
A pointer to the source that this node was created from.
Public Class Methods
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 lib/prism/node.rb, line 153 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
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 lib/prism/node.rb, line 139 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
The end offset of the node in the source. This method is effectively a delegate method to the location object.
# File lib/prism/node.rb, line 40 def end_offset location = @location location.is_a?(Location) ? location.end_offset : ((location >> 32) + (location & 0xFFFFFFFF)) end
A Location
instance that represents the location of this node in the source.
# File lib/prism/node.rb, line 25 def location location = @location return location if location.is_a?(Location) @location = Location.new(source, location >> 32, location & 0xFFFFFFFF) end
Returns true if the node has the newline flag set.
# File lib/prism/node.rb, line 72 def newline? flags.anybits?(NodeFlags::NEWLINE) end
Similar to inspect, but respects the current level of indentation given by the pretty print object.
# File lib/prism/node.rb, line 83 def pretty_print(q) q.seplist(inspect.chomp.each_line, -> { q.breakable }) do |line| q.text(line.chomp) end q.current_group.break end
An alias for source_lines
, used to mimic the API from RubyVM::AbstractSyntaxTree
to make it easier to migrate.
Slice the location of the node from the source.
# File lib/prism/node.rb, line 55 def slice location.slice 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.
# File lib/prism/node.rb, line 62 def slice_lines location.slice_lines end
Returns all of the lines of the source code associated with this node.
# File lib/prism/node.rb, line 46 def source_lines location.source_lines end
The start offset of the node in the source. This method is effectively a delegate method to the location object.
# File lib/prism/node.rb, line 33 def start_offset location = @location location.is_a?(Location) ? location.start_offset : location >> 32 end
Returns true if the node has the static literal flag set.
# File lib/prism/node.rb, line 77 def static_literal? flags.anybits?(NodeFlags::STATIC_LITERAL) end
Convert this node into a graphviz dot graph string.
# File lib/prism/node.rb, line 91 def to_dot # @type self: node DotVisitor.new.tap { |visitor| accept(visitor) }.to_dot 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.
# File lib/prism/node.rb, line 102 def tunnel(line, column) queue = [self] #: Array[Prism::node] result = [] 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
↑ topPublic Class Methods
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 lib/prism/node.rb, line 218 def self.type raise NoMethodError, "undefined method `type' for #{inspect}" end
Public Instance Methods
Accepts a visitor and calls back into the specialized visit function.
# File lib/prism/node.rb, line 169 def accept(visitor) raise NoMethodError, "undefined method `accept' for #{inspect}" end
Returns an array of child nodes, including ‘nil`s in the place of optional nodes that were not present.
# File lib/prism/node.rb, line 175 def child_nodes raise NoMethodError, "undefined method `child_nodes' for #{inspect}" end
Returns an array of child nodes and locations that could potentially have comments attached to them.
# File lib/prism/node.rb, line 189 def comment_targets raise NoMethodError, "undefined method `comment_targets' for #{inspect}" end
Returns an array of child nodes, excluding any ‘nil`s in the place of optional nodes that were not present.
# File lib/prism/node.rb, line 183 def compact_child_nodes raise NoMethodError, "undefined method `compact_child_nodes' for #{inspect}" end
Returns a string representation of the node.
# File lib/prism/node.rb, line 194 def inspect raise NoMethodError, "undefined method `inspect' 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.
# File lib/prism/node.rb, line 210 def type raise NoMethodError, "undefined method `type' for #{inspect}" end