Class: TreeHaver::Node

Inherits:
Object
  • Object
show all
Includes:
Comparable, Enumerable
Defined in:
lib/tree_haver/node.rb

Overview

Note:

This is the key to tree_haver’s “write once, run anywhere” promise

Unified Node wrapper providing a consistent API across all backends

This class wraps backend-specific node objects (TreeSitter::Node, TreeStump::Node, etc.) and provides a unified interface so code works identically regardless of which backend is being used.

The wrapper automatically maps backend differences:

  • TreeStump uses node.kind → mapped to node.type

  • TreeStump uses node.is_named? → mapped to node.named?

  • All backends return consistent Point objects from position methods

Examples:

Basic node traversal

tree = parser.parse(source)
root = tree.root_node

puts root.type        # => "document"
puts root.start_byte  # => 0
puts root.text        # => full source text

root.children.each do |child|
  puts "#{child.type} at line #{child.start_point.row + 1}"
end

Position information

node = tree.root_node.children.first

# Point objects work as both objects and hashes
point = node.start_point
point.row              # => 0 (method access)
point[:row]            # => 0 (hash access)
point.column           # => 0

# Byte offsets
node.start_byte        # => 0
node.end_byte          # => 23

Error detection

if node.has_error?
  puts "Parse error in subtree"
end

if node.missing?
  puts "This node was inserted by error recovery"
end

Accessing backend-specific features

# Via passthrough (method_missing delegates to inner_node)
node.grammar_name  # TreeStump-specific, automatically delegated

# Or explicitly via inner_node
node.inner_node.grammar_name  # Same result

# Check if backend supports a feature
if node.inner_node.respond_to?(:some_feature)
  node.some_feature
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(node, source: nil) ⇒ Node

Returns a new instance of Node.

Parameters:

  • node (Object) —

    Backend-specific node object

  • source (String) (defaults to: nil) —

    Source text for text extraction



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# File 'lib/tree_haver/node.rb', line 94

def initialize(node, source: nil)
  @inner_node = node
  @source = source
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_name, *args, **kwargs, &block) ⇒ Object

Note:

This maintains backward compatibility with code written for specific backends while providing the benefits of the unified API

Delegate unknown methods to the underlying backend-specific node

This provides passthrough access for advanced usage when you need backend-specific features not exposed by TreeHaver’s unified API.

The delegation is automatic and transparent - you can call backend-specific methods directly on the TreeHaver::Node and they’ll be forwarded to the underlying node implementation.

Examples:

Using TreeStump-specific methods

# These methods don't exist in the unified API but are in TreeStump
node.grammar_name      # => "toml" (delegated to inner_node)
node.grammar_id        # => Integer (delegated to inner_node)
node.kind_id           # => Integer (delegated to inner_node)

Safe usage with respond_to? check

if node.respond_to?(:grammar_name)
  puts "Using #{node.grammar_name} grammar"
end

Equivalent explicit access

node.grammar_name              # Via passthrough (method_missing)
node.inner_node.grammar_name   # Explicit access (same result)

Parameters:

  • method_name (Symbol) —

    method to call

  • args (Array) —

    arguments to pass

  • block (Proc) —

    block to pass

Returns:

  • (Object) —

    result from the underlying node



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# File 'lib/tree_haver/node.rb', line 568

def method_missing(method_name, *args, **kwargs, &block)
  if @inner_node.respond_to?(method_name)
    @inner_node.public_send(method_name, *args, **kwargs, &block)
  else
    super
  end
end

Instance Attribute Details

#inner_node ⇒ Object (readonly)

The wrapped backend-specific node object

This provides direct access to the underlying backend node for advanced usage when you need backend-specific features not exposed by the unified API.

Examples:

Accessing backend-specific methods

# TreeStump-specific: grammar information
if node.inner_node.respond_to?(:grammar_name)
  puts node.inner_node.grammar_name  # => "toml"
  puts node.inner_node.grammar_id    # => Integer
end

# Check backend type
case node.inner_node.class.name
when /TreeStump/
  # TreeStump-specific code
when /TreeSitter/
  # ruby_tree_sitter-specific code
end

Returns:

  • (Object) —

    The underlying node (TreeSitter::Node, TreeStump::Node, etc.)



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# File 'lib/tree_haver/node.rb', line 86

def inner_node
  @inner_node
end

#source ⇒ String (readonly)

The source text for text extraction

Returns:

  • (String) 


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# File 'lib/tree_haver/node.rb', line 90

def source
  @source
end

Instance Method Details

#<=>(other) ⇒ Integer?

Compare nodes for ordering (used by Comparable module)

Nodes are ordered by their position in the source:

  1. First by start_byte (earlier nodes come first)

  2. Then by end_byte for tie-breaking (shorter spans come first)

  3. Then by type for deterministic ordering

This allows nodes to be sorted by position and used in sorted collections. The Comparable module provides <, <=, ==, >=, >, and between? based on this.

Parameters:

  • other (Node) —

    node to compare with

Returns:

  • (Integer, nil) —

    -1, 0, 1, or nil if not comparable



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# File 'lib/tree_haver/node.rb', line 483

def <=>(other)
  return unless other.is_a?(Node)

  # Compare by position first (start_byte, then end_byte)
  cmp = start_byte <=> other.start_byte
  return cmp if cmp.nonzero?

  cmp = end_byte <=> other.end_byte
  return cmp if cmp.nonzero?

  # For nodes at the same position with same span, compare by type
  type <=> other.type
end

#==(other) ⇒ Boolean Also known as: eql?

Check equality based on inner_node identity

Two nodes are equal if they wrap the same backend node object. This is separate from the <=> comparison which orders by position. Nodes at the same position but wrapping different backend nodes are equal according to <=> (positional equality) but not equal according to == (identity equality).

Note: We override Comparable’s default == behavior to check inner_node identity rather than just relying on <=> returning 0, because we want identity-based equality for testing and collection membership, not position-based equality.

Parameters:

  • other (Object) —

    object to compare with

Returns:

  • (Boolean) —

    true if both nodes wrap the same inner_node



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# File 'lib/tree_haver/node.rb', line 510

def ==(other)
  return false unless other.is_a?(Node)
  @inner_node == other.inner_node
end

#child(index) ⇒ Node?

Get a child by index

Parameters:

  • index (Integer) —

    Child index

Returns:

  • (Node, nil) —

    Wrapped child node, or nil if index out of bounds



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# File 'lib/tree_haver/node.rb', line 308

def child(index)
  child_node = @inner_node.child(index)
  return if child_node.nil?
  Node.new(child_node, source: @source)
rescue IndexError
  # Some backends (e.g., MRI w/ ruby_tree_sitter) raise IndexError for out of bounds
  nil
end

#child_by_field_name(name) ⇒ Node? Also known as: field

Get a child by field name

Parameters:

  • name (String, Symbol) —

    Field name

Returns:

  • (Node, nil) —

    The child node for that field



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# File 'lib/tree_haver/node.rb', line 415

def child_by_field_name(name)
  if @inner_node.respond_to?(:child_by_field_name)
    child_node = @inner_node.child_by_field_name(name.to_s)
    return if child_node.nil?
    Node.new(child_node, source: @source)
  else
    # Not all backends support field names
    nil
  end
end

#child_count ⇒ Integer

Get the number of children

Returns:

  • (Integer) 


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# File 'lib/tree_haver/node.rb', line 300

def child_count
  @inner_node.child_count
end

#children ⇒ Array<Node>

Get all children as wrapped nodes

Returns:

  • (Array<Node>) —

    Array of wrapped child nodes



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# File 'lib/tree_haver/node.rb', line 391

def children
  (0...child_count).map { |i| child(i) }.compact
end

#each {|Node| ... } ⇒ Enumerator?

Iterate over children

Yields:

  • (Node) —

    Each child node

Returns:

  • (Enumerator, nil) 


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# File 'lib/tree_haver/node.rb', line 406

def each(&block)
  return to_enum(__method__) unless block_given?
  children.each(&block)
end

#end_byte ⇒ Integer

Get the node’s end byte offset

Returns:

  • (Integer) 


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# File 'lib/tree_haver/node.rb', line 125

def end_byte
  @inner_node.end_byte
end

#end_line ⇒ Integer

Get the 1-based line number where this node ends

Convenience method that converts 0-based row to 1-based line number.

Returns:

  • (Integer) —

    1-based line number



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# File 'lib/tree_haver/node.rb', line 194

def end_line
  end_point.row + 1
end

#end_point ⇒ Point

Get the node’s end position (row, column)

Returns:

  • (Point) —

    with row and column accessors (also works as Hash)



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# File 'lib/tree_haver/node.rb', line 157

def end_point
  if @inner_node.respond_to?(:end_point)
    point = @inner_node.end_point
    # Handle both Point objects and hashes
    if point.is_a?(Hash)
      Point.new(point[:row], point[:column])
    else
      Point.new(point.row, point.column)
    end
  elsif @inner_node.respond_to?(:end_position)
    point = @inner_node.end_position
    # Handle both Point objects and hashes
    if point.is_a?(Hash)
      Point.new(point[:row], point[:column])
    else
      Point.new(point.row, point.column)
    end
  else
    raise TreeHaver::Error, "Backend node does not support end_point/end_position"
  end
end

#first_child ⇒ Node?

Get the first child node

Convenience method for iteration patterns that expect first_child.

Returns:

  • (Node, nil) —

    First child node or nil if no children



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# File 'lib/tree_haver/node.rb', line 221

def first_child
  child(0)
end

#has_error? ⇒ Boolean

Check if the node has an error

Returns:

  • (Boolean) 


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# File 'lib/tree_haver/node.rb', line 255

def has_error?
  @inner_node.has_error?
end

#hash ⇒ Integer

Generate hash value for this node

Uses the hash of the inner_node to ensure nodes wrapping the same backend node have the same hash value.

Returns:

  • (Integer) —

    hash value



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# File 'lib/tree_haver/node.rb', line 524

def hash
  @inner_node.hash
end

#inspect ⇒ String

String representation for debugging

Returns:

  • (String) 


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# File 'lib/tree_haver/node.rb', line 461

def inspect
  "#<#{self.class} type=#{type} bytes=#{start_byte}..#{end_byte}>"
end

#missing? ⇒ Boolean

Check if the node is missing

Returns:

  • (Boolean) 


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# File 'lib/tree_haver/node.rb', line 261

def missing?
  return false unless @inner_node.respond_to?(:missing?)
  @inner_node.missing?
end

#named? ⇒ Boolean

Check if the node is named

Returns:

  • (Boolean) 


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# File 'lib/tree_haver/node.rb', line 268

def named?
  if @inner_node.respond_to?(:named?)
    @inner_node.named?
  elsif @inner_node.respond_to?(:is_named?)
    @inner_node.is_named?
  else
    true # Default to true if not supported
  end
end

#named_child(index) ⇒ Node?

Get a named child by index

Returns the nth named child (skipping unnamed children). Uses backend’s native named_child if available, otherwise provides fallback.

Parameters:

  • index (Integer) —

    Named child index (0-based)

Returns:

  • (Node, nil) —

    Wrapped named child node, or nil if index out of bounds



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# File 'lib/tree_haver/node.rb', line 324

def named_child(index)
  # Try native implementation first
  if @inner_node.respond_to?(:named_child)
    child_node = @inner_node.named_child(index)
    return if child_node.nil?
    return Node.new(child_node, source: @source)
  end

  # Fallback: manually iterate through children and count named ones
  named_count = 0
  (0...child_count).each do |i|
    child_node = @inner_node.child(i)
    next if child_node.nil?

    # Check if this child is named
    is_named = if child_node.respond_to?(:named?)
      child_node.named?
    elsif child_node.respond_to?(:is_named?)
      child_node.is_named?
    else
      true  # Assume named if we can't determine
    end

    if is_named
      return Node.new(child_node, source: @source) if named_count == index
      named_count += 1
    end
  end

  nil  # Index out of bounds
end

#named_child_count ⇒ Integer

Get the count of named children

Uses backend’s native named_child_count if available, otherwise provides fallback.

Returns:

  • (Integer) —

    Number of named children



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# File 'lib/tree_haver/node.rb', line 361

def named_child_count
  # Try native implementation first
  if @inner_node.respond_to?(:named_child_count)
    return @inner_node.named_child_count
  end

  # Fallback: count named children manually
  count = 0
  (0...child_count).each do |i|
    child_node = @inner_node.child(i)
    next if child_node.nil?

    # Check if this child is named
    is_named = if child_node.respond_to?(:named?)
      child_node.named?
    elsif child_node.respond_to?(:is_named?)
      child_node.is_named?
    else
      true  # Assume named if we can't determine
    end

    count += 1 if is_named
  end

  count
end

#named_children ⇒ Array<Node>

Get named children only

Returns:

  • (Array<Node>) —

    Array of named child nodes



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# File 'lib/tree_haver/node.rb', line 398

def named_children
  children.select(&:named?)
end

#next_sibling ⇒ Node?

Get next sibling

Returns:



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# File 'lib/tree_haver/node.rb', line 442

def next_sibling
  return unless @inner_node.respond_to?(:next_sibling)
  sibling = @inner_node.next_sibling
  return if sibling.nil?
  Node.new(sibling, source: @source)
end

#parent ⇒ Node?

Get the parent node

Returns:

  • (Node, nil) —

    The parent node



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# File 'lib/tree_haver/node.rb', line 432

def parent
  return unless @inner_node.respond_to?(:parent)
  parent_node = @inner_node.parent
  return if parent_node.nil?
  Node.new(parent_node, source: @source)
end

#prev_sibling ⇒ Node?

Get previous sibling

Returns:



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# File 'lib/tree_haver/node.rb', line 452

def prev_sibling
  return unless @inner_node.respond_to?(:prev_sibling)
  sibling = @inner_node.prev_sibling
  return if sibling.nil?
  Node.new(sibling, source: @source)
end

#respond_to_missing?(method_name, include_private = false) ⇒ Boolean

Check if node responds to a method (includes delegation to inner_node)

Parameters:

  • method_name (Symbol) —

    method to check

  • include_private (Boolean) (defaults to: false) —

    include private methods

Returns:

  • (Boolean) 


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# File 'lib/tree_haver/node.rb', line 533

def respond_to_missing?(method_name, include_private = false)
  @inner_node.respond_to?(method_name, include_private) || super
end

#source_position ⇒ Hash{Symbol => Integer}

Get position information as a hash

Returns a hash with 1-based line numbers and 0-based columns. This format is compatible with *-merge gems’ FileAnalysisBase.

Examples:

node.source_position
# => { start_line: 1, end_line: 3, start_column: 0, end_column: 10 }

Returns:

  • (Hash{Symbol => Integer}) —

    Position hash



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# File 'lib/tree_haver/node.rb', line 207

def source_position
  {
    start_line: start_line,
    end_line: end_line,
    start_column: start_point.column,
    end_column: end_point.column,
  }
end

#start_byte ⇒ Integer

Get the node’s start byte offset

Returns:

  • (Integer) 


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# File 'lib/tree_haver/node.rb', line 119

def start_byte
  @inner_node.start_byte
end

#start_line ⇒ Integer

Get the 1-based line number where this node starts

Convenience method that converts 0-based row to 1-based line number. This is useful for error messages and matching with editor line numbers.

Returns:

  • (Integer) —

    1-based line number



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# File 'lib/tree_haver/node.rb', line 185

def start_line
  start_point.row + 1
end

#start_point ⇒ Point

Get the node’s start position (row, column)

Returns:

  • (Point) —

    with row and column accessors (also works as Hash)



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# File 'lib/tree_haver/node.rb', line 132

def start_point
  if @inner_node.respond_to?(:start_point)
    point = @inner_node.start_point
    # Handle both Point objects and hashes
    if point.is_a?(Hash)
      Point.new(point[:row], point[:column])
    else
      Point.new(point.row, point.column)
    end
  elsif @inner_node.respond_to?(:start_position)
    point = @inner_node.start_position
    # Handle both Point objects and hashes
    if point.is_a?(Hash)
      Point.new(point[:row], point[:column])
    else
      Point.new(point.row, point.column)
    end
  else
    raise TreeHaver::Error, "Backend node does not support start_point/start_position"
  end
end

#structural? ⇒ Boolean

Check if the node is structural (non-terminal)

In tree-sitter, this is equivalent to being a “named” node. Named nodes represent actual syntactic constructs (e.g., table, keyvalue, string) while anonymous nodes are syntax/punctuation (e.g., [, =, whitespace).

For Citrus backends, this checks if the node is a non-terminal rule.

Returns:

  • (Boolean) —

    true if this is a structural (non-terminal) node



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# File 'lib/tree_haver/node.rb', line 287

def structural?
  # Delegate to inner_node if it has its own structural? method (e.g., Citrus)
  if @inner_node.respond_to?(:structural?)
    @inner_node.structural?
  else
    # For tree-sitter backends, named? is equivalent to structural?
    # Named nodes are syntactic constructs; anonymous nodes are punctuation
    named?
  end
end

#text ⇒ String

Get the node’s text content

Returns:

  • (String) 


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# File 'lib/tree_haver/node.rb', line 228

def text
  if @inner_node.respond_to?(:text)
    # Some backends (like TreeStump) require source as argument
    # Check arity to determine how to call
    arity = @inner_node.method(:text).arity
    if arity == 0 || arity == -1
      # No required arguments, or optional arguments only
      @inner_node.text
    elsif arity >= 1 && @source
      # Has required argument(s) - pass source
      @inner_node.text(@source)
    elsif @source
      # Fallback to byte extraction
      @source[start_byte...end_byte] || ""
    else
      raise TreeHaver::Error, "Cannot extract text: backend requires source but none provided"
    end
  elsif @source
    # Fallback: extract from source using byte positions
    @source[start_byte...end_byte] || ""
  else
    raise TreeHaver::Error, "Cannot extract text: node has no text method and no source provided"
  end
end

#to_s ⇒ String

String representation

Returns:

  • (String) 


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# File 'lib/tree_haver/node.rb', line 467

def to_s
  text
end

#type ⇒ String

Get the node’s type/kind as a string

Maps backend-specific methods to a unified API:

  • ruby_tree_sitter: node.type

  • tree_stump: node.kind

  • FFI: node.type

Returns:

  • (String) —

    The node type



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# File 'lib/tree_haver/node.rb', line 107

def type
  if @inner_node.respond_to?(:type)
    @inner_node.type.to_s
  elsif @inner_node.respond_to?(:kind)
    @inner_node.kind.to_s
  else
    raise TreeHaver::Error, "Backend node does not support type/kind"
  end
end