Module: SyntaxTree::WithScope

Defined in:
lib/syntax_tree/with_scope.rb

Overview

WithScope is a module intended to be included in classes inheriting from Visitor. The module overrides a few visit methods to automatically keep track of local variables and arguments defined in the current scope. Example usage:

class MyVisitor < Visitor
  include WithScope

  def visit_ident(node)
    # Check if we're visiting an identifier for an argument, a local
    # variable or something else
    local = current_scope.find_local(node)

    if local.type == :argument
      # handle identifiers for arguments
    elsif local.type == :variable
      # handle identifiers for variables
    else
      # handle other identifiers, such as method names
    end
  end
end

Defined Under Namespace

Classes: Scope

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#current_scope ⇒ Object (readonly)

Returns the value of attribute current_scope.



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# File 'lib/syntax_tree/with_scope.rb', line 120

def current_scope
  @current_scope
end

Instance Method Details

#initialize(*args, **kwargs, &block) ⇒ Object 



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# File 'lib/syntax_tree/with_scope.rb', line 122

def initialize(*args, **kwargs, &block)
  super

  @current_scope = Scope.new(0)
  @next_scope_id = 0
end

#visit_binary(node) ⇒ Object

Visit for capturing local variables defined in regex named capture groups



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# File 'lib/syntax_tree/with_scope.rb', line 236

def visit_binary(node)
  if node.operator == :=~
    left = node.left

    if left.is_a?(RegexpLiteral) && left.parts.length == 1 &&
         left.parts.first.is_a?(TStringContent)
      content = left.parts.first

      value = content.value
      location = content.location
      start_line = location.start_line

      Regexp
        .new(value, Regexp::FIXEDENCODING)
        .names
        .each do |name|
          offset = value.index(/\(\?<#{Regexp.escape(name)}>/)
          line = start_line + value[0...offset].count("\n")

          # We need to add 3 to account for these three characters
          # prefixing a named capture (?<
          column = location.start_column + offset + 3
          if value[0...offset].include?("\n")
            column =
              value[0...offset].length - value[0...offset].rindex("\n") +
                3 - 1
          end

          ident_location =
            Location.new(
              start_line: line,
              start_char: location.start_char + offset,
              start_column: column,
              end_line: line,
              end_char: location.start_char + offset + name.length,
              end_column: column + name.length
            )

          identifier = Ident.new(value: name, location: ident_location)
          current_scope.add_local_definition(identifier, :variable)
        end
    end
  end

  super
end

#visit_block_var(node) ⇒ Object Also known as: visit_lambda_var 



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# File 'lib/syntax_tree/with_scope.rb', line 189

def visit_block_var(node)
  node.locals.each do |local|
    current_scope.add_local_definition(local, :variable)
  end

  super
end

#visit_blockarg(node) ⇒ Object 



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# File 'lib/syntax_tree/with_scope.rb', line 182

def visit_blockarg(node)
  name = node.name
  current_scope.add_local_definition(name, :argument) if name

  super
end

#visit_class(node) ⇒ Object

Visits for nodes that create new scopes, such as classes, modules and method definitions.



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# File 'lib/syntax_tree/with_scope.rb', line 131

def visit_class(node)
  with_scope { super }
end

#visit_def(node) ⇒ Object 



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# File 'lib/syntax_tree/with_scope.rb', line 147

def visit_def(node)
  with_scope { super }
end

#visit_kwrest_param(node) ⇒ Object 



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# File 'lib/syntax_tree/with_scope.rb', line 175

def visit_kwrest_param(node)
  name = node.name
  current_scope.add_local_definition(name, :argument) if name

  super
end

#visit_method_add_block(node) ⇒ Object

When we find a method invocation with a block, only the code that happens inside of the block needs a fresh scope. The method invocation itself happens in the same scope.



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# File 'lib/syntax_tree/with_scope.rb', line 142

def visit_method_add_block(node)
  visit(node.call)
  with_scope(current_scope) { visit(node.block) }
end

#visit_module(node) ⇒ Object 



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# File 'lib/syntax_tree/with_scope.rb', line 135

def visit_module(node)
  with_scope { super }
end

#visit_params(node) ⇒ Object

Visit for keeping track of local arguments, such as method and block arguments.



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# File 'lib/syntax_tree/with_scope.rb', line 153

def visit_params(node)
  add_argument_definitions(node.requireds)
  add_argument_definitions(node.posts)

  node.keywords.each do |param|
    current_scope.add_local_definition(param.first, :argument)
  end

  node.optionals.each do |param|
    current_scope.add_local_definition(param.first, :argument)
  end

  super
end

#visit_pinned_var_ref(node) ⇒ Object

Visit for keeping track of local variable definitions



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# File 'lib/syntax_tree/with_scope.rb', line 207

def visit_pinned_var_ref(node)
  value = node.value
  current_scope.add_local_usage(value, :variable) if value.is_a?(Ident)

  super
end

#visit_rest_param(node) ⇒ Object 



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# File 'lib/syntax_tree/with_scope.rb', line 168

def visit_rest_param(node)
  name = node.name
  current_scope.add_local_definition(name, :argument) if name

  super
end

#visit_var_field(node) ⇒ Object

Visit for keeping track of local variable definitions



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# File 'lib/syntax_tree/with_scope.rb', line 199

def visit_var_field(node)
  value = node.value
  current_scope.add_local_definition(value, :variable) if value.is_a?(Ident)

  super
end

#visit_var_ref(node) ⇒ Object

Visits for keeping track of variable and argument usages



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# File 'lib/syntax_tree/with_scope.rb', line 215

def visit_var_ref(node)
  value = node.value

  if value.is_a?(Ident)
    definition = current_scope.find_local(value.value)
    current_scope.add_local_usage(value, definition.type) if definition
  end

  super
end

#visit_vcall(node) ⇒ Object

When using regex named capture groups, vcalls might actually be a variable



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# File 'lib/syntax_tree/with_scope.rb', line 227

def visit_vcall(node)
  value = node.value
  definition = current_scope.find_local(value.value)
  current_scope.add_local_usage(value, definition.type) if definition

  super
end