Predicator.Visitor behaviour (predicator v3.8.0)

Behaviour for AST visitors.

Visitors implement the visitor pattern to traverse and transform Abstract Syntax Trees into various representations.

Examples

defmodule MyVisitor do
  @behaviour Predicator.Visitor

  @impl true
  def visit({:literal, value}, _opts) do
    value
  end

  @impl true
  def visit({:identifier, name}, _opts) do
    name
  end

  @impl true
  def visit({:comparison, op, left, right}, opts) do
    left_result = visit(left, opts)
    right_result = visit(right, opts)
    {op, left_result, right_result}
  end
end

Summary

Callbacks

visit(ast_node, opts)

Visits an AST node and returns the transformed result.

Functions

accept(ast_node, visitor_module, opts \\ [])

Utility function to accept a visitor and process an AST.

Callbacks

visit(ast_node, opts)

@callback visit(
  ast_node :: Predicator.Parser.ast() | Predicator.Parser.bare_ast(),
  opts :: keyword()
) ::
  term()

Visits an AST node and returns the transformed result.

Parameters

ast_node - The AST node to visit
opts - Optional visitor-specific options

Returns

The transformed representation (type depends on visitor implementation)

Source positions

Implementations accept either a positioned AST or the position-free shape Predicator 3.6 produced, normalizing with Predicator.Parser.ensure_positions/1 on the way in.

Functions

accept(ast_node, visitor_module, opts \\ [])

@spec accept(
  Predicator.Parser.ast() | Predicator.Parser.bare_ast(),
  module(),
  keyword()
) :: term()

Utility function to accept a visitor and process an AST.

This provides a convenient interface for applying visitors to AST nodes.

Examples

iex> ast = {:literal, 42}
iex> Predicator.Visitor.accept(ast, MyVisitor)
42