Implement visitor pattern (#4)

README.md

@@ -5,7 +5,7 @@ in Rust.
 
 Features:
 
-- Python 3.10 compatibility
+- Python 3.8 compatibility
 - [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired
   cache semantics
 - [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)

src/bin/rust_python_linter.rs

@@ -4,13 +4,13 @@ use std::time::{Duration, Instant};
 
 use ::rust_python_linter::fs::collect_python_files;
 use ::rust_python_linter::linter::check_path;
-use ::rust_python_linter::message::Message;
 use anyhow::Result;
 use clap::{Parser, ValueHint};
 use colored::Colorize;
 use log::{debug, error};
 use notify::{watcher, RecursiveMode, Watcher};
 use rayon::prelude::*;
+use rust_python_linter::message::Message;
 use walkdir::DirEntry;
 
 #[derive(Debug, Parser)]

src/check.rs

@@ -1,94 +0,0 @@
-use std::path::Path;
-
-use rustpython_parser::ast::{ExprKind, Stmt, StmtKind, Suite};
-
-use crate::message::Message;
-
-fn check_statement(path: &Path, stmt: &Stmt) -> Vec<Message> {
-    let mut messages: Vec<Message> = vec![];
-    match &stmt.node {
-        StmtKind::FunctionDef { body, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::AsyncFunctionDef { body, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::ClassDef { body, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::Return { .. } => {}
-        StmtKind::Delete { .. } => {}
-        StmtKind::Assign { .. } => {}
-        StmtKind::AugAssign { .. } => {}
-        StmtKind::AnnAssign { .. } => {}
-        StmtKind::For { body, orelse, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::AsyncFor { body, orelse, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::While { body, orelse, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::If { test, body, orelse } => {
-            if let ExprKind::Tuple { .. } = test.node {
-                messages.push(Message::IfTuple {
-                    filename: path.to_path_buf(),
-                    location: stmt.location,
-                });
-            }
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::With { body, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::AsyncWith { body, .. } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-        }
-        StmtKind::Raise { .. } => {}
-        StmtKind::Try {
-            body,
-            orelse,
-            finalbody,
-            ..
-        } => {
-            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
-            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
-            messages.extend(
-                finalbody
-                    .iter()
-                    .flat_map(|stmt| check_statement(path, stmt)),
-            );
-        }
-        StmtKind::Assert { .. } => {}
-        StmtKind::Import { .. } => {}
-        StmtKind::ImportFrom { names, .. } => {
-            for alias in names {
-                if alias.name == "*" {
-                    messages.push(Message::ImportStarUsage {
-                        filename: path.to_path_buf(),
-                        location: stmt.location,
-                    });
-                }
-            }
-        }
-        StmtKind::Global { .. } => {}
-        StmtKind::Nonlocal { .. } => {}
-        StmtKind::Expr { .. } => {}
-        StmtKind::Pass => {}
-        StmtKind::Break => {}
-        StmtKind::Continue => {}
-    }
-    messages
-}
-
-pub fn check_ast(path: &Path, python_ast: &Suite) -> Vec<Message> {
-    python_ast
-        .iter()
-        .flat_map(|stmt| check_statement(path, stmt))
-        .collect()
-}

src/checker.rs

@@ -0,0 +1,46 @@
+use rustpython_parser::ast::{ExprKind, Stmt, StmtKind, Suite};
+
+use crate::message::{Check, CheckKind};
+use crate::visitor::{walk_stmt, Visitor};
+
+struct Checker {
+    checks: Vec<Check>,
+}
+
+impl Visitor for Checker {
+    fn visit_stmt(&mut self, stmt: &Stmt) {
+        match &stmt.node {
+            StmtKind::ImportFrom { names, .. } => {
+                for alias in names {
+                    if alias.name == "*" {
+                        self.checks.push(Check {
+                            kind: CheckKind::ImportStarUsage,
+                            location: stmt.location,
+                        });
+                    }
+                }
+            }
+            StmtKind::If { test, .. } => {
+                if let ExprKind::Tuple { .. } = test.node {
+                    self.checks.push(Check {
+                        kind: CheckKind::IfTuple,
+                        location: stmt.location,
+                    });
+                }
+            }
+            _ => {}
+        }
+        walk_stmt(self, stmt);
+    }
+}
+
+pub fn check_ast(python_ast: &Suite) -> Vec<Check> {
+    python_ast
+        .iter()
+        .flat_map(|stmt| {
+            let mut checker = Checker { checks: vec![] };
+            checker.visit_stmt(stmt);
+            checker.checks
+        })
+        .collect()
+}

src/fs.rs

@@ -1,4 +1,5 @@
 use std::path::PathBuf;
+
 use walkdir::{DirEntry, WalkDir};
 
 fn is_not_hidden(entry: &DirEntry) -> bool {

src/lib.rs

@@ -1,6 +1,7 @@
 mod cache;
-mod check;
+mod checker;
 pub mod fs;
 pub mod linter;
 pub mod message;
 mod parser;
+mod visitor;

src/linter.rs

@@ -4,7 +4,7 @@ use anyhow::Result;
 use log::debug;
 use serde::{Deserialize, Serialize};
 
-use crate::check::check_ast;
+use crate::checker::check_ast;
 use crate::message::Message;
 use crate::{cache, parser};
 
@@ -29,7 +29,14 @@ pub fn check_path(path: &Path) -> Result<Vec<Message>> {
 
     // Run the linter.
     let python_ast = parser::parse(path)?;
-    let messages = check_ast(path, &python_ast);
+    let messages: Vec<Message> = check_ast(&python_ast)
+        .into_iter()
+        .map(|check| Message {
+            kind: check.kind,
+            location: check.location,
+            filename: path.to_string_lossy().to_string(),
+        })
+        .collect();
     cache::set(path, &messages);
 
     Ok(messages)

src/message.rs

@@ -1,5 +1,4 @@
 use std::fmt;
-use std::path::PathBuf;
 
 use colored::Colorize;
 use rustpython_parser::ast::Location;
@@ -21,62 +20,54 @@ impl From<LocationDef> for Location {
 }
 
 #[derive(Serialize, Deserialize)]
-pub enum Message {
-    ImportStarUsage {
-        filename: PathBuf,
-        #[serde(with = "LocationDef")]
-        location: Location,
-    },
-    IfTuple {
-        filename: PathBuf,
-        #[serde(with = "LocationDef")]
-        location: Location,
-    },
+pub enum CheckKind {
+    ImportStarUsage,
+    IfTuple,
 }
 
-impl Message {
-    /// A four-letter shorthand code for the message.
+impl CheckKind {
+    /// A four-letter shorthand code for the check.
     pub fn code(&self) -> &'static str {
         match self {
-            Message::ImportStarUsage { .. } => "F403",
-            Message::IfTuple { .. } => "F634",
+            CheckKind::ImportStarUsage => "F403",
+            CheckKind::IfTuple => "F634",
         }
     }
 
-    /// The body text for the message.
+    /// The body text for the check.
     pub fn body(&self) -> &'static str {
         match self {
-            Message::ImportStarUsage { .. } => "Unable to detect undefined names",
-            Message::IfTuple { .. } => "If test is a tuple, which is always `True`",
+            CheckKind::ImportStarUsage => "Unable to detect undefined names",
+            CheckKind::IfTuple => "If test is a tuple, which is always `True`",
         }
     }
 }
 
+pub struct Check {
+    pub kind: CheckKind,
+    pub location: Location,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Message {
+    pub kind: CheckKind,
+    #[serde(with = "LocationDef")]
+    pub location: Location,
+    pub filename: String,
+}
+
 impl fmt::Display for Message {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            Message::ImportStarUsage { filename, location } => write!(
-                f,
-                "{}{}{}{}{}\t{}\t{}",
-                filename.to_string_lossy().white().bold(),
-                ":".cyan(),
-                location.column(),
-                ":".cyan(),
-                location.row(),
-                self.code().red().bold(),
-                self.body()
-            ),
-            Message::IfTuple { filename, location } => write!(
-                f,
-                "{}{}{}{}{}\t{}\t{}",
-                filename.to_string_lossy().white().bold(),
-                ":".cyan(),
-                location.column(),
-                ":".cyan(),
-                location.row(),
-                self.code().red().bold(),
-                self.body()
-            ),
-        }
+        write!(
+            f,
+            "{}{}{}{}{}\t{}\t{}",
+            self.filename.white().bold(),
+            ":".cyan(),
+            self.location.column(),
+            ":".cyan(),
+            self.location.row(),
+            self.kind.code().red().bold(),
+            self.kind.body()
+        )
     }
 }

src/visitor.rs

@@ -0,0 +1,538 @@
+use rustpython_parser::ast::{
+    Alias, Arg, Arguments, Boolop, Cmpop, Comprehension, Constant, Excepthandler,
+    ExcepthandlerKind, Expr, ExprContext, ExprKind, Keyword, Operator, Stmt, StmtKind, Unaryop,
+    Withitem,
+};
+
+#[allow(unused_variables)]
+pub trait Visitor {
+    fn visit_ident(&mut self, ident: &str) {
+        // Nothing to walk.
+    }
+    fn visit_constant(&mut self, constant: &Constant) {
+        walk_constant(self, constant);
+    }
+    fn visit_stmt(&mut self, stmt: &Stmt) {
+        walk_stmt(self, stmt);
+    }
+    fn visit_expr(&mut self, expr: &Expr) {
+        walk_expr(self, expr);
+    }
+    fn visit_expr_context(&mut self, expr_content: &ExprContext) {
+        // Nothing to walk.
+    }
+    fn visit_boolop(&mut self, boolop: &Boolop) {
+        // Nothing to walk.
+    }
+    fn visit_operator(&mut self, operator: &Operator) {
+        // Nothing to walk.
+    }
+    fn visit_unaryop(&mut self, unaryop: &Unaryop) {
+        // Nothing to walk.
+    }
+    fn visit_cmpop(&mut self, cmpop: &Cmpop) {
+        // Nothing to walk.
+    }
+    fn visit_comprehension(&mut self, comprehension: &Comprehension) {
+        walk_comprehension(self, comprehension);
+    }
+    fn visit_excepthandler(&mut self, excepthandler: &Excepthandler) {
+        walk_excepthandler(self, excepthandler);
+    }
+    fn visit_arguments(&mut self, arguments: &Arguments) {
+        walk_arguments(self, arguments);
+    }
+    fn visit_arg(&mut self, arg: &Arg) {
+        walk_arg(self, arg);
+    }
+    fn visit_keyword(&mut self, keyword: &Keyword) {
+        walk_keyword(self, keyword);
+    }
+    fn visit_alias(&mut self, alias: &Alias) {
+        // Nothing to walk.
+    }
+    fn visit_withitem(&mut self, withitem: &Withitem) {
+        walk_withitem(self, withitem);
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
+    match &stmt.node {
+        StmtKind::FunctionDef {
+            name,
+            args,
+            body,
+            decorator_list,
+            returns,
+            type_comment,
+        } => {
+            visitor.visit_ident(name);
+            visitor.visit_arguments(args);
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for expr in decorator_list {
+                visitor.visit_expr(expr)
+            }
+            for expr in returns {
+                visitor.visit_expr(expr);
+            }
+        }
+        StmtKind::AsyncFunctionDef {
+            name,
+            args,
+            body,
+            decorator_list,
+            returns,
+            type_comment,
+        } => {
+            visitor.visit_ident(name);
+            visitor.visit_arguments(args);
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for expr in decorator_list {
+                visitor.visit_expr(expr)
+            }
+            for expr in returns {
+                visitor.visit_expr(expr);
+            }
+        }
+        StmtKind::ClassDef {
+            name,
+            bases,
+            keywords,
+            body,
+            decorator_list,
+        } => {
+            visitor.visit_ident(name);
+            for expr in bases {
+                visitor.visit_expr(expr)
+            }
+            for keyword in keywords {
+                visitor.visit_keyword(keyword)
+            }
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for expr in decorator_list {
+                visitor.visit_expr(expr)
+            }
+        }
+        StmtKind::Return { value } => {
+            if let Some(expr) = value {
+                visitor.visit_expr(expr)
+            }
+        }
+        StmtKind::Delete { targets } => {
+            for expr in targets {
+                visitor.visit_expr(expr)
+            }
+        }
+        StmtKind::Assign {
+            targets,
+            value,
+            type_comment,
+        } => {
+            for expr in targets {
+                visitor.visit_expr(expr)
+            }
+            visitor.visit_expr(value)
+        }
+        StmtKind::AugAssign { target, op, value } => {
+            // TODO(charlie): Implement operator.
+            visitor.visit_expr(target);
+            visitor.visit_expr(value);
+        }
+        StmtKind::AnnAssign {
+            target,
+            annotation,
+            value,
+            simple,
+        } => {
+            visitor.visit_expr(target);
+            visitor.visit_expr(annotation);
+            if let Some(expr) = value {
+                visitor.visit_expr(expr)
+            }
+        }
+        StmtKind::For {
+            target,
+            iter,
+            body,
+            orelse,
+            type_comment,
+        } => {
+            visitor.visit_expr(target);
+            visitor.visit_expr(iter);
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for stmt in orelse {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::AsyncFor {
+            target,
+            iter,
+            body,
+            orelse,
+            type_comment,
+        } => {
+            visitor.visit_expr(target);
+            visitor.visit_expr(iter);
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for stmt in orelse {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::While { test, body, orelse } => {
+            visitor.visit_expr(test);
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for stmt in orelse {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::If { test, body, orelse } => {
+            visitor.visit_expr(test);
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for stmt in orelse {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::With {
+            items,
+            body,
+            type_comment,
+        } => {
+            for withitem in items {
+                visitor.visit_withitem(withitem);
+            }
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::AsyncWith {
+            items,
+            body,
+            type_comment,
+        } => {
+            for withitem in items {
+                visitor.visit_withitem(withitem);
+            }
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::Raise { exc, cause } => {
+            if let Some(expr) = exc {
+                visitor.visit_expr(expr)
+            };
+            if let Some(expr) = cause {
+                visitor.visit_expr(expr)
+            };
+        }
+        StmtKind::Try {
+            body,
+            handlers,
+            orelse,
+            finalbody,
+        } => {
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+            for excepthandler in handlers {
+                visitor.visit_excepthandler(excepthandler)
+            }
+            for stmt in orelse {
+                visitor.visit_stmt(stmt)
+            }
+            for stmt in finalbody {
+                visitor.visit_stmt(stmt)
+            }
+        }
+        StmtKind::Assert { test, msg } => {
+            visitor.visit_expr(test);
+            if let Some(expr) = msg {
+                visitor.visit_expr(expr)
+            }
+        }
+        StmtKind::Import { names } => {
+            for alias in names {
+                visitor.visit_alias(alias);
+            }
+        }
+        StmtKind::ImportFrom {
+            module,
+            names,
+            level,
+        } => {
+            for alias in names {
+                visitor.visit_alias(alias);
+            }
+        }
+        StmtKind::Global { names } => {
+            for ident in names {
+                visitor.visit_ident(ident)
+            }
+        }
+        StmtKind::Nonlocal { names } => {
+            for ident in names {
+                visitor.visit_ident(ident)
+            }
+        }
+        StmtKind::Expr { value } => visitor.visit_expr(value),
+        StmtKind::Pass => {}
+        StmtKind::Break => {}
+        StmtKind::Continue => {}
+    }
+}
+
+#[allow(unused_variables)]
+fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
+    match &expr.node {
+        ExprKind::BoolOp { op, values } => {
+            visitor.visit_boolop(op);
+            for expr in values {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::NamedExpr { target, value } => {
+            visitor.visit_expr(target);
+            visitor.visit_expr(value);
+        }
+        ExprKind::BinOp { left, op, right } => {
+            visitor.visit_expr(left);
+            visitor.visit_operator(op);
+            visitor.visit_expr(right);
+        }
+        ExprKind::UnaryOp { op, operand } => {
+            visitor.visit_unaryop(op);
+            visitor.visit_expr(operand);
+        }
+        ExprKind::Lambda { args, body } => {
+            visitor.visit_arguments(args);
+            visitor.visit_expr(body);
+        }
+        ExprKind::IfExp { test, body, orelse } => {
+            visitor.visit_expr(test);
+            visitor.visit_expr(body);
+            visitor.visit_expr(orelse);
+        }
+        ExprKind::Dict { keys, values } => {
+            for expr in keys.iter().flatten() {
+                visitor.visit_expr(expr)
+            }
+            for expr in values {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::Set { elts } => {
+            for expr in elts {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::ListComp { elt, generators } => {
+            visitor.visit_expr(elt);
+            for comprehension in generators {
+                visitor.visit_comprehension(comprehension)
+            }
+        }
+        ExprKind::SetComp { elt, generators } => {
+            visitor.visit_expr(elt);
+            for comprehension in generators {
+                visitor.visit_comprehension(comprehension)
+            }
+        }
+        ExprKind::DictComp {
+            key,
+            value,
+            generators,
+        } => {
+            visitor.visit_expr(key);
+            visitor.visit_expr(value);
+            for comprehension in generators {
+                visitor.visit_comprehension(comprehension)
+            }
+        }
+        ExprKind::GeneratorExp { elt, generators } => {
+            visitor.visit_expr(elt);
+            for comprehension in generators {
+                visitor.visit_comprehension(comprehension)
+            }
+        }
+        ExprKind::Await { value } => visitor.visit_expr(value),
+        ExprKind::Yield { value } => {
+            if let Some(expr) = value {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::YieldFrom { value } => visitor.visit_expr(value),
+        ExprKind::Compare {
+            left,
+            ops,
+            comparators,
+        } => {
+            visitor.visit_expr(left);
+            for cmpop in ops {
+                visitor.visit_cmpop(cmpop);
+            }
+            for expr in comparators {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::Call {
+            func,
+            args,
+            keywords,
+        } => {
+            visitor.visit_expr(func);
+            for expr in args {
+                visitor.visit_expr(expr);
+            }
+            for keyword in keywords {
+                visitor.visit_keyword(keyword);
+            }
+        }
+        ExprKind::FormattedValue {
+            value,
+            conversion,
+            format_spec,
+        } => {
+            visitor.visit_expr(value);
+            if let Some(expr) = format_spec {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::JoinedStr { values } => {
+            for expr in values {
+                visitor.visit_expr(expr)
+            }
+        }
+        ExprKind::Constant { value, kind } => visitor.visit_constant(value),
+        ExprKind::Attribute { value, attr, ctx } => {
+            visitor.visit_expr(value);
+            visitor.visit_expr_context(ctx);
+        }
+        ExprKind::Subscript { value, slice, ctx } => {
+            visitor.visit_expr(value);
+            visitor.visit_expr(slice);
+            visitor.visit_expr_context(ctx);
+        }
+        ExprKind::Starred { value, ctx } => {
+            visitor.visit_expr(value);
+            visitor.visit_expr_context(ctx);
+        }
+        ExprKind::Name { id, ctx } => {
+            visitor.visit_ident(id);
+            visitor.visit_expr_context(ctx);
+        }
+        ExprKind::List { elts, ctx } => {
+            for expr in elts {
+                visitor.visit_expr(expr);
+            }
+            visitor.visit_expr_context(ctx);
+        }
+        ExprKind::Tuple { elts, ctx } => {
+            for expr in elts {
+                visitor.visit_expr(expr);
+            }
+            visitor.visit_expr_context(ctx);
+        }
+        ExprKind::Slice { lower, upper, step } => {
+            if let Some(expr) = lower {
+                visitor.visit_expr(expr);
+            }
+            if let Some(expr) = upper {
+                visitor.visit_expr(expr);
+            }
+            if let Some(expr) = step {
+                visitor.visit_expr(expr);
+            }
+        }
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant) {
+    if let Constant::Tuple(constants) = constant {
+        for constant in constants {
+            visitor.visit_constant(constant)
+        }
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &Comprehension) {
+    visitor.visit_expr(&comprehension.target);
+    visitor.visit_expr(&comprehension.iter);
+    for expr in &comprehension.ifs {
+        visitor.visit_expr(expr);
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &Excepthandler) {
+    match &excepthandler.node {
+        ExcepthandlerKind::ExceptHandler { type_, name, body } => {
+            if let Some(expr) = type_ {
+                visitor.visit_expr(expr)
+            }
+            for stmt in body {
+                visitor.visit_stmt(stmt)
+            }
+        }
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Arguments) {
+    for arg in &arguments.posonlyargs {
+        visitor.visit_arg(arg);
+    }
+    for arg in &arguments.args {
+        visitor.visit_arg(arg);
+    }
+    if let Some(arg) = &arguments.vararg {
+        visitor.visit_arg(arg)
+    }
+    for arg in &arguments.kwonlyargs {
+        visitor.visit_arg(arg);
+    }
+    for expr in arguments.kw_defaults.iter().flatten() {
+        visitor.visit_expr(expr)
+    }
+    if let Some(arg) = &arguments.kwarg {
+        visitor.visit_arg(arg)
+    }
+    for expr in &arguments.defaults {
+        visitor.visit_expr(expr)
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_arg<V: Visitor + ?Sized>(visitor: &mut V, arg: &Arg) {
+    if let Some(expr) = &arg.node.annotation {
+        visitor.visit_expr(expr)
+    }
+}
+
+#[allow(unused_variables)]
+pub fn walk_keyword<V: Visitor + ?Sized>(visitor: &mut V, keyword: &Keyword) {
+    visitor.visit_expr(&keyword.node.value);
+}
+
+#[allow(unused_variables)]
+pub fn walk_withitem<V: Visitor + ?Sized>(visitor: &mut V, withitem: &Withitem) {
+    visitor.visit_expr(&withitem.context_expr);
+    if let Some(expr) = &withitem.optional_vars {
+        visitor.visit_expr(expr);
+    }
+}