rust/crates/assists/src/handlers/extract_function.rs

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use either::Either;
use hir::{HirDisplay, Local};
use ide_db::{
defs::{Definition, NameRefClass},
search::{FileReference, ReferenceAccess, SearchScope},
};
use itertools::Itertools;
use stdx::format_to;
use syntax::{
algo::SyntaxRewriter,
ast::{
self,
edit::{AstNodeEdit, IndentLevel},
AstNode,
},
Direction, SyntaxElement,
SyntaxKind::{self, BLOCK_EXPR, BREAK_EXPR, COMMENT, PATH_EXPR, RETURN_EXPR},
SyntaxNode, SyntaxToken, TextRange, TextSize, TokenAtOffset, T,
};
use test_utils::mark;
use crate::{
assist_context::{AssistContext, Assists},
AssistId,
};
// Assist: extract_function
//
// Extracts selected statements into new function.
//
// ```
// fn main() {
// let n = 1;
// $0let m = n + 2;
// let k = m + n;$0
// let g = 3;
// }
// ```
// ->
// ```
// fn main() {
// let n = 1;
// fun_name(n);
// let g = 3;
// }
//
// fn $0fun_name(n: i32) {
// let m = n + 2;
// let k = m + n;
// }
// ```
pub(crate) fn extract_function(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
if ctx.frange.range.is_empty() {
return None;
}
let node = ctx.covering_element();
if node.kind() == COMMENT {
mark::hit!(extract_function_in_comment_is_not_applicable);
return None;
}
let node = element_to_node(node);
let body = extraction_target(&node, ctx.frange.range)?;
let vars_used_in_body = vars_used_in_body(ctx, &body);
let self_param = self_param_from_usages(ctx, &body, &vars_used_in_body);
let anchor = if self_param.is_some() { Anchor::Method } else { Anchor::Freestanding };
let insert_after = scope_for_fn_insertion(&body, anchor)?;
let module = ctx.sema.scope(&insert_after).module()?;
let vars_defined_in_body_and_outlive = vars_defined_in_body_and_outlive(ctx, &body);
let ret_ty = body_return_ty(ctx, &body)?;
// FIXME: we compute variables that outlive here just to check `never!` condition
// this requires traversing whole `body` (cheap) and finding all references (expensive)
// maybe we can move this check to `edit` closure somehow?
if stdx::never!(!vars_defined_in_body_and_outlive.is_empty() && !ret_ty.is_unit()) {
// We should not have variables that outlive body if we have expression block
return None;
}
let target_range = match &body {
FunctionBody::Expr(expr) => expr.syntax().text_range(),
FunctionBody::Span { .. } => ctx.frange.range,
};
acc.add(
AssistId("extract_function", crate::AssistKind::RefactorExtract),
"Extract into function",
target_range,
move |builder| {
let params = extracted_function_params(ctx, &body, &vars_used_in_body);
let fun = Function {
name: "fun_name".to_string(),
self_param: self_param.map(|(_, pat)| pat),
params,
ret_ty,
body,
vars_defined_in_body_and_outlive,
};
builder.replace(target_range, format_replacement(ctx, &fun));
let indent = IndentLevel::from_node(&insert_after);
let fn_def = format_function(ctx, module, &fun, indent);
let insert_offset = insert_after.text_range().end();
builder.insert(insert_offset, fn_def);
},
)
}
#[derive(Debug)]
struct Function {
name: String,
self_param: Option<ast::SelfParam>,
params: Vec<Param>,
ret_ty: RetType,
body: FunctionBody,
vars_defined_in_body_and_outlive: Vec<Local>,
}
#[derive(Debug)]
struct Param {
var: Local,
ty: hir::Type,
has_usages_afterwards: bool,
has_mut_inside_body: bool,
is_copy: bool,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum ParamKind {
Value,
MutValue,
SharedRef,
MutRef,
}
impl ParamKind {
fn is_ref(&self) -> bool {
matches!(self, ParamKind::SharedRef | ParamKind::MutRef)
}
}
impl Param {
fn kind(&self) -> ParamKind {
match (self.has_usages_afterwards, self.has_mut_inside_body, self.is_copy) {
(true, true, _) => ParamKind::MutRef,
(true, false, false) => ParamKind::SharedRef,
(false, true, _) => ParamKind::MutValue,
(true, false, true) | (false, false, _) => ParamKind::Value,
}
}
fn value_prefix(&self) -> &'static str {
match self.kind() {
ParamKind::Value | ParamKind::MutValue => "",
ParamKind::SharedRef => "&",
ParamKind::MutRef => "&mut ",
}
}
fn type_prefix(&self) -> &'static str {
match self.kind() {
ParamKind::Value | ParamKind::MutValue => "",
ParamKind::SharedRef => "&",
ParamKind::MutRef => "&mut ",
}
}
fn mut_pattern(&self) -> &'static str {
match self.kind() {
ParamKind::MutValue => "mut ",
_ => "",
}
}
}
#[derive(Debug)]
enum RetType {
Expr(hir::Type),
Stmt,
}
impl RetType {
fn is_unit(&self) -> bool {
match self {
RetType::Expr(ty) => ty.is_unit(),
RetType::Stmt => true,
}
}
fn as_fn_ret(&self) -> Option<&hir::Type> {
match self {
RetType::Stmt => None,
RetType::Expr(ty) if ty.is_unit() => None,
RetType::Expr(ty) => Some(ty),
}
}
}
/// Semantically same as `ast::Expr`, but preserves identity when using only part of the Block
#[derive(Debug)]
enum FunctionBody {
Expr(ast::Expr),
Span { elements: Vec<SyntaxElement>, leading_indent: String },
}
impl FunctionBody {
fn from_whole_node(node: SyntaxNode) -> Option<Self> {
match node.kind() {
PATH_EXPR => None,
BREAK_EXPR => ast::BreakExpr::cast(node).and_then(|e| e.expr()).map(Self::Expr),
RETURN_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()).map(Self::Expr),
BLOCK_EXPR => ast::BlockExpr::cast(node)
.filter(|it| it.is_standalone())
.map(Into::into)
.map(Self::Expr),
_ => ast::Expr::cast(node).map(Self::Expr),
}
}
fn from_range(node: &SyntaxNode, range: TextRange) -> Option<FunctionBody> {
let mut first = node.token_at_offset(range.start()).left_biased()?;
let last = node.token_at_offset(range.end()).right_biased()?;
let mut leading_indent = String::new();
let leading_trivia = first
.siblings_with_tokens(Direction::Prev)
.skip(1)
.take_while(|e| e.kind() == SyntaxKind::WHITESPACE && e.as_token().is_some());
for e in leading_trivia {
let token = e.as_token().unwrap();
let text = token.text();
match text.rfind('\n') {
Some(pos) => {
leading_indent = text[pos..].to_owned();
break;
}
None => first = token.clone(),
}
}
let mut elements: Vec<_> = first
.siblings_with_tokens(Direction::Next)
.take_while(|e| e.as_token() != Some(&last))
.collect();
if !(last.kind() == SyntaxKind::WHITESPACE && last.text().lines().count() <= 2) {
elements.push(last.into());
}
Some(FunctionBody::Span { elements, leading_indent })
}
fn tail_expr(&self) -> Option<ast::Expr> {
match &self {
FunctionBody::Expr(expr) => Some(expr.clone()),
FunctionBody::Span { elements, .. } => {
elements.iter().rev().find_map(|e| e.as_node()).cloned().and_then(ast::Expr::cast)
}
}
}
fn descendants(&self) -> impl Iterator<Item = SyntaxNode> + '_ {
match self {
FunctionBody::Expr(expr) => Either::Right(expr.syntax().descendants()),
FunctionBody::Span { elements, .. } => Either::Left(
elements
.iter()
.filter_map(SyntaxElement::as_node)
.flat_map(SyntaxNode::descendants),
),
}
}
fn text_range(&self) -> TextRange {
match self {
FunctionBody::Expr(expr) => expr.syntax().text_range(),
FunctionBody::Span { elements, .. } => TextRange::new(
elements.first().unwrap().text_range().start(),
elements.last().unwrap().text_range().end(),
),
}
}
fn contains_range(&self, range: TextRange) -> bool {
self.text_range().contains_range(range)
}
fn preceedes_range(&self, range: TextRange) -> bool {
self.text_range().end() <= range.start()
}
fn contains_node(&self, node: &SyntaxNode) -> bool {
self.contains_range(node.text_range())
}
}
impl HasTokenAtOffset for FunctionBody {
fn token_at_offset(&self, offset: TextSize) -> TokenAtOffset<SyntaxToken> {
match self {
FunctionBody::Expr(expr) => expr.syntax().token_at_offset(offset),
FunctionBody::Span { elements, .. } => {
stdx::always!(self.text_range().contains(offset));
let mut iter = elements
.iter()
.filter(|element| element.text_range().contains_inclusive(offset));
let element1 = iter.next().expect("offset does not fall into body");
let element2 = iter.next();
stdx::always!(iter.next().is_none(), "> 2 tokens at offset");
let t1 = match element1 {
syntax::NodeOrToken::Node(node) => node.token_at_offset(offset),
syntax::NodeOrToken::Token(token) => TokenAtOffset::Single(token.clone()),
};
let t2 = element2.map(|e| match e {
syntax::NodeOrToken::Node(node) => node.token_at_offset(offset),
syntax::NodeOrToken::Token(token) => TokenAtOffset::Single(token.clone()),
});
match t2 {
Some(t2) => match (t1.clone().right_biased(), t2.clone().left_biased()) {
(Some(e1), Some(e2)) => TokenAtOffset::Between(e1, e2),
(Some(_), None) => t1,
(None, _) => t2,
},
None => t1,
}
}
}
}
}
/// node or token's parent
fn element_to_node(node: SyntaxElement) -> SyntaxNode {
match node {
syntax::NodeOrToken::Node(n) => n,
syntax::NodeOrToken::Token(t) => t.parent(),
}
}
/// Try to guess what user wants to extract
///
/// We have basically have two cases:
/// * We want whole node, like `loop {}`, `2 + 2`, `{ let n = 1; }` exprs.
/// Then we can use `ast::Expr`
/// * We want a few statements for a block. E.g.
/// ```rust,no_run
/// fn foo() -> i32 {
/// let m = 1;
/// $0
/// let n = 2;
/// let k = 3;
/// k + n
/// $0
/// }
/// ```
///
fn extraction_target(node: &SyntaxNode, selection_range: TextRange) -> Option<FunctionBody> {
// we have selected exactly the expr node
// wrap it before anything else
if node.text_range() == selection_range {
let body = FunctionBody::from_whole_node(node.clone());
if body.is_some() {
return body;
}
}
// we have selected a few statements in a block
// so covering_element returns the whole block
if node.kind() == BLOCK_EXPR {
let body = FunctionBody::from_range(&node, selection_range);
if body.is_some() {
return body;
}
}
// we have selected single statement
// `from_whole_node` failed because (let) statement is not and expression
// so we try to expand covering_element to parent and repeat the previous
if let Some(parent) = node.parent() {
if parent.kind() == BLOCK_EXPR {
let body = FunctionBody::from_range(&parent, selection_range);
if body.is_some() {
return body;
}
}
}
// select the closest containing expr (both ifs are used)
std::iter::once(node.clone()).chain(node.ancestors()).find_map(FunctionBody::from_whole_node)
}
/// list local variables that are referenced in `body`
fn vars_used_in_body(ctx: &AssistContext, body: &FunctionBody) -> Vec<Local> {
// FIXME: currently usages inside macros are not found
body.descendants()
.filter_map(ast::NameRef::cast)
.filter_map(|name_ref| NameRefClass::classify(&ctx.sema, &name_ref))
.map(|name_kind| name_kind.referenced(ctx.db()))
.filter_map(|definition| match definition {
Definition::Local(local) => Some(local),
_ => None,
})
.unique()
.collect()
}
/// find `self` param, that was not defined inside `body`
///
/// It should skip `self` params from impls inside `body`
fn self_param_from_usages(
ctx: &AssistContext,
body: &FunctionBody,
vars_used_in_body: &[Local],
) -> Option<(Local, ast::SelfParam)> {
let mut iter = vars_used_in_body
.iter()
.filter(|var| var.is_self(ctx.db()))
.map(|var| (var, var.source(ctx.db())))
.filter(|(_, src)| is_defined_before(ctx, body, src))
.filter_map(|(&node, src)| match src.value {
Either::Right(it) => Some((node, it)),
Either::Left(_) => {
stdx::never!(false, "Local::is_self returned true, but source is IdentPat");
None
}
});
let self_param = iter.next();
stdx::always!(
iter.next().is_none(),
"body references two different self params, both defined outside"
);
self_param
}
/// find variables that should be extracted as params
///
/// Computes additional info that affects param type and mutability
fn extracted_function_params(
ctx: &AssistContext,
body: &FunctionBody,
vars_used_in_body: &[Local],
) -> Vec<Param> {
vars_used_in_body
.iter()
.filter(|var| !var.is_self(ctx.db()))
.map(|node| (node, node.source(ctx.db())))
.filter(|(_, src)| is_defined_before(ctx, body, src))
.filter_map(|(&node, src)| {
if src.value.is_left() {
Some(node)
} else {
stdx::never!(false, "Local::is_self returned false, but source is SelfParam");
None
}
})
.map(|var| {
let usages = LocalUsages::find(ctx, var);
let ty = var.ty(ctx.db());
let is_copy = ty.is_copy(ctx.db());
Param {
var,
ty,
has_usages_afterwards: has_usages_after_body(&usages, body),
has_mut_inside_body: has_exclusive_usages(ctx, &usages, body),
is_copy,
}
})
.collect()
}
fn has_usages_after_body(usages: &LocalUsages, body: &FunctionBody) -> bool {
usages.iter().any(|reference| body.preceedes_range(reference.range))
}
/// checks if relevant var is used with `&mut` access inside body
fn has_exclusive_usages(ctx: &AssistContext, usages: &LocalUsages, body: &FunctionBody) -> bool {
usages
.iter()
.filter(|reference| body.contains_range(reference.range))
.any(|reference| reference_is_exclusive(reference, body, ctx))
}
/// checks if this reference requires `&mut` access inside body
fn reference_is_exclusive(
reference: &FileReference,
body: &FunctionBody,
ctx: &AssistContext,
) -> bool {
// we directly modify variable with set: `n = 0`, `n += 1`
if reference.access == Some(ReferenceAccess::Write) {
return true;
}
// we take `&mut` reference to variable: `&mut v`
let path = path_element_of_reference(body, reference);
if is_mut_ref_expr(path.as_ref()).unwrap_or(false) {
return true;
}
// we call method with `&mut self` receiver
if is_mut_method_call_receiver(ctx, path.as_ref()).unwrap_or(false) {
return true;
}
false
}
/// Container of local varaible usages
///
/// Semanticall same as `UsageSearchResult`, but provides more convenient interface
struct LocalUsages(ide_db::search::UsageSearchResult);
impl LocalUsages {
fn find(ctx: &AssistContext, var: Local) -> Self {
Self(
Definition::Local(var)
.usages(&ctx.sema)
.in_scope(SearchScope::single_file(ctx.frange.file_id))
.all(),
)
}
fn iter(&self) -> impl Iterator<Item = &FileReference> + '_ {
self.0.iter().flat_map(|(_, rs)| rs.iter())
}
}
trait HasTokenAtOffset {
fn token_at_offset(&self, offset: TextSize) -> TokenAtOffset<SyntaxToken>;
}
impl HasTokenAtOffset for SyntaxNode {
fn token_at_offset(&self, offset: TextSize) -> TokenAtOffset<SyntaxToken> {
SyntaxNode::token_at_offset(&self, offset)
}
}
/// find relevant `ast::PathExpr` for reference
///
/// # Preconditions
///
/// `node` must cover `reference`, that is `node.text_range().contains_range(reference.range)`
fn path_element_of_reference(
node: &dyn HasTokenAtOffset,
reference: &FileReference,
) -> Option<ast::Expr> {
let token = node.token_at_offset(reference.range.start()).right_biased().or_else(|| {
stdx::never!(false, "cannot find token at variable usage: {:?}", reference);
None
})?;
let path = token.ancestors().find_map(ast::Expr::cast).or_else(|| {
stdx::never!(false, "cannot find path parent of variable usage: {:?}", token);
None
})?;
stdx::always!(matches!(path, ast::Expr::PathExpr(_)));
Some(path)
}
fn is_mut_ref_expr(path: Option<&ast::Expr>) -> Option<bool> {
let path = path?;
let ref_expr = path.syntax().parent().and_then(ast::RefExpr::cast)?;
Some(ref_expr.mut_token().is_some())
}
/// checks if `path` is the receiver in method call that requires `&mut self` access
fn is_mut_method_call_receiver(ctx: &AssistContext, path: Option<&ast::Expr>) -> Option<bool> {
let path = path?;
let method_call = path.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
let func = ctx.sema.resolve_method_call(&method_call)?;
let self_param = func.self_param(ctx.db())?;
let access = self_param.access(ctx.db());
Some(matches!(access, hir::Access::Exclusive))
}
/// list local variables defined inside `body`
fn vars_defined_in_body(body: &FunctionBody, ctx: &AssistContext) -> Vec<Local> {
// FIXME: this doesn't work well with macros
// see https://github.com/rust-analyzer/rust-analyzer/pull/7535#discussion_r570048550
body.descendants()
.filter_map(ast::IdentPat::cast)
.filter_map(|let_stmt| ctx.sema.to_def(&let_stmt))
.unique()
.collect()
}
/// list local variables defined inside `body` that should be returned from extracted function
fn vars_defined_in_body_and_outlive(ctx: &AssistContext, body: &FunctionBody) -> Vec<Local> {
let mut vars_defined_in_body = vars_defined_in_body(&body, ctx);
vars_defined_in_body.retain(|var| var_outlives_body(ctx, body, var));
vars_defined_in_body
}
/// checks if the relevant local was defined before(outside of) body
fn is_defined_before(
ctx: &AssistContext,
body: &FunctionBody,
src: &hir::InFile<Either<ast::IdentPat, ast::SelfParam>>,
) -> bool {
src.file_id.original_file(ctx.db()) == ctx.frange.file_id
&& !body.contains_node(&either_syntax(&src.value))
}
fn either_syntax(value: &Either<ast::IdentPat, ast::SelfParam>) -> &SyntaxNode {
match value {
Either::Left(pat) => pat.syntax(),
Either::Right(it) => it.syntax(),
}
}
/// checks if local variable is used after(outside of) body
fn var_outlives_body(ctx: &AssistContext, body: &FunctionBody, var: &Local) -> bool {
let usages = Definition::Local(*var)
.usages(&ctx.sema)
.in_scope(SearchScope::single_file(ctx.frange.file_id))
.all();
let mut usages = usages.iter().flat_map(|(_, rs)| rs.iter());
usages.any(|reference| body.preceedes_range(reference.range))
}
fn body_return_ty(ctx: &AssistContext, body: &FunctionBody) -> Option<RetType> {
match body.tail_expr() {
Some(expr) => {
let ty = ctx.sema.type_of_expr(&expr)?;
Some(RetType::Expr(ty))
}
None => Some(RetType::Stmt),
}
}
/// Where to put extracted function definition
#[derive(Debug)]
enum Anchor {
/// Extract free function and put right after current top-level function
Freestanding,
/// Extract method and put right after current function in the impl-block
Method,
}
/// find where to put extracted function definition
///
/// Function should be put right after returned node
fn scope_for_fn_insertion(body: &FunctionBody, anchor: Anchor) -> Option<SyntaxNode> {
match body {
FunctionBody::Expr(e) => scope_for_fn_insertion_node(e.syntax(), anchor),
FunctionBody::Span { elements, .. } => {
let node = elements.iter().find_map(|e| e.as_node())?;
scope_for_fn_insertion_node(&node, anchor)
}
}
}
fn scope_for_fn_insertion_node(node: &SyntaxNode, anchor: Anchor) -> Option<SyntaxNode> {
let mut ancestors = node.ancestors().peekable();
let mut last_ancestor = None;
while let Some(next_ancestor) = ancestors.next() {
match next_ancestor.kind() {
SyntaxKind::SOURCE_FILE => break,
SyntaxKind::ITEM_LIST => {
if !matches!(anchor, Anchor::Freestanding) {
continue;
}
if ancestors.peek().map(SyntaxNode::kind) == Some(SyntaxKind::MODULE) {
break;
}
}
SyntaxKind::ASSOC_ITEM_LIST => {
if !matches!(anchor, Anchor::Method) {
continue;
}
if ancestors.peek().map(SyntaxNode::kind) == Some(SyntaxKind::IMPL) {
break;
}
}
_ => {}
}
last_ancestor = Some(next_ancestor);
}
last_ancestor
}
fn format_replacement(ctx: &AssistContext, fun: &Function) -> String {
let mut buf = String::new();
match fun.vars_defined_in_body_and_outlive.as_slice() {
[] => {}
[var] => format_to!(buf, "let {} = ", var.name(ctx.db()).unwrap()),
[v0, vs @ ..] => {
buf.push_str("let (");
format_to!(buf, "{}", v0.name(ctx.db()).unwrap());
for var in vs {
format_to!(buf, ", {}", var.name(ctx.db()).unwrap());
}
buf.push_str(") = ");
}
}
if fun.self_param.is_some() {
format_to!(buf, "self.");
}
format_to!(buf, "{}(", fun.name);
format_arg_list_to(&mut buf, fun, ctx);
format_to!(buf, ")");
if fun.ret_ty.is_unit() {
format_to!(buf, ";");
}
buf
}
fn format_arg_list_to(buf: &mut String, fun: &Function, ctx: &AssistContext) {
let mut it = fun.params.iter();
if let Some(param) = it.next() {
format_arg_to(buf, ctx, param);
}
for param in it {
buf.push_str(", ");
format_arg_to(buf, ctx, param);
}
}
fn format_arg_to(buf: &mut String, ctx: &AssistContext, param: &Param) {
format_to!(buf, "{}{}", param.value_prefix(), param.var.name(ctx.db()).unwrap());
}
fn format_function(
ctx: &AssistContext,
module: hir::Module,
fun: &Function,
indent: IndentLevel,
) -> String {
let mut fn_def = String::new();
format_to!(fn_def, "\n\n{}fn $0{}(", indent, fun.name);
format_function_param_list_to(&mut fn_def, ctx, module, fun);
fn_def.push(')');
format_function_ret_to(&mut fn_def, ctx, module, fun);
fn_def.push_str(" {");
format_function_body_to(&mut fn_def, ctx, indent, fun);
format_to!(fn_def, "{}}}", indent);
fn_def
}
fn format_function_param_list_to(
fn_def: &mut String,
ctx: &AssistContext,
module: hir::Module,
fun: &Function,
) {
let mut it = fun.params.iter();
if let Some(self_param) = &fun.self_param {
format_to!(fn_def, "{}", self_param);
} else if let Some(param) = it.next() {
format_param_to(fn_def, ctx, module, param);
}
for param in it {
fn_def.push_str(", ");
format_param_to(fn_def, ctx, module, param);
}
}
fn format_param_to(fn_def: &mut String, ctx: &AssistContext, module: hir::Module, param: &Param) {
format_to!(
fn_def,
"{}{}: {}{}",
param.mut_pattern(),
param.var.name(ctx.db()).unwrap(),
param.type_prefix(),
format_type(&param.ty, ctx, module)
);
}
fn format_function_ret_to(
fn_def: &mut String,
ctx: &AssistContext,
module: hir::Module,
fun: &Function,
) {
if let Some(ty) = fun.ret_ty.as_fn_ret() {
format_to!(fn_def, " -> {}", format_type(ty, ctx, module));
} else {
match fun.vars_defined_in_body_and_outlive.as_slice() {
[] => {}
[var] => {
format_to!(fn_def, " -> {}", format_type(&var.ty(ctx.db()), ctx, module));
}
[v0, vs @ ..] => {
format_to!(fn_def, " -> ({}", format_type(&v0.ty(ctx.db()), ctx, module));
for var in vs {
format_to!(fn_def, ", {}", format_type(&var.ty(ctx.db()), ctx, module));
}
fn_def.push(')');
}
}
}
}
fn format_function_body_to(
fn_def: &mut String,
ctx: &AssistContext,
indent: IndentLevel,
fun: &Function,
) {
match &fun.body {
FunctionBody::Expr(expr) => {
fn_def.push('\n');
let expr = expr.indent(indent);
let expr = fix_param_usages(ctx, &fun.params, expr.syntax());
format_to!(fn_def, "{}{}", indent + 1, expr);
fn_def.push('\n');
}
FunctionBody::Span { elements, leading_indent } => {
format_to!(fn_def, "{}", leading_indent);
for element in elements {
match element {
syntax::NodeOrToken::Node(node) => {
format_to!(fn_def, "{}", fix_param_usages(ctx, &fun.params, node));
}
syntax::NodeOrToken::Token(token) => {
format_to!(fn_def, "{}", token);
}
}
}
if !fn_def.ends_with('\n') {
fn_def.push('\n');
}
}
}
match fun.vars_defined_in_body_and_outlive.as_slice() {
[] => {}
[var] => format_to!(fn_def, "{}{}\n", indent + 1, var.name(ctx.db()).unwrap()),
[v0, vs @ ..] => {
format_to!(fn_def, "{}({}", indent + 1, v0.name(ctx.db()).unwrap());
for var in vs {
format_to!(fn_def, ", {}", var.name(ctx.db()).unwrap());
}
fn_def.push_str(")\n");
}
}
}
fn format_type(ty: &hir::Type, ctx: &AssistContext, module: hir::Module) -> String {
ty.display_source_code(ctx.db(), module.into()).ok().unwrap_or_else(|| "()".to_string())
}
/// change all usages to account for added `&`/`&mut` for some params
fn fix_param_usages(ctx: &AssistContext, params: &[Param], syntax: &SyntaxNode) -> SyntaxNode {
let mut rewriter = SyntaxRewriter::default();
for param in params {
if !param.kind().is_ref() {
continue;
}
let usages = LocalUsages::find(ctx, param.var);
let usages = usages
.iter()
.filter(|reference| syntax.text_range().contains_range(reference.range))
.filter_map(|reference| path_element_of_reference(syntax, reference));
for path in usages {
match path.syntax().ancestors().skip(1).find_map(ast::Expr::cast) {
Some(ast::Expr::MethodCallExpr(_)) => {
// do nothing
}
Some(ast::Expr::RefExpr(node))
if param.kind() == ParamKind::MutRef && node.mut_token().is_some() =>
{
rewriter.replace_ast(&node.clone().into(), &node.expr().unwrap());
}
Some(ast::Expr::RefExpr(node))
if param.kind() == ParamKind::SharedRef && node.mut_token().is_none() =>
{
rewriter.replace_ast(&node.clone().into(), &node.expr().unwrap());
}
Some(_) | None => {
rewriter.replace_ast(&path, &ast::make::expr_prefix(T![*], path.clone()));
}
};
}
}
rewriter.rewrite(syntax)
}
#[cfg(test)]
mod tests {
use crate::tests::{check_assist, check_assist_not_applicable};
use super::*;
#[test]
fn no_args_from_binary_expr() {
check_assist(
extract_function,
r#"
fn foo() {
foo($01 + 1$0);
}"#,
r#"
fn foo() {
foo(fun_name());
}
fn $0fun_name() -> i32 {
1 + 1
}"#,
);
}
#[test]
fn no_args_from_binary_expr_in_module() {
check_assist(
extract_function,
r#"
mod bar {
fn foo() {
foo($01 + 1$0);
}
}"#,
r#"
mod bar {
fn foo() {
foo(fun_name());
}
fn $0fun_name() -> i32 {
1 + 1
}
}"#,
);
}
#[test]
fn no_args_from_binary_expr_indented() {
check_assist(
extract_function,
r#"
fn foo() {
$0{ 1 + 1 }$0;
}"#,
r#"
fn foo() {
fun_name();
}
fn $0fun_name() -> i32 {
{ 1 + 1 }
}"#,
);
}
#[test]
fn no_args_from_stmt_with_last_expr() {
check_assist(
extract_function,
r#"
fn foo() -> i32 {
let k = 1;
$0let m = 1;
m + 1$0
}"#,
r#"
fn foo() -> i32 {
let k = 1;
fun_name()
}
fn $0fun_name() -> i32 {
let m = 1;
m + 1
}"#,
);
}
#[test]
fn no_args_from_stmt_unit() {
check_assist(
extract_function,
r#"
fn foo() {
let k = 3;
$0let m = 1;
let n = m + 1;$0
let g = 5;
}"#,
r#"
fn foo() {
let k = 3;
fun_name();
let g = 5;
}
fn $0fun_name() {
let m = 1;
let n = m + 1;
}"#,
);
}
#[test]
fn no_args_if() {
check_assist(
extract_function,
r#"
fn foo() {
$0if true { }$0
}"#,
r#"
fn foo() {
fun_name();
}
fn $0fun_name() {
if true { }
}"#,
);
}
#[test]
fn no_args_if_else() {
check_assist(
extract_function,
r#"
fn foo() -> i32 {
$0if true { 1 } else { 2 }$0
}"#,
r#"
fn foo() -> i32 {
fun_name()
}
fn $0fun_name() -> i32 {
if true { 1 } else { 2 }
}"#,
);
}
#[test]
fn no_args_if_let_else() {
check_assist(
extract_function,
r#"
fn foo() -> i32 {
$0if let true = false { 1 } else { 2 }$0
}"#,
r#"
fn foo() -> i32 {
fun_name()
}
fn $0fun_name() -> i32 {
if let true = false { 1 } else { 2 }
}"#,
);
}
#[test]
fn no_args_match() {
check_assist(
extract_function,
r#"
fn foo() -> i32 {
$0match true {
true => 1,
false => 2,
}$0
}"#,
r#"
fn foo() -> i32 {
fun_name()
}
fn $0fun_name() -> i32 {
match true {
true => 1,
false => 2,
}
}"#,
);
}
#[test]
fn no_args_while() {
check_assist(
extract_function,
r#"
fn foo() {
$0while true { }$0
}"#,
r#"
fn foo() {
fun_name();
}
fn $0fun_name() {
while true { }
}"#,
);
}
#[test]
fn no_args_for() {
check_assist(
extract_function,
r#"
fn foo() {
$0for v in &[0, 1] { }$0
}"#,
r#"
fn foo() {
fun_name();
}
fn $0fun_name() {
for v in &[0, 1] { }
}"#,
);
}
#[test]
fn no_args_from_loop_unit() {
check_assist(
extract_function,
r#"
fn foo() {
$0loop {
let m = 1;
}$0
}"#,
r#"
fn foo() {
fun_name()
}
fn $0fun_name() -> ! {
loop {
let m = 1;
}
}"#,
);
}
#[test]
fn no_args_from_loop_with_return() {
check_assist(
extract_function,
r#"
fn foo() {
let v = $0loop {
let m = 1;
break m;
}$0;
}"#,
r#"
fn foo() {
let v = fun_name();
}
fn $0fun_name() -> i32 {
loop {
let m = 1;
break m;
}
}"#,
);
}
#[test]
fn no_args_from_match() {
check_assist(
extract_function,
r#"
fn foo() {
let v: i32 = $0match Some(1) {
Some(x) => x,
None => 0,
}$0;
}"#,
r#"
fn foo() {
let v: i32 = fun_name();
}
fn $0fun_name() -> i32 {
match Some(1) {
Some(x) => x,
None => 0,
}
}"#,
);
}
#[test]
fn argument_form_expr() {
check_assist(
extract_function,
r"
fn foo() -> u32 {
let n = 2;
$0n+2$0
}",
r"
fn foo() -> u32 {
let n = 2;
fun_name(n)
}
fn $0fun_name(n: u32) -> u32 {
n+2
}",
)
}
#[test]
fn argument_used_twice_form_expr() {
check_assist(
extract_function,
r"
fn foo() -> u32 {
let n = 2;
$0n+n$0
}",
r"
fn foo() -> u32 {
let n = 2;
fun_name(n)
}
fn $0fun_name(n: u32) -> u32 {
n+n
}",
)
}
#[test]
fn two_arguments_form_expr() {
check_assist(
extract_function,
r"
fn foo() -> u32 {
let n = 2;
let m = 3;
$0n+n*m$0
}",
r"
fn foo() -> u32 {
let n = 2;
let m = 3;
fun_name(n, m)
}
fn $0fun_name(n: u32, m: u32) -> u32 {
n+n*m
}",
)
}
#[test]
fn argument_and_locals() {
check_assist(
extract_function,
r"
fn foo() -> u32 {
let n = 2;
$0let m = 1;
n + m$0
}",
r"
fn foo() -> u32 {
let n = 2;
fun_name(n)
}
fn $0fun_name(n: u32) -> u32 {
let m = 1;
n + m
}",
)
}
#[test]
fn in_comment_is_not_applicable() {
mark::check!(extract_function_in_comment_is_not_applicable);
check_assist_not_applicable(extract_function, r"fn main() { 1 + /* $0comment$0 */ 1; }");
}
#[test]
fn part_of_expr_stmt() {
check_assist(
extract_function,
"
fn foo() {
$01$0 + 1;
}",
"
fn foo() {
fun_name() + 1;
}
fn $0fun_name() -> i32 {
1
}",
);
}
#[test]
fn function_expr() {
check_assist(
extract_function,
r#"
fn foo() {
$0bar(1 + 1)$0
}"#,
r#"
fn foo() {
fun_name();
}
fn $0fun_name() {
bar(1 + 1)
}"#,
)
}
#[test]
fn extract_from_nested() {
check_assist(
extract_function,
r"
fn main() {
let x = true;
let tuple = match x {
true => ($02 + 2$0, true)
_ => (0, false)
};
}",
r"
fn main() {
let x = true;
let tuple = match x {
true => (fun_name(), true)
_ => (0, false)
};
}
fn $0fun_name() -> i32 {
2 + 2
}",
);
}
#[test]
fn param_from_closure() {
check_assist(
extract_function,
r"
fn main() {
let lambda = |x: u32| $0x * 2$0;
}",
r"
fn main() {
let lambda = |x: u32| fun_name(x);
}
fn $0fun_name(x: u32) -> u32 {
x * 2
}",
);
}
#[test]
fn extract_return_stmt() {
check_assist(
extract_function,
r"
fn foo() -> u32 {
$0return 2 + 2$0;
}",
r"
fn foo() -> u32 {
return fun_name();
}
fn $0fun_name() -> u32 {
2 + 2
}",
);
}
#[test]
fn does_not_add_extra_whitespace() {
check_assist(
extract_function,
r"
fn foo() -> u32 {
$0return 2 + 2$0;
}",
r"
fn foo() -> u32 {
return fun_name();
}
fn $0fun_name() -> u32 {
2 + 2
}",
);
}
#[test]
fn break_stmt() {
check_assist(
extract_function,
r"
fn main() {
let result = loop {
$0break 2 + 2$0;
};
}",
r"
fn main() {
let result = loop {
break fun_name();
};
}
fn $0fun_name() -> i32 {
2 + 2
}",
);
}
#[test]
fn extract_cast() {
check_assist(
extract_function,
r"
fn main() {
let v = $00f32 as u32$0;
}",
r"
fn main() {
let v = fun_name();
}
fn $0fun_name() -> u32 {
0f32 as u32
}",
);
}
#[test]
fn return_not_applicable() {
check_assist_not_applicable(extract_function, r"fn foo() { $0return$0; } ");
}
#[test]
fn method_to_freestanding() {
check_assist(
extract_function,
r"
struct S;
impl S {
fn foo(&self) -> i32 {
$01+1$0
}
}",
r"
struct S;
impl S {
fn foo(&self) -> i32 {
fun_name()
}
}
fn $0fun_name() -> i32 {
1+1
}",
);
}
#[test]
fn method_with_reference() {
check_assist(
extract_function,
r"
struct S { f: i32 };
impl S {
fn foo(&self) -> i32 {
$01+self.f$0
}
}",
r"
struct S { f: i32 };
impl S {
fn foo(&self) -> i32 {
self.fun_name()
}
fn $0fun_name(&self) -> i32 {
1+self.f
}
}",
);
}
#[test]
fn method_with_mut() {
check_assist(
extract_function,
r"
struct S { f: i32 };
impl S {
fn foo(&mut self) {
$0self.f += 1;$0
}
}",
r"
struct S { f: i32 };
impl S {
fn foo(&mut self) {
self.fun_name();
}
fn $0fun_name(&mut self) {
self.f += 1;
}
}",
);
}
#[test]
fn variable_defined_inside_and_used_after_no_ret() {
check_assist(
extract_function,
r"
fn foo() {
let n = 1;
$0let k = n * n;$0
let m = k + 1;
}",
r"
fn foo() {
let n = 1;
let k = fun_name(n);
let m = k + 1;
}
fn $0fun_name(n: i32) -> i32 {
let k = n * n;
k
}",
);
}
#[test]
fn two_variables_defined_inside_and_used_after_no_ret() {
check_assist(
extract_function,
r"
fn foo() {
let n = 1;
$0let k = n * n;
let m = k + 2;$0
let h = k + m;
}",
r"
fn foo() {
let n = 1;
let (k, m) = fun_name(n);
let h = k + m;
}
fn $0fun_name(n: i32) -> (i32, i32) {
let k = n * n;
let m = k + 2;
(k, m)
}",
);
}
#[test]
fn nontrivial_patterns_define_variables() {
check_assist(
extract_function,
r"
struct Counter(i32);
fn foo() {
$0let Counter(n) = Counter(0);$0
let m = n;
}",
r"
struct Counter(i32);
fn foo() {
let n = fun_name();
let m = n;
}
fn $0fun_name() -> i32 {
let Counter(n) = Counter(0);
n
}",
);
}
#[test]
fn struct_with_two_fields_pattern_define_variables() {
check_assist(
extract_function,
r"
struct Counter { n: i32, m: i32 };
fn foo() {
$0let Counter { n, m: k } = Counter { n: 1, m: 2 };$0
let h = n + k;
}",
r"
struct Counter { n: i32, m: i32 };
fn foo() {
let (n, k) = fun_name();
let h = n + k;
}
fn $0fun_name() -> (i32, i32) {
let Counter { n, m: k } = Counter { n: 1, m: 2 };
(n, k)
}",
);
}
#[test]
fn mut_var_from_outer_scope() {
check_assist(
extract_function,
r"
fn foo() {
let mut n = 1;
$0n += 1;$0
let m = n + 1;
}",
r"
fn foo() {
let mut n = 1;
fun_name(&mut n);
let m = n + 1;
}
fn $0fun_name(n: &mut i32) {
*n += 1;
}",
);
}
#[test]
fn mut_param_many_usages_stmt() {
check_assist(
extract_function,
r"
fn bar(k: i32) {}
trait I: Copy {
fn succ(&self) -> Self;
fn inc(&mut self) -> Self { let v = self.succ(); *self = v; v }
}
impl I for i32 {
fn succ(&self) -> Self { *self + 1 }
}
fn foo() {
let mut n = 1;
$0n += n;
bar(n);
bar(n+1);
bar(n*n);
bar(&n);
n.inc();
let v = &mut n;
*v = v.succ();
n.succ();$0
let m = n + 1;
}",
r"
fn bar(k: i32) {}
trait I: Copy {
fn succ(&self) -> Self;
fn inc(&mut self) -> Self { let v = self.succ(); *self = v; v }
}
impl I for i32 {
fn succ(&self) -> Self { *self + 1 }
}
fn foo() {
let mut n = 1;
fun_name(&mut n);
let m = n + 1;
}
fn $0fun_name(n: &mut i32) {
*n += *n;
bar(*n);
bar(*n+1);
bar(*n**n);
bar(&*n);
n.inc();
let v = n;
*v = v.succ();
n.succ();
}",
);
}
#[test]
fn mut_param_many_usages_expr() {
check_assist(
extract_function,
r"
fn bar(k: i32) {}
trait I: Copy {
fn succ(&self) -> Self;
fn inc(&mut self) -> Self { let v = self.succ(); *self = v; v }
}
impl I for i32 {
fn succ(&self) -> Self { *self + 1 }
}
fn foo() {
let mut n = 1;
$0{
n += n;
bar(n);
bar(n+1);
bar(n*n);
bar(&n);
n.inc();
let v = &mut n;
*v = v.succ();
n.succ();
}$0
let m = n + 1;
}",
r"
fn bar(k: i32) {}
trait I: Copy {
fn succ(&self) -> Self;
fn inc(&mut self) -> Self { let v = self.succ(); *self = v; v }
}
impl I for i32 {
fn succ(&self) -> Self { *self + 1 }
}
fn foo() {
let mut n = 1;
fun_name(&mut n);
let m = n + 1;
}
fn $0fun_name(n: &mut i32) {
{
*n += *n;
bar(*n);
bar(*n+1);
bar(*n**n);
bar(&*n);
n.inc();
let v = n;
*v = v.succ();
n.succ();
}
}",
);
}
#[test]
fn mut_param_by_value() {
check_assist(
extract_function,
r"
fn foo() {
let mut n = 1;
$0n += 1;$0
}",
r"
fn foo() {
let mut n = 1;
fun_name(n);
}
fn $0fun_name(mut n: i32) {
n += 1;
}",
);
}
#[test]
fn mut_param_because_of_mut_ref() {
check_assist(
extract_function,
r"
fn foo() {
let mut n = 1;
$0let v = &mut n;
*v += 1;$0
let k = n;
}",
r"
fn foo() {
let mut n = 1;
fun_name(&mut n);
let k = n;
}
fn $0fun_name(n: &mut i32) {
let v = n;
*v += 1;
}",
);
}
#[test]
fn mut_param_by_value_because_of_mut_ref() {
check_assist(
extract_function,
r"
fn foo() {
let mut n = 1;
$0let v = &mut n;
*v += 1;$0
}",
r"
fn foo() {
let mut n = 1;
fun_name(n);
}
fn $0fun_name(mut n: i32) {
let v = &mut n;
*v += 1;
}",
);
}
#[test]
fn mut_method_call() {
check_assist(
extract_function,
r"
trait I {
fn inc(&mut self);
}
impl I for i32 {
fn inc(&mut self) { *self += 1 }
}
fn foo() {
let mut n = 1;
$0n.inc();$0
}",
r"
trait I {
fn inc(&mut self);
}
impl I for i32 {
fn inc(&mut self) { *self += 1 }
}
fn foo() {
let mut n = 1;
fun_name(n);
}
fn $0fun_name(mut n: i32) {
n.inc();
}",
);
}
#[test]
fn shared_method_call() {
check_assist(
extract_function,
r"
trait I {
fn succ(&self);
}
impl I for i32 {
fn succ(&self) { *self + 1 }
}
fn foo() {
let mut n = 1;
$0n.succ();$0
}",
r"
trait I {
fn succ(&self);
}
impl I for i32 {
fn succ(&self) { *self + 1 }
}
fn foo() {
let mut n = 1;
fun_name(n);
}
fn $0fun_name(n: i32) {
n.succ();
}",
);
}
#[test]
fn mut_method_call_with_other_receiver() {
check_assist(
extract_function,
r"
trait I {
fn inc(&mut self, n: i32);
}
impl I for i32 {
fn inc(&mut self, n: i32) { *self += n }
}
fn foo() {
let mut n = 1;
$0let mut m = 2;
m.inc(n);$0
}",
r"
trait I {
fn inc(&mut self, n: i32);
}
impl I for i32 {
fn inc(&mut self, n: i32) { *self += n }
}
fn foo() {
let mut n = 1;
fun_name(n);
}
fn $0fun_name(n: i32) {
let mut m = 2;
m.inc(n);
}",
);
}
#[test]
fn non_copy_without_usages_after() {
check_assist(
extract_function,
r"
struct Counter(i32);
fn foo() {
let c = Counter(0);
$0let n = c.0;$0
}",
r"
struct Counter(i32);
fn foo() {
let c = Counter(0);
fun_name(c);
}
fn $0fun_name(c: Counter) {
let n = c.0;
}",
);
}
#[test]
fn non_copy_used_after() {
check_assist(
extract_function,
r"
struct Counter(i32);
fn foo() {
let c = Counter(0);
$0let n = c.0;$0
let m = c.0;
}",
r"
struct Counter(i32);
fn foo() {
let c = Counter(0);
fun_name(&c);
let m = c.0;
}
fn $0fun_name(c: &Counter) {
let n = *c.0;
}",
);
}
}