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Simplify extract_function assist

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This commit is contained in:
Lukas Wirth 2021-07-29 22:01:24 +02:00
parent b537cb186e
commit b21f66fce3
3 changed files with 236 additions and 218 deletions
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235
crates/ide_assists/src/handlers/extract_function.rs
View file

@ -74,20 +74,12 @@ pub(crate) fn extract_function(acc: &mut Assists, ctx: &AssistContext) -> Option
let (locals_used, has_await, self_param) = analyze_body(&ctx.sema, &body);
let anchor = if self_param.is_some() { Anchor::Method } else { Anchor::Freestanding };
let insert_after = scope_for_fn_insertion(&body, anchor)?;
let insert_after = node_to_insert_after(&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, node.parent().as_ref().unwrap_or(&node));
let ret_ty = body_return_ty(ctx, &body)?;
let ret_values = ret_values(ctx, &body, node.parent().as_ref().unwrap_or(&node));
// 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 control_flow = external_control_flow(ctx, &body)?;
let target_range = body.text_range();
@ -97,16 +89,22 @@ pub(crate) fn extract_function(acc: &mut Assists, ctx: &AssistContext) -> Option
"Extract into function",
target_range,
move |builder| {
let ret_values: Vec<_> = ret_values.collect();
if stdx::never!(!ret_values.is_empty() && !ret_ty.is_unit()) {
// We should not have variables that outlive body if we have expression block
return;
}
let params = extracted_function_params(ctx, &body, locals_used.iter().copied());
let fun = Function {
name: "fun_name".to_string(),
self_param: self_param.map(|(_, pat)| pat),
self_param,
params,
control_flow,
ret_ty,
body,
vars_defined_in_body_and_outlive,
vars_defined_in_body_and_outlive: ret_values,
};
let new_indent = IndentLevel::from_node(&insert_after);
@ -124,68 +122,46 @@ pub(crate) fn extract_function(acc: &mut Assists, ctx: &AssistContext) -> Option
)
}
/// Analyses the function body for external control flow.
fn external_control_flow(ctx: &AssistContext, body: &FunctionBody) -> Option<ControlFlow> {
let mut ret_expr = None;
let mut try_expr = None;
let mut break_expr = None;
let mut continue_expr = None;
let (syntax, text_range) = match body {
FunctionBody::Expr(expr) => (expr.syntax(), expr.syntax().text_range()),
FunctionBody::Span { parent, text_range } => (parent.syntax(), *text_range),
};
let mut nested_loop = None;
let mut nested_scope = None;
let mut loop_depth = 0;
for e in syntax.preorder() {
let e = match e {
body.preorder_expr(&mut |expr| {
let expr = match expr {
WalkEvent::Enter(e) => e,
WalkEvent::Leave(e) => {
if nested_loop.as_ref() == Some(&e) {
nested_loop = None;
}
if nested_scope.as_ref() == Some(&e) {
nested_scope = None;
}
continue;
WalkEvent::Leave(
ast::Expr::LoopExpr(_) | ast::Expr::ForExpr(_) | ast::Expr::WhileExpr(_),
) => {
loop_depth -= 1;
return false;
}
WalkEvent::Leave(_) => return false,
};
if nested_scope.is_some() {
continue;
}
if !text_range.contains_range(e.text_range()) {
continue;
}
match e.kind() {
SyntaxKind::LOOP_EXPR | SyntaxKind::WHILE_EXPR | SyntaxKind::FOR_EXPR => {
if nested_loop.is_none() {
nested_loop = Some(e);
}
match expr {
ast::Expr::LoopExpr(_) | ast::Expr::ForExpr(_) | ast::Expr::WhileExpr(_) => {
loop_depth += 1;
}
SyntaxKind::FN
| SyntaxKind::CONST
| SyntaxKind::STATIC
| SyntaxKind::IMPL
| SyntaxKind::MODULE => {
if nested_scope.is_none() {
nested_scope = Some(e);
}
ast::Expr::ReturnExpr(it) => {
ret_expr = Some(it);
}
SyntaxKind::RETURN_EXPR => {
ret_expr = Some(ast::ReturnExpr::cast(e).unwrap());
ast::Expr::TryExpr(it) => {
try_expr = Some(it);
}
SyntaxKind::TRY_EXPR => {
try_expr = Some(ast::TryExpr::cast(e).unwrap());
ast::Expr::BreakExpr(it) if loop_depth == 0 => {
break_expr = Some(it);
}
SyntaxKind::BREAK_EXPR if nested_loop.is_none() => {
break_expr = Some(ast::BreakExpr::cast(e).unwrap());
}
SyntaxKind::CONTINUE_EXPR if nested_loop.is_none() => {
continue_expr = Some(ast::ContinueExpr::cast(e).unwrap());
ast::Expr::ContinueExpr(it) if loop_depth == 0 => {
continue_expr = Some(it);
}
_ => {}
}
}
false
});
let kind = match (try_expr, ret_expr, break_expr, continue_expr) {
(Some(e), None, None, None) => {
@ -272,11 +248,6 @@ struct Param {
is_copy: bool,
}
#[derive(Debug)]
struct ControlFlow {
kind: Option<FlowKind>,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum ParamKind {
Value,
@ -355,6 +326,11 @@ impl Param {
}
}
#[derive(Debug)]
struct ControlFlow {
kind: Option<FlowKind>,
}
/// Control flow that is exported from extracted function
///
/// E.g.:
@ -456,6 +432,7 @@ impl RetType {
}
/// Semantically same as `ast::Expr`, but preserves identity when using only part of the Block
/// This is the future function body, the part that is being extracted.
#[derive(Debug)]
enum FunctionBody {
Expr(ast::Expr),
@ -488,11 +465,7 @@ impl FunctionBody {
FunctionBody::Expr(expr) => Some(expr.clone()),
FunctionBody::Span { parent, text_range } => {
let tail_expr = parent.tail_expr()?;
if text_range.contains_range(tail_expr.syntax().text_range()) {
Some(tail_expr)
} else {
None
}
text_range.contains_range(tail_expr.syntax().text_range()).then(|| tail_expr)
}
}
}
@ -520,6 +493,29 @@ impl FunctionBody {
}
}
fn preorder_expr(&self, cb: &mut dyn FnMut(WalkEvent<ast::Expr>) -> bool) {
match self {
FunctionBody::Expr(expr) => expr.preorder(cb),
FunctionBody::Span { parent, text_range } => {
parent
.statements()
.filter(|stmt| text_range.contains_range(stmt.syntax().text_range()))
.filter_map(|stmt| match stmt {
ast::Stmt::ExprStmt(expr_stmt) => expr_stmt.expr(),
ast::Stmt::Item(_) => None,
ast::Stmt::LetStmt(stmt) => stmt.initializer(),
})
.for_each(|expr| expr.preorder(cb));
if let Some(expr) = parent
.tail_expr()
.filter(|it| text_range.contains_range(it.syntax().text_range()))
{
expr.preorder(cb);
}
}
}
}
fn walk_pat(&self, cb: &mut dyn FnMut(ast::Pat)) {
match self {
FunctionBody::Expr(expr) => expr.walk_patterns(cb),
@ -556,7 +552,7 @@ impl FunctionBody {
fn text_range(&self) -> TextRange {
match self {
FunctionBody::Expr(expr) => expr.syntax().text_range(),
FunctionBody::Span { parent: _, text_range } => *text_range,
&FunctionBody::Span { text_range, .. } => text_range,
}
}
@ -564,7 +560,7 @@ impl FunctionBody {
self.text_range().contains_range(range)
}
fn preceedes_range(&self, range: TextRange) -> bool {
fn precedes_range(&self, range: TextRange) -> bool {
self.text_range().end() <= range.start()
}
@ -668,7 +664,7 @@ fn extraction_target(node: &SyntaxNode, selection_range: TextRange) -> Option<Fu
fn analyze_body(
sema: &Semantics<RootDatabase>,
body: &FunctionBody,
) -> (FxIndexSet<Local>, bool, Option<(Local, ast::SelfParam)>) {
) -> (FxIndexSet<Local>, bool, Option<ast::SelfParam>) {
// FIXME: currently usages inside macros are not found
let mut has_await = false;
let mut self_param = None;
@ -692,7 +688,7 @@ fn analyze_body(
match local_ref.source(sema.db).value {
Either::Right(it) => {
stdx::always!(
self_param.replace((local_ref, it)).is_none(),
self_param.replace(it).is_none(),
"body references two different self params"
);
}
@ -743,7 +739,7 @@ fn extracted_function_params(
}
fn has_usages_after_body(usages: &LocalUsages, body: &FunctionBody) -> bool {
usages.iter().any(|reference| body.preceedes_range(reference.range))
usages.iter().any(|reference| body.precedes_range(reference.range))
}
/// checks if relevant var is used with `&mut` access inside body
@ -828,7 +824,7 @@ impl LocalUsages {
}
fn iter(&self) -> impl Iterator<Item = &FileReference> + '_ {
self.0.iter().flat_map(|(_, rs)| rs.iter())
self.0.iter().flat_map(|(_, rs)| rs)
}
}
@ -868,13 +864,16 @@ fn path_element_of_reference(
}
/// list local variables defined inside `body`
fn locals_defined_in_body(body: &FunctionBody, ctx: &AssistContext) -> FxIndexSet<Local> {
fn locals_defined_in_body(
sema: &Semantics<RootDatabase>,
body: &FunctionBody,
) -> FxIndexSet<Local> {
// FIXME: this doesn't work well with macros
// see https://github.com/rust-analyzer/rust-analyzer/pull/7535#discussion_r570048550
let mut res = FxIndexSet::default();
body.walk_pat(&mut |pat| {
if let ast::Pat::IdentPat(pat) = pat {
if let Some(local) = ctx.sema.to_def(&pat) {
if let Some(local) = sema.to_def(&pat) {
res.insert(local);
}
}
@ -882,17 +881,42 @@ fn locals_defined_in_body(body: &FunctionBody, ctx: &AssistContext) -> FxIndexSe
res
}
/// list local variables defined inside `body` that should be returned from extracted function
fn vars_defined_in_body_and_outlive(
ctx: &AssistContext,
/// Local variables defined inside `body` that are accessed outside of it
fn ret_values<'a>(
ctx: &'a AssistContext,
body: &FunctionBody,
parent: &SyntaxNode,
) -> Vec<OutlivedLocal> {
let vars_defined_in_body = locals_defined_in_body(body, ctx);
vars_defined_in_body
) -> impl Iterator<Item = OutlivedLocal> + 'a {
let parent = parent.clone();
let range = body.text_range();
locals_defined_in_body(&ctx.sema, body)
.into_iter()
.filter_map(|var| var_outlives_body(ctx, body, var, parent))
.collect()
.filter_map(move |local| local_outlives_body(ctx, range, local, &parent))
}
/// Returns usage details if local variable is used after(outside of) body
fn local_outlives_body(
ctx: &AssistContext,
body_range: TextRange,
local: Local,
parent: &SyntaxNode,
) -> Option<OutlivedLocal> {
let usages = LocalUsages::find(ctx, local);
let mut has_mut_usages = false;
let mut any_outlives = false;
for usage in usages.iter() {
if body_range.end() <= usage.range.start() {
has_mut_usages |= reference_is_exclusive(usage, parent, ctx);
any_outlives |= true;
if has_mut_usages {
break; // no need to check more elements we have all the info we wanted
}
}
}
if !any_outlives {
return None;
}
Some(OutlivedLocal { local, mut_usage_outside_body: has_mut_usages })
}
/// checks if the relevant local was defined before(outside of) body
@ -912,25 +936,6 @@ fn either_syntax(value: &Either<ast::IdentPat, ast::SelfParam>) -> &SyntaxNode {
}
}
/// returns usage details if local variable is used after(outside of) body
fn var_outlives_body(
ctx: &AssistContext,
body: &FunctionBody,
var: Local,
parent: &SyntaxNode,
) -> Option<OutlivedLocal> {
let usages = LocalUsages::find(ctx, var);
let has_usages = usages.iter().any(|reference| body.preceedes_range(reference.range));
if !has_usages {
return None;
}
let has_mut_usages = usages
.iter()
.filter(|reference| body.preceedes_range(reference.range))
.any(|reference| reference_is_exclusive(reference, parent, ctx));
Some(OutlivedLocal { local: var, mut_usage_outside_body: has_mut_usages })
}
fn body_return_ty(ctx: &AssistContext, body: &FunctionBody) -> Option<RetType> {
match body.tail_expr() {
Some(expr) => {
@ -940,6 +945,7 @@ fn body_return_ty(ctx: &AssistContext, body: &FunctionBody) -> Option<RetType> {
None => Some(RetType::Stmt),
}
}
/// Where to put extracted function definition
#[derive(Debug)]
enum Anchor {
@ -952,36 +958,31 @@ enum Anchor {
/// 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 { parent, .. } => scope_for_fn_insertion_node(parent.syntax(), anchor),
}
}
fn scope_for_fn_insertion_node(node: &SyntaxNode, anchor: Anchor) -> Option<SyntaxNode> {
fn node_to_insert_after(body: &FunctionBody, anchor: Anchor) -> Option<SyntaxNode> {
let node = match body {
FunctionBody::Expr(e) => e.syntax(),
FunctionBody::Span { parent, .. } => parent.syntax(),
};
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,
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;
}
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);
}

118
crates/syntax/src/ast/expr_ext.rs
View file

@ -1,5 +1,7 @@
//! Various extension methods to ast Expr Nodes, which are hard to code-generate.
use rowan::WalkEvent;
use crate::{
ast::{self, support, AstChildren, AstNode},
AstToken,
@ -34,6 +36,122 @@ impl ast::Expr {
}
None
}
/// Preorder walk all the expression's child expressions.
pub fn walk(&self, cb: &mut dyn FnMut(ast::Expr)) {
self.preorder(&mut |ev| {
if let WalkEvent::Enter(expr) = ev {
cb(expr);
}
false
})
}
/// Preorder walk all the expression's child expressions preserving events.
/// If the callback returns true the subtree of the expression will be skipped.
/// Note that the subtree may already be skipped due to the context analysis this function does.
pub fn preorder(&self, cb: &mut dyn FnMut(WalkEvent<ast::Expr>) -> bool) {
let mut preorder = self.syntax().preorder();
while let Some(event) = preorder.next() {
let node = match event {
WalkEvent::Enter(node) => node,
WalkEvent::Leave(node) => {
if let Some(expr) = ast::Expr::cast(node) {
cb(WalkEvent::Leave(expr));
}
continue;
}
};
match ast::Stmt::cast(node.clone()) {
// recursively walk the initializer, skipping potential const pat expressions
// let statements aren't usually nested too deeply so this is fine to recurse on
Some(ast::Stmt::LetStmt(l)) => {
if let Some(expr) = l.initializer() {
expr.preorder(cb);
}
preorder.skip_subtree();
}
// Don't skip subtree since we want to process the expression child next
Some(ast::Stmt::ExprStmt(_)) => (),
// skip inner items which might have their own expressions
Some(ast::Stmt::Item(_)) => preorder.skip_subtree(),
None => {
// skip const args, those expressions are a different context
if ast::GenericArg::can_cast(node.kind()) {
preorder.skip_subtree();
} else if let Some(expr) = ast::Expr::cast(node) {
let is_different_context = match &expr {
ast::Expr::EffectExpr(effect) => {
matches!(
effect.effect(),
ast::Effect::Async(_)
| ast::Effect::Try(_)
| ast::Effect::Const(_)
)
}
ast::Expr::ClosureExpr(_) => true,
_ => false,
};
let skip = cb(WalkEvent::Enter(expr));
if skip || is_different_context {
preorder.skip_subtree();
}
}
}
}
}
}
/// Preorder walk all the expression's child patterns.
pub fn walk_patterns(&self, cb: &mut dyn FnMut(ast::Pat)) {
let mut preorder = self.syntax().preorder();
while let Some(event) = preorder.next() {
let node = match event {
WalkEvent::Enter(node) => node,
WalkEvent::Leave(_) => continue,
};
match ast::Stmt::cast(node.clone()) {
Some(ast::Stmt::LetStmt(l)) => {
if let Some(pat) = l.pat() {
pat.walk(cb);
}
if let Some(expr) = l.initializer() {
expr.walk_patterns(cb);
}
preorder.skip_subtree();
}
// Don't skip subtree since we want to process the expression child next
Some(ast::Stmt::ExprStmt(_)) => (),
// skip inner items which might have their own patterns
Some(ast::Stmt::Item(_)) => preorder.skip_subtree(),
None => {
// skip const args, those are a different context
if ast::GenericArg::can_cast(node.kind()) {
preorder.skip_subtree();
} else if let Some(expr) = ast::Expr::cast(node.clone()) {
let is_different_context = match &expr {
ast::Expr::EffectExpr(effect) => {
matches!(
effect.effect(),
ast::Effect::Async(_)
| ast::Effect::Try(_)
| ast::Effect::Const(_)
)
}
ast::Expr::ClosureExpr(_) => true,
_ => false,
};
if is_different_context {
preorder.skip_subtree();
}
} else if let Some(pat) = ast::Pat::cast(node) {
preorder.skip_subtree();
pat.walk(cb);
}
}
}
}
}
}
#[derive(Debug, Clone, PartialEq, Eq)]

101
crates/syntax/src/ast/node_ext.rs
View file

@ -55,107 +55,6 @@ impl ast::BlockExpr {
}
}
impl ast::Expr {
/// Preorder walk all the expression's child expressions.
pub fn walk(&self, cb: &mut dyn FnMut(ast::Expr)) {
let mut preorder = self.syntax().preorder();
while let Some(event) = preorder.next() {
let node = match event {
WalkEvent::Enter(node) => node,
WalkEvent::Leave(_) => continue,
};
match ast::Stmt::cast(node.clone()) {
// recursively walk the initializer, skipping potential const pat expressions
// let statements aren't usually nested too deeply so this is fine to recurse on
Some(ast::Stmt::LetStmt(l)) => {
if let Some(expr) = l.initializer() {
expr.walk(cb);
}
preorder.skip_subtree();
}
// Don't skip subtree since we want to process the expression child next
Some(ast::Stmt::ExprStmt(_)) => (),
// skip inner items which might have their own expressions
Some(ast::Stmt::Item(_)) => preorder.skip_subtree(),
None => {
// skip const args, those expressions are a different context
if ast::GenericArg::can_cast(node.kind()) {
preorder.skip_subtree();
} else if let Some(expr) = ast::Expr::cast(node) {
let is_different_context = match &expr {
ast::Expr::EffectExpr(effect) => {
matches!(
effect.effect(),
ast::Effect::Async(_)
| ast::Effect::Try(_)
| ast::Effect::Const(_)
)
}
ast::Expr::ClosureExpr(_) => true,
_ => false,
};
cb(expr);
if is_different_context {
preorder.skip_subtree();
}
}
}
}
}
}
/// Preorder walk all the expression's child patterns.
pub fn walk_patterns(&self, cb: &mut dyn FnMut(ast::Pat)) {
let mut preorder = self.syntax().preorder();
while let Some(event) = preorder.next() {
let node = match event {
WalkEvent::Enter(node) => node,
WalkEvent::Leave(_) => continue,
};
match ast::Stmt::cast(node.clone()) {
Some(ast::Stmt::LetStmt(l)) => {
if let Some(pat) = l.pat() {
pat.walk(cb);
}
if let Some(expr) = l.initializer() {
expr.walk_patterns(cb);
}
preorder.skip_subtree();
}
// Don't skip subtree since we want to process the expression child next
Some(ast::Stmt::ExprStmt(_)) => (),
// skip inner items which might have their own patterns
Some(ast::Stmt::Item(_)) => preorder.skip_subtree(),
None => {
// skip const args, those are a different context
if ast::GenericArg::can_cast(node.kind()) {
preorder.skip_subtree();
} else if let Some(expr) = ast::Expr::cast(node.clone()) {
let is_different_context = match &expr {
ast::Expr::EffectExpr(effect) => {
matches!(
effect.effect(),
ast::Effect::Async(_)
| ast::Effect::Try(_)
| ast::Effect::Const(_)
)
}
ast::Expr::ClosureExpr(_) => true,
_ => false,
};
if is_different_context {
preorder.skip_subtree();
}
} else if let Some(pat) = ast::Pat::cast(node) {
preorder.skip_subtree();
pat.walk(cb);
}
}
}
}
}
}
impl ast::Pat {
/// Preorder walk all the pattern's sub patterns.
pub fn walk(&self, cb: &mut dyn FnMut(ast::Pat)) {