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internal: Deduplicate ast expression walking logic #9413

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Merged
merged 1 commit into from
Jun 26, 2021
Merged

internal: Deduplicate ast expression walking logic #9413

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162 changes: 6 additions & 156 deletions crates/ide/src/highlight_related.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,13 @@ use hir::Semantics;
use ide_db::{
base_db::FilePosition,
defs::Definition,
helpers::pick_best_token,
helpers::{for_each_break_expr, for_each_tail_expr, pick_best_token},
search::{FileReference, ReferenceAccess, SearchScope},
RootDatabase,
};
use syntax::{
ast::{self, LoopBodyOwner},
match_ast, AstNode, SyntaxNode, SyntaxToken, TextRange, WalkEvent, T,
match_ast, AstNode, SyntaxNode, SyntaxToken, TextRange, T,
};

use crate::{display::TryToNav, references, NavigationTarget};
Expand Down Expand Up @@ -95,7 +95,7 @@ fn highlight_exit_points(
) -> Option<Vec<HighlightedRange>> {
let mut highlights = Vec::new();
let body = body?;
walk(&body, &mut |expr| match expr {
body.walk(&mut |expr| match expr {
ast::Expr::ReturnExpr(expr) => {
if let Some(token) = expr.return_token() {
highlights.push(HighlightedRange { access: None, range: token.text_range() });
Expand All @@ -120,7 +120,7 @@ fn highlight_exit_points(
};

if let Some(tail) = tail {
for_each_inner_tail(&tail, &mut |tail| {
for_each_tail_expr(&tail, &mut |tail| {
let range = match tail {
ast::Expr::BreakExpr(b) => b
.break_token()
Expand Down Expand Up @@ -161,7 +161,7 @@ fn highlight_break_points(token: SyntaxToken) -> Option<Vec<HighlightedRange>> {
label.as_ref().map(|it| it.syntax().text_range()),
);
highlights.extend(range.map(|range| HighlightedRange { access: None, range }));
for_each_break(label, body, &mut |break_| {
for_each_break_expr(label, body, &mut |break_| {
let range = cover_range(
break_.break_token().map(|it| it.text_range()),
break_.lifetime().map(|it| it.syntax().text_range()),
Expand Down Expand Up @@ -216,7 +216,7 @@ fn highlight_yield_points(token: SyntaxToken) -> Option<Vec<HighlightedRange>> {
let mut highlights = Vec::new();
highlights.push(HighlightedRange { access: None, range: async_token?.text_range() });
if let Some(body) = body {
walk(&body, &mut |expr| {
body.walk(&mut |expr| {
if let ast::Expr::AwaitExpr(expr) = expr {
if let Some(token) = expr.await_token() {
highlights
Expand All @@ -240,156 +240,6 @@ fn highlight_yield_points(token: SyntaxToken) -> Option<Vec<HighlightedRange>> {
None
}

/// Preorder walk all the expression's child expressions
fn walk(expr: &ast::Expr, cb: &mut dyn FnMut(ast::Expr)) {
let mut preorder = expr.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
// lets 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() {
walk(&expr, 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 => {
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();
}
} else {
preorder.skip_subtree();
}
}
}
}
}

// FIXME: doesn't account for labeled breaks in labeled blocks
fn for_each_inner_tail(expr: &ast::Expr, cb: &mut dyn FnMut(&ast::Expr)) {
match expr {
ast::Expr::BlockExpr(b) => {
if let Some(e) = b.tail_expr() {
for_each_inner_tail(&e, cb);
}
}
ast::Expr::EffectExpr(e) => match e.effect() {
ast::Effect::Label(label) => {
for_each_break(Some(label), e.block_expr(), &mut |b| cb(&ast::Expr::BreakExpr(b)));
if let Some(b) = e.block_expr() {
for_each_inner_tail(&ast::Expr::BlockExpr(b), cb);
}
}
ast::Effect::Unsafe(_) => {
if let Some(e) = e.block_expr().and_then(|b| b.tail_expr()) {
for_each_inner_tail(&e, cb);
}
}
ast::Effect::Async(_) | ast::Effect::Try(_) | ast::Effect::Const(_) => cb(expr),
},
ast::Expr::IfExpr(if_) => {
if_.blocks().for_each(|block| for_each_inner_tail(&ast::Expr::BlockExpr(block), cb))
}
ast::Expr::LoopExpr(l) => {
for_each_break(l.label(), l.loop_body(), &mut |b| cb(&ast::Expr::BreakExpr(b)))
}
ast::Expr::MatchExpr(m) => {
if let Some(arms) = m.match_arm_list() {
arms.arms().filter_map(|arm| arm.expr()).for_each(|e| for_each_inner_tail(&e, cb));
}
}
ast::Expr::ArrayExpr(_)
| ast::Expr::AwaitExpr(_)
| ast::Expr::BinExpr(_)
| ast::Expr::BoxExpr(_)
| ast::Expr::BreakExpr(_)
| ast::Expr::CallExpr(_)
| ast::Expr::CastExpr(_)
| ast::Expr::ClosureExpr(_)
| ast::Expr::ContinueExpr(_)
| ast::Expr::FieldExpr(_)
| ast::Expr::ForExpr(_)
| ast::Expr::IndexExpr(_)
| ast::Expr::Literal(_)
| ast::Expr::MacroCall(_)
| ast::Expr::MacroStmts(_)
| ast::Expr::MethodCallExpr(_)
| ast::Expr::ParenExpr(_)
| ast::Expr::PathExpr(_)
| ast::Expr::PrefixExpr(_)
| ast::Expr::RangeExpr(_)
| ast::Expr::RecordExpr(_)
| ast::Expr::RefExpr(_)
| ast::Expr::ReturnExpr(_)
| ast::Expr::TryExpr(_)
| ast::Expr::TupleExpr(_)
| ast::Expr::WhileExpr(_)
| ast::Expr::YieldExpr(_) => cb(expr),
}
}

fn for_each_break(
label: Option<ast::Label>,
body: Option<ast::BlockExpr>,
cb: &mut dyn FnMut(ast::BreakExpr),
) {
let label = label.and_then(|lbl| lbl.lifetime());
let mut depth = 0;
if let Some(b) = body {
let preorder = &mut b.syntax().preorder();
let ev_as_expr = |ev| match ev {
WalkEvent::Enter(it) => Some(WalkEvent::Enter(ast::Expr::cast(it)?)),
WalkEvent::Leave(it) => Some(WalkEvent::Leave(ast::Expr::cast(it)?)),
};
let eq_label = |lt: Option<ast::Lifetime>| {
lt.zip(label.as_ref()).map_or(false, |(lt, lbl)| lt.text() == lbl.text())
};
while let Some(node) = preorder.find_map(ev_as_expr) {
match node {
WalkEvent::Enter(expr) => match expr {
ast::Expr::LoopExpr(_) | ast::Expr::WhileExpr(_) | ast::Expr::ForExpr(_) => {
depth += 1
}
ast::Expr::EffectExpr(e) if e.label().is_some() => depth += 1,
ast::Expr::BreakExpr(b)
if (depth == 0 && b.lifetime().is_none()) || eq_label(b.lifetime()) =>
{
cb(b);
}
_ => (),
},
WalkEvent::Leave(expr) => match expr {
ast::Expr::LoopExpr(_) | ast::Expr::WhileExpr(_) | ast::Expr::ForExpr(_) => {
depth -= 1
}
ast::Expr::EffectExpr(e) if e.label().is_some() => depth -= 1,
_ => (),
},
}
}
}
}

fn cover_range(r0: Option<TextRange>, r1: Option<TextRange>) -> Option<TextRange> {
match (r0, r1) {
(Some(r0), Some(r1)) => Some(r0.cover(r1)),
Expand Down
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