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|
//! Various helper functions to work with SyntaxNodes.
use itertools::Itertools;
use parser::T;
use syntax::{
ast::{self, HasLoopBody, MacroCall, PathSegmentKind, VisibilityKind},
AstNode, AstToken, Preorder, RustLanguage, WalkEvent,
};
pub fn expr_as_name_ref(expr: &ast::Expr) -> Option<ast::NameRef> {
if let ast::Expr::PathExpr(expr) = expr {
let path = expr.path()?;
path.as_single_name_ref()
} else {
None
}
}
pub fn full_path_of_name_ref(name_ref: &ast::NameRef) -> Option<ast::Path> {
let mut ancestors = name_ref.syntax().ancestors();
let _ = ancestors.next()?; // skip self
let _ = ancestors.next().filter(|it| ast::PathSegment::can_cast(it.kind()))?; // skip self
ancestors.take_while(|it| ast::Path::can_cast(it.kind())).last().and_then(ast::Path::cast)
}
pub fn block_as_lone_tail(block: &ast::BlockExpr) -> Option<ast::Expr> {
block.statements().next().is_none().then(|| block.tail_expr()).flatten()
}
/// Preorder walk all the expression's child expressions.
pub fn walk_expr(expr: &ast::Expr, cb: &mut dyn FnMut(ast::Expr)) {
preorder_expr(expr, &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 on an [`WalkEvent::Enter`], 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_expr(start: &ast::Expr, cb: &mut dyn FnMut(WalkEvent<ast::Expr>) -> bool) {
let mut preorder = start.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;
}
};
if let Some(let_stmt) = node.parent().and_then(ast::LetStmt::cast) {
if Some(node.clone()) != let_stmt.initializer().map(|it| it.syntax().clone()) {
// skipping potential const pat expressions in let statements
preorder.skip_subtree();
continue;
}
}
match ast::Stmt::cast(node.clone()) {
// Don't skip subtree since we want to process the expression child next
Some(ast::Stmt::ExprStmt(_)) | Some(ast::Stmt::LetStmt(_)) => (),
// 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::BlockExpr(block_expr) => {
matches!(
block_expr.modifier(),
Some(
ast::BlockModifier::Async(_)
| ast::BlockModifier::Try(_)
| ast::BlockModifier::Const(_)
)
)
}
ast::Expr::ClosureExpr(_) => true,
_ => false,
} && expr.syntax() != start.syntax();
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_in_expr(start: &ast::Expr, cb: &mut dyn FnMut(ast::Pat)) {
let mut preorder = start.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() {
walk_pat(&pat, cb);
}
if let Some(expr) = l.initializer() {
walk_patterns_in_expr(&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 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::BlockExpr(block_expr) => {
matches!(
block_expr.modifier(),
Some(
ast::BlockModifier::Async(_)
| ast::BlockModifier::Try(_)
| ast::BlockModifier::Const(_)
)
)
}
ast::Expr::ClosureExpr(_) => true,
_ => false,
} && expr.syntax() != start.syntax();
if is_different_context {
preorder.skip_subtree();
}
} else if let Some(pat) = ast::Pat::cast(node) {
preorder.skip_subtree();
walk_pat(&pat, cb);
}
}
}
}
}
/// Preorder walk all the pattern's sub patterns.
pub fn walk_pat(pat: &ast::Pat, cb: &mut dyn FnMut(ast::Pat)) {
let mut preorder = pat.syntax().preorder();
while let Some(event) = preorder.next() {
let node = match event {
WalkEvent::Enter(node) => node,
WalkEvent::Leave(_) => continue,
};
let kind = node.kind();
match ast::Pat::cast(node) {
Some(pat @ ast::Pat::ConstBlockPat(_)) => {
preorder.skip_subtree();
cb(pat);
}
Some(pat) => {
cb(pat);
}
// skip const args
None if ast::GenericArg::can_cast(kind) => {
preorder.skip_subtree();
}
None => (),
}
}
}
/// Preorder walk all the type's sub types.
// FIXME: Make the control flow more proper
pub fn walk_ty(ty: &ast::Type, cb: &mut dyn FnMut(ast::Type) -> bool) {
let mut preorder = ty.syntax().preorder();
while let Some(event) = preorder.next() {
let node = match event {
WalkEvent::Enter(node) => node,
WalkEvent::Leave(_) => continue,
};
let kind = node.kind();
match ast::Type::cast(node) {
Some(ty @ ast::Type::MacroType(_)) => {
preorder.skip_subtree();
cb(ty);
}
Some(ty) => {
if cb(ty) {
preorder.skip_subtree();
}
}
// skip const args
None if ast::ConstArg::can_cast(kind) => {
preorder.skip_subtree();
}
None => (),
}
}
}
pub fn vis_eq(this: &ast::Visibility, other: &ast::Visibility) -> bool {
match (this.kind(), other.kind()) {
(VisibilityKind::In(this), VisibilityKind::In(other)) => {
stdx::iter_eq_by(this.segments(), other.segments(), |lhs, rhs| {
lhs.kind().zip(rhs.kind()).map_or(false, |it| match it {
(PathSegmentKind::CrateKw, PathSegmentKind::CrateKw)
| (PathSegmentKind::SelfKw, PathSegmentKind::SelfKw)
| (PathSegmentKind::SuperKw, PathSegmentKind::SuperKw) => true,
(PathSegmentKind::Name(lhs), PathSegmentKind::Name(rhs)) => {
lhs.text() == rhs.text()
}
_ => false,
})
})
}
(VisibilityKind::PubSelf, VisibilityKind::PubSelf)
| (VisibilityKind::PubSuper, VisibilityKind::PubSuper)
| (VisibilityKind::PubCrate, VisibilityKind::PubCrate)
| (VisibilityKind::Pub, VisibilityKind::Pub) => true,
_ => false,
}
}
/// Returns the `let` only if there is exactly one (that is, `let pat = expr`
/// or `((let pat = expr))`, but not `let pat = expr && expr` or `non_let_expr`).
pub fn single_let(expr: ast::Expr) -> Option<ast::LetExpr> {
match expr {
ast::Expr::ParenExpr(expr) => expr.expr().and_then(single_let),
ast::Expr::LetExpr(expr) => Some(expr),
_ => None,
}
}
pub fn is_pattern_cond(expr: ast::Expr) -> bool {
match expr {
ast::Expr::BinExpr(expr)
if expr.op_kind() == Some(ast::BinaryOp::LogicOp(ast::LogicOp::And)) =>
{
expr.lhs()
.map(is_pattern_cond)
.or_else(|| expr.rhs().map(is_pattern_cond))
.unwrap_or(false)
}
ast::Expr::ParenExpr(expr) => expr.expr().map_or(false, is_pattern_cond),
ast::Expr::LetExpr(_) => true,
_ => false,
}
}
/// Calls `cb` on each expression inside `expr` that is at "tail position".
/// Does not walk into `break` or `return` expressions.
/// Note that modifying the tree while iterating it will cause undefined iteration which might
/// potentially results in an out of bounds panic.
pub fn for_each_tail_expr(expr: &ast::Expr, cb: &mut dyn FnMut(&ast::Expr)) {
let walk_loop = |cb: &mut dyn FnMut(&ast::Expr), label, body: Option<ast::BlockExpr>| {
for_each_break_expr(label, body.and_then(|it| it.stmt_list()), &mut |b| {
cb(&ast::Expr::BreakExpr(b))
})
};
match expr {
ast::Expr::BlockExpr(b) => {
match b.modifier() {
Some(
ast::BlockModifier::Async(_)
| ast::BlockModifier::Try(_)
| ast::BlockModifier::Const(_),
) => return cb(expr),
Some(ast::BlockModifier::Label(label)) => {
for_each_break_expr(Some(label), b.stmt_list(), &mut |b| {
cb(&ast::Expr::BreakExpr(b))
});
}
Some(ast::BlockModifier::Unsafe(_)) => (),
None => (),
}
if let Some(stmt_list) = b.stmt_list() {
if let Some(e) = stmt_list.tail_expr() {
for_each_tail_expr(&e, cb);
}
}
}
ast::Expr::IfExpr(if_) => {
let mut if_ = if_.clone();
loop {
if let Some(block) = if_.then_branch() {
for_each_tail_expr(&ast::Expr::BlockExpr(block), cb);
}
match if_.else_branch() {
Some(ast::ElseBranch::IfExpr(it)) => if_ = it,
Some(ast::ElseBranch::Block(block)) => {
for_each_tail_expr(&ast::Expr::BlockExpr(block), cb);
break;
}
None => break,
}
}
}
ast::Expr::LoopExpr(l) => walk_loop(cb, l.label(), l.loop_body()),
ast::Expr::WhileExpr(w) => walk_loop(cb, w.label(), w.loop_body()),
ast::Expr::ForExpr(f) => walk_loop(cb, f.label(), f.loop_body()),
ast::Expr::MatchExpr(m) => {
if let Some(arms) = m.match_arm_list() {
arms.arms().filter_map(|arm| arm.expr()).for_each(|e| for_each_tail_expr(&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::IndexExpr(_)
| ast::Expr::Literal(_)
| ast::Expr::MacroExpr(_)
| 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::LetExpr(_)
| ast::Expr::UnderscoreExpr(_)
| ast::Expr::YieldExpr(_)
| ast::Expr::YeetExpr(_) => cb(expr),
}
}
pub fn for_each_break_and_continue_expr(
label: Option<ast::Label>,
body: Option<ast::StmtList>,
cb: &mut dyn FnMut(ast::Expr),
) {
let label = label.and_then(|lbl| lbl.lifetime());
if let Some(b) = body {
let tree_depth_iterator = TreeWithDepthIterator::new(b);
for (expr, depth) in tree_depth_iterator {
match expr {
ast::Expr::BreakExpr(b)
if (depth == 0 && b.lifetime().is_none())
|| eq_label_lt(&label, &b.lifetime()) =>
{
cb(ast::Expr::BreakExpr(b));
}
ast::Expr::ContinueExpr(c)
if (depth == 0 && c.lifetime().is_none())
|| eq_label_lt(&label, &c.lifetime()) =>
{
cb(ast::Expr::ContinueExpr(c));
}
_ => (),
}
}
}
}
fn for_each_break_expr(
label: Option<ast::Label>,
body: Option<ast::StmtList>,
cb: &mut dyn FnMut(ast::BreakExpr),
) {
let label = label.and_then(|lbl| lbl.lifetime());
if let Some(b) = body {
let tree_depth_iterator = TreeWithDepthIterator::new(b);
for (expr, depth) in tree_depth_iterator {
match expr {
ast::Expr::BreakExpr(b)
if (depth == 0 && b.lifetime().is_none())
|| eq_label_lt(&label, &b.lifetime()) =>
{
cb(b);
}
_ => (),
}
}
}
}
fn eq_label_lt(lt1: &Option<ast::Lifetime>, lt2: &Option<ast::Lifetime>) -> bool {
lt1.as_ref().zip(lt2.as_ref()).map_or(false, |(lt, lbl)| lt.text() == lbl.text())
}
struct TreeWithDepthIterator {
preorder: Preorder<RustLanguage>,
depth: u32,
}
impl TreeWithDepthIterator {
fn new(body: ast::StmtList) -> Self {
let preorder = body.syntax().preorder();
Self { preorder, depth: 0 }
}
}
impl Iterator for TreeWithDepthIterator {
type Item = (ast::Expr, u32);
fn next(&mut self) -> Option<Self::Item> {
while let Some(event) = self.preorder.find_map(|ev| match ev {
WalkEvent::Enter(it) => ast::Expr::cast(it).map(WalkEvent::Enter),
WalkEvent::Leave(it) => ast::Expr::cast(it).map(WalkEvent::Leave),
}) {
match event {
WalkEvent::Enter(
ast::Expr::LoopExpr(_) | ast::Expr::WhileExpr(_) | ast::Expr::ForExpr(_),
) => {
self.depth += 1;
}
WalkEvent::Leave(
ast::Expr::LoopExpr(_) | ast::Expr::WhileExpr(_) | ast::Expr::ForExpr(_),
) => {
self.depth -= 1;
}
WalkEvent::Enter(ast::Expr::BlockExpr(e)) if e.label().is_some() => {
self.depth += 1;
}
WalkEvent::Leave(ast::Expr::BlockExpr(e)) if e.label().is_some() => {
self.depth -= 1;
}
WalkEvent::Enter(expr) => return Some((expr, self.depth)),
_ => (),
}
}
None
}
}
/// Parses the input token tree as comma separated plain paths.
pub fn parse_tt_as_comma_sep_paths(input: ast::TokenTree) -> Option<Vec<ast::Path>> {
let r_paren = input.r_paren_token();
let tokens =
input.syntax().children_with_tokens().skip(1).map_while(|it| match it.into_token() {
// seeing a keyword means the attribute is unclosed so stop parsing here
Some(tok) if tok.kind().is_keyword() => None,
// don't include the right token tree parenthesis if it exists
tok @ Some(_) if tok == r_paren => None,
// only nodes that we can find are other TokenTrees, those are unexpected in this parse though
None => None,
Some(tok) => Some(tok),
});
let input_expressions = tokens.group_by(|tok| tok.kind() == T![,]);
let paths = input_expressions
.into_iter()
.filter_map(|(is_sep, group)| (!is_sep).then_some(group))
.filter_map(|mut tokens| {
syntax::hacks::parse_expr_from_str(&tokens.join("")).and_then(|expr| match expr {
ast::Expr::PathExpr(it) => it.path(),
_ => None,
})
})
.collect();
Some(paths)
}
pub fn macro_call_for_string_token(string: &ast::String) -> Option<MacroCall> {
let macro_call = string.syntax().parent_ancestors().find_map(ast::MacroCall::cast)?;
Some(macro_call)
}
|