264 lines
8.3 KiB
Rust
264 lines
8.3 KiB
Rust
//! This module provides a simplified abstraction for working with
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//! code blocks identified by their integer `NodeId`. In particular,
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//! it captures a common set of attributes that all "function-like
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//! things" (represented by `FnLike` instances) share. For example,
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//! all `FnLike` instances have a type signature (be it explicit or
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//! inferred). And all `FnLike` instances have a body, i.e., the code
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//! that is run when the function-like thing it represents is invoked.
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//!
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//! With the above abstraction in place, one can treat the program
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//! text as a collection of blocks of code (and most such blocks are
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//! nested within a uniquely determined `FnLike`), and users can ask
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//! for the `Code` associated with a particular NodeId.
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use crate::hir::map::Map;
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use rustc_ast::ast::Attribute;
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use rustc_hir as hir;
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use rustc_hir::intravisit::FnKind;
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use rustc_hir::{Expr, FnDecl, Node};
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use rustc_span::symbol::Ident;
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use rustc_span::Span;
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/// An FnLikeNode is a Node that is like a fn, in that it has a decl
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/// and a body (as well as a NodeId, a span, etc).
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///
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/// More specifically, it is one of either:
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///
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/// - A function item,
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/// - A closure expr (i.e., an ExprKind::Closure), or
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/// - The default implementation for a trait method.
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///
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/// To construct one, use the `Code::from_node` function.
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#[derive(Copy, Clone, Debug)]
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pub struct FnLikeNode<'a> {
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node: Node<'a>,
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}
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/// MaybeFnLike wraps a method that indicates if an object
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/// corresponds to some FnLikeNode.
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trait MaybeFnLike {
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fn is_fn_like(&self) -> bool;
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}
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impl MaybeFnLike for hir::Item<'_> {
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fn is_fn_like(&self) -> bool {
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match self.kind {
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hir::ItemKind::Fn(..) => true,
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_ => false,
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}
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}
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}
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impl MaybeFnLike for hir::ImplItem<'_> {
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fn is_fn_like(&self) -> bool {
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match self.kind {
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hir::ImplItemKind::Fn(..) => true,
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_ => false,
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}
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}
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}
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impl MaybeFnLike for hir::TraitItem<'_> {
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fn is_fn_like(&self) -> bool {
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match self.kind {
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hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)) => true,
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_ => false,
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}
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}
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}
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impl MaybeFnLike for hir::Expr<'_> {
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fn is_fn_like(&self) -> bool {
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match self.kind {
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hir::ExprKind::Closure(..) => true,
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_ => false,
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}
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}
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}
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/// Carries either an FnLikeNode or a Expr, as these are the two
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/// constructs that correspond to "code" (as in, something from which
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/// we can construct a control-flow graph).
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#[derive(Copy, Clone)]
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pub enum Code<'a> {
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FnLike(FnLikeNode<'a>),
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Expr(&'a Expr<'a>),
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}
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impl<'a> Code<'a> {
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pub fn id(&self) -> hir::HirId {
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match *self {
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Code::FnLike(node) => node.id(),
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Code::Expr(block) => block.hir_id,
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}
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}
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/// Attempts to construct a Code from presumed FnLike or Expr node input.
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pub fn from_node(map: &Map<'a>, id: hir::HirId) -> Option<Code<'a>> {
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match map.get(id) {
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Node::Block(_) => {
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// Use the parent, hopefully an expression node.
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Code::from_node(map, map.get_parent_node(id))
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}
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Node::Expr(expr) => Some(Code::Expr(expr)),
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node => FnLikeNode::from_node(node).map(Code::FnLike),
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}
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}
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}
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/// These are all the components one can extract from a fn item for
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/// use when implementing FnLikeNode operations.
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struct ItemFnParts<'a> {
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ident: Ident,
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decl: &'a hir::FnDecl<'a>,
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header: hir::FnHeader,
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vis: &'a hir::Visibility<'a>,
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generics: &'a hir::Generics<'a>,
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body: hir::BodyId,
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id: hir::HirId,
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span: Span,
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attrs: &'a [Attribute],
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}
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/// These are all the components one can extract from a closure expr
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/// for use when implementing FnLikeNode operations.
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struct ClosureParts<'a> {
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decl: &'a FnDecl<'a>,
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body: hir::BodyId,
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id: hir::HirId,
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span: Span,
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attrs: &'a [Attribute],
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}
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impl<'a> ClosureParts<'a> {
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fn new(
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d: &'a FnDecl<'a>,
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b: hir::BodyId,
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id: hir::HirId,
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s: Span,
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attrs: &'a [Attribute],
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) -> Self {
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ClosureParts { decl: d, body: b, id, span: s, attrs }
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}
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}
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impl<'a> FnLikeNode<'a> {
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/// Attempts to construct a FnLikeNode from presumed FnLike node input.
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pub fn from_node(node: Node<'_>) -> Option<FnLikeNode<'_>> {
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let fn_like = match node {
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Node::Item(item) => item.is_fn_like(),
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Node::TraitItem(tm) => tm.is_fn_like(),
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Node::ImplItem(it) => it.is_fn_like(),
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Node::Expr(e) => e.is_fn_like(),
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_ => false,
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};
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fn_like.then_some(FnLikeNode { node })
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}
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pub fn body(self) -> hir::BodyId {
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self.handle(
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|i: ItemFnParts<'a>| i.body,
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|_, _, _: &'a hir::FnSig<'a>, _, body: hir::BodyId, _, _| body,
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|c: ClosureParts<'a>| c.body,
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)
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}
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pub fn decl(self) -> &'a FnDecl<'a> {
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self.handle(
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|i: ItemFnParts<'a>| &*i.decl,
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|_, _, sig: &'a hir::FnSig<'a>, _, _, _, _| &sig.decl,
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|c: ClosureParts<'a>| c.decl,
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)
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}
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pub fn span(self) -> Span {
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self.handle(
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|i: ItemFnParts<'_>| i.span,
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|_, _, _: &'a hir::FnSig<'a>, _, _, span, _| span,
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|c: ClosureParts<'_>| c.span,
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)
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}
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pub fn id(self) -> hir::HirId {
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self.handle(
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|i: ItemFnParts<'_>| i.id,
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|id, _, _: &'a hir::FnSig<'a>, _, _, _, _| id,
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|c: ClosureParts<'_>| c.id,
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)
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}
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pub fn constness(self) -> hir::Constness {
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self.kind().header().map_or(hir::Constness::NotConst, |header| header.constness)
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}
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pub fn asyncness(self) -> hir::IsAsync {
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self.kind().header().map_or(hir::IsAsync::NotAsync, |header| header.asyncness)
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}
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pub fn unsafety(self) -> hir::Unsafety {
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self.kind().header().map_or(hir::Unsafety::Normal, |header| header.unsafety)
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}
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pub fn kind(self) -> FnKind<'a> {
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let item = |p: ItemFnParts<'a>| -> FnKind<'a> {
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FnKind::ItemFn(p.ident, p.generics, p.header, p.vis, p.attrs)
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};
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let closure = |c: ClosureParts<'a>| FnKind::Closure(c.attrs);
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let method = |_, ident: Ident, sig: &'a hir::FnSig<'a>, vis, _, _, attrs| {
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FnKind::Method(ident, sig, vis, attrs)
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};
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self.handle(item, method, closure)
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}
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fn handle<A, I, M, C>(self, item_fn: I, method: M, closure: C) -> A
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where
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I: FnOnce(ItemFnParts<'a>) -> A,
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M: FnOnce(
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hir::HirId,
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Ident,
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&'a hir::FnSig<'a>,
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Option<&'a hir::Visibility<'a>>,
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hir::BodyId,
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Span,
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&'a [Attribute],
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) -> A,
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C: FnOnce(ClosureParts<'a>) -> A,
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{
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match self.node {
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Node::Item(i) => match i.kind {
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hir::ItemKind::Fn(ref sig, ref generics, block) => item_fn(ItemFnParts {
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id: i.hir_id,
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ident: i.ident,
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decl: &sig.decl,
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body: block,
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vis: &i.vis,
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span: i.span,
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attrs: &i.attrs,
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header: sig.header,
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generics,
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}),
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_ => bug!("item FnLikeNode that is not fn-like"),
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},
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Node::TraitItem(ti) => match ti.kind {
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hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
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method(ti.hir_id, ti.ident, sig, None, body, ti.span, &ti.attrs)
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}
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_ => bug!("trait method FnLikeNode that is not fn-like"),
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},
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Node::ImplItem(ii) => match ii.kind {
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hir::ImplItemKind::Fn(ref sig, body) => {
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method(ii.hir_id, ii.ident, sig, Some(&ii.vis), body, ii.span, &ii.attrs)
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}
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_ => bug!("impl method FnLikeNode that is not fn-like"),
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},
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Node::Expr(e) => match e.kind {
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hir::ExprKind::Closure(_, ref decl, block, _fn_decl_span, _gen) => {
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closure(ClosureParts::new(&decl, block, e.hir_id, e.span, &e.attrs))
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}
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_ => bug!("expr FnLikeNode that is not fn-like"),
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},
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_ => bug!("other FnLikeNode that is not fn-like"),
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}
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}
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}
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