rustc_middle/thir/
visit.rs

1use super::{
2    AdtExpr, AdtExprBase, Arm, Block, ClosureExpr, Expr, ExprKind, InlineAsmExpr, InlineAsmOperand,
3    Pat, PatKind, Stmt, StmtKind, Thir,
4};
5use crate::thir::LoopMatchMatchData;
6
7/// Every `walk_*` method uses deconstruction to access fields of structs and
8/// enums. This will result in a compile error if a field is added, which makes
9/// it more likely the appropriate visit call will be added for it.
10pub trait Visitor<'thir, 'tcx: 'thir>: Sized {
11    fn thir(&self) -> &'thir Thir<'tcx>;
12
13    fn visit_expr(&mut self, expr: &'thir Expr<'tcx>) {
14        walk_expr(self, expr);
15    }
16
17    fn visit_stmt(&mut self, stmt: &'thir Stmt<'tcx>) {
18        walk_stmt(self, stmt);
19    }
20
21    fn visit_block(&mut self, block: &'thir Block) {
22        walk_block(self, block);
23    }
24
25    fn visit_arm(&mut self, arm: &'thir Arm<'tcx>) {
26        walk_arm(self, arm);
27    }
28
29    fn visit_pat(&mut self, pat: &'thir Pat<'tcx>) {
30        walk_pat(self, pat);
31    }
32
33    // Note: We don't have visitors for `ty::Const` and `mir::Const`
34    // (even though these types occur in THIR) for consistency and to reduce confusion,
35    // since the lazy creation of constants during thir construction causes most
36    // 'constants' to not be of type `ty::Const` or `mir::Const` at that
37    // stage (they are mostly still identified by `DefId` or `hir::Lit`, see
38    // the variants `Literal`, `NonHirLiteral` and `NamedConst` in `thir::ExprKind`).
39    // You have to manually visit `ty::Const` and `mir::Const` through the
40    // other `visit*` functions.
41}
42
43pub fn walk_expr<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
44    visitor: &mut V,
45    expr: &'thir Expr<'tcx>,
46) {
47    use ExprKind::*;
48    let Expr { kind, ty: _, temp_scope_id: _, span: _ } = expr;
49    match *kind {
50        Scope { value, region_scope: _, hir_id: _ } => visitor.visit_expr(&visitor.thir()[value]),
51        Box { value } => visitor.visit_expr(&visitor.thir()[value]),
52        If { cond, then, else_opt, if_then_scope: _ } => {
53            visitor.visit_expr(&visitor.thir()[cond]);
54            visitor.visit_expr(&visitor.thir()[then]);
55            if let Some(else_expr) = else_opt {
56                visitor.visit_expr(&visitor.thir()[else_expr]);
57            }
58        }
59        Call { fun, ref args, ty: _, from_hir_call: _, fn_span: _ } => {
60            visitor.visit_expr(&visitor.thir()[fun]);
61            for &arg in &**args {
62                visitor.visit_expr(&visitor.thir()[arg]);
63            }
64        }
65        ByUse { expr, span: _ } => {
66            visitor.visit_expr(&visitor.thir()[expr]);
67        }
68        Deref { arg } => visitor.visit_expr(&visitor.thir()[arg]),
69        Binary { lhs, rhs, op: _ } | LogicalOp { lhs, rhs, op: _ } => {
70            visitor.visit_expr(&visitor.thir()[lhs]);
71            visitor.visit_expr(&visitor.thir()[rhs]);
72        }
73        Unary { arg, op: _ } => visitor.visit_expr(&visitor.thir()[arg]),
74        Cast { source } => visitor.visit_expr(&visitor.thir()[source]),
75        Use { source } => visitor.visit_expr(&visitor.thir()[source]),
76        NeverToAny { source } => visitor.visit_expr(&visitor.thir()[source]),
77        PointerCoercion { source, cast: _, is_from_as_cast: _ } => {
78            visitor.visit_expr(&visitor.thir()[source])
79        }
80        Let { expr, ref pat } => {
81            visitor.visit_expr(&visitor.thir()[expr]);
82            visitor.visit_pat(pat);
83        }
84        Loop { body } => visitor.visit_expr(&visitor.thir()[body]),
85        LoopMatch { match_data: box LoopMatchMatchData { scrutinee, ref arms, .. }, .. }
86        | Match { scrutinee, ref arms, .. } => {
87            visitor.visit_expr(&visitor.thir()[scrutinee]);
88            for &arm in &**arms {
89                visitor.visit_arm(&visitor.thir()[arm]);
90            }
91        }
92        Block { block } => visitor.visit_block(&visitor.thir()[block]),
93        Assign { lhs, rhs } | AssignOp { lhs, rhs, op: _ } => {
94            visitor.visit_expr(&visitor.thir()[lhs]);
95            visitor.visit_expr(&visitor.thir()[rhs]);
96        }
97        Field { lhs, variant_index: _, name: _ } => visitor.visit_expr(&visitor.thir()[lhs]),
98        Index { lhs, index } => {
99            visitor.visit_expr(&visitor.thir()[lhs]);
100            visitor.visit_expr(&visitor.thir()[index]);
101        }
102        VarRef { id: _ } | UpvarRef { closure_def_id: _, var_hir_id: _ } => {}
103        Borrow { arg, borrow_kind: _ } => visitor.visit_expr(&visitor.thir()[arg]),
104        RawBorrow { arg, mutability: _ } => visitor.visit_expr(&visitor.thir()[arg]),
105        Break { value, label: _ } => {
106            if let Some(value) = value {
107                visitor.visit_expr(&visitor.thir()[value])
108            }
109        }
110        Continue { label: _ } => {}
111        ConstContinue { value, label: _ } => visitor.visit_expr(&visitor.thir()[value]),
112        Return { value } => {
113            if let Some(value) = value {
114                visitor.visit_expr(&visitor.thir()[value])
115            }
116        }
117        Become { value } => visitor.visit_expr(&visitor.thir()[value]),
118        ConstBlock { did: _, args: _ } => {}
119        Repeat { value, count: _ } => {
120            visitor.visit_expr(&visitor.thir()[value]);
121        }
122        Array { ref fields } | Tuple { ref fields } => {
123            for &field in &**fields {
124                visitor.visit_expr(&visitor.thir()[field]);
125            }
126        }
127        Adt(box AdtExpr {
128            ref fields,
129            ref base,
130            adt_def: _,
131            variant_index: _,
132            args: _,
133            user_ty: _,
134        }) => {
135            for field in &**fields {
136                visitor.visit_expr(&visitor.thir()[field.expr]);
137            }
138            if let AdtExprBase::Base(base) = base {
139                visitor.visit_expr(&visitor.thir()[base.base]);
140            }
141        }
142        PlaceTypeAscription { source, user_ty: _, user_ty_span: _ }
143        | ValueTypeAscription { source, user_ty: _, user_ty_span: _ } => {
144            visitor.visit_expr(&visitor.thir()[source])
145        }
146        PlaceUnwrapUnsafeBinder { source }
147        | ValueUnwrapUnsafeBinder { source }
148        | WrapUnsafeBinder { source } => visitor.visit_expr(&visitor.thir()[source]),
149        Closure(box ClosureExpr {
150            closure_id: _,
151            args: _,
152            upvars: _,
153            movability: _,
154            fake_reads: _,
155        }) => {}
156        Literal { lit: _, neg: _ } => {}
157        NonHirLiteral { lit: _, user_ty: _ } => {}
158        ZstLiteral { user_ty: _ } => {}
159        NamedConst { def_id: _, args: _, user_ty: _ } => {}
160        ConstParam { param: _, def_id: _ } => {}
161        StaticRef { alloc_id: _, ty: _, def_id: _ } => {}
162        InlineAsm(box InlineAsmExpr {
163            asm_macro: _,
164            ref operands,
165            template: _,
166            options: _,
167            line_spans: _,
168        }) => {
169            for op in &**operands {
170                use InlineAsmOperand::*;
171                match op {
172                    In { expr, reg: _ }
173                    | Out { expr: Some(expr), reg: _, late: _ }
174                    | InOut { expr, reg: _, late: _ } => visitor.visit_expr(&visitor.thir()[*expr]),
175                    SplitInOut { in_expr, out_expr, reg: _, late: _ } => {
176                        visitor.visit_expr(&visitor.thir()[*in_expr]);
177                        if let Some(out_expr) = out_expr {
178                            visitor.visit_expr(&visitor.thir()[*out_expr]);
179                        }
180                    }
181                    Out { expr: None, reg: _, late: _ }
182                    | Const { value: _, span: _ }
183                    | SymFn { value: _ }
184                    | SymStatic { def_id: _ } => {}
185                    Label { block } => visitor.visit_block(&visitor.thir()[*block]),
186                }
187            }
188        }
189        ThreadLocalRef(_) => {}
190        Yield { value } => visitor.visit_expr(&visitor.thir()[value]),
191    }
192}
193
194pub fn walk_stmt<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
195    visitor: &mut V,
196    stmt: &'thir Stmt<'tcx>,
197) {
198    let Stmt { kind } = stmt;
199    match kind {
200        StmtKind::Expr { expr, scope: _ } => visitor.visit_expr(&visitor.thir()[*expr]),
201        StmtKind::Let {
202            initializer,
203            remainder_scope: _,
204            init_scope: _,
205            pattern,
206            hir_id: _,
207            else_block,
208            span: _,
209        } => {
210            if let Some(init) = initializer {
211                visitor.visit_expr(&visitor.thir()[*init]);
212            }
213            visitor.visit_pat(pattern);
214            if let Some(block) = else_block {
215                visitor.visit_block(&visitor.thir()[*block])
216            }
217        }
218    }
219}
220
221pub fn walk_block<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
222    visitor: &mut V,
223    block: &'thir Block,
224) {
225    let Block { stmts, expr, targeted_by_break: _, region_scope: _, span: _, safety_mode: _ } =
226        block;
227    for &stmt in &*stmts {
228        visitor.visit_stmt(&visitor.thir()[stmt]);
229    }
230    if let Some(expr) = expr {
231        visitor.visit_expr(&visitor.thir()[*expr]);
232    }
233}
234
235pub fn walk_arm<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
236    visitor: &mut V,
237    arm: &'thir Arm<'tcx>,
238) {
239    let Arm { guard, pattern, body, hir_id: _, span: _, scope: _ } = arm;
240    if let Some(expr) = guard {
241        visitor.visit_expr(&visitor.thir()[*expr])
242    }
243    visitor.visit_pat(pattern);
244    visitor.visit_expr(&visitor.thir()[*body]);
245}
246
247pub fn walk_pat<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
248    visitor: &mut V,
249    pat: &'thir Pat<'tcx>,
250) {
251    for_each_immediate_subpat(pat, |p| visitor.visit_pat(p));
252}
253
254/// Invokes `callback` on each immediate subpattern of `pat`, if any.
255/// A building block for assembling THIR pattern visitors.
256pub(crate) fn for_each_immediate_subpat<'a, 'tcx>(
257    pat: &'a Pat<'tcx>,
258    mut callback: impl FnMut(&'a Pat<'tcx>),
259) {
260    let Pat { kind, ty: _, span: _, extra: _ } = pat;
261    match kind {
262        PatKind::Missing
263        | PatKind::Wild
264        | PatKind::Binding { subpattern: None, .. }
265        | PatKind::Constant { value: _ }
266        | PatKind::Range(_)
267        | PatKind::Never
268        | PatKind::Error(_) => {}
269
270        PatKind::Binding { subpattern: Some(subpattern), .. }
271        | PatKind::Deref { subpattern, .. }
272        | PatKind::DerefPattern { subpattern, .. } => callback(subpattern),
273
274        PatKind::Variant { subpatterns, .. } | PatKind::Leaf { subpatterns } => {
275            for field_pat in subpatterns {
276                callback(&field_pat.pattern);
277            }
278        }
279
280        PatKind::Slice { prefix, slice, suffix } | PatKind::Array { prefix, slice, suffix } => {
281            for pat in prefix.iter().chain(slice.as_deref()).chain(suffix) {
282                callback(pat);
283            }
284        }
285
286        PatKind::Or { pats } => {
287            for pat in pats {
288                callback(pat);
289            }
290        }
291    }
292}
rustc_middle/thir/visit.rs

rustc_middle/thir/
visit.rs
