Split out ExpressionStore from Body

crates/hir-def/src/expr_store.rs

@@ -0,0 +1,744 @@
+//! Defines `ExpressionStore`: a lowered representation of functions, statics and
+//! consts.
+mod body;
+mod lower;
+mod pretty;
+pub mod scope;
+
+#[cfg(test)]
+mod tests;
+
+use std::ops::{Deref, Index};
+
+use cfg::{CfgExpr, CfgOptions};
+use either::Either;
+use hir_expand::{name::Name, ExpandError, InFile};
+use la_arena::{Arena, ArenaMap};
+use rustc_hash::FxHashMap;
+use smallvec::SmallVec;
+use span::{Edition, MacroFileId, SyntaxContextData};
+use syntax::{ast, AstPtr, SyntaxNodePtr};
+use triomphe::Arc;
+use tt::TextRange;
+
+use crate::{
+    db::DefDatabase,
+    hir::{
+        Array, AsmOperand, Binding, BindingId, Expr, ExprId, ExprOrPatId, Label, LabelId, Pat,
+        PatId, RecordFieldPat, Statement,
+    },
+    nameres::DefMap,
+    path::{ModPath, Path},
+    type_ref::{TypeRef, TypeRefId, TypesMap, TypesSourceMap},
+    BlockId, DefWithBodyId, Lookup, SyntheticSyntax,
+};
+
+pub use self::body::{Body, BodySourceMap};
+
+/// A wrapper around [`span::SyntaxContextId`] that is intended only for comparisons.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct HygieneId(span::SyntaxContextId);
+
+impl HygieneId {
+    // The edition doesn't matter here, we only use this for comparisons and to lookup the macro.
+    pub const ROOT: Self = Self(span::SyntaxContextId::root(Edition::Edition2015));
+
+    pub fn new(mut ctx: span::SyntaxContextId) -> Self {
+        // See `Name` for why we're doing that.
+        ctx.remove_root_edition();
+        Self(ctx)
+    }
+
+    pub(crate) fn lookup(self, db: &dyn DefDatabase) -> SyntaxContextData {
+        db.lookup_intern_syntax_context(self.0)
+    }
+
+    pub(crate) fn is_root(self) -> bool {
+        self.0.is_root()
+    }
+}
+
+pub type ExprPtr = AstPtr<ast::Expr>;
+pub type ExprSource = InFile<ExprPtr>;
+
+pub type PatPtr = AstPtr<ast::Pat>;
+pub type PatSource = InFile<PatPtr>;
+
+pub type LabelPtr = AstPtr<ast::Label>;
+pub type LabelSource = InFile<LabelPtr>;
+
+pub type FieldPtr = AstPtr<ast::RecordExprField>;
+pub type FieldSource = InFile<FieldPtr>;
+
+pub type PatFieldPtr = AstPtr<Either<ast::RecordExprField, ast::RecordPatField>>;
+pub type PatFieldSource = InFile<PatFieldPtr>;
+
+pub type ExprOrPatPtr = AstPtr<Either<ast::Expr, ast::Pat>>;
+pub type ExprOrPatSource = InFile<ExprOrPatPtr>;
+
+pub type SelfParamPtr = AstPtr<ast::SelfParam>;
+pub type MacroCallPtr = AstPtr<ast::MacroCall>;
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct ExpressionStore {
+    pub exprs: Arena<Expr>,
+    pub pats: Arena<Pat>,
+    pub bindings: Arena<Binding>,
+    pub labels: Arena<Label>,
+    /// Id of the closure/coroutine that owns the corresponding binding. If a binding is owned by the
+    /// top level expression, it will not be listed in here.
+    pub binding_owners: FxHashMap<BindingId, ExprId>,
+    pub types: TypesMap,
+    /// Block expressions in this store that may contain inner items.
+    block_scopes: Box<[BlockId]>,
+
+    /// A map from binding to its hygiene ID.
+    ///
+    /// Bindings that don't come from macro expansion are not allocated to save space, so not all bindings appear here.
+    /// If a binding does not appear here it has `SyntaxContextId::ROOT`.
+    ///
+    /// Note that this may not be the direct `SyntaxContextId` of the binding's expansion, because transparent
+    /// expansions are attributed to their parent expansion (recursively).
+    binding_hygiene: FxHashMap<BindingId, HygieneId>,
+    /// A map from an variable usages to their hygiene ID.
+    ///
+    /// Expressions (and destructuing patterns) that can be recorded here are single segment path, although not all single segments path refer
+    /// to variables and have hygiene (some refer to items, we don't know at this stage).
+    ident_hygiene: FxHashMap<ExprOrPatId, HygieneId>,
+}
+
+#[derive(Debug, Eq, PartialEq, Default)]
+pub struct ExpressionStoreSourceMap {
+    // AST expressions can create patterns in destructuring assignments. Therefore, `ExprSource` can also map
+    // to `PatId`, and `PatId` can also map to `ExprSource` (the other way around is unaffected).
+    expr_map: FxHashMap<ExprSource, ExprOrPatId>,
+    expr_map_back: ArenaMap<ExprId, ExprSource>,
+
+    pat_map: FxHashMap<PatSource, PatId>,
+    pat_map_back: ArenaMap<PatId, ExprOrPatSource>,
+
+    label_map: FxHashMap<LabelSource, LabelId>,
+    label_map_back: ArenaMap<LabelId, LabelSource>,
+
+    binding_definitions: FxHashMap<BindingId, SmallVec<[PatId; 4]>>,
+
+    /// We don't create explicit nodes for record fields (`S { record_field: 92 }`).
+    /// Instead, we use id of expression (`92`) to identify the field.
+    field_map_back: FxHashMap<ExprId, FieldSource>,
+    pat_field_map_back: FxHashMap<PatId, PatFieldSource>,
+
+    pub types: TypesSourceMap,
+
+    template_map: Option<Box<FormatTemplate>>,
+
+    expansions: FxHashMap<InFile<MacroCallPtr>, MacroFileId>,
+
+    /// Diagnostics accumulated during lowering. These contain `AstPtr`s and so are stored in
+    /// the source map (since they're just as volatile).
+    diagnostics: Vec<ExpressionStoreDiagnostics>,
+}
+
+/// The body of an item (function, const etc.).
+#[derive(Debug, Eq, PartialEq, Default)]
+pub struct ExpressionStoreBuilder {
+    pub exprs: Arena<Expr>,
+    pub pats: Arena<Pat>,
+    pub bindings: Arena<Binding>,
+    pub labels: Arena<Label>,
+    pub binding_owners: FxHashMap<BindingId, ExprId>,
+    pub types: TypesMap,
+    block_scopes: Vec<BlockId>,
+    binding_hygiene: FxHashMap<BindingId, HygieneId>,
+    ident_hygiene: FxHashMap<ExprOrPatId, HygieneId>,
+}
+
+#[derive(Default, Debug, Eq, PartialEq)]
+struct FormatTemplate {
+    /// A map from `format_args!()` expressions to their captures.
+    format_args_to_captures: FxHashMap<ExprId, (HygieneId, Vec<(syntax::TextRange, Name)>)>,
+    /// A map from `asm!()` expressions to their captures.
+    asm_to_captures: FxHashMap<ExprId, Vec<Vec<(syntax::TextRange, usize)>>>,
+    /// A map from desugared expressions of implicit captures to their source.
+    ///
+    /// The value stored for each capture is its template literal and offset inside it. The template literal
+    /// is from the `format_args[_nl]!()` macro and so needs to be mapped up once to go to the user-written
+    /// template.
+    implicit_capture_to_source: FxHashMap<ExprId, InFile<(ExprPtr, TextRange)>>,
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub enum ExpressionStoreDiagnostics {
+    InactiveCode { node: InFile<SyntaxNodePtr>, cfg: CfgExpr, opts: CfgOptions },
+    MacroError { node: InFile<MacroCallPtr>, err: ExpandError },
+    UnresolvedMacroCall { node: InFile<MacroCallPtr>, path: ModPath },
+    UnreachableLabel { node: InFile<AstPtr<ast::Lifetime>>, name: Name },
+    AwaitOutsideOfAsync { node: InFile<AstPtr<ast::AwaitExpr>>, location: String },
+    UndeclaredLabel { node: InFile<AstPtr<ast::Lifetime>>, name: Name },
+}
+
+impl ExpressionStoreBuilder {
+    fn finish(self) -> ExpressionStore {
+        let Self {
+            block_scopes,
+            mut exprs,
+            mut labels,
+            mut pats,
+            mut bindings,
+            mut binding_owners,
+            mut binding_hygiene,
+            mut ident_hygiene,
+            mut types,
+        } = self;
+        exprs.shrink_to_fit();
+        labels.shrink_to_fit();
+        pats.shrink_to_fit();
+        bindings.shrink_to_fit();
+        binding_owners.shrink_to_fit();
+        binding_hygiene.shrink_to_fit();
+        ident_hygiene.shrink_to_fit();
+        types.shrink_to_fit();
+
+        ExpressionStore {
+            exprs,
+            pats,
+            bindings,
+            labels,
+            binding_owners,
+            types,
+            block_scopes: block_scopes.into_boxed_slice(),
+            binding_hygiene,
+            ident_hygiene,
+        }
+    }
+}
+
+impl ExpressionStore {
+    /// Returns an iterator over all block expressions in this store that define inner items.
+    pub fn blocks<'a>(
+        &'a self,
+        db: &'a dyn DefDatabase,
+    ) -> impl Iterator<Item = (BlockId, Arc<DefMap>)> + 'a {
+        self.block_scopes.iter().map(move |&block| (block, db.block_def_map(block)))
+    }
+
+    pub fn walk_bindings_in_pat(&self, pat_id: PatId, mut f: impl FnMut(BindingId)) {
+        self.walk_pats(pat_id, &mut |pat| {
+            if let Pat::Bind { id, .. } = &self[pat] {
+                f(*id);
+            }
+        });
+    }
+
+    pub fn walk_pats_shallow(&self, pat_id: PatId, mut f: impl FnMut(PatId)) {
+        let pat = &self[pat_id];
+        match pat {
+            Pat::Range { .. }
+            | Pat::Lit(..)
+            | Pat::Path(..)
+            | Pat::ConstBlock(..)
+            | Pat::Wild
+            | Pat::Missing
+            | Pat::Expr(_) => {}
+            &Pat::Bind { subpat, .. } => {
+                if let Some(subpat) = subpat {
+                    f(subpat);
+                }
+            }
+            Pat::Or(args) | Pat::Tuple { args, .. } | Pat::TupleStruct { args, .. } => {
+                args.iter().copied().for_each(f);
+            }
+            Pat::Ref { pat, .. } => f(*pat),
+            Pat::Slice { prefix, slice, suffix } => {
+                let total_iter = prefix.iter().chain(slice.iter()).chain(suffix.iter());
+                total_iter.copied().for_each(f);
+            }
+            Pat::Record { args, .. } => {
+                args.iter().for_each(|RecordFieldPat { pat, .. }| f(*pat));
+            }
+            Pat::Box { inner } => f(*inner),
+        }
+    }
+
+    pub fn walk_pats(&self, pat_id: PatId, f: &mut impl FnMut(PatId)) {
+        f(pat_id);
+        self.walk_pats_shallow(pat_id, |p| self.walk_pats(p, f));
+    }
+
+    pub fn is_binding_upvar(&self, binding: BindingId, relative_to: ExprId) -> bool {
+        match self.binding_owners.get(&binding) {
+            Some(it) => {
+                // We assign expression ids in a way that outer closures will receive
+                // a lower id
+                it.into_raw() < relative_to.into_raw()
+            }
+            None => true,
+        }
+    }
+
+    pub fn walk_child_exprs(&self, expr_id: ExprId, mut f: impl FnMut(ExprId)) {
+        let expr = &self[expr_id];
+        match expr {
+            Expr::Continue { .. }
+            | Expr::Const(_)
+            | Expr::Missing
+            | Expr::Path(_)
+            | Expr::OffsetOf(_)
+            | Expr::Literal(_)
+            | Expr::Underscore => {}
+            Expr::InlineAsm(it) => it.operands.iter().for_each(|(_, op)| match op {
+                AsmOperand::In { expr, .. }
+                | AsmOperand::Out { expr: Some(expr), .. }
+                | AsmOperand::InOut { expr, .. } => f(*expr),
+                AsmOperand::SplitInOut { in_expr, out_expr, .. } => {
+                    f(*in_expr);
+                    if let Some(out_expr) = out_expr {
+                        f(*out_expr);
+                    }
+                }
+                AsmOperand::Out { expr: None, .. }
+                | AsmOperand::Const(_)
+                | AsmOperand::Label(_)
+                | AsmOperand::Sym(_) => (),
+            }),
+            Expr::If { condition, then_branch, else_branch } => {
+                f(*condition);
+                f(*then_branch);
+                if let &Some(else_branch) = else_branch {
+                    f(else_branch);
+                }
+            }
+            Expr::Let { expr, pat } => {
+                self.walk_exprs_in_pat(*pat, &mut f);
+                f(*expr);
+            }
+            Expr::Block { statements, tail, .. }
+            | Expr::Unsafe { statements, tail, .. }
+            | Expr::Async { statements, tail, .. } => {
+                for stmt in statements.iter() {
+                    match stmt {
+                        Statement::Let { initializer, else_branch, pat, .. } => {
+                            if let &Some(expr) = initializer {
+                                f(expr);
+                            }
+                            if let &Some(expr) = else_branch {
+                                f(expr);
+                            }
+                            self.walk_exprs_in_pat(*pat, &mut f);
+                        }
+                        Statement::Expr { expr: expression, .. } => f(*expression),
+                        Statement::Item(_) => (),
+                    }
+                }
+                if let &Some(expr) = tail {
+                    f(expr);
+                }
+            }
+            Expr::Loop { body, .. } => f(*body),
+            Expr::Call { callee, args, .. } => {
+                f(*callee);
+                args.iter().copied().for_each(f);
+            }
+            Expr::MethodCall { receiver, args, .. } => {
+                f(*receiver);
+                args.iter().copied().for_each(f);
+            }
+            Expr::Match { expr, arms } => {
+                f(*expr);
+                arms.iter().for_each(|arm| {
+                    f(arm.expr);
+                    self.walk_exprs_in_pat(arm.pat, &mut f);
+                });
+            }
+            Expr::Break { expr, .. }
+            | Expr::Return { expr }
+            | Expr::Yield { expr }
+            | Expr::Yeet { expr } => {
+                if let &Some(expr) = expr {
+                    f(expr);
+                }
+            }
+            Expr::Become { expr } => f(*expr),
+            Expr::RecordLit { fields, spread, .. } => {
+                for field in fields.iter() {
+                    f(field.expr);
+                }
+                if let &Some(expr) = spread {
+                    f(expr);
+                }
+            }
+            Expr::Closure { body, .. } => {
+                f(*body);
+            }
+            Expr::BinaryOp { lhs, rhs, .. } => {
+                f(*lhs);
+                f(*rhs);
+            }
+            Expr::Range { lhs, rhs, .. } => {
+                if let &Some(lhs) = rhs {
+                    f(lhs);
+                }
+                if let &Some(rhs) = lhs {
+                    f(rhs);
+                }
+            }
+            Expr::Index { base, index, .. } => {
+                f(*base);
+                f(*index);
+            }
+            Expr::Field { expr, .. }
+            | Expr::Await { expr }
+            | Expr::Cast { expr, .. }
+            | Expr::Ref { expr, .. }
+            | Expr::UnaryOp { expr, .. }
+            | Expr::Box { expr } => {
+                f(*expr);
+            }
+            Expr::Tuple { exprs, .. } => exprs.iter().copied().for_each(f),
+            Expr::Array(a) => match a {
+                Array::ElementList { elements, .. } => elements.iter().copied().for_each(f),
+                Array::Repeat { initializer, repeat } => {
+                    f(*initializer);
+                    f(*repeat)
+                }
+            },
+            &Expr::Assignment { target, value } => {
+                self.walk_exprs_in_pat(target, &mut f);
+                f(value);
+            }
+        }
+    }
+
+    pub fn walk_child_exprs_without_pats(&self, expr_id: ExprId, mut f: impl FnMut(ExprId)) {
+        let expr = &self[expr_id];
+        match expr {
+            Expr::Continue { .. }
+            | Expr::Const(_)
+            | Expr::Missing
+            | Expr::Path(_)
+            | Expr::OffsetOf(_)
+            | Expr::Literal(_)
+            | Expr::Underscore => {}
+            Expr::InlineAsm(it) => it.operands.iter().for_each(|(_, op)| match op {
+                AsmOperand::In { expr, .. }
+                | AsmOperand::Out { expr: Some(expr), .. }
+                | AsmOperand::InOut { expr, .. } => f(*expr),
+                AsmOperand::SplitInOut { in_expr, out_expr, .. } => {
+                    f(*in_expr);
+                    if let Some(out_expr) = out_expr {
+                        f(*out_expr);
+                    }
+                }
+                AsmOperand::Out { expr: None, .. }
+                | AsmOperand::Const(_)
+                | AsmOperand::Label(_)
+                | AsmOperand::Sym(_) => (),
+            }),
+            Expr::If { condition, then_branch, else_branch } => {
+                f(*condition);
+                f(*then_branch);
+                if let &Some(else_branch) = else_branch {
+                    f(else_branch);
+                }
+            }
+            Expr::Let { expr, .. } => {
+                f(*expr);
+            }
+            Expr::Block { statements, tail, .. }
+            | Expr::Unsafe { statements, tail, .. }
+            | Expr::Async { statements, tail, .. } => {
+                for stmt in statements.iter() {
+                    match stmt {
+                        Statement::Let { initializer, else_branch, .. } => {
+                            if let &Some(expr) = initializer {
+                                f(expr);
+                            }
+                            if let &Some(expr) = else_branch {
+                                f(expr);
+                            }
+                        }
+                        Statement::Expr { expr: expression, .. } => f(*expression),
+                        Statement::Item(_) => (),
+                    }
+                }
+                if let &Some(expr) = tail {
+                    f(expr);
+                }
+            }
+            Expr::Loop { body, .. } => f(*body),
+            Expr::Call { callee, args, .. } => {
+                f(*callee);
+                args.iter().copied().for_each(f);
+            }
+            Expr::MethodCall { receiver, args, .. } => {
+                f(*receiver);
+                args.iter().copied().for_each(f);
+            }
+            Expr::Match { expr, arms } => {
+                f(*expr);
+                arms.iter().map(|arm| arm.expr).for_each(f);
+            }
+            Expr::Break { expr, .. }
+            | Expr::Return { expr }
+            | Expr::Yield { expr }
+            | Expr::Yeet { expr } => {
+                if let &Some(expr) = expr {
+                    f(expr);
+                }
+            }
+            Expr::Become { expr } => f(*expr),
+            Expr::RecordLit { fields, spread, .. } => {
+                for field in fields.iter() {
+                    f(field.expr);
+                }
+                if let &Some(expr) = spread {
+                    f(expr);
+                }
+            }
+            Expr::Closure { body, .. } => {
+                f(*body);
+            }
+            Expr::BinaryOp { lhs, rhs, .. } => {
+                f(*lhs);
+                f(*rhs);
+            }
+            Expr::Range { lhs, rhs, .. } => {
+                if let &Some(lhs) = rhs {
+                    f(lhs);
+                }
+                if let &Some(rhs) = lhs {
+                    f(rhs);
+                }
+            }
+            Expr::Index { base, index, .. } => {
+                f(*base);
+                f(*index);
+            }
+            Expr::Field { expr, .. }
+            | Expr::Await { expr }
+            | Expr::Cast { expr, .. }
+            | Expr::Ref { expr, .. }
+            | Expr::UnaryOp { expr, .. }
+            | Expr::Box { expr } => {
+                f(*expr);
+            }
+            Expr::Tuple { exprs, .. } => exprs.iter().copied().for_each(f),
+            Expr::Array(a) => match a {
+                Array::ElementList { elements, .. } => elements.iter().copied().for_each(f),
+                Array::Repeat { initializer, repeat } => {
+                    f(*initializer);
+                    f(*repeat)
+                }
+            },
+            &Expr::Assignment { target: _, value } => f(value),
+        }
+    }
+
+    pub fn walk_exprs_in_pat(&self, pat_id: PatId, f: &mut impl FnMut(ExprId)) {
+        self.walk_pats(pat_id, &mut |pat| {
+            if let Pat::Expr(expr) | Pat::ConstBlock(expr) = self[pat] {
+                f(expr);
+            }
+        });
+    }
+
+    fn binding_hygiene(&self, binding: BindingId) -> HygieneId {
+        self.binding_hygiene.get(&binding).copied().unwrap_or(HygieneId::ROOT)
+    }
+
+    pub fn expr_path_hygiene(&self, expr: ExprId) -> HygieneId {
+        self.ident_hygiene.get(&expr.into()).copied().unwrap_or(HygieneId::ROOT)
+    }
+
+    pub fn pat_path_hygiene(&self, pat: PatId) -> HygieneId {
+        self.ident_hygiene.get(&pat.into()).copied().unwrap_or(HygieneId::ROOT)
+    }
+
+    pub fn expr_or_pat_path_hygiene(&self, id: ExprOrPatId) -> HygieneId {
+        match id {
+            ExprOrPatId::ExprId(id) => self.expr_path_hygiene(id),
+            ExprOrPatId::PatId(id) => self.pat_path_hygiene(id),
+        }
+    }
+}
+
+impl Index<ExprId> for ExpressionStore {
+    type Output = Expr;
+
+    fn index(&self, expr: ExprId) -> &Expr {
+        &self.exprs[expr]
+    }
+}
+
+impl Index<PatId> for ExpressionStore {
+    type Output = Pat;
+
+    fn index(&self, pat: PatId) -> &Pat {
+        &self.pats[pat]
+    }
+}
+
+impl Index<LabelId> for ExpressionStore {
+    type Output = Label;
+
+    fn index(&self, label: LabelId) -> &Label {
+        &self.labels[label]
+    }
+}
+
+impl Index<BindingId> for ExpressionStore {
+    type Output = Binding;
+
+    fn index(&self, b: BindingId) -> &Binding {
+        &self.bindings[b]
+    }
+}
+
+impl Index<TypeRefId> for ExpressionStore {
+    type Output = TypeRef;
+
+    fn index(&self, b: TypeRefId) -> &TypeRef {
+        &self.types[b]
+    }
+}
+
+// FIXME: Change `node_` prefix to something more reasonable.
+// Perhaps `expr_syntax` and `expr_id`?
+impl ExpressionStoreSourceMap {
+    pub fn expr_or_pat_syntax(&self, id: ExprOrPatId) -> Result<ExprOrPatSource, SyntheticSyntax> {
+        match id {
+            ExprOrPatId::ExprId(id) => self.expr_syntax(id).map(|it| it.map(AstPtr::wrap_left)),
+            ExprOrPatId::PatId(id) => self.pat_syntax(id),
+        }
+    }
+
+    pub fn expr_syntax(&self, expr: ExprId) -> Result<ExprSource, SyntheticSyntax> {
+        self.expr_map_back.get(expr).cloned().ok_or(SyntheticSyntax)
+    }
+
+    pub fn node_expr(&self, node: InFile<&ast::Expr>) -> Option<ExprOrPatId> {
+        let src = node.map(AstPtr::new);
+        self.expr_map.get(&src).cloned()
+    }
+
+    pub fn node_macro_file(&self, node: InFile<&ast::MacroCall>) -> Option<MacroFileId> {
+        let src = node.map(AstPtr::new);
+        self.expansions.get(&src).cloned()
+    }
+
+    pub fn macro_calls(&self) -> impl Iterator<Item = (InFile<MacroCallPtr>, MacroFileId)> + '_ {
+        self.expansions.iter().map(|(&a, &b)| (a, b))
+    }
+
+    pub fn pat_syntax(&self, pat: PatId) -> Result<ExprOrPatSource, SyntheticSyntax> {
+        self.pat_map_back.get(pat).cloned().ok_or(SyntheticSyntax)
+    }
+
+    pub fn node_pat(&self, node: InFile<&ast::Pat>) -> Option<PatId> {
+        self.pat_map.get(&node.map(AstPtr::new)).cloned()
+    }
+
+    pub fn label_syntax(&self, label: LabelId) -> LabelSource {
+        self.label_map_back[label]
+    }
+
+    pub fn patterns_for_binding(&self, binding: BindingId) -> &[PatId] {
+        self.binding_definitions.get(&binding).map_or(&[], Deref::deref)
+    }
+
+    pub fn node_label(&self, node: InFile<&ast::Label>) -> Option<LabelId> {
+        let src = node.map(AstPtr::new);
+        self.label_map.get(&src).cloned()
+    }
+
+    pub fn field_syntax(&self, expr: ExprId) -> FieldSource {
+        self.field_map_back[&expr]
+    }
+
+    pub fn pat_field_syntax(&self, pat: PatId) -> PatFieldSource {
+        self.pat_field_map_back[&pat]
+    }
+
+    pub fn macro_expansion_expr(&self, node: InFile<&ast::MacroExpr>) -> Option<ExprOrPatId> {
+        let src = node.map(AstPtr::new).map(AstPtr::upcast::<ast::MacroExpr>).map(AstPtr::upcast);
+        self.expr_map.get(&src).copied()
+    }
+
+    pub fn expansions(&self) -> impl Iterator<Item = (&InFile<MacroCallPtr>, &MacroFileId)> {
+        self.expansions.iter()
+    }
+
+    pub fn implicit_format_args(
+        &self,
+        node: InFile<&ast::FormatArgsExpr>,
+    ) -> Option<(HygieneId, &[(syntax::TextRange, Name)])> {
+        let src = node.map(AstPtr::new).map(AstPtr::upcast::<ast::Expr>);
+        let (hygiene, names) = self
+            .template_map
+            .as_ref()?
+            .format_args_to_captures
+            .get(&self.expr_map.get(&src)?.as_expr()?)?;
+        Some((*hygiene, &**names))
+    }
+
+    pub fn format_args_implicit_capture(
+        &self,
+        capture_expr: ExprId,
+    ) -> Option<InFile<(ExprPtr, TextRange)>> {
+        self.template_map.as_ref()?.implicit_capture_to_source.get(&capture_expr).copied()
+    }
+
+    pub fn asm_template_args(
+        &self,
+        node: InFile<&ast::AsmExpr>,
+    ) -> Option<(ExprId, &[Vec<(syntax::TextRange, usize)>])> {
+        let src = node.map(AstPtr::new).map(AstPtr::upcast::<ast::Expr>);
+        let expr = self.expr_map.get(&src)?.as_expr()?;
+        Some(expr)
+            .zip(self.template_map.as_ref()?.asm_to_captures.get(&expr).map(std::ops::Deref::deref))
+    }
+
+    /// Get a reference to the source map's diagnostics.
+    pub fn diagnostics(&self) -> &[ExpressionStoreDiagnostics] {
+        &self.diagnostics
+    }
+
+    fn shrink_to_fit(&mut self) {
+        let Self {
+            expr_map,
+            expr_map_back,
+            pat_map,
+            pat_map_back,
+            label_map,
+            label_map_back,
+            field_map_back,
+            pat_field_map_back,
+            expansions,
+            template_map,
+            diagnostics,
+            binding_definitions,
+            types,
+        } = self;
+        if let Some(template_map) = template_map {
+            let FormatTemplate {
+                format_args_to_captures,
+                asm_to_captures,
+                implicit_capture_to_source,
+            } = &mut **template_map;
+            format_args_to_captures.shrink_to_fit();
+            asm_to_captures.shrink_to_fit();
+            implicit_capture_to_source.shrink_to_fit();
+        }
+        expr_map.shrink_to_fit();
+        expr_map_back.shrink_to_fit();
+        pat_map.shrink_to_fit();
+        pat_map_back.shrink_to_fit();
+        label_map.shrink_to_fit();
+        label_map_back.shrink_to_fit();
+        field_map_back.shrink_to_fit();
+        pat_field_map_back.shrink_to_fit();
+        expansions.shrink_to_fit();
+        diagnostics.shrink_to_fit();
+        binding_definitions.shrink_to_fit();
+        types.shrink_to_fit();
+    }
+}