src/librustc_mir/hair/cx/block.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use hair::*;
  12 use hair::cx::Cx;
  13 use hair::cx::to_ref::ToRef;
  14 use rustc::middle::region::{self, BlockRemainder};
  15 use rustc::hir;
  16
  17 use rustc_data_structures::indexed_vec::Idx;
  18
  19 impl<'tcx> Mirror<'tcx> for &'tcx hir::Block {
  20     type Output = Block<'tcx>;
  21
  22     fn make_mirror<'a, 'gcx>(self, cx: &mut Cx<'a, 'gcx, 'tcx>) -> Block<'tcx> {
  23         // We have to eagerly lower the "spine" of the statements
  24         // in order to get the lexical scoping correctly.
  25         let stmts = mirror_stmts(cx, self.hir_id.local_id, &*self.stmts);
  26         let opt_destruction_scope =
  27             cx.region_scope_tree.opt_destruction_scope(self.hir_id.local_id);
  28         Block {
  29             targeted_by_break: self.targeted_by_break,
  30             region_scope: region::Scope::Node(self.hir_id.local_id),
  31             opt_destruction_scope,
  32             span: self.span,
  33             stmts,
  34             expr: self.expr.to_ref(),
  35             safety_mode: match self.rules {
  36                 hir::BlockCheckMode::DefaultBlock =>
  37                     BlockSafety::Safe,
  38                 hir::BlockCheckMode::UnsafeBlock(..) =>
  39                     BlockSafety::ExplicitUnsafe(self.id),
  40                 hir::BlockCheckMode::PushUnsafeBlock(..) =>
  41                     BlockSafety::PushUnsafe,
  42                 hir::BlockCheckMode::PopUnsafeBlock(..) =>
  43                     BlockSafety::PopUnsafe
  44             },
  45         }
  46     }
  47 }
  48
  49 fn mirror_stmts<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
  50                                 block_id: hir::ItemLocalId,
  51                                 stmts: &'tcx [hir::Stmt])
  52                                 -> Vec<StmtRef<'tcx>> {
  53     let mut result = vec![];
  54     for (index, stmt) in stmts.iter().enumerate() {
  55         let hir_id = cx.tcx.hir.node_to_hir_id(stmt.node.id());
  56         let opt_dxn_ext = cx.region_scope_tree.opt_destruction_scope(hir_id.local_id);
  57         match stmt.node {
  58             hir::StmtExpr(ref expr, _) |
  59             hir::StmtSemi(ref expr, _) => {
  60                 result.push(StmtRef::Mirror(Box::new(Stmt {
  61                     kind: StmtKind::Expr {
  62                         scope: region::Scope::Node(hir_id.local_id),
  63                         expr: expr.to_ref(),
  64                     },
  65                     opt_destruction_scope: opt_dxn_ext,
  66                 })))
  67             }
  68             hir::StmtDecl(ref decl, _) => {
  69                 match decl.node {
  70                     hir::DeclItem(..) => {
  71                         // ignore for purposes of the MIR
  72                     }
  73                     hir::DeclLocal(ref local) => {
  74                         let remainder_scope = region::Scope::Remainder(BlockRemainder {
  75                             block: block_id,
  76                             first_statement_index: region::FirstStatementIndex::new(index),
  77                         });
  78
  79                         let ty = local.ty.clone().map(|ty| ty.hir_id);
  80                         let pattern = cx.pattern_from_hir(&local.pat);
  81                         result.push(StmtRef::Mirror(Box::new(Stmt {
  82                             kind: StmtKind::Let {
  83                                 remainder_scope: remainder_scope,
  84                                 init_scope: region::Scope::Node(hir_id.local_id),
  85                                 pattern,
  86                                 ty,
  87                                 initializer: local.init.to_ref(),
  88                                 lint_level: cx.lint_level_of(local.id),
  89                             },
  90                             opt_destruction_scope: opt_dxn_ext,
  91                         })));
  92                     }
  93                 }
  94             }
  95         }
  96     }
  97     return result;
  98 }
  99
 100 pub fn to_expr_ref<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
 101                                    block: &'tcx hir::Block)
 102                                    -> ExprRef<'tcx> {
 103     let block_ty = cx.tables().node_id_to_type(block.hir_id);
 104     let temp_lifetime = cx.region_scope_tree.temporary_scope(block.hir_id.local_id);
 105     let expr = Expr {
 106         ty: block_ty,
 107         temp_lifetime,
 108         span: block.span,
 109         kind: ExprKind::Block { body: block },
 110     };
 111     expr.to_ref()
 112 }