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.
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.
11 use build::{BlockAnd, BlockAndExtension, Builder};
17 impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
18 pub fn ast_block(&mut self,
19 destination: &Lvalue<'tcx>,
21 ast_block: &'tcx hir::Block,
22 source_info: SourceInfo)
24 let Block { extent, span, stmts, expr, targeted_by_break } = self.hir.mirror(ast_block);
25 self.in_scope(extent, block, move |this| {
26 if targeted_by_break {
27 // This is a `break`-able block (currently only `catch { ... }`)
28 let exit_block = this.cfg.start_new_block();
29 let block_exit = this.in_breakable_scope(None, exit_block,
30 destination.clone(), |this| {
31 this.ast_block_stmts(destination, block, span, stmts, expr)
33 this.cfg.terminate(unpack!(block_exit), source_info,
34 TerminatorKind::Goto { target: exit_block });
37 this.ast_block_stmts(destination, block, span, stmts, expr)
42 fn ast_block_stmts(&mut self,
43 destination: &Lvalue<'tcx>,
44 mut block: BasicBlock,
46 stmts: Vec<StmtRef<'tcx>>,
47 expr: Option<ExprRef<'tcx>>)
51 // This convoluted structure is to avoid using recursion as we walk down a list
52 // of statements. Basically, the structure we get back is something like:
54 // let x = <init> in {
56 // let y = <init> in {
63 // The let bindings are valid till the end of block so all we have to do is to pop all
64 // the let-scopes at the end.
66 // First we build all the statements in the block.
67 let mut let_extent_stack = Vec::with_capacity(8);
68 let outer_visibility_scope = this.visibility_scope;
70 let Stmt { span: _, kind } = this.hir.mirror(stmt);
72 StmtKind::Expr { scope, expr } => {
73 unpack!(block = this.in_scope(scope, block, |this| {
74 let expr = this.hir.mirror(expr);
75 this.stmt_expr(block, expr)
78 StmtKind::Let { remainder_scope, init_scope, pattern, initializer } => {
79 let tcx = this.hir.tcx();
81 // Enter the remainder scope, i.e. the bindings' destruction scope.
82 this.push_scope(remainder_scope);
83 let_extent_stack.push(remainder_scope);
85 // Declare the bindings, which may create a visibility scope.
86 let remainder_span = remainder_scope.span(&tcx.region_maps(), &tcx.hir);
87 let remainder_span = remainder_span.unwrap_or(span);
88 let scope = this.declare_bindings(None, remainder_span, &pattern);
90 // Evaluate the initializer, if present.
91 if let Some(init) = initializer {
92 unpack!(block = this.in_scope(init_scope, block, move |this| {
94 this.expr_into_pattern(block, pattern, init)
97 this.visit_bindings(&pattern, &mut |this, _, _, node, span, _| {
98 this.storage_live_binding(block, node, span);
99 this.schedule_drop_for_binding(node, span);
103 // Enter the visibility scope, after evaluating the initializer.
104 if let Some(visibility_scope) = scope {
105 this.visibility_scope = visibility_scope;
110 // Then, the block may have an optional trailing expression which is a “return” value
112 if let Some(expr) = expr {
113 unpack!(block = this.into(destination, block, expr));
115 let source_info = this.source_info(span);
116 this.cfg.push_assign_unit(block, source_info, destination);
118 // Finally, we pop all the let scopes before exiting out from the scope of block
120 for extent in let_extent_stack.into_iter().rev() {
121 unpack!(block = this.pop_scope(extent, block));
123 // Restore the original visibility scope.
124 this.visibility_scope = outer_visibility_scope;