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| author | Nick Cameron <ncameron@mozilla.com> | 2015-09-28 15:00:15 +1300 |
|---|---|---|
| committer | Nick Cameron <ncameron@mozilla.com> | 2015-10-09 11:53:41 +1300 |
| commit | 20083c1e1f6916eb79e3d967c1c9ab63342c71ae (patch) | |
| tree | 671e474800b5aacf481581cc46e700dcde46f808 /src/libsyntax/ext | |
| parent | 56713a1684c22742a3a4d3d2b19fa09fa6832024 (diff) | |
| download | rust-20083c1e1f6916eb79e3d967c1c9ab63342c71ae.tar.gz rust-20083c1e1f6916eb79e3d967c1c9ab63342c71ae.zip | |
Move `for` loop desugaring to lowering
Diffstat (limited to 'src/libsyntax/ext')
| -rw-r--r-- | src/libsyntax/ext/expand.rs | 96 |
1 files changed, 2 insertions, 94 deletions
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs index b15c51490a1..8cfad6341de 100644 --- a/src/libsyntax/ext/expand.rs +++ b/src/libsyntax/ext/expand.rs @@ -360,102 +360,10 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> { fld.cx.expr(span, ast::ExprLoop(loop_block, opt_ident)) } - // Desugar ExprForLoop - // From: `[opt_ident]: for <pat> in <head> <body>` ast::ExprForLoop(pat, head, body, opt_ident) => { - // to: - // - // { - // let result = match ::std::iter::IntoIterator::into_iter(<head>) { - // mut iter => { - // [opt_ident]: loop { - // match ::std::iter::Iterator::next(&mut iter) { - // ::std::option::Option::Some(<pat>) => <body>, - // ::std::option::Option::None => break - // } - // } - // } - // }; - // result - // } - - push_compiler_expansion(fld, span, CompilerExpansionFormat::ForLoop); - - let span = fld.new_span(span); - - // expand <head> let head = fld.fold_expr(head); - - let iter = token::gensym_ident("iter"); - - let pat_span = fld.new_span(pat.span); - // `::std::option::Option::Some(<pat>) => <body>` - let pat_arm = { - let body_expr = fld.cx.expr_block(body); - let pat = fld.fold_pat(pat); - let some_pat = fld.cx.pat_some(pat_span, pat); - - fld.cx.arm(pat_span, vec![some_pat], body_expr) - }; - - // `::std::option::Option::None => break` - let break_arm = { - let break_expr = fld.cx.expr_break(span); - - fld.cx.arm(span, vec![fld.cx.pat_none(span)], break_expr) - }; - - // `match ::std::iter::Iterator::next(&mut iter) { ... }` - let match_expr = { - let next_path = { - let strs = fld.cx.std_path(&["iter", "Iterator", "next"]); - - fld.cx.path_global(span, strs) - }; - let ref_mut_iter = fld.cx.expr_mut_addr_of(span, fld.cx.expr_ident(span, iter)); - let next_expr = - fld.cx.expr_call(span, fld.cx.expr_path(next_path), vec![ref_mut_iter]); - let arms = vec![pat_arm, break_arm]; - - fld.cx.expr(pat_span, - ast::ExprMatch(next_expr, arms, ast::MatchSource::ForLoopDesugar)) - }; - - // `[opt_ident]: loop { ... }` - let loop_block = fld.cx.block_expr(match_expr); - let (loop_block, opt_ident) = expand_loop_block(loop_block, opt_ident, fld); - let loop_expr = fld.cx.expr(span, ast::ExprLoop(loop_block, opt_ident)); - - // `mut iter => { ... }` - let iter_arm = { - let iter_pat = - fld.cx.pat_ident_binding_mode(span, iter, ast::BindByValue(ast::MutMutable)); - fld.cx.arm(span, vec![iter_pat], loop_expr) - }; - - // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }` - let into_iter_expr = { - let into_iter_path = { - let strs = fld.cx.std_path(&["iter", "IntoIterator", - "into_iter"]); - - fld.cx.path_global(span, strs) - }; - - fld.cx.expr_call(span, fld.cx.expr_path(into_iter_path), vec![head]) - }; - - let match_expr = fld.cx.expr_match(span, into_iter_expr, vec![iter_arm]); - - // `{ let result = ...; result }` - let result_ident = token::gensym_ident("result"); - let result = fld.cx.expr_block( - fld.cx.block_all( - span, - vec![fld.cx.stmt_let(span, false, result_ident, match_expr)], - Some(fld.cx.expr_ident(span, result_ident)))); - fld.cx.bt_pop(); - result + let (body, opt_ident) = expand_loop_block(body, opt_ident, fld); + fld.cx.expr(span, ast::ExprForLoop(pat, head, body, opt_ident)) } ast::ExprClosure(capture_clause, fn_decl, block) => { |