user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Implement 'else if'

Browse source
This commit is contained in:
Graydon Hoare 2011-02-01 16:23:48 -08:00
parent eb16942c1d
commit 70bf54bcac
7 changed files with 104 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/comp/front/ast.rs
View file

@ -149,7 +149,7 @@ tag expr_ {
expr_unary(unop, @expr, ann);
expr_lit(@lit, ann);
expr_cast(@expr, @ty, ann);
expr_if(@expr, block, option.t[block], ann);
expr_if(@expr, block, vec[tup(@expr, block)], option.t[block], ann);
expr_while(@expr, block, ann);
expr_for(@decl, @expr, block, ann);
expr_do_while(block, @expr, ann);

42
src/comp/front/parser.rs
View file

@ -891,18 +891,40 @@ impure fn parse_if_expr(parser p) -> @ast.expr {
auto cond = parse_expr(p);
expect(p, token.RPAREN);
auto thn = parse_block(p);
let option.t[ast.block] els = none[ast.block];
hi = thn.span;
alt (p.peek()) {
case (token.ELSE) {
p.bump();
auto eblk = parse_block(p);
els = some(eblk);
hi = eblk.span;
let vec[tup(@ast.expr, ast.block)] elifs = vec();
let option.t[ast.block] els = none[ast.block];
let bool parsing_elses = true;
while (parsing_elses) {
alt (p.peek()) {
case (token.ELSE) {
expect(p, token.ELSE);
alt (p.peek()) {
case (token.IF) {
expect(p, token.IF);
expect(p, token.LPAREN);
auto elifcond = parse_expr(p);
expect(p, token.RPAREN);
auto elifthn = parse_block(p);
elifs += tup(elifcond, elifthn);
hi = elifthn.span;
}
case (_) {
auto eblk = parse_block(p);
els = some(eblk);
hi = eblk.span;
parsing_elses = false;
}
}
}
case (_) {
parsing_elses = false;
}
}
case (_) { /* fall through */ }
}
ret @spanned(lo, hi, ast.expr_if(cond, thn, els, ast.ann_none));
ret @spanned(lo, hi, ast.expr_if(cond, thn, elifs, els, ast.ann_none));
}
impure fn parse_head_local(parser p) -> @ast.decl {
@ -1331,7 +1353,7 @@ fn stmt_ends_with_semi(@ast.stmt stmt) -> bool {
case (ast.expr_unary(_,_,_)) { ret true; }
case (ast.expr_lit(_,_)) { ret true; }
case (ast.expr_cast(_,_,_)) { ret true; }
case (ast.expr_if(_,_,_,_)) { ret false; }
case (ast.expr_if(_,_,_,_,_)) { ret false; }
case (ast.expr_for(_,_,_,_)) { ret false; }
case (ast.expr_while(_,_,_)) { ret false; }
case (ast.expr_do_while(_,_,_)) { ret false; }