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Teach rustc about phi nodes, block relationships. Translate if- and block-expressions.

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This commit is contained in:
Graydon Hoare 2010-10-04 15:55:12 -07:00
parent a87e81b929
commit 44e4b2d63a
5 changed files with 325 additions and 113 deletions
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60
src/comp/front/parser.rs
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@ -2,15 +2,9 @@ import std._io;
import driver.session;
import util.common;
import util.common.new_str_hash;
// FIXME: import std.util.option and use it here.
// import std.util.option;
tag option[T] {
none;
some(T);
}
import util.common.option;
import util.common.some;
import util.common.none;
state type parser =
state obj {
@ -414,8 +408,35 @@ io fn parse_or_expr(parser p) -> @ast.expr {
ret parse_binary_exprs(p, sub, vec(tup(token.OROR, ast.or)));
}
io fn parse_if_expr(parser p) -> @ast.expr {
expect(p, token.IF);
expect(p, token.LPAREN);
auto cond = parse_expr(p);
expect(p, token.RPAREN);
auto thn = parse_block(p);
let option[ast.block] els = none[ast.block];
alt (p.peek()) {
case (token.ELSE) {
p.bump();
els = some(parse_block(p));
}
}
ret @ast.expr_if(cond, thn, els);
}
io fn parse_expr(parser p) -> @ast.expr {
ret parse_or_expr(p);
alt (p.peek()) {
case (token.LBRACE) {
ret @ast.expr_block(parse_block(p));
}
case (token.IF) {
ret parse_if_expr(p);
}
case (_) {
ret parse_or_expr(p);
}
}
}
io fn parse_stmt(parser p) -> @ast.stmt {
@ -426,6 +447,25 @@ io fn parse_stmt(parser p) -> @ast.stmt {
expect(p, token.SEMI);
ret @ast.stmt_log(e);
}
// Handle the (few) block-expr stmts first.
case (token.IF) {
ret @ast.stmt_expr(parse_expr(p));
}
case (token.LBRACE) {
ret @ast.stmt_expr(parse_expr(p));
}
// Remainder are line-expr stmts.
case (_) {
auto e = parse_expr(p);
expect(p, token.SEMI);
ret @ast.stmt_expr(e);
}
}
p.err("expected statement");
fail;