Move some functions from pprust to classify

As per a FIXME in syntax::parse::classify, move predicates on exprs
and stmts into classify, out of pprust

1 files changed, 47 insertions, 2 deletions

diff --git a/src/librustsyntax/parse/classify.rs b/src/librustsyntax/parse/classify.rs
index f2c9aece0c1..caba09bfefc 100644
--- a/src/librustsyntax/parse/classify.rs
+++ b/src/librustsyntax/parse/classify.rs
@@ -1,5 +1,6 @@
-// FIXME: There are a bunch of similar functions in pprust that
-// likely belong here
+/*
+  Predicates on exprs and stmts that the pretty-printer and parser use
+ */
 
 fn expr_requires_semi_to_be_stmt(e: @ast::expr) -> bool {
     alt e.node {
@@ -29,3 +30,47 @@ fn stmt_ends_with_semi(stmt: ast::stmt) -> bool {
       }
     }
 }
+
+fn operator_prec(op: ast::binop) -> int {
+    for vec::each(*parse::prec::binop_prec_table()) {|spec|
+        if spec.op == op { ret spec.prec; }
+    }
+    core::unreachable();
+}
+
+fn need_parens(expr: @ast::expr, outer_prec: int) -> bool {
+    alt expr.node {
+      ast::expr_binary(op, _, _) { operator_prec(op) < outer_prec }
+      ast::expr_cast(_, _) { parse::prec::as_prec < outer_prec }
+      // This may be too conservative in some cases
+      ast::expr_assign(_, _) { true }
+      ast::expr_move(_, _) { true }
+      ast::expr_swap(_, _) { true }
+      ast::expr_assign_op(_, _, _) { true }
+      ast::expr_ret(_) { true }
+      ast::expr_be(_) { true }
+      ast::expr_assert(_) { true }
+      ast::expr_check(_, _) { true }
+      ast::expr_log(_, _, _) { true }
+      _ { !parse::classify::expr_requires_semi_to_be_stmt(expr) }
+    }
+}
+
+fn ends_in_lit_int(ex: @ast::expr) -> bool {
+    alt ex.node {
+      ast::expr_lit(@{node: ast::lit_int(_, ast::ty_i), _}) { true }
+      ast::expr_binary(_, _, sub) | ast::expr_unary(_, sub) |
+      ast::expr_move(_, sub) | ast::expr_copy(sub) |
+      ast::expr_assign(_, sub) | ast::expr_be(sub) |
+      ast::expr_assign_op(_, _, sub) | ast::expr_swap(_, sub) |
+      ast::expr_log(_, _, sub) | ast::expr_assert(sub) |
+      ast::expr_check(_, sub) { ends_in_lit_int(sub) }
+      ast::expr_fail(osub) | ast::expr_ret(osub) {
+        alt osub {
+          some(ex) { ends_in_lit_int(ex) }
+          _ { false }
+        }
+      }
+      _ { false }
+    }
+}