pprust.rs

import parse::classify::*;
import parse::comments;
import parse::lexer;
import codemap::codemap;
import pp::{break_offset, word, printer,
            space, zerobreak, hardbreak, breaks, consistent,
            inconsistent, eof};
import diagnostic;

// The ps is stored here to prevent recursive type.
enum ann_node {
    node_block(ps, ast::blk),
    node_item(ps, @ast::item),
    node_expr(ps, @ast::expr),
    node_pat(ps, @ast::pat),
}
type pp_ann = {pre: fn@(ann_node), post: fn@(ann_node)};

fn no_ann() -> pp_ann {
    fn ignore(_node: ann_node) { }
    ret {pre: ignore, post: ignore};
}

type ps =
    @{s: pp::printer,
      cm: option<codemap>,
      comments: option<[comments::cmnt]>,
      literals: option<[comments::lit]>,
      mut cur_cmnt: uint,
      mut cur_lit: uint,
      mut boxes: [pp::breaks],
      ann: pp_ann};

fn ibox(s: ps, u: uint) { s.boxes += [pp::inconsistent]; pp::ibox(s.s, u); }

fn end(s: ps) { vec::pop(s.boxes); pp::end(s.s); }

fn rust_printer(writer: io::writer) -> ps {
    let boxes: [pp::breaks] = [];
    ret @{s: pp::mk_printer(writer, default_columns),
          cm: none::<codemap>,
          comments: none::<[comments::cmnt]>,
          literals: none::<[comments::lit]>,
          mut cur_cmnt: 0u,
          mut cur_lit: 0u,
          mut boxes: boxes,
          ann: no_ann()};
}

const indent_unit: uint = 4u;
const alt_indent_unit: uint = 2u;

const default_columns: uint = 78u;

// Requires you to pass an input filename and reader so that
// it can scan the input text for comments and literals to
// copy forward.
fn print_crate(cm: codemap, span_diagnostic: diagnostic::span_handler,
               crate: @ast::crate, filename: str, in: io::reader,
               out: io::writer, ann: pp_ann) {
    let boxes: [pp::breaks] = [];
    let r = comments::gather_comments_and_literals(span_diagnostic,
                                                   filename, in);
    let s =
        @{s: pp::mk_printer(out, default_columns),
          cm: some(cm),
          comments: some(r.cmnts),
          literals: some(r.lits),
          mut cur_cmnt: 0u,
          mut cur_lit: 0u,
          mut boxes: boxes,
          ann: ann};
    print_crate_(s, crate);
}

fn print_crate_(s: ps, &&crate: @ast::crate) {
    print_mod(s, crate.node.module, crate.node.attrs);
    print_remaining_comments(s);
    eof(s.s);
}

fn ty_to_str(ty: @ast::ty) -> str { be to_str(ty, print_type); }

fn pat_to_str(pat: @ast::pat) -> str { be to_str(pat, print_pat); }

fn expr_to_str(e: @ast::expr) -> str { be to_str(e, print_expr); }

fn stmt_to_str(s: ast::stmt) -> str { be to_str(s, print_stmt); }

fn item_to_str(i: @ast::item) -> str { be to_str(i, print_item); }

fn attr_to_str(i: ast::attribute) -> str { be to_str(i, print_attribute); }

fn typarams_to_str(tps: [ast::ty_param]) -> str {
    be to_str(tps, print_type_params)
}

fn path_to_str(&&p: @ast::path) -> str {
    be to_str(p, bind print_path(_, _, false));
}

fn fun_to_str(decl: ast::fn_decl, name: ast::ident,
              params: [ast::ty_param]) -> str {
    let buffer = io::mem_buffer();
    let s = rust_printer(io::mem_buffer_writer(buffer));
    print_fn(s, decl, name, params);
    end(s); // Close the head box
    end(s); // Close the outer box
    eof(s.s);
    io::mem_buffer_str(buffer)
}

#[test]
fn test_fun_to_str() {
    let decl: ast::fn_decl = {
        inputs: [],
        output: @{id: 0,
                  node: ast::ty_nil,
                  span: ast_util::dummy_sp()},
        purity: ast::impure_fn,
        cf: ast::return_val,
        constraints: []
    };
    assert fun_to_str(decl, "a", []) == "fn a()";
}

fn res_to_str(decl: ast::fn_decl, name: ast::ident,
              params: [ast::ty_param], rp: ast::region_param) -> str {
    let buffer = io::mem_buffer();
    let s = rust_printer(io::mem_buffer_writer(buffer));
    print_res(s, decl, name, params, rp);
    end(s); // Close the head box
    end(s); // Close the outer box
    eof(s.s);
    io::mem_buffer_str(buffer)
}

#[test]
fn test_res_to_str() {
    let decl: ast::fn_decl = {
        inputs: [{
            mode: ast::expl(ast::by_val),
            ty: @{id: 0,
                  node: ast::ty_nil,
                  span: ast_util::dummy_sp()},
            ident: "b",
            id: 0
        }],
        output: @{id: 0,
                  node: ast::ty_nil,
                  span: ast_util::dummy_sp()},
        purity: ast::impure_fn,
        cf: ast::return_val,
        constraints: []
    };
    assert res_to_str(decl, "a", []) == "resource a(b: ())";
}

fn block_to_str(blk: ast::blk) -> str {
    let buffer = io::mem_buffer();
    let s = rust_printer(io::mem_buffer_writer(buffer));
    // containing cbox, will be closed by print-block at }
    cbox(s, indent_unit);
    // head-ibox, will be closed by print-block after {
    ibox(s, 0u);
    print_block(s, blk);
    eof(s.s);
    io::mem_buffer_str(buffer)
}

fn meta_item_to_str(mi: ast::meta_item) -> str {
    ret to_str(@mi, print_meta_item);
}

fn attribute_to_str(attr: ast::attribute) -> str {
    be to_str(attr, print_attribute);
}

fn variant_to_str(var: ast::variant) -> str {
    be to_str(var, print_variant);
}

#[test]
fn test_variant_to_str() {
    let var = ast_util::respan(ast_util::dummy_sp(), {
        name: "principle_skinner",
        attrs: [],
        args: [],
        id: 0,
        disr_expr: none
    });

    let varstr = variant_to_str(var);
    assert varstr == "principle_skinner";
}

fn cbox(s: ps, u: uint) { s.boxes += [pp::consistent]; pp::cbox(s.s, u); }

fn box(s: ps, u: uint, b: pp::breaks) { s.boxes += [b]; pp::box(s.s, u, b); }

fn nbsp(s: ps) { word(s.s, " "); }

fn word_nbsp(s: ps, w: str) { word(s.s, w); nbsp(s); }

fn word_space(s: ps, w: str) { word(s.s, w); space(s.s); }

fn popen(s: ps) { word(s.s, "("); }

fn pclose(s: ps) { word(s.s, ")"); }

fn head(s: ps, w: str) {
    // outer-box is consistent
    cbox(s, indent_unit);
    // head-box is inconsistent
    ibox(s, str::len(w) + 1u);
    // keyword that starts the head
    word_nbsp(s, w);
}

fn bopen(s: ps) {
    word(s.s, "{");
    end(s); // close the head-box
}

fn bclose_(s: ps, span: codemap::span, indented: uint) {
    maybe_print_comment(s, span.hi);
    break_offset_if_not_bol(s, 1u, -(indented as int));
    word(s.s, "}");
    end(s); // close the outer-box
}
fn bclose(s: ps, span: codemap::span) { bclose_(s, span, indent_unit); }

fn is_begin(s: ps) -> bool {
    alt s.s.last_token() { pp::BEGIN(_) { true } _ { false } }
}

fn is_end(s: ps) -> bool {
    alt s.s.last_token() { pp::END { true } _ { false } }
}

fn is_bol(s: ps) -> bool {
    ret s.s.last_token() == pp::EOF ||
            s.s.last_token() == pp::hardbreak_tok();
}

fn in_cbox(s: ps) -> bool {
    let len = vec::len(s.boxes);
    if len == 0u { ret false; }
    ret s.boxes[len - 1u] == pp::consistent;
}

fn hardbreak_if_not_bol(s: ps) { if !is_bol(s) { hardbreak(s.s); } }
fn space_if_not_bol(s: ps) { if !is_bol(s) { space(s.s); } }
fn break_offset_if_not_bol(s: ps, n: uint, off: int) {
    if !is_bol(s) {
        break_offset(s.s, n, off);
    } else {
        if off != 0 && s.s.last_token() == pp::hardbreak_tok() {
            // We do something pretty sketchy here: tuck the nonzero
            // offset-adjustment we were going to deposit along with the
            // break into the previous hardbreak.
            s.s.replace_last_token(pp::hardbreak_tok_offset(off));
        }
    }
}

// Synthesizes a comment that was not textually present in the original source
// file.
fn synth_comment(s: ps, text: str) {
    word(s.s, "/*");
    space(s.s);
    word(s.s, text);
    space(s.s);
    word(s.s, "*/");
}

fn commasep<IN>(s: ps, b: breaks, elts: [IN], op: fn(ps, IN)) {
    box(s, 0u, b);
    let mut first = true;
    for elts.each {|elt|
        if first { first = false; } else { word_space(s, ","); }
        op(s, elt);
    }
    end(s);
}


fn commasep_cmnt<IN>(s: ps, b: breaks, elts: [IN], op: fn(ps, IN),
                     get_span: fn(IN) -> codemap::span) {
    box(s, 0u, b);
    let len = vec::len::<IN>(elts);
    let mut i = 0u;
    for elts.each {|elt|
        maybe_print_comment(s, get_span(elt).hi);
        op(s, elt);
        i += 1u;
        if i < len {
            word(s.s, ",");
            maybe_print_trailing_comment(s, get_span(elt),
                                         some(get_span(elts[i]).hi));
            space_if_not_bol(s);
        }
    }
    end(s);
}

fn commasep_exprs(s: ps, b: breaks, exprs: [@ast::expr]) {
    fn expr_span(&&expr: @ast::expr) -> codemap::span { ret expr.span; }
    commasep_cmnt(s, b, exprs, print_expr, expr_span);
}

fn print_mod(s: ps, _mod: ast::_mod, attrs: [ast::attribute]) {
    print_inner_attributes(s, attrs);
    for _mod.view_items.each {|vitem|
        print_view_item(s, vitem);
    }
    for _mod.items.each {|item| print_item(s, item); }
}

fn print_native_mod(s: ps, nmod: ast::native_mod, attrs: [ast::attribute]) {
    print_inner_attributes(s, attrs);
    for nmod.view_items.each {|vitem|
        print_view_item(s, vitem);
    }
    for nmod.items.each {|item| print_native_item(s, item); }
}

fn print_region(s: ps, region: ast::region) {
    alt region.node {
      ast::re_anon { /* no-op */ }
      ast::re_named(name) { word(s.s, name); word(s.s, "."); }
      ast::re_static { word(s.s, "static"); word(s.s, "."); }
    }
}

fn print_type(s: ps, &&ty: @ast::ty) {
    maybe_print_comment(s, ty.span.lo);
    ibox(s, 0u);
    alt ty.node {
      ast::ty_nil { word(s.s, "()"); }
      ast::ty_bot { word(s.s, "!"); }
      ast::ty_box(mt) { word(s.s, "@"); print_mt(s, mt); }
      ast::ty_uniq(mt) { word(s.s, "~"); print_mt(s, mt); }
      ast::ty_vec(mt) {
        word(s.s, "[");
        alt mt.mutbl {
          ast::m_mutbl { word_space(s, "mut"); }
          ast::m_const { word_space(s, "const"); }
          ast::m_imm { }
        }
        print_type(s, mt.ty);
        word(s.s, "]");
      }
      ast::ty_ptr(mt) { word(s.s, "*"); print_mt(s, mt); }
      ast::ty_rptr(region, mt) {
        word(s.s, "&");
        print_region(s, region);
        print_mt(s, mt);
      }
      ast::ty_rec(fields) {
        word(s.s, "{");
        fn print_field(s: ps, f: ast::ty_field) {
            cbox(s, indent_unit);
            print_mutability(s, f.node.mt.mutbl);
            word(s.s, f.node.ident);
            word_space(s, ":");
            print_type(s, f.node.mt.ty);
            end(s);
        }
        fn get_span(f: ast::ty_field) -> codemap::span { ret f.span; }
        commasep_cmnt(s, consistent, fields, print_field, get_span);
        word(s.s, ",}");
      }
      ast::ty_tup(elts) {
        popen(s);
        commasep(s, inconsistent, elts, print_type);
        pclose(s);
      }
      ast::ty_fn(proto, d) {
        print_ty_fn(s, some(proto), d, none, none);
      }
      ast::ty_path(path, _) { print_path(s, path, false); }
      ast::ty_constr(t, cs) {
        print_type(s, t);
        space(s.s);
        word(s.s, constrs_str(cs, ty_constr_to_str));
      }
      ast::ty_vstore(t, v) {
        print_type(s, t);
        print_vstore(s, v);
      }
      ast::ty_mac(_) {
          fail "print_type doesn't know how to print a ty_mac";
      }
      ast::ty_infer {
          fail "print_type shouldn't see a ty_infer";
      }

    }
    end(s);
}

fn print_native_item(s: ps, item: @ast::native_item) {
    hardbreak_if_not_bol(s);
    maybe_print_comment(s, item.span.lo);
    print_outer_attributes(s, item.attrs);
    alt item.node {
      ast::native_item_fn(decl, typarams) {
        print_fn(s, decl, item.ident, typarams);
        end(s); // end head-ibox
        word(s.s, ";");
        end(s); // end the outer fn box
      }
    }
}

fn print_item(s: ps, &&item: @ast::item) {
    hardbreak_if_not_bol(s);
    maybe_print_comment(s, item.span.lo);
    print_outer_attributes(s, item.attrs);
    let ann_node = node_item(s, item);
    s.ann.pre(ann_node);
    alt item.node {
      ast::item_const(ty, expr) {
        head(s, "const");
        word_space(s, item.ident + ":");
        print_type(s, ty);
        space(s.s);
        end(s); // end the head-ibox

        word_space(s, "=");
        print_expr(s, expr);
        word(s.s, ";");
        end(s); // end the outer cbox

      }
      ast::item_fn(decl, typarams, body) {
        print_fn(s, decl, item.ident, typarams);
        word(s.s, " ");
        print_block_with_attrs(s, body, item.attrs);
      }
      ast::item_mod(_mod) {
        head(s, "mod");
        word_nbsp(s, item.ident);
        bopen(s);
        print_mod(s, _mod, item.attrs);
        bclose(s, item.span);
      }
      ast::item_native_mod(nmod) {
        head(s, "native");
        word_nbsp(s, "mod");
        word_nbsp(s, item.ident);
        bopen(s);
        print_native_mod(s, nmod, item.attrs);
        bclose(s, item.span);
      }
      ast::item_ty(ty, params, rp) {
        ibox(s, indent_unit);
        ibox(s, 0u);
        word_nbsp(s, "type");
        word(s.s, item.ident);
        print_region_param(s, rp);
        print_type_params(s, params);
        end(s); // end the inner ibox

        space(s.s);
        word_space(s, "=");
        print_type(s, ty);
        word(s.s, ";");
        end(s); // end the outer ibox
      }
      ast::item_enum(variants, params, rp) {
        let newtype =
            vec::len(variants) == 1u &&
                str::eq(item.ident, variants[0].node.name) &&
                vec::len(variants[0].node.args) == 1u;
        if newtype {
            ibox(s, indent_unit);
            word_space(s, "enum");
        } else { head(s, "enum"); }
        word(s.s, item.ident);
        print_region_param(s, rp);
        print_type_params(s, params);
        space(s.s);
        if newtype {
            word_space(s, "=");
            print_type(s, variants[0].node.args[0].ty);
            word(s.s, ";");
            end(s);
        } else {
            bopen(s);
            for variants.each {|v|
                space_if_not_bol(s);
                maybe_print_comment(s, v.span.lo);
                print_outer_attributes(s, v.node.attrs);
                ibox(s, indent_unit);
                print_variant(s, v);
                word(s.s, ",");
                end(s);
                maybe_print_trailing_comment(s, v.span, none::<uint>);
            }
            bclose(s, item.span);
        }
      }
      ast::item_class(tps,ifaces,items,ctor, rp) {
          head(s, "class");
          word_nbsp(s, item.ident);
          print_region_param(s, rp);
          print_type_params(s, tps);
          word_space(s, "implements");
          commasep(s, inconsistent, ifaces, {|s, p|
                      print_path(s, p.path, false)});
          bopen(s);
          hardbreak_if_not_bol(s);
          maybe_print_comment(s, ctor.span.lo);
          head(s, "new");
          print_fn_args_and_ret(s, ctor.node.dec);
          space(s.s);
          print_block(s, ctor.node.body);
          for items.each {|ci|
                  /*
                     FIXME: collect all private items and print them
                     in a single "priv" section
                   */
             hardbreak_if_not_bol(s);
             maybe_print_comment(s, ci.span.lo);
             let pr = ast_util::class_member_privacy(ci);
             alt pr {
                ast::priv {
                    head(s, "priv");
                    bopen(s);
                    hardbreak_if_not_bol(s);
                }
                _ {}
             }
             alt ci.node {
                ast::instance_var(nm, t, mt, _,_) {
                    word_nbsp(s, "let");
                    alt mt {
                      ast::class_mutable { word_nbsp(s, "mut"); }
                      _ {}
                    }
                    word(s.s, nm);
                    word_nbsp(s, ":");
                    print_type(s, t);
                    word(s.s, ";");
                }
                ast::class_method(m) {
                    print_method(s, m);
                }
             }
             alt pr {
                 ast::priv { bclose(s, ci.span); }
                 _ {}
             }
          }
          bclose(s, item.span);
       }
      ast::item_impl(tps, ifce, ty, methods) {
        head(s, "impl");
        word(s.s, item.ident);
        print_type_params(s, tps);
        space(s.s);
        alt ifce {
          some(ty) {
            word_nbsp(s, "of");
            print_type(s, ty);
            space(s.s);
          }
          _ {}
        }
        word_nbsp(s, "for");
        print_type(s, ty);
        space(s.s);
        bopen(s);
        for methods.each {|meth|
           print_method(s, meth);
        }
        bclose(s, item.span);
      }
      ast::item_iface(tps, methods) {
        head(s, "iface");
        word(s.s, item.ident);
        print_type_params(s, tps);
        word(s.s, " ");
        bopen(s);
        for methods.each {|meth| print_ty_method(s, meth); }
        bclose(s, item.span);
      }
      ast::item_res(decl, tps, body, dt_id, ct_id, rp) {
        print_res(s, decl, item.ident, tps, rp);
        print_block(s, body);
      }
    }
    s.ann.post(ann_node);
}

fn print_res(s: ps, decl: ast::fn_decl, name: ast::ident,
             typarams: [ast::ty_param], rp: ast::region_param) {
    head(s, "resource");
    word(s.s, name);
    print_region_param(s, rp);
    print_type_params(s, typarams);
    popen(s);
    word_space(s, decl.inputs[0].ident + ":");
    print_type(s, decl.inputs[0].ty);
    pclose(s);
    space(s.s);
}

fn print_variant(s: ps, v: ast::variant) {
    word(s.s, v.node.name);
    if vec::len(v.node.args) > 0u {
        popen(s);
        fn print_variant_arg(s: ps, arg: ast::variant_arg) {
            print_type(s, arg.ty);
        }
        commasep(s, consistent, v.node.args, print_variant_arg);
        pclose(s);
    }
    alt v.node.disr_expr {
      some(d) {
        space(s.s);
        word_space(s, "=");
        print_expr(s, d);
      }
      _ {}
    }
}

fn print_ty_method(s: ps, m: ast::ty_method) {
    hardbreak_if_not_bol(s);
    maybe_print_comment(s, m.span.lo);
    print_outer_attributes(s, m.attrs);
    print_ty_fn(s, none, m.decl, some(m.ident), some(m.tps));
    word(s.s, ";");
}

fn print_method(s: ps, meth: @ast::method) {
    hardbreak_if_not_bol(s);
    maybe_print_comment(s, meth.span.lo);
    print_outer_attributes(s, meth.attrs);
    print_fn(s, meth.decl, meth.ident, meth.tps);
    word(s.s, " ");
    print_block_with_attrs(s, meth.body, meth.attrs);
}

fn print_outer_attributes(s: ps, attrs: [ast::attribute]) {
    let mut count = 0;
    for attrs.each {|attr|
        alt attr.node.style {
          ast::attr_outer { print_attribute(s, attr); count += 1; }
          _ {/* fallthrough */ }
        }
    }
    if count > 0 { hardbreak_if_not_bol(s); }
}

fn print_inner_attributes(s: ps, attrs: [ast::attribute]) {
    let mut count = 0;
    for attrs.each {|attr|
        alt attr.node.style {
          ast::attr_inner {
            print_attribute(s, attr);
            word(s.s, ";");
            count += 1;
          }
          _ {/* fallthrough */ }
        }
    }
    if count > 0 { hardbreak_if_not_bol(s); }
}

fn print_attribute(s: ps, attr: ast::attribute) {
    hardbreak_if_not_bol(s);
    maybe_print_comment(s, attr.span.lo);
    word(s.s, "#[");
    print_meta_item(s, @attr.node.value);
    word(s.s, "]");
}


fn print_stmt(s: ps, st: ast::stmt) {
    maybe_print_comment(s, st.span.lo);
    alt st.node {
      ast::stmt_decl(decl, _) {
        print_decl(s, decl);
      }
      ast::stmt_expr(expr, _) {
        space_if_not_bol(s);
        print_expr(s, expr);
      }
      ast::stmt_semi(expr, _) {
        space_if_not_bol(s);
        print_expr(s, expr);
        word(s.s, ";");
      }
    }
    if parse::classify::stmt_ends_with_semi(st) { word(s.s, ";"); }
    maybe_print_trailing_comment(s, st.span, none::<uint>);
}

fn print_block(s: ps, blk: ast::blk) {
    print_possibly_embedded_block(s, blk, block_normal, indent_unit);
}

fn print_block_with_attrs(s: ps, blk: ast::blk, attrs: [ast::attribute]) {
    print_possibly_embedded_block_(s, blk, block_normal, indent_unit, attrs);
}

enum embed_type { block_macro, block_block_fn, block_normal, }

fn print_possibly_embedded_block(s: ps, blk: ast::blk, embedded: embed_type,
                                 indented: uint) {
    print_possibly_embedded_block_(
        s, blk, embedded, indented, []);
}

fn print_possibly_embedded_block_(s: ps, blk: ast::blk, embedded: embed_type,
                                  indented: uint, attrs: [ast::attribute]) {
    alt blk.node.rules {
      ast::unchecked_blk { word(s.s, "unchecked"); }
      ast::unsafe_blk { word(s.s, "unsafe"); }
      ast::default_blk { }
    }
    maybe_print_comment(s, blk.span.lo);
    let ann_node = node_block(s, blk);
    s.ann.pre(ann_node);
    alt embedded {
      block_macro { word(s.s, "#{"); end(s); }
      block_block_fn { end(s); }
      block_normal { bopen(s); }
    }

    print_inner_attributes(s, attrs);

    for blk.node.view_items.each {|vi| print_view_item(s, vi); }
    for blk.node.stmts.each {|st|
        print_stmt(s, *st);
    }
    alt blk.node.expr {
      some(expr) {
        space_if_not_bol(s);
        print_expr(s, expr);
        maybe_print_trailing_comment(s, expr.span, some(blk.span.hi));
      }
      _ { }
    }
    bclose_(s, blk.span, indented);
    s.ann.post(ann_node);
}

// ret and fail, without arguments cannot appear is the discriminant of if,
// alt, do, & while unambiguously without being parenthesized
fn print_maybe_parens_discrim(s: ps, e: @ast::expr) {
    let disambig = alt e.node {
      ast::expr_ret(none) | ast::expr_fail(none) { true }
      _ { false }
    };
    if disambig { popen(s); }
    print_expr(s, e);
    if disambig { pclose(s); }
}

fn print_if(s: ps, test: @ast::expr, blk: ast::blk,
            elseopt: option<@ast::expr>, chk: bool) {
    head(s, "if");
    if chk { word_nbsp(s, "check"); }
    print_maybe_parens_discrim(s, test);
    space(s.s);
    print_block(s, blk);
    fn do_else(s: ps, els: option<@ast::expr>) {
        alt els {
          some(_else) {
            alt _else.node {
              // "another else-if"
              ast::expr_if(i, t, e) {
                cbox(s, indent_unit - 1u);
                ibox(s, 0u);
                word(s.s, " else if ");
                print_maybe_parens_discrim(s, i);
                space(s.s);
                print_block(s, t);
                do_else(s, e);
              }
              // "final else"
              ast::expr_block(b) {
                cbox(s, indent_unit - 1u);
                ibox(s, 0u);
                word(s.s, " else ");
                print_block(s, b);
              }
              // BLEAH, constraints would be great here
              _ {
                  fail "print_if saw if with weird alternative";
              }
            }
          }
          _ {/* fall through */ }
        }
    }
    do_else(s, elseopt);
}

fn print_mac(s: ps, m: ast::mac) {
    alt m.node {
      ast::mac_invoc(path, arg, body) {
        word(s.s, "#");
        print_path(s, path, false);
        alt arg {
          some(@{node: ast::expr_vec(_, _), _}) { }
          _ { word(s.s, " "); }
        }
        option::iter(arg, bind print_expr(s, _));
        // FIXME: extension 'body'
      }
      ast::mac_embed_type(ty) {
        word(s.s, "#<");
        print_type(s, ty);
        word(s.s, ">");
      }
      ast::mac_embed_block(blk) {
        print_possibly_embedded_block(s, blk, block_normal, indent_unit);
      }
      ast::mac_ellipsis { word(s.s, "..."); }
      ast::mac_var(v) { word(s.s, #fmt("$%u", v)); }
      _ { /* fixme */ }
    }
}

fn print_vstore(s: ps, t: ast::vstore) {
    alt t {
      ast::vstore_fixed(some(i)) { word_space(s, #fmt("/%u", i)); }
      ast::vstore_fixed(none) { word_space(s, "/_"); }
      ast::vstore_uniq { word_space(s, "/~"); }
      ast::vstore_box { word_space(s, "/@"); }
      ast::vstore_slice(r) {
        alt r.node {
          ast::re_anon { word_space(s, "/&"); }
          ast::re_static { word_space(s, "/&static"); }
          ast::re_named(name) {
            word(s.s, "/&");
            word_space(s, name);
          }
        }
      }
    }
}

fn print_expr(s: ps, &&expr: @ast::expr) {
    maybe_print_comment(s, expr.span.lo);
    ibox(s, indent_unit);
    let ann_node = node_expr(s, expr);
    s.ann.pre(ann_node);
    alt expr.node {
      ast::expr_vstore(e, v) {
        print_expr(s, e);
        print_vstore(s, v);
      }
      ast::expr_vec(exprs, mutbl) {
        ibox(s, indent_unit);
        word(s.s, "[");
        if mutbl == ast::m_mutbl {
            word(s.s, "mut");
            if vec::len(exprs) > 0u { nbsp(s); }
        }
        commasep_exprs(s, inconsistent, exprs);
        word(s.s, "]");
        end(s);
      }
      ast::expr_rec(fields, wth) {
        fn print_field(s: ps, field: ast::field) {
            ibox(s, indent_unit);
            if field.node.mutbl == ast::m_mutbl { word_nbsp(s, "mut"); }
            word(s.s, field.node.ident);
            word_space(s, ":");
            print_expr(s, field.node.expr);
            end(s);
        }
        fn get_span(field: ast::field) -> codemap::span { ret field.span; }
        word(s.s, "{");
        commasep_cmnt(s, consistent, fields, print_field, get_span);
        alt wth {
          some(expr) {
            if vec::len(fields) > 0u { space(s.s); }
            ibox(s, indent_unit);
            word_space(s, "with");
            print_expr(s, expr);
            end(s);
          }
          _ { word(s.s, ","); }
        }
        word(s.s, "}");
      }
      ast::expr_tup(exprs) {
        popen(s);
        commasep_exprs(s, inconsistent, exprs);
        pclose(s);
      }
      ast::expr_call(func, args, has_block) {
        let mut base_args = args;
        let blk = if has_block {
            let blk_arg = vec::pop(base_args);
            alt blk_arg.node {
              ast::expr_loop_body(_) { word_nbsp(s, "for"); }
              _ {}
            }
            some(blk_arg)
        } else { none };
        print_expr_parens_if_not_bot(s, func);
        if !has_block || vec::len(base_args) > 0u {
            popen(s);
            commasep_exprs(s, inconsistent, base_args);
            pclose(s);
        }
        if has_block {
            nbsp(s);
            print_expr(s, option::get(blk));
        }
      }
      ast::expr_bind(func, args) {
        fn print_opt(s: ps, expr: option<@ast::expr>) {
            alt expr {
              some(expr) { print_expr(s, expr); }
              _ { word(s.s, "_"); }
            }
        }

        // "bind" keyword is only needed if there are no "_" arguments.
        if !vec::any(args) {|arg| option::is_none(arg) } {
            word_nbsp(s, "bind");
        }

        print_expr(s, func);
        popen(s);
        commasep(s, inconsistent, args, print_opt);
        pclose(s);
      }
      ast::expr_binary(op, lhs, rhs) {
        let prec = operator_prec(op);
        print_op_maybe_parens(s, lhs, prec);
        space(s.s);
        word_space(s, ast_util::binop_to_str(op));
        print_op_maybe_parens(s, rhs, prec + 1);
      }
      ast::expr_unary(op, expr) {
        word(s.s, ast_util::unop_to_str(op));
        print_op_maybe_parens(s, expr, parse::prec::unop_prec);
      }
      ast::expr_addr_of(m, expr) {
        word(s.s, "&");
        print_mutability(s, m);
        print_expr(s, expr);
      }
      ast::expr_lit(lit) { print_literal(s, lit); }
      ast::expr_cast(expr, ty) {
        print_op_maybe_parens(s, expr, parse::prec::as_prec);
        space(s.s);
        word_space(s, "as");
        print_type(s, ty);
      }
      ast::expr_if(test, blk, elseopt) {
        print_if(s, test, blk, elseopt, false);
      }
      ast::expr_if_check(test, blk, elseopt) {
        print_if(s, test, blk, elseopt, true);
      }
      ast::expr_while(test, blk) {
        head(s, "while");
        print_maybe_parens_discrim(s, test);
        space(s.s);
        print_block(s, blk);
      }
      ast::expr_loop(blk) {
        head(s, "loop");
        space(s.s);
        print_block(s, blk);
      }
      ast::expr_do_while(blk, expr) {
        head(s, "do");
        space(s.s);
        print_block(s, blk);
        space(s.s);
        word_space(s, "while");
        print_expr(s, expr);
      }
      ast::expr_alt(expr, arms, mode) {
        cbox(s, alt_indent_unit);
        ibox(s, 4u);
        word_nbsp(s, "alt");
        if mode == ast::alt_check { word_nbsp(s, "check"); }
        print_maybe_parens_discrim(s, expr);
        space(s.s);
        bopen(s);
        for arms.each {|arm|
            space(s.s);
            cbox(s, alt_indent_unit);
            ibox(s, 0u);
            let mut first = true;
            for arm.pats.each {|p|
                if first {
                    first = false;
                } else { space(s.s); word_space(s, "|"); }
                print_pat(s, p);
            }
            space(s.s);
            alt arm.guard {
              some(e) { word_space(s, "if"); print_expr(s, e); space(s.s); }
              none { }
            }
            print_possibly_embedded_block(s, arm.body, block_normal,
                                          alt_indent_unit);
        }
        bclose_(s, expr.span, alt_indent_unit);
      }
      ast::expr_fn(proto, decl, body, cap_clause) {
        // containing cbox, will be closed by print-block at }
        cbox(s, indent_unit);
        // head-box, will be closed by print-block at start
        ibox(s, 0u);
        word(s.s, proto_to_str(proto));
        print_cap_clause(s, *cap_clause);
        print_fn_args_and_ret(s, decl);
        space(s.s);
        print_block(s, body);
      }
      ast::expr_fn_block(decl, body) {
        // containing cbox, will be closed by print-block at }
        cbox(s, indent_unit);
        // head-box, will be closed by print-block at start
        ibox(s, 0u);
        word(s.s, "{");
        print_fn_block_args(s, decl);
        print_possibly_embedded_block(s, body, block_block_fn, indent_unit);
      }
      ast::expr_loop_body(body) {
        print_expr(s, body);
      }
      ast::expr_block(blk) {
        // containing cbox, will be closed by print-block at }
        cbox(s, indent_unit);
        // head-box, will be closed by print-block after {
        ibox(s, 0u);
        print_block(s, blk);
      }
      ast::expr_copy(e) { word_space(s, "copy"); print_expr(s, e); }
      ast::expr_move(lhs, rhs) {
        print_expr(s, lhs);
        space(s.s);
        word_space(s, "<-");
        print_expr(s, rhs);
      }
      ast::expr_assign(lhs, rhs) {
        print_expr(s, lhs);
        space(s.s);
        word_space(s, "=");
        print_expr(s, rhs);
      }
      ast::expr_swap(lhs, rhs) {
        print_expr(s, lhs);
        space(s.s);
        word_space(s, "<->");
        print_expr(s, rhs);
      }
      ast::expr_assign_op(op, lhs, rhs) {
        print_expr(s, lhs);
        space(s.s);
        word(s.s, ast_util::binop_to_str(op));
        word_space(s, "=");
        print_expr(s, rhs);
      }
      ast::expr_field(expr, id, tys) {
        // Deal with '10.x'
        if ends_in_lit_int(expr) {
            popen(s); print_expr(s, expr); pclose(s);
        } else {
            print_expr_parens_if_not_bot(s, expr);
        }
        word(s.s, ".");
        word(s.s, id);
        if vec::len(tys) > 0u {
            word(s.s, "::<");
            commasep(s, inconsistent, tys, print_type);
            word(s.s, ">");
        }
      }
      ast::expr_index(expr, index) {
        print_expr_parens_if_not_bot(s, expr);
        word(s.s, "[");
        print_expr(s, index);
        word(s.s, "]");
      }
      ast::expr_path(path) { print_path(s, path, true); }
      ast::expr_fail(maybe_fail_val) {
        word(s.s, "fail");
        alt maybe_fail_val {
          some(expr) { word(s.s, " "); print_expr(s, expr); }
          _ { }
        }
      }
      ast::expr_break { word(s.s, "break"); }
      ast::expr_cont { word(s.s, "cont"); }
      ast::expr_ret(result) {
        word(s.s, "ret");
        alt result {
          some(expr) { word(s.s, " "); print_expr(s, expr); }
          _ { }
        }
      }
      ast::expr_be(result) { word_nbsp(s, "be"); print_expr(s, result); }
      ast::expr_log(lvl, lexp, expr) {
        alt check lvl {
          1 { word_nbsp(s, "log"); print_expr(s, expr); }
          0 { word_nbsp(s, "log_err"); print_expr(s, expr); }
          2 {
            word_nbsp(s, "log");
            popen(s);
            print_expr(s, lexp);
            word(s.s, ",");
            space_if_not_bol(s);
            print_expr(s, expr);
            pclose(s);
          }
        }
      }
      ast::expr_check(m, expr) {
        alt m {
          ast::claimed_expr { word_nbsp(s, "claim"); }
          ast::checked_expr { word_nbsp(s, "check"); }
        }
        popen(s);
        print_expr(s, expr);
        pclose(s);
      }
      ast::expr_assert(expr) {
        word_nbsp(s, "assert");
        print_expr(s, expr);
      }
      ast::expr_new(p, _, v) {
        word_nbsp(s, "new");
        popen(s);
        print_expr(s, p);
        pclose(s);
        print_expr(s, v);
      }
      ast::expr_mac(m) { print_mac(s, m); }
    }
    s.ann.post(ann_node);
    end(s);
}

fn print_expr_parens_if_not_bot(s: ps, ex: @ast::expr) {
    let parens = alt ex.node {
      ast::expr_fail(_) | ast::expr_ret(_) |
      ast::expr_binary(_, _, _) | ast::expr_unary(_, _) |
      ast::expr_move(_, _) | ast::expr_copy(_) |
      ast::expr_assign(_, _) | ast::expr_be(_) |
      ast::expr_assign_op(_, _, _) | ast::expr_swap(_, _) |
      ast::expr_log(_, _, _) | ast::expr_assert(_) |
      ast::expr_call(_, _, true) |
      ast::expr_check(_, _) { true }
      _ { false }
    };
    if parens { popen(s); }
    print_expr(s, ex);
    if parens { pclose(s); }
}

fn print_local_decl(s: ps, loc: @ast::local) {
    print_pat(s, loc.node.pat);
    alt loc.node.ty.node {
      ast::ty_infer { }
      _ { word_space(s, ":"); print_type(s, loc.node.ty); }
    }
}

fn print_decl(s: ps, decl: @ast::decl) {
    maybe_print_comment(s, decl.span.lo);
    alt decl.node {
      ast::decl_local(locs) {
        space_if_not_bol(s);
        ibox(s, indent_unit);
        word_nbsp(s, "let");

        // if any are mut, all are mut
        if vec::any(locs) {|l| l.node.is_mutbl } {
            assert vec::all(locs) {|l| l.node.is_mutbl };
            word_nbsp(s, "mut");
        }

        fn print_local(s: ps, &&loc: @ast::local) {
            ibox(s, indent_unit);
            print_local_decl(s, loc);
            end(s);
            alt loc.node.init {
              some(init) {
                nbsp(s);
                alt init.op {
                  ast::init_assign { word_space(s, "="); }
                  ast::init_move { word_space(s, "<-"); }
                }
                print_expr(s, init.expr);
              }
              _ { }
            }
        }
        commasep(s, consistent, locs, print_local);
        end(s);
      }
      ast::decl_item(item) { print_item(s, item); }
    }
}

fn print_ident(s: ps, ident: ast::ident) { word(s.s, ident); }

fn print_for_decl(s: ps, loc: @ast::local, coll: @ast::expr) {
    print_local_decl(s, loc);
    space(s.s);
    word_space(s, "in");
    print_expr(s, coll);
}

fn print_path(s: ps, &&path: @ast::path, colons_before_params: bool) {
    maybe_print_comment(s, path.span.lo);
    if path.node.global { word(s.s, "::"); }
    let mut first = true;
    for path.node.idents.each {|id|
        if first { first = false; } else { word(s.s, "::"); }
        word(s.s, id);
    }
    if vec::len(path.node.types) > 0u {
        if colons_before_params { word(s.s, "::"); }
        word(s.s, "<");
        commasep(s, inconsistent, path.node.types, print_type);
        word(s.s, ">");
    }
}

fn print_pat(s: ps, &&pat: @ast::pat) {
    maybe_print_comment(s, pat.span.lo);
    let ann_node = node_pat(s, pat);
    s.ann.pre(ann_node);
    /* Pat isn't normalized, but the beauty of it
     is that it doesn't matter */
    alt pat.node {
      ast::pat_wild { word(s.s, "_"); }
      ast::pat_ident(path, sub) {
        print_path(s, path, true);
        alt sub {
          some(p) { word(s.s, "@"); print_pat(s, p); }
          _ {}
        }
      }
      ast::pat_enum(path, args) {
        print_path(s, path, true);
        if vec::len(args) > 0u {
            popen(s);
            commasep(s, inconsistent, args, print_pat);
            pclose(s);
        } else { }
      }
      ast::pat_rec(fields, etc) {
        word(s.s, "{");
        fn print_field(s: ps, f: ast::field_pat) {
            cbox(s, indent_unit);
            word(s.s, f.ident);
            word_space(s, ":");
            print_pat(s, f.pat);
            end(s);
        }
        fn get_span(f: ast::field_pat) -> codemap::span { ret f.pat.span; }
        commasep_cmnt(s, consistent, fields, print_field, get_span);
        if etc {
            if vec::len(fields) != 0u { word_space(s, ","); }
            word(s.s, "_");
        }
        word(s.s, "}");
      }
      ast::pat_tup(elts) {
        popen(s);
        commasep(s, inconsistent, elts, print_pat);
        pclose(s);
      }
      ast::pat_box(inner) { word(s.s, "@"); print_pat(s, inner); }
      ast::pat_uniq(inner) { word(s.s, "~"); print_pat(s, inner); }
      ast::pat_lit(e) { print_expr(s, e); }
      ast::pat_range(begin, end) {
        print_expr(s, begin);
        space(s.s);
        word_space(s, "to");
        print_expr(s, end);
      }
    }
    s.ann.post(ann_node);
}

fn print_fn(s: ps, decl: ast::fn_decl, name: ast::ident,
            typarams: [ast::ty_param]) {
    alt decl.purity {
      ast::impure_fn { head(s, "fn"); }
      ast::unsafe_fn { head(s, "unsafe fn"); }
      ast::pure_fn { head(s, "pure fn"); }
      ast::crust_fn { head(s, "crust fn"); }
    }
    word(s.s, name);
    print_type_params(s, typarams);
    print_fn_args_and_ret(s, decl);
}

fn print_cap_clause(s: ps, cap_clause: ast::capture_clause) {
    fn print_cap_item(s: ps, &&cap_item: @ast::capture_item) {
        word(s.s, cap_item.name);
    }

    let has_copies = vec::is_not_empty(cap_clause.copies);
    let has_moves = vec::is_not_empty(cap_clause.moves);
    if !has_copies && !has_moves { ret; }

    word(s.s, "[");

    if has_copies {
        word_nbsp(s, "copy");
        commasep(s, inconsistent, cap_clause.copies, print_cap_item);
        if has_moves {
            word_space(s, ";");
        }
    }

    if has_moves {
        word_nbsp(s, "move");
        commasep(s, inconsistent, cap_clause.moves, print_cap_item);
    }

    word(s.s, "]");
}

fn print_fn_args_and_ret(s: ps, decl: ast::fn_decl) {
    popen(s);
    fn print_arg(s: ps, x: ast::arg) {
        ibox(s, indent_unit);
        print_arg_mode(s, x.mode);
        word_space(s, x.ident + ":");
        print_type(s, x.ty);
        end(s);
    }
    commasep(s, inconsistent, decl.inputs, print_arg);
    pclose(s);
    word(s.s, constrs_str(decl.constraints, {|c|
        ast_fn_constr_to_str(decl, c)
    }));

    maybe_print_comment(s, decl.output.span.lo);
    if decl.output.node != ast::ty_nil {
        space_if_not_bol(s);
        word_space(s, "->");
        print_type(s, decl.output);
    }
}

fn print_fn_block_args(s: ps, decl: ast::fn_decl) {
    word(s.s, "|");
    fn print_arg(s: ps, x: ast::arg) {
        ibox(s, indent_unit);
        print_arg_mode(s, x.mode);
        word(s.s, x.ident);
        end(s);
    }
    commasep(s, inconsistent, decl.inputs, print_arg);
    word(s.s, "|");
    if decl.output.node != ast::ty_infer {
        space_if_not_bol(s);
        word_space(s, "->");
        print_type(s, decl.output);
    }
    maybe_print_comment(s, decl.output.span.lo);
}

fn mode_to_str(m: ast::mode) -> str {
    alt m {
      ast::expl(ast::by_mutbl_ref) { "&" }
      ast::expl(ast::by_move) { "-" }
      ast::expl(ast::by_ref) { "&&" }
      ast::expl(ast::by_val) { "++" }
      ast::expl(ast::by_copy) { "+" }
      ast::infer(_) { "" }
    }
}

fn print_arg_mode(s: ps, m: ast::mode) {
    let ms = mode_to_str(m);
    if ms != "" { word(s.s, ms); }
}

fn print_bounds(s: ps, bounds: @[ast::ty_param_bound]) {
    if vec::len(*bounds) > 0u {
        word(s.s, ":");
        for vec::each(*bounds) {|bound|
            nbsp(s);
            alt bound {
              ast::bound_copy { word(s.s, "copy"); }
              ast::bound_send { word(s.s, "send"); }
              ast::bound_iface(t) { print_type(s, t); }
            }
        }
    }
}

fn print_region_param(s: ps, rp: ast::region_param) {
    alt rp {
      ast::rp_self { word(s.s, "/&") }
      ast::rp_none { }
    }
}

fn print_type_params(s: ps, &&params: [ast::ty_param]) {
    if vec::len(params) > 0u {
        word(s.s, "<");
        fn printParam(s: ps, param: ast::ty_param) {
            word(s.s, param.ident);
            print_bounds(s, param.bounds);
        }
        commasep(s, inconsistent, params, printParam);
        word(s.s, ">");
    }
}

fn print_meta_item(s: ps, &&item: @ast::meta_item) {
    ibox(s, indent_unit);
    alt item.node {
      ast::meta_word(name) { word(s.s, name); }
      ast::meta_name_value(name, value) {
        word_space(s, name);
        word_space(s, "=");
        print_literal(s, @value);
      }
      ast::meta_list(name, items) {
        word(s.s, name);
        popen(s);
        commasep(s, consistent, items, print_meta_item);
        pclose(s);
      }
    }
    end(s);
}

fn print_view_path(s: ps, &&vp: @ast::view_path) {
    alt vp.node {
      ast::view_path_simple(ident, path, _) {
        if path.node.idents[vec::len(path.node.idents)-1u] != ident {
            word_space(s, ident);
            word_space(s, "=");
        }
        print_path(s, path, false);
      }

      ast::view_path_glob(path, _) {
        print_path(s, path, false);
        word(s.s, "::*");
      }

      ast::view_path_list(path, idents, _) {
        print_path(s, path, false);
        word(s.s, "::{");
        commasep(s, inconsistent, idents) {|s, w|
            word(s.s, w.node.name)
        }
        word(s.s, "}");
      }
    }
}

fn print_view_paths(s: ps, vps: [@ast::view_path]) {
    commasep(s, inconsistent, vps, print_view_path);
}

fn print_view_item(s: ps, item: @ast::view_item) {
    hardbreak_if_not_bol(s);
    maybe_print_comment(s, item.span.lo);
    alt item.node {
      ast::view_item_use(id, mta, _) {
        head(s, "use");
        word(s.s, id);
        if vec::len(mta) > 0u {
            popen(s);
            commasep(s, consistent, mta, print_meta_item);
            pclose(s);
        }
      }

      ast::view_item_import(vps) {
        head(s, "import");
        print_view_paths(s, vps);
      }

      ast::view_item_export(vps) {
        head(s, "export");
        print_view_paths(s, vps);
      }
    }
    word(s.s, ";");
    end(s); // end inner head-block
    end(s); // end outer head-block
}

fn print_op_maybe_parens(s: ps, expr: @ast::expr, outer_prec: int) {
    let add_them = need_parens(expr, outer_prec);
    if add_them { popen(s); }
    print_expr(s, expr);
    if add_them { pclose(s); }
}

fn print_mutability(s: ps, mutbl: ast::mutability) {
    alt mutbl {
      ast::m_mutbl { word_nbsp(s, "mut"); }
      ast::m_const { word_nbsp(s, "const"); }
      ast::m_imm {/* nothing */ }
    }
}

fn print_mt(s: ps, mt: ast::mt) {
    print_mutability(s, mt.mutbl);
    print_type(s, mt.ty);
}

fn print_ty_fn(s: ps, opt_proto: option<ast::proto>,
               decl: ast::fn_decl, id: option<ast::ident>,
               tps: option<[ast::ty_param]>) {
    ibox(s, indent_unit);
    word(s.s, opt_proto_to_str(opt_proto));
    alt id { some(id) { word(s.s, " "); word(s.s, id); } _ { } }
    alt tps { some(tps) { print_type_params(s, tps); } _ { } }
    zerobreak(s.s);
    popen(s);
    fn print_arg(s: ps, input: ast::arg) {
        print_arg_mode(s, input.mode);
        if str::len(input.ident) > 0u {
            word_space(s, input.ident + ":");
        }
        print_type(s, input.ty);
    }
    commasep(s, inconsistent, decl.inputs, print_arg);
    pclose(s);
    maybe_print_comment(s, decl.output.span.lo);
    if decl.output.node != ast::ty_nil {
        space_if_not_bol(s);
        ibox(s, indent_unit);
        word_space(s, "->");
        if decl.cf == ast::noreturn { word_nbsp(s, "!"); }
        else { print_type(s, decl.output); }
        end(s);
    }
    word(s.s, constrs_str(decl.constraints, ast_ty_fn_constr_to_str));
    end(s);
}

fn maybe_print_trailing_comment(s: ps, span: codemap::span,
                                next_pos: option<uint>) {
    let mut cm;
    alt s.cm { some(ccm) { cm = ccm; } _ { ret; } }
    alt next_comment(s) {
      some(cmnt) {
        if cmnt.style != comments::trailing { ret; }
        let span_line = codemap::lookup_char_pos(cm, span.hi);
        let comment_line = codemap::lookup_char_pos(cm, cmnt.pos);
        let mut next = cmnt.pos + 1u;
        alt next_pos { none { } some(p) { next = p; } }
        if span.hi < cmnt.pos && cmnt.pos < next &&
               span_line.line == comment_line.line {
            print_comment(s, cmnt);
            s.cur_cmnt += 1u;
        }
      }
      _ { }
    }
}

fn print_remaining_comments(s: ps) {
    // If there aren't any remaining comments, then we need to manually
    // make sure there is a line break at the end.
    if option::is_none(next_comment(s)) { hardbreak(s.s); }
    loop {
        alt next_comment(s) {
          some(cmnt) { print_comment(s, cmnt); s.cur_cmnt += 1u; }
          _ { break; }
        }
    }
}

fn print_literal(s: ps, &&lit: @ast::lit) {
    maybe_print_comment(s, lit.span.lo);
    alt next_lit(s, lit.span.lo) {
      some(lt) {
        word(s.s, lt.lit);
        ret;
      }
      _ {}
    }
    alt lit.node {
      ast::lit_str(st) { print_string(s, st); }
      ast::lit_int(ch, ast::ty_char) {
        word(s.s, "'" + escape_str(str::from_char(ch as char), '\'') + "'");
      }
      ast::lit_int(i, t) {
        if i < 0_i64 {
            word(s.s,
                 "-" + u64::to_str(-i as u64, 10u)
                 + ast_util::int_ty_to_str(t));
        } else {
            word(s.s,
                 u64::to_str(i as u64, 10u)
                 + ast_util::int_ty_to_str(t));
        }
      }
      ast::lit_uint(u, t) {
        word(s.s,
             u64::to_str(u, 10u)
             + ast_util::uint_ty_to_str(t));
      }
      ast::lit_float(f, t) {
        word(s.s, f + ast_util::float_ty_to_str(t));
      }
      ast::lit_nil { word(s.s, "()"); }
      ast::lit_bool(val) {
        if val { word(s.s, "true"); } else { word(s.s, "false"); }
      }
    }
}

fn lit_to_str(l: @ast::lit) -> str { be to_str(l, print_literal); }

fn next_lit(s: ps, pos: uint) -> option<comments::lit> {
    alt s.literals {
      some(lits) {
        while s.cur_lit < vec::len(lits) {
            let lt = lits[s.cur_lit];
            if lt.pos > pos { ret none; }
            s.cur_lit += 1u;
            if lt.pos == pos { ret some(lt); }
        }
        ret none;
      }
      _ { ret none; }
    }
}

fn maybe_print_comment(s: ps, pos: uint) {
    loop {
        alt next_comment(s) {
          some(cmnt) {
            if cmnt.pos < pos {
                print_comment(s, cmnt);
                s.cur_cmnt += 1u;
            } else { break; }
          }
          _ { break; }
        }
    }
}

fn print_comment(s: ps, cmnt: comments::cmnt) {
    alt cmnt.style {
      comments::mixed {
        assert (vec::len(cmnt.lines) == 1u);
        zerobreak(s.s);
        word(s.s, cmnt.lines[0]);
        zerobreak(s.s);
      }
      comments::isolated {
        pprust::hardbreak_if_not_bol(s);
        for cmnt.lines.each {|line|
            // Don't print empty lines because they will end up as trailing
            // whitespace
            if str::is_not_empty(line) { word(s.s, line); }
            hardbreak(s.s);
        }
      }
      comments::trailing {
        word(s.s, " ");
        if vec::len(cmnt.lines) == 1u {
            word(s.s, cmnt.lines[0]);
            hardbreak(s.s);
        } else {
            ibox(s, 0u);
            for cmnt.lines.each {|line|
                if str::is_not_empty(line) { word(s.s, line); }
                hardbreak(s.s);
            }
            end(s);
        }
      }
      comments::blank_line {
        // We need to do at least one, possibly two hardbreaks.
        let is_semi =
            alt s.s.last_token() {
              pp::STRING(s, _) { s == ";" }
              _ { false }
            };
        if is_semi || is_begin(s) || is_end(s) { hardbreak(s.s); }
        hardbreak(s.s);
      }
    }
}

fn print_string(s: ps, st: str) {
    word(s.s, "\"");
    word(s.s, escape_str(st, '"'));
    word(s.s, "\"");
}

fn escape_str(st: str, to_escape: char) -> str {
    let mut out: str = "";
    let len = str::len(st);
    let mut i = 0u;
    while i < len {
        alt st[i] as char {
          '\n' { out += "\\n"; }
          '\t' { out += "\\t"; }
          '\r' { out += "\\r"; }
          '\\' { out += "\\\\"; }
          cur {
            if cur == to_escape { out += "\\"; }
            // FIXME some (or all?) non-ascii things should be escaped

            str::push_char(out, cur);
          }
        }
        i += 1u;
    }
    ret out;
}

fn to_str<T>(t: T, f: fn@(ps, T)) -> str {
    let buffer = io::mem_buffer();
    let s = rust_printer(io::mem_buffer_writer(buffer));
    f(s, t);
    eof(s.s);
    io::mem_buffer_str(buffer)
}

fn next_comment(s: ps) -> option<comments::cmnt> {
    alt s.comments {
      some(cmnts) {
        if s.cur_cmnt < vec::len(cmnts) {
            ret some(cmnts[s.cur_cmnt]);
        } else { ret none::<comments::cmnt>; }
      }
      _ { ret none::<comments::cmnt>; }
    }
}

fn constr_args_to_str<T>(f: fn@(T) -> str, args: [@ast::sp_constr_arg<T>]) ->
   str {
    let mut comma = false;
    let mut s = "(";
    for args.each {|a|
        if comma { s += ", "; } else { comma = true; }
        s += constr_arg_to_str::<T>(f, a.node);
    }
    s += ")";
    ret s;
}

fn constr_arg_to_str<T>(f: fn@(T) -> str, c: ast::constr_arg_general_<T>) ->
   str {
    alt c {
      ast::carg_base { ret "*"; }
      ast::carg_ident(i) { ret f(i); }
      ast::carg_lit(l) { ret lit_to_str(l); }
    }
}

// needed b/c constr_args_to_str needs
// something that takes an alias
// (argh)
fn uint_to_str(&&i: uint) -> str { ret uint::str(i); }

fn ast_ty_fn_constr_to_str(&&c: @ast::constr) -> str {
    ret path_to_str(c.node.path) +
            constr_args_to_str(uint_to_str, c.node.args);
}

fn ast_fn_constr_to_str(decl: ast::fn_decl, &&c: @ast::constr) -> str {
    let arg_to_str = bind fn_arg_idx_to_str(decl, _);
    ret path_to_str(c.node.path) +
            constr_args_to_str(arg_to_str, c.node.args);
}

fn ty_constr_to_str(&&c: @ast::ty_constr) -> str {
    fn ty_constr_path_to_str(&&p: @ast::path) -> str { "*." + path_to_str(p) }

    ret path_to_str(c.node.path) +
            constr_args_to_str::<@ast::path>(ty_constr_path_to_str,
                                             c.node.args);
}

fn constrs_str<T>(constrs: [T], elt: fn(T) -> str) -> str {
    let mut s = "", colon = true;
    for constrs.each {|c|
        if colon { s += " : "; colon = false; } else { s += ", "; }
        s += elt(c);
    }
    ret s;
}

fn fn_arg_idx_to_str(decl: ast::fn_decl, &&idx: uint) -> str {
    decl.inputs[idx].ident
}

fn opt_proto_to_str(opt_p: option<ast::proto>) -> str {
    alt opt_p {
      none { "fn" }
      some(p) { proto_to_str(p) }
    }
}

fn proto_to_str(p: ast::proto) -> str {
    ret alt p {
      ast::proto_bare { "native fn" }
      ast::proto_any { "fn" }
      ast::proto_block { "fn&" }
      ast::proto_uniq { "fn~" }
      ast::proto_box { "fn@" }
    };
}

//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//