rust/src/libsyntax/ast.rs

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// The Rust abstract syntax tree.

use codemap::{span, spanned};
use abi::AbiSet;
use opt_vec::OptVec;

use core::cast;
use core::option::{None, Option, Some};
use core::task;
use core::to_bytes;
use core::to_str::ToStr;
use std::serialize::{Encodable, Decodable, Encoder, Decoder};


/* can't import macros yet, so this is copied from token.rs. See its comment
 * there. */
macro_rules! interner_key (
    () => (cast::transmute::<(uint, uint),
            &fn(+v: @@::parse::token::ident_interner)>(
        (-3 as uint, 0u)))
)

// an identifier contains an index into the interner
// table and a SyntaxContext to track renaming and
// macro expansion per Flatt et al., "Macros
// That Work Together"
#[deriving(Eq)]
pub struct ident { repr: Name }

// a SyntaxContext represents a chain of macro-expandings
// and renamings. Each macro expansion corresponds to
// a fresh uint
#[deriving(Eq)]
pub enum SyntaxContext {
    MT,
    Mark (Mrk,~SyntaxContext),
    Rename (~ident,Name,~SyntaxContext)
}

/*
// ** this is going to have to apply to paths, not to idents.
// Returns true if these two identifiers access the same
// local binding or top-level binding... that's what it
// should do. For now, it just compares the names.
pub fn free_ident_eq (a : ident, b: ident) -> bool{
    a.repr == b.repr
}
*/
// a name represents a string, interned
type Name = uint;
// a mark represents a unique id associated
// with a macro expansion
type Mrk = uint;

impl<S:Encoder> Encodable<S> for ident {
    fn encode(&self, s: &S) {
        let intr = match unsafe {
            task::local_data::local_data_get(interner_key!())
        } {
            None => fail!(~"encode: TLS interner not set up"),
            Some(intr) => intr
        };

        s.emit_str(*(*intr).get(*self));
    }
}

impl<D:Decoder> Decodable<D> for ident {
    fn decode(d: &D) -> ident {
        let intr = match unsafe {
            task::local_data::local_data_get(interner_key!())
        } {
            None => fail!(~"decode: TLS interner not set up"),
            Some(intr) => intr
        };

        (*intr).intern(@d.read_str())
    }
}

impl to_bytes::IterBytes for ident {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        self.repr.iter_bytes(lsb0, f)
    }
}

// Functions may or may not have names.
pub type fn_ident = Option<ident>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct Lifetime {
    id: node_id,
    span: span,
    ident: ident
}

// a "Path" is essentially Rust's notion of a name;
// for instance: core::cmp::Eq  .  It's represented
// as a sequence of identifiers, along with a bunch
// of supporting information.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct path {
    span: span,
    global: bool,
    idents: ~[ident],
    rp: Option<@Lifetime>,
    types: ~[@Ty],
}

pub type crate_num = int;

pub type node_id = int;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct def_id {
    crate: crate_num,
    node: node_id,
}

pub static local_crate: crate_num = 0;
pub static crate_node_id: node_id = 0;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
// The AST represents all type param bounds as types.
// typeck::collect::compute_bounds matches these against
// the "special" built-in traits (see middle::lang_items) and
// detects Copy, Send, Owned, and Const.
pub enum TyParamBound {
    TraitTyParamBound(@trait_ref),
    RegionTyParamBound
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct TyParam {
    ident: ident,
    id: node_id,
    bounds: @OptVec<TyParamBound>
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct Generics {
    lifetimes: OptVec<Lifetime>,
    ty_params: OptVec<TyParam>
}

pub impl Generics {
    fn is_parameterized(&self) -> bool {
        self.lifetimes.len() + self.ty_params.len() > 0
    }
    fn is_lt_parameterized(&self) -> bool {
        self.lifetimes.len() > 0
    }
    fn is_type_parameterized(&self) -> bool {
        self.ty_params.len() > 0
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum def {
    def_fn(def_id, purity),
    def_static_method(/* method */ def_id,
                      /* trait */  Option<def_id>,
                      purity),
    def_self(node_id, bool /* is_implicit */),
    def_self_ty(/* trait id */ node_id),
    def_mod(def_id),
    def_foreign_mod(def_id),
    def_const(def_id),
    def_arg(node_id, mode, bool /* is_mutbl */),
    def_local(node_id, bool /* is_mutbl */),
    def_variant(def_id /* enum */, def_id /* variant */),
    def_ty(def_id),
    def_trait(def_id),
    def_prim_ty(prim_ty),
    def_ty_param(def_id, uint),
    def_binding(node_id, binding_mode),
    def_use(def_id),
    def_upvar(node_id,  // id of closed over var
              @def,     // closed over def
              node_id,  // expr node that creates the closure
              node_id), // id for the block/body of the closure expr
    def_struct(def_id),
    def_typaram_binder(node_id), /* struct, impl or trait with ty params */
    def_region(node_id),
    def_label(node_id)
}


// The set of meta_items that define the compilation environment of the crate,
// used to drive conditional compilation
pub type crate_cfg = ~[@meta_item];

pub type crate = spanned<crate_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct crate_ {
    module: _mod,
    attrs: ~[attribute],
    config: crate_cfg,
}

pub type meta_item = spanned<meta_item_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum meta_item_ {
    meta_word(@~str),
    meta_list(@~str, ~[@meta_item]),
    meta_name_value(@~str, lit),
}

pub type blk = spanned<blk_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct blk_ {
    view_items: ~[@view_item],
    stmts: ~[@stmt],
    expr: Option<@expr>,
    id: node_id,
    rules: blk_check_mode,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct pat {
    id: node_id,
    node: pat_,
    span: span,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct field_pat {
    ident: ident,
    pat: @pat,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum binding_mode {
    bind_by_copy,
    bind_by_ref(mutability),
    bind_infer
}

impl to_bytes::IterBytes for binding_mode {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        match *self {
          bind_by_copy => 0u8.iter_bytes(lsb0, f),

          bind_by_ref(ref m) =>
          to_bytes::iter_bytes_2(&1u8, m, lsb0, f),

          bind_infer =>
          2u8.iter_bytes(lsb0, f),
        }
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum pat_ {
    pat_wild,
    // A pat_ident may either be a new bound variable,
    // or a nullary enum (in which case the second field
    // is None).
    // In the nullary enum case, the parser can't determine
    // which it is. The resolver determines this, and
    // records this pattern's node_id in an auxiliary
    // set (of "pat_idents that refer to nullary enums")
    pat_ident(binding_mode, @path, Option<@pat>),
    pat_enum(@path, Option<~[@pat]>), /* "none" means a * pattern where
                                       * we don't bind the fields to names */
    pat_struct(@path, ~[field_pat], bool),
    pat_tup(~[@pat]),
    pat_box(@pat),
    pat_uniq(@pat),
    pat_region(@pat), // borrowed pointer pattern
    pat_lit(@expr),
    pat_range(@expr, @expr),
    // [a, b, ..i, y, z] is represented as
    // pat_vec(~[a, b], Some(i), ~[y, z])
    pat_vec(~[@pat], Option<@pat>, ~[@pat])
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum mutability { m_mutbl, m_imm, m_const, }

impl to_bytes::IterBytes for mutability {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum Sigil {
    BorrowedSigil,
    OwnedSigil,
    ManagedSigil
}

impl to_bytes::IterBytes for Sigil {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as uint).iter_bytes(lsb0, f)
    }
}

impl ToStr for Sigil {
    fn to_str(&self) -> ~str {
        match *self {
            BorrowedSigil => ~"&",
            OwnedSigil => ~"~",
            ManagedSigil => ~"@"
         }
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum vstore {
    // FIXME (#3469): Change uint to @expr (actually only constant exprs)
    vstore_fixed(Option<uint>),     // [1,2,3,4]
    vstore_uniq,                    // ~[1,2,3,4]
    vstore_box,                     // @[1,2,3,4]
    vstore_slice(Option<@Lifetime>) // &'foo? [1,2,3,4]
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum expr_vstore {
    expr_vstore_uniq,                  // ~[1,2,3,4]
    expr_vstore_box,                   // @[1,2,3,4]
    expr_vstore_mut_box,               // @mut [1,2,3,4]
    expr_vstore_slice,                 // &[1,2,3,4]
    expr_vstore_mut_slice,             // &mut [1,2,3,4]
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum binop {
    add,
    subtract,
    mul,
    div,
    rem,
    and,
    or,
    bitxor,
    bitand,
    bitor,
    shl,
    shr,
    eq,
    lt,
    le,
    ne,
    ge,
    gt,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum unop {
    box(mutability),
    uniq(mutability),
    deref,
    not,
    neg
}

// Generally, after typeck you can get the inferred value
// using ty::resolved_T(...).
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum inferable<T> {
    expl(T),
    infer(node_id)
}

impl<T:to_bytes::IterBytes> to_bytes::IterBytes for inferable<T> {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        match *self {
          expl(ref t) =>
          to_bytes::iter_bytes_2(&0u8, t, lsb0, f),

          infer(ref n) =>
          to_bytes::iter_bytes_2(&1u8, n, lsb0, f),
        }
    }
}

// "resolved" mode: the real modes.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum rmode { by_ref, by_copy }

impl to_bytes::IterBytes for rmode {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

// inferable mode.
pub type mode = inferable<rmode>;

pub type stmt = spanned<stmt_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum stmt_ {
    stmt_decl(@decl, node_id),

    // expr without trailing semi-colon (must have unit type):
    stmt_expr(@expr, node_id),

    // expr with trailing semi-colon (may have any type):
    stmt_semi(@expr, node_id),

    // bool: is there a trailing sem-colon?
    stmt_mac(mac, bool),
}

// FIXME (pending discussion of #1697, #2178...): local should really be
// a refinement on pat.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct local_ {
    is_mutbl: bool,
    ty: @Ty,
    pat: @pat,
    init: Option<@expr>,
    id: node_id,
}

pub type local = spanned<local_>;

pub type decl = spanned<decl_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum decl_ { decl_local(~[@local]), decl_item(@item), }

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct arm {
    pats: ~[@pat],
    guard: Option<@expr>,
    body: blk,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct field_ {
    mutbl: mutability,
    ident: ident,
    expr: @expr,
}

pub type field = spanned<field_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum blk_check_mode { default_blk, unsafe_blk, }

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct expr {
    id: node_id,
    // Extra node ID is only used for index, assign_op, unary, binary, method
    // call
    callee_id: node_id,
    node: expr_,
    span: span,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum CallSugar {
    NoSugar,
    DoSugar,
    ForSugar
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum expr_ {
    expr_vstore(@expr, expr_vstore),
    expr_vec(~[@expr], mutability),
    expr_call(@expr, ~[@expr], CallSugar),
    expr_method_call(@expr, ident, ~[@Ty], ~[@expr], CallSugar),
    expr_tup(~[@expr]),
    expr_binary(binop, @expr, @expr),
    expr_unary(unop, @expr),
    expr_lit(@lit),
    expr_cast(@expr, @Ty),
    expr_if(@expr, blk, Option<@expr>),
    expr_while(@expr, blk),
    /* Conditionless loop (can be exited with break, cont, or ret)
       Same semantics as while(true) { body }, but typestate knows that the
       (implicit) condition is always true. */
    expr_loop(blk, Option<ident>),
    expr_match(@expr, ~[arm]),
    expr_fn_block(fn_decl, blk),
    // Inner expr is always an expr_fn_block. We need the wrapping node to
    // easily type this (a function returning nil on the inside but bool on
    // the outside).
    expr_loop_body(@expr),
    // Like expr_loop_body but for 'do' blocks
    expr_do_body(@expr),
    expr_block(blk),

    expr_copy(@expr),
    expr_assign(@expr, @expr),
    expr_swap(@expr, @expr),
    expr_assign_op(binop, @expr, @expr),
    expr_field(@expr, ident, ~[@Ty]),
    expr_index(@expr, @expr),
    expr_path(@path),
    expr_addr_of(mutability, @expr),
    expr_break(Option<ident>),
    expr_again(Option<ident>),
    expr_ret(Option<@expr>),
    expr_log(@expr, @expr),

    expr_inline_asm(inline_asm),

    expr_mac(mac),

    // A struct literal expression.
    expr_struct(@path, ~[field], Option<@expr>),

    // A vector literal constructed from one repeated element.
    expr_repeat(@expr /* element */, @expr /* count */, mutability),

    // No-op: used solely so we can pretty-print faithfully
    expr_paren(@expr)
}

// When the main rust parser encounters a syntax-extension invocation, it
// parses the arguments to the invocation as a token-tree. This is a very
// loose structure, such that all sorts of different AST-fragments can
// be passed to syntax extensions using a uniform type.
//
// If the syntax extension is an MBE macro, it will attempt to match its
// LHS "matchers" against the provided token tree, and if it finds a
// match, will transcribe the RHS token tree, splicing in any captured
// macro_parser::matched_nonterminals into the tt_nonterminals it finds.
//
// The RHS of an MBE macro is the only place a tt_nonterminal or tt_seq
// makes any real sense. You could write them elsewhere but nothing
// else knows what to do with them, so you'll probably get a syntax
// error.
//
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
#[doc="For macro invocations; parsing is delegated to the macro"]
pub enum token_tree {
    // a single token
    tt_tok(span, ::parse::token::Token),
    // a delimited sequence (the delimiters appear as the first
    // and last elements of the vector)
    tt_delim(~[token_tree]),
    // These only make sense for right-hand-sides of MBE macros:

    // a kleene-style repetition sequence with a span, a tt_forest,
    // an optional separator (?), and a boolean where true indicates
    // zero or more (*), and false indicates one or more (+).
    tt_seq(span, ~[token_tree], Option<::parse::token::Token>, bool),

    // a syntactic variable that will be filled in by macro expansion.
    tt_nonterminal(span, ident)
}

//
// Matchers are nodes defined-by and recognized-by the main rust parser and
// language, but they're only ever found inside syntax-extension invocations;
// indeed, the only thing that ever _activates_ the rules in the rust parser
// for parsing a matcher is a matcher looking for the 'matchers' nonterminal
// itself. Matchers represent a small sub-language for pattern-matching
// token-trees, and are thus primarily used by the macro-defining extension
// itself.
//
// match_tok
// ---------
//
//     A matcher that matches a single token, denoted by the token itself. So
//     long as there's no $ involved.
//
//
// match_seq
// ---------
//
//     A matcher that matches a sequence of sub-matchers, denoted various
//     possible ways:
//
//             $(M)*       zero or more Ms
//             $(M)+       one or more Ms
//             $(M),+      one or more comma-separated Ms
//             $(A B C);*  zero or more semi-separated 'A B C' seqs
//
//
// match_nonterminal
// -----------------
//
//     A matcher that matches one of a few interesting named rust
//     nonterminals, such as types, expressions, items, or raw token-trees. A
//     black-box matcher on expr, for example, binds an expr to a given ident,
//     and that ident can re-occur as an interpolation in the RHS of a
//     macro-by-example rule. For example:
//
//        $foo:expr   =>     1 + $foo    // interpolate an expr
//        $foo:tt     =>     $foo        // interpolate a token-tree
//        $foo:tt     =>     bar! $foo   // only other valid interpolation
//                                       // is in arg position for another
//                                       // macro
//
// As a final, horrifying aside, note that macro-by-example's input is
// also matched by one of these matchers. Holy self-referential! It is matched
// by an match_seq, specifically this one:
//
//                   $( $lhs:matchers => $rhs:tt );+
//
// If you understand that, you have closed to loop and understand the whole
// macro system. Congratulations.
//
pub type matcher = spanned<matcher_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum matcher_ {
    // match one token
    match_tok(::parse::token::Token),
    // match repetitions of a sequence: body, separator, zero ok?,
    // lo, hi position-in-match-array used:
    match_seq(~[matcher], Option<::parse::token::Token>, bool, uint, uint),
    // parse a Rust NT: name to bind, name of NT, position in match array:
    match_nonterminal(ident, ident, uint)
}

pub type mac = spanned<mac_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum mac_ {
    mac_invoc_tt(@path,~[token_tree]),   // new macro-invocation
}

pub type lit = spanned<lit_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum lit_ {
    lit_str(@~str),
    lit_int(i64, int_ty),
    lit_uint(u64, uint_ty),
    lit_int_unsuffixed(i64),
    lit_float(@~str, float_ty),
    lit_float_unsuffixed(@~str),
    lit_nil,
    lit_bool(bool),
}

// NB: If you change this, you'll probably want to change the corresponding
// type structure in middle/ty.rs as well.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct mt {
    ty: @Ty,
    mutbl: mutability,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct ty_field_ {
    ident: ident,
    mt: mt,
}

pub type ty_field = spanned<ty_field_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct ty_method {
    ident: ident,
    attrs: ~[attribute],
    purity: purity,
    decl: fn_decl,
    generics: Generics,
    self_ty: self_ty,
    id: node_id,
    span: span,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
// A trait method is either required (meaning it doesn't have an
// implementation, just a signature) or provided (meaning it has a default
// implementation).
pub enum trait_method {
    required(ty_method),
    provided(@method),
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum int_ty { ty_i, ty_char, ty_i8, ty_i16, ty_i32, ty_i64, }

impl ToStr for int_ty {
    fn to_str(&self) -> ~str {
        ::ast_util::int_ty_to_str(*self)
    }
}

impl to_bytes::IterBytes for int_ty {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum uint_ty { ty_u, ty_u8, ty_u16, ty_u32, ty_u64, }

impl ToStr for uint_ty {
    fn to_str(&self) -> ~str {
        ::ast_util::uint_ty_to_str(*self)
    }
}

impl to_bytes::IterBytes for uint_ty {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum float_ty { ty_f, ty_f32, ty_f64, }

impl ToStr for float_ty {
    fn to_str(&self) -> ~str {
        ::ast_util::float_ty_to_str(*self)
    }
}

impl to_bytes::IterBytes for float_ty {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

// NB Eq method appears below.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct Ty {
    id: node_id,
    node: ty_,
    span: span,
}

// Not represented directly in the AST, referred to by name through a ty_path.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum prim_ty {
    ty_int(int_ty),
    ty_uint(uint_ty),
    ty_float(float_ty),
    ty_str,
    ty_bool,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum Onceness {
    Once,
    Many
}

impl ToStr for Onceness {
    fn to_str(&self) -> ~str {
        match *self {
            Once => ~"once",
            Many => ~"many"
        }
    }
}

impl to_bytes::IterBytes for Onceness {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as uint).iter_bytes(lsb0, f);
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct TyClosure {
    sigil: Sigil,
    region: Option<@Lifetime>,
    lifetimes: OptVec<Lifetime>,
    purity: purity,
    onceness: Onceness,
    decl: fn_decl
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct TyBareFn {
    purity: purity,
    abis: AbiSet,
    lifetimes: OptVec<Lifetime>,
    decl: fn_decl
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum ty_ {
    ty_nil,
    ty_bot, /* bottom type */
    ty_box(mt),
    ty_uniq(mt),
    ty_vec(mt),
    ty_fixed_length_vec(mt, @expr),
    ty_ptr(mt),
    ty_rptr(Option<@Lifetime>, mt),
    ty_closure(@TyClosure),
    ty_bare_fn(@TyBareFn),
    ty_tup(~[@Ty]),
    ty_path(@path, node_id),
    ty_mac(mac),
    // ty_infer means the type should be inferred instead of it having been
    // specified. This should only appear at the "top level" of a type and not
    // nested in one.
    ty_infer,
}

impl to_bytes::IterBytes for Ty {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        to_bytes::iter_bytes_2(&self.span.lo, &self.span.hi, lsb0, f);
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum asm_dialect {
    asm_att,
    asm_intel
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct inline_asm {
    asm: @~str,
    clobbers: @~str,
    inputs: ~[(@~str, @expr)],
    outputs: ~[(@~str, @expr)],
    volatile: bool,
    alignstack: bool,
    dialect: asm_dialect
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct arg {
    mode: mode,
    is_mutbl: bool,
    ty: @Ty,
    pat: @pat,
    id: node_id,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct fn_decl {
    inputs: ~[arg],
    output: @Ty,
    cf: ret_style,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum purity {
    pure_fn, // declared with "pure fn"
    unsafe_fn, // declared with "unsafe fn"
    impure_fn, // declared with "fn"
    extern_fn, // declared with "extern fn"
}

impl ToStr for purity {
    fn to_str(&self) -> ~str {
        match *self {
            impure_fn => ~"impure",
            unsafe_fn => ~"unsafe",
            pure_fn => ~"pure",
            extern_fn => ~"extern"
        }
    }
}

impl to_bytes::IterBytes for purity {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum ret_style {
    noreturn, // functions with return type _|_ that always
              // raise an error or exit (i.e. never return to the caller)
    return_val, // everything else
}

impl to_bytes::IterBytes for ret_style {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum self_ty_ {
    sty_static,                                // no self
    sty_value,                                 // `self`
    sty_region(Option<@Lifetime>, mutability), // `&'lt self`
    sty_box(mutability),                       // `@self`
    sty_uniq(mutability)                       // `~self`
}

impl self_ty_ {
    fn is_borrowed(&self) -> bool {
        match *self {
            sty_region(*) => true,
            _ => false
        }
    }
}

pub type self_ty = spanned<self_ty_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct method {
    ident: ident,
    attrs: ~[attribute],
    generics: Generics,
    self_ty: self_ty,
    purity: purity,
    decl: fn_decl,
    body: blk,
    id: node_id,
    span: span,
    self_id: node_id,
    vis: visibility,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct _mod {
    view_items: ~[@view_item],
    items: ~[@item],
}

// Foreign mods can be named or anonymous
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum foreign_mod_sort { named, anonymous }

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct foreign_mod {
    sort: foreign_mod_sort,
    abis: AbiSet,
    view_items: ~[@view_item],
    items: ~[@foreign_item],
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct variant_arg {
    ty: @Ty,
    id: node_id,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum variant_kind {
    tuple_variant_kind(~[variant_arg]),
    struct_variant_kind(@struct_def),
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct enum_def {
    variants: ~[variant],
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct variant_ {
    name: ident,
    attrs: ~[attribute],
    kind: variant_kind,
    id: node_id,
    disr_expr: Option<@expr>,
    vis: visibility,
}

pub type variant = spanned<variant_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct path_list_ident_ {
    name: ident,
    id: node_id,
}

pub type path_list_ident = spanned<path_list_ident_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum namespace { module_ns, type_value_ns }

pub type view_path = spanned<view_path_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum view_path_ {

    // quux = foo::bar::baz
    //
    // or just
    //
    // foo::bar::baz  (with 'baz =' implicitly on the left)
    view_path_simple(ident, @path, namespace, node_id),

    // foo::bar::*
    view_path_glob(@path, node_id),

    // foo::bar::{a,b,c}
    view_path_list(@path, ~[path_list_ident], node_id)
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct view_item {
    node: view_item_,
    attrs: ~[attribute],
    vis: visibility,
    span: span,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum view_item_ {
    view_item_extern_mod(ident, ~[@meta_item], node_id),
    view_item_use(~[@view_path]),
}

// Meta-data associated with an item
pub type attribute = spanned<attribute_>;

// Distinguishes between attributes that decorate items and attributes that
// are contained as statements within items. These two cases need to be
// distinguished for pretty-printing.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum attr_style { attr_outer, attr_inner, }

// doc-comments are promoted to attributes that have is_sugared_doc = true
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct attribute_ {
    style: attr_style,
    value: @meta_item,
    is_sugared_doc: bool,
}

/*
  trait_refs appear in impls.
  resolve maps each trait_ref's ref_id to its defining trait; that's all
  that the ref_id is for. The impl_id maps to the "self type" of this impl.
  If this impl is an item_impl, the impl_id is redundant (it could be the
  same as the impl's node id).
 */
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct trait_ref {
    path: @path,
    ref_id: node_id,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum visibility { public, private, inherited }

impl visibility {
    fn inherit_from(&self, parent_visibility: visibility) -> visibility {
        match self {
            &inherited => parent_visibility,
            &public | &private => *self
        }
    }
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct struct_field_ {
    kind: struct_field_kind,
    id: node_id,
    ty: @Ty,
}

pub type struct_field = spanned<struct_field_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum struct_field_kind {
    named_field(ident, struct_mutability, visibility),
    unnamed_field   // element of a tuple-like struct
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct struct_def {
    fields: ~[@struct_field], /* fields */
    /* (not including ctor or dtor) */
    /* dtor is optional */
    dtor: Option<struct_dtor>,
    /* ID of the constructor. This is only used for tuple- or enum-like
     * structs. */
    ctor_id: Option<node_id>
}

/*
  FIXME (#3300): Should allow items to be anonymous. Right now
  we just use dummy names for anon items.
 */
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct item {
    ident: ident,
    attrs: ~[attribute],
    id: node_id,
    node: item_,
    vis: visibility,
    span: span,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum item_ {
    item_const(@Ty, @expr),
    item_fn(fn_decl, purity, AbiSet, Generics, blk),
    item_mod(_mod),
    item_foreign_mod(foreign_mod),
    item_ty(@Ty, Generics),
    item_enum(enum_def, Generics),
    item_struct(@struct_def, Generics),
    item_trait(Generics, ~[@trait_ref], ~[trait_method]),
    item_impl(Generics,
              Option<@trait_ref>, // (optional) trait this impl implements
              @Ty, // self
              ~[@method]),
    // a macro invocation (which includes macro definition)
    item_mac(mac),
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum struct_mutability { struct_mutable, struct_immutable }

impl to_bytes::IterBytes for struct_mutability {
    fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
        (*self as u8).iter_bytes(lsb0, f)
    }
}

pub type struct_dtor = spanned<struct_dtor_>;

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct struct_dtor_ {
    id: node_id,
    attrs: ~[attribute],
    self_id: node_id,
    body: blk,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub struct foreign_item {
    ident: ident,
    attrs: ~[attribute],
    node: foreign_item_,
    id: node_id,
    span: span,
    vis: visibility,
}

#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum foreign_item_ {
    foreign_item_fn(fn_decl, purity, Generics),
    foreign_item_const(@Ty)
}

// The data we save and restore about an inlined item or method.  This is not
// part of the AST that we parse from a file, but it becomes part of the tree
// that we trans.
#[auto_encode]
#[auto_decode]
#[deriving(Eq)]
pub enum inlined_item {
    ii_item(@item),
    ii_method(def_id /* impl id */, @method),
    ii_foreign(@foreign_item),
    ii_dtor(struct_dtor, ident, Generics, def_id /* parent id */)
}

#[cfg(test)]
mod test {
    //are asts encodable?

    // it looks like this *will* be a compiler bug, after
    // I get deriving_eq for crates into incoming :)
    /*
    use std;
    use codemap::*;
    use super::*;

    #[test] fn check_asts_encodable() {
        let bogus_span = span {lo:BytePos(10),
                               hi:BytePos(20),
                               expn_info:None};
        let _e : crate =
            spanned{
            node: crate_{
                module: _mod {view_items: ~[], items: ~[]},
                attrs: ~[],
                config: ~[]
            },
            span: bogus_span};
        // doesn't matter which encoder we use....
        let _f = (_e as std::serialize::Encodable::<std::json::Encoder>);
    }
    */
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//