import std::str;
import std::istr;
import std::option;
import codemap::span;
import ast::*;

fn respan<@T>(sp: &span, t: &T) -> spanned<T> { ret {node: t, span: sp}; }

/* assuming that we're not in macro expansion */
fn mk_sp(lo: uint, hi: uint) -> span {
    ret {lo: lo, hi: hi, expanded_from: codemap::os_none};
}

// make this a const, once the compiler supports it
fn dummy_sp() -> span { ret mk_sp(0u, 0u); }

fn path_name(p: &path) -> istr { path_name_i(p.node.idents) }

fn path_name_i(idents: &[ident]) -> istr {
    istr::connect(idents, ~"::")
}

fn local_def(id: node_id) -> def_id { ret {crate: local_crate, node: id}; }

fn variant_def_ids(d: &def) -> {tg: def_id, var: def_id} {
    alt d { def_variant(tag_id, var_id) { ret {tg: tag_id, var: var_id}; } }
}

fn def_id_of_def(d: def) -> def_id {
    alt d {
      def_fn(id, _) { ret id; }
      def_obj_field(id) { ret id; }
      def_mod(id) { ret id; }
      def_native_mod(id) { ret id; }
      def_const(id) { ret id; }
      def_arg(id) { ret id; }
      def_local(id) { ret id; }
      def_variant(_, id) { ret id; }
      def_ty(id) { ret id; }
      def_ty_arg(_, _) { fail; }
      def_binding(id) { ret id; }
      def_use(id) { ret id; }
      def_native_ty(id) { ret id; }
      def_native_fn(id) { ret id; }
      def_upvar(id, _) { ret id; }
    }
}

type pat_id_map = std::map::hashmap<istr, ast::node_id>;

// This is used because same-named variables in alternative patterns need to
// use the node_id of their namesake in the first pattern.
fn pat_id_map(pat: &@pat) -> pat_id_map {
    let map = std::map::new_str_hash::<node_id>();
    for each bound in pat_bindings(pat) {
        let name = alt bound.node { pat_bind(n) { n } };
        map.insert(name, bound.id);
    }
    ret map;
}

// FIXME: could return a constrained type
iter pat_bindings(pat: &@pat) -> @pat {
    alt pat.node {
      pat_bind(_) { put pat; }
      pat_tag(_, sub) {
        for p in sub { for each b in pat_bindings(p) { put b; } }
      }
      pat_rec(fields, _) {
        for f in fields { for each b in pat_bindings(f.pat) { put b; } }
      }
      pat_tup(elts) {
        for elt in elts { for each b in pat_bindings(elt) { put b; } }
      }
      pat_box(sub) { for each b in pat_bindings(sub) { put b; } }
      pat_wild. | pat_lit(_) { }
    }
}

fn pat_binding_ids(pat: &@pat) -> [node_id] {
    let found = [];
    for each b in pat_bindings(pat) { found += [b.id]; }
    ret found;
}

fn binop_to_str(op: binop) -> istr {
    alt op {
      add. { ret ~"+"; }
      sub. { ret ~"-"; }
      mul. { ret ~"*"; }
      div. { ret ~"/"; }
      rem. { ret ~"%"; }
      and. { ret ~"&&"; }
      or. { ret ~"||"; }
      bitxor. { ret ~"^"; }
      bitand. { ret ~"&"; }
      bitor. { ret ~"|"; }
      lsl. { ret ~"<<"; }
      lsr. { ret ~">>"; }
      asr. { ret ~">>>"; }
      eq. { ret ~"=="; }
      lt. { ret ~"<"; }
      le. { ret ~"<="; }
      ne. { ret ~"!="; }
      ge. { ret ~">="; }
      gt. { ret ~">"; }
    }
}

pure fn lazy_binop(b: binop) -> bool {
    alt b { and. { true } or. { true } _ { false } }
}

fn unop_to_str(op: unop) -> istr {
    alt op {
      box(mt) { if mt == mut { ret ~"@mutable "; } ret ~"@"; }
      deref. { ret ~"*"; }
      not. { ret ~"!"; }
      neg. { ret ~"-"; }
    }
}

fn is_path(e: &@expr) -> bool {
    ret alt e.node { expr_path(_) { true } _ { false } };
}

fn ty_mach_to_str(tm: ty_mach) -> istr {
    alt tm {
      ty_u8. { ret ~"u8"; }
      ty_u16. { ret ~"u16"; }
      ty_u32. { ret ~"u32"; }
      ty_u64. { ret ~"u64"; }
      ty_i8. { ret ~"i8"; }
      ty_i16. { ret ~"i16"; }
      ty_i32. { ret ~"i32"; }
      ty_i64. { ret ~"i64"; }
      ty_f32. { ret ~"f32"; }
      ty_f64. { ret ~"f64"; }
    }
}


fn is_exported(i: ident, m: _mod) -> bool {
    let nonlocal = true;
    for it: @ast::item in m.items {
        if it.ident == i { nonlocal = false; }
        alt it.node {
          item_tag(variants, _) {
            for v: variant in variants {
                if v.node.name == i { nonlocal = false; }
            }
          }
          _ { }
        }
        if !nonlocal { break; }
    }
    let count = 0u;
    for vi: @ast::view_item in m.view_items {
        alt vi.node {
          ast::view_item_export(ids, _) {
            for id in ids { if istr::eq(i, id) { ret true; } }
            count += 1u;
          }
          _ {/* fall through */ }
        }
    }
    // If there are no declared exports then
    // everything not imported is exported
    // even if it's nonlocal (since it's explicit)
    ret count == 0u && !nonlocal;
}

pure fn is_call_expr(e: @expr) -> bool {
    alt e.node { expr_call(_, _) { true } _ { false } }
}

fn is_constraint_arg(e: @expr) -> bool {
    alt e.node {
      expr_lit(_) { ret true; }
      expr_path(_) { ret true; }
      _ { ret false; }
    }
}

fn eq_ty(a: &@ty, b: &@ty) -> bool { ret std::box::ptr_eq(a, b); }

fn hash_ty(t: &@ty) -> uint { ret t.span.lo << 16u + t.span.hi; }

fn block_from_expr(e: @expr) -> blk {
    let blk_ = checked_blk([], option::some::<@expr>(e), e.id);
    ret {node: blk_, span: e.span};
}

fn checked_blk(stmts1: [@stmt], expr1: option::t<@expr>, id1: node_id)
    -> blk_ {
    ret {stmts: stmts1, expr: expr1, id: id1, rules: checked};
}

fn obj_field_from_anon_obj_field(f: &anon_obj_field) -> obj_field {
    ret {mut: f.mut, ty: f.ty, ident: f.ident, id: f.id};
}

// This is a convenience function to transfor ternary expressions to if
// expressions so that they can be treated the same
fn ternary_to_if(e: &@expr) -> @ast::expr {
    alt e.node {
      expr_ternary(cond, then, els) {
        let then_blk = block_from_expr(then);
        let els_blk = block_from_expr(els);
        let els_expr =
            @{id: els.id, node: expr_block(els_blk), span: els.span};
        ret @{id: e.id,
              node: expr_if(cond, then_blk, option::some(els_expr)),
              span: e.span};
      }
      _ { fail; }
    }
}