import std::str;
import std::vec;
import std::option;
import std::map::hashmap;
import driver::session::session;
import codemap::span;
import std::map::new_str_hash;
import codemap;

type syntax_expander =
    fn(&ext_ctxt, span, @ast::expr, &option::t<istr>) -> @ast::expr;
type macro_def = {ident: istr, ext: syntax_extension};
type macro_definer =
    fn(&ext_ctxt, span, @ast::expr, &option::t<istr>) -> macro_def;

tag syntax_extension {
    normal(syntax_expander);
    macro_defining(macro_definer);
}

// A temporary hard-coded map of methods for expanding syntax extension
// AST nodes into full ASTs
fn syntax_expander_table() -> hashmap<istr, syntax_extension> {
    let syntax_expanders = new_str_hash::<syntax_extension>();
    syntax_expanders.insert(~"fmt", normal(ext::fmt::expand_syntax_ext));
    syntax_expanders.insert(~"env", normal(ext::env::expand_syntax_ext));
    syntax_expanders.insert(~"macro",
                            macro_defining(ext::simplext::add_new_extension));
    syntax_expanders.insert(~"concat_idents",
                            normal(ext::concat_idents::expand_syntax_ext));
    syntax_expanders.insert(~"ident_to_str",
                            normal(ext::ident_to_str::expand_syntax_ext));
    syntax_expanders.insert(~"log_syntax",
                            normal(ext::log_syntax::expand_syntax_ext));
    ret syntax_expanders;
}

obj ext_ctxt(sess: @session,
             crate_file_name_hack: istr,
             mutable backtrace: codemap::opt_span) {
    fn crate_file_name() -> istr { ret crate_file_name_hack; }

    fn session() -> @session { ret sess; }

    fn print_backtrace() { }

    fn backtrace() -> codemap::opt_span { ret backtrace; }

    fn bt_push(sp: span) {
        backtrace =
            codemap::os_some(@{lo: sp.lo,
                               hi: sp.hi,
                               expanded_from: backtrace});
    }
    fn bt_pop() {
        alt backtrace {
          codemap::os_some(@{expanded_from: pre, _}) {
            let tmp = pre;
            backtrace = tmp;
          }
          _ { self.bug(~"tried to pop without a push"); }
        }
    }

    fn span_fatal(sp: span, msg: istr) -> ! {
        self.print_backtrace();
        sess.span_fatal(sp, msg);
    }
    fn span_err(sp: span, msg: istr) {
        self.print_backtrace();
        sess.span_err(sp, msg);
    }
    fn span_unimpl(sp: span, msg: istr) -> ! {
        self.print_backtrace();
        sess.span_unimpl(sp, msg);
    }
    fn span_bug(sp: span, msg: istr) -> ! {
        self.print_backtrace();
        sess.span_bug(sp, msg);
    }
    fn bug(msg: istr) -> ! {
        self.print_backtrace();
        sess.bug(msg);
    }
    fn next_id() -> ast::node_id { ret sess.next_node_id(); }

}

fn mk_ctxt(sess: &session) -> ext_ctxt {
    // FIXME: Some extensions work by building ASTs with paths to functions
    // they need to call at runtime. As those functions live in the std crate,
    // the paths are prefixed with "std::". Unfortunately, these paths can't
    // work for code called from inside the stdard library, so here we pass
    // the extensions the file name of the crate being compiled so they can
    // use it to guess whether paths should be prepended with "std::". This is
    // super-ugly and needs a better solution.
    let crate_file_name_hack = sess.get_codemap().files[0].name;

    ret ext_ctxt(@sess, crate_file_name_hack,
                 codemap::os_none);
}

fn expr_to_str(cx: &ext_ctxt, expr: @ast::expr, error: &istr) -> istr {
    alt expr.node {
      ast::expr_lit(l) {
        alt l.node {
          ast::lit_str(s) { ret s; }
          _ { cx.span_fatal(l.span, error); }
        }
      }
      _ { cx.span_fatal(expr.span, error); }
    }
}

fn expr_to_ident(cx: &ext_ctxt, expr: @ast::expr,
                 error: &istr) -> ast::ident {
    alt expr.node {
      ast::expr_path(p) {
        if vec::len(p.node.types) > 0u || vec::len(p.node.idents) != 1u {
            cx.span_fatal(expr.span, error);
        } else { ret p.node.idents[0]; }
      }
      _ { cx.span_fatal(expr.span, error); }
    }
}

fn make_new_lit(cx: &ext_ctxt, sp: codemap::span, lit: ast::lit_) ->
   @ast::expr {
    let sp_lit = @{node: lit, span: sp};
    ret @{id: cx.next_id(), node: ast::expr_lit(sp_lit), span: sp};
}



//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//