rust/src/libsyntax/ext/base.rs

import std::map::hashmap;
import parse::parser;
import diagnostic::span_handler;
import codemap::{codemap, span, expn_info, expanded_from};
import std::map::str_hash;

// obsolete old-style #macro code:
//
//    syntax_expander, normal, macro_defining, macro_definer,
//    builtin
//
// new-style macro! tt code:
//
//    syntax_expander_tt, syntax_expander_tt_item, mac_result,
//    expr_tt, item_tt
//
// also note that ast::mac has way too many cases and can probably
// be trimmed down substantially.

// second argument is the span to blame for general argument problems
type syntax_expander_ =
    fn@(ext_ctxt, span, ast::mac_arg, ast::mac_body) -> @ast::expr;
// second argument is the origin of the macro, if user-defined
type syntax_expander = {expander: syntax_expander_, span: option<span>};

type macro_def = {ident: ast::ident, ext: syntax_extension};

// macro_definer is obsolete, remove when #old_macros go away.
type macro_definer =
    fn@(ext_ctxt, span, ast::mac_arg, ast::mac_body) -> macro_def;

type item_decorator =
    fn@(ext_ctxt, span, ast::meta_item, ~[@ast::item]) -> ~[@ast::item];

type syntax_expander_tt = {expander: syntax_expander_tt_, span: option<span>};
type syntax_expander_tt_ = fn@(ext_ctxt, span, ~[ast::token_tree])
    -> mac_result;

type syntax_expander_tt_item
    = {expander: syntax_expander_tt_item_, span: option<span>};
type syntax_expander_tt_item_
    = fn@(ext_ctxt, span, ast::ident, ~[ast::token_tree]) -> mac_result;

enum mac_result {
    mr_expr(@ast::expr),
    mr_item(@ast::item),
    mr_def(macro_def)
}

enum syntax_extension {

    // normal() is obsolete, remove when #old_macros go away.
    normal(syntax_expander),

    // macro_defining() is obsolete, remove when #old_macros go away.
    macro_defining(macro_definer),

    // #[auto_serialize] and such. will probably survive death of #old_macros
    item_decorator(item_decorator),

    // Token-tree expanders
    expr_tt(syntax_expander_tt),
    item_tt(syntax_expander_tt_item),
}

// A temporary hard-coded map of methods for expanding syntax extension
// AST nodes into full ASTs
fn syntax_expander_table() -> hashmap<~str, syntax_extension> {
    fn builtin(f: syntax_expander_) -> syntax_extension
        {normal({expander: f, span: none})}
    fn builtin_item_tt(f: syntax_expander_tt_item_) -> syntax_extension {
        item_tt({expander: f, span: none})
    }
    let syntax_expanders = str_hash::<syntax_extension>();
    syntax_expanders.insert(~"macro",
                            macro_defining(ext::simplext::add_new_extension));
    syntax_expanders.insert(~"macro_rules",
                            builtin_item_tt(
                                ext::tt::macro_rules::add_new_extension));
    syntax_expanders.insert(~"fmt", builtin(ext::fmt::expand_syntax_ext));
    syntax_expanders.insert(~"auto_serialize",
                            item_decorator(ext::auto_serialize::expand));
    syntax_expanders.insert(~"env", builtin(ext::env::expand_syntax_ext));
    syntax_expanders.insert(~"concat_idents",
                            builtin(ext::concat_idents::expand_syntax_ext));
    syntax_expanders.insert(~"ident_to_str",
                            builtin(ext::ident_to_str::expand_syntax_ext));
    syntax_expanders.insert(~"log_syntax",
                            builtin(ext::log_syntax::expand_syntax_ext));
    syntax_expanders.insert(~"ast",
                            builtin(ext::qquote::expand_ast));
    syntax_expanders.insert(~"line",
                            builtin(ext::source_util::expand_line));
    syntax_expanders.insert(~"col",
                            builtin(ext::source_util::expand_col));
    syntax_expanders.insert(~"file",
                            builtin(ext::source_util::expand_file));
    syntax_expanders.insert(~"stringify",
                            builtin(ext::source_util::expand_stringify));
    syntax_expanders.insert(~"include",
                            builtin(ext::source_util::expand_include));
    syntax_expanders.insert(~"include_str",
                            builtin(ext::source_util::expand_include_str));
    syntax_expanders.insert(~"include_bin",
                            builtin(ext::source_util::expand_include_bin));
    syntax_expanders.insert(~"module",
                            builtin(ext::source_util::expand_mod));
    syntax_expanders.insert(~"proto",
                            builtin_item_tt(ext::pipes::expand_proto));
    ret syntax_expanders;
}


// One of these is made during expansion and incrementally updated as we go;
// when a macro expansion occurs, the resulting nodes have the backtrace()
// -> expn_info of their expansion context stored into their span.
iface ext_ctxt {
    fn codemap() -> codemap;
    fn parse_sess() -> parse::parse_sess;
    fn cfg() -> ast::crate_cfg;
    fn print_backtrace();
    fn backtrace() -> expn_info;
    fn mod_push(mod_name: ast::ident);
    fn mod_pop();
    fn mod_path() -> ~[ast::ident];
    fn bt_push(ei: codemap::expn_info_);
    fn bt_pop();
    fn span_fatal(sp: span, msg: ~str) -> !;
    fn span_err(sp: span, msg: ~str);
    fn span_warn(sp: span, msg: ~str);
    fn span_unimpl(sp: span, msg: ~str) -> !;
    fn span_bug(sp: span, msg: ~str) -> !;
    fn bug(msg: ~str) -> !;
    fn next_id() -> ast::node_id;
}

fn mk_ctxt(parse_sess: parse::parse_sess,
           cfg: ast::crate_cfg) -> ext_ctxt {
    type ctxt_repr = {parse_sess: parse::parse_sess,
                      cfg: ast::crate_cfg,
                      mut backtrace: expn_info,
                      mut mod_path: ~[ast::ident]};
    impl of ext_ctxt for ctxt_repr {
        fn codemap() -> codemap { self.parse_sess.cm }
        fn parse_sess() -> parse::parse_sess { self.parse_sess }
        fn cfg() -> ast::crate_cfg { self.cfg }
        fn print_backtrace() { }
        fn backtrace() -> expn_info { self.backtrace }
        fn mod_push(i: ast::ident) { vec::push(self.mod_path, i); }
        fn mod_pop() { vec::pop(self.mod_path); }
        fn mod_path() -> ~[ast::ident] { ret self.mod_path; }
        fn bt_push(ei: codemap::expn_info_) {
            alt ei {
              expanded_from({call_site: cs, callie: callie}) {
                self.backtrace =
                    some(@expanded_from({
                        call_site: {lo: cs.lo, hi: cs.hi,
                                    expn_info: self.backtrace},
                        callie: callie}));
              }
            }
        }
        fn bt_pop() {
            alt self.backtrace {
              some(@expanded_from({call_site: {expn_info: prev, _}, _})) {
                self.backtrace = prev
              }
              _ { self.bug(~"tried to pop without a push"); }
            }
        }
        fn span_fatal(sp: span, msg: ~str) -> ! {
            self.print_backtrace();
            self.parse_sess.span_diagnostic.span_fatal(sp, msg);
        }
        fn span_err(sp: span, msg: ~str) {
            self.print_backtrace();
            self.parse_sess.span_diagnostic.span_err(sp, msg);
        }
        fn span_warn(sp: span, msg: ~str) {
            self.print_backtrace();
            self.parse_sess.span_diagnostic.span_warn(sp, msg);
        }
        fn span_unimpl(sp: span, msg: ~str) -> ! {
            self.print_backtrace();
            self.parse_sess.span_diagnostic.span_unimpl(sp, msg);
        }
        fn span_bug(sp: span, msg: ~str) -> ! {
            self.print_backtrace();
            self.parse_sess.span_diagnostic.span_bug(sp, msg);
        }
        fn bug(msg: ~str) -> ! {
            self.print_backtrace();
            self.parse_sess.span_diagnostic.handler().bug(msg);
        }
        fn next_id() -> ast::node_id {
            ret parse::next_node_id(self.parse_sess);
        }
    }
    let imp : ctxt_repr = {
        parse_sess: parse_sess,
        cfg: cfg,
        mut backtrace: none,
        mut mod_path: ~[]
    };
    ret imp as ext_ctxt
}

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

fn get_mac_args_no_max(cx: ext_ctxt, sp: span, arg: ast::mac_arg,
                       min: uint, name: ~str) -> ~[@ast::expr] {
    ret get_mac_args(cx, sp, arg, min, none, name);
}

fn get_mac_args(cx: ext_ctxt, sp: span, arg: ast::mac_arg,
                min: uint, max: option<uint>, name: ~str) -> ~[@ast::expr] {
    alt arg {
      some(expr) {
        alt expr.node {
          ast::expr_vec(elts, _) {
            let elts_len = vec::len(elts);
            alt max {
              some(max) if ! (min <= elts_len && elts_len <= max) {
                cx.span_fatal(sp,
                              fmt!{"#%s takes between %u and %u arguments.",
                                   name, min, max});
              }
              none if ! (min <= elts_len) {
                cx.span_fatal(sp, fmt!{"#%s needs at least %u arguments.",
                                       name, min});
              }
              _ { ret elts; /* we're good */}
            }
          }
          _ {
            cx.span_fatal(sp, fmt!{"#%s: malformed invocation", name})
          }
        }
      }
      none {cx.span_fatal(sp, fmt!{"#%s: missing arguments", name})}
    }
}

fn get_mac_body(cx: ext_ctxt, sp: span, args: ast::mac_body)
    -> ast::mac_body_
{
    alt (args) {
      some(body) {body}
      none {cx.span_fatal(sp, ~"missing macro body")}
    }
}

// Massage syntactic form of new-style arguments to internal representation
// of old-style macro args, such that old-style macro can be run and invoked
// using new syntax. This will be obsolete when #old_macros go away.
fn tt_args_to_original_flavor(cx: ext_ctxt, sp: span, arg: ~[ast::token_tree])
    -> ast::mac_arg {
    import ast::{matcher, matcher_, match_tok, match_seq, match_nonterminal};
    import parse::lexer::{new_tt_reader, tt_reader_as_reader, reader};
    import tt::earley_parser::{parse_or_else, matched_seq,
                               matched_nonterminal};

    // these spans won't matter, anyways
    fn ms(m: matcher_) -> matcher {
        {node: m, span: {lo: 0u, hi: 0u, expn_info: none}}
    }

    let argument_gram = ~[ms(match_seq(~[
        ms(match_nonterminal(@~"arg",@~"expr", 0u))
    ], some(parse::token::COMMA), true, 0u, 1u))];

    let arg_reader = new_tt_reader(cx.parse_sess().span_diagnostic,
                                   cx.parse_sess().interner, none, arg);
    let args =
        alt parse_or_else(cx.parse_sess(), cx.cfg(), arg_reader as reader,
                          argument_gram).get(@~"arg") {
          @matched_seq(s, _) {
            do s.map() |lf| {
                alt lf {
                  @matched_nonterminal(parse::token::nt_expr(arg)) {
                    arg /* whew! list of exprs, here we come! */
                  }
                  _ { fail ~"badly-structured parse result"; }
                }
            }
          }
          _ { fail ~"badly-structured parse result"; }
        };

    ret some(@{id: parse::next_node_id(cx.parse_sess()),
               callee_id: parse::next_node_id(cx.parse_sess()),
               node: ast::expr_vec(args, ast::m_imm), span: sp});
}

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