1 files changed, 157 insertions, 0 deletions
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
new file mode 100644
index 00000000000..90487e27956
--- /dev/null
+++ b/src/libsyntax/ext/expand.rs
@@ -0,0 +1,157 @@
+import std::map::hashmap;
+
+import ast::{crate, expr_, expr_mac, mac_invoc};
+import fold::*;
+import ext::base::*;
+import ext::qquote::{qq_helper};
+import parse::parser;
+import parse::parse_expr_from_source_str;
+
+
+import codemap::{span, expanded_from};
+
+fn expand_expr(exts: hashmap<str, syntax_extension>, cx: ext_ctxt,
+               e: expr_, s: span, fld: ast_fold,
+               orig: fn@(expr_, span, ast_fold) -> (expr_, span))
+    -> (expr_, span)
+{
+    ret alt e {
+          expr_mac(mac) {
+            alt mac.node {
+              mac_invoc(pth, args, body) {
+                assert (vec::len(pth.idents) > 0u);
+                let extname = pth.idents[0];
+                alt exts.find(extname) {
+                  none {
+                    cx.span_fatal(pth.span,
+                                  #fmt["macro undefined: '%s'", extname])
+                  }
+                  some(item_decorator(_)) {
+                    cx.span_fatal(
+                        pth.span,
+                        #fmt["%s can only be used as a decorator", extname]);
+                  }
+                  some(normal({expander: exp, span: exp_sp})) {
+                    let expanded = exp(cx, pth.span, args, body);
+
+                    cx.bt_push(expanded_from({call_site: s,
+                                callie: {name: extname, span: exp_sp}}));
+                    //keep going, outside-in
+                    let fully_expanded = fld.fold_expr(expanded).node;
+                    cx.bt_pop();
+
+                    (fully_expanded, s)
+                  }
+                  some(macro_defining(ext)) {
+                    let named_extension = ext(cx, pth.span, args, body);
+                    exts.insert(named_extension.ident, named_extension.ext);
+                    (ast::expr_rec([], none), s)
+                  }
+                }
+              }
+              _ { cx.span_bug(mac.span, "naked syntactic bit") }
+            }
+          }
+          _ { orig(e, s, fld) }
+        };
+}
+
+fn expand_mod_items(exts: hashmap<str, syntax_extension>, cx: ext_ctxt,
+                    module: ast::_mod, fld: ast_fold,
+                    orig: fn@(ast::_mod, ast_fold) -> ast::_mod)
+    -> ast::_mod
+{
+    // Fold the contents first:
+    let module = orig(module, fld);
+
+    // For each item, look through the attributes.  If any of them are
+    // decorated with "item decorators", then use that function to transform
+    // the item into a new set of items.
+    let new_items = vec::flat_map(module.items) {|item|
+        vec::foldr(item.attrs, [item]) {|attr, items|
+            let mname = alt attr.node.value.node {
+              ast::meta_word(n) { n }
+              ast::meta_name_value(n, _) { n }
+              ast::meta_list(n, _) { n }
+            };
+            alt exts.find(mname) {
+              none | some(normal(_)) | some(macro_defining(_)) {
+                items
+              }
+
+              some(item_decorator(dec_fn)) {
+                dec_fn(cx, attr.span, attr.node.value, items)
+              }
+            }
+        }
+    };
+
+    ret {items: new_items with module};
+}
+
+/* record module we enter for `#mod` */
+fn expand_item(cx: ext_ctxt, &&it: @ast::item, fld: ast_fold,
+               orig: fn@(&&@ast::item, ast_fold) -> @ast::item)
+    -> @ast::item
+{
+    let is_mod = alt it.node {
+      ast::item_mod(_) | ast::item_native_mod(_) {true}
+      _ {false}
+    };
+    if is_mod { cx.mod_push(it.ident); }
+    let ret_val = orig(it, fld);
+    if is_mod { cx.mod_pop(); }
+    ret ret_val;
+}
+
+fn new_span(cx: ext_ctxt, sp: span) -> span {
+    /* this discards information in the case of macro-defining macros */
+    ret {lo: sp.lo, hi: sp.hi, expn_info: cx.backtrace()};
+}
+
+// FIXME: this is a terrible kludge to inject some macros into the default
+// compilation environment. When the macro-definition system is substantially
+// more mature, these should move from here, into a compiled part of libcore
+// at very least. (Issue #2247)
+
+fn core_macros() -> str {
+    ret
+"{
+    #macro([#error[f, ...], log(core::error, #fmt[f, ...])]);
+    #macro([#warn[f, ...], log(core::warn, #fmt[f, ...])]);
+    #macro([#info[f, ...], log(core::info, #fmt[f, ...])]);
+    #macro([#debug[f, ...], log(core::debug, #fmt[f, ...])]);
+}";
+}
+
+fn expand_crate(parse_sess: parse::parse_sess,
+                cfg: ast::crate_cfg, c: @crate) -> @crate {
+    let exts = syntax_expander_table();
+    let afp = default_ast_fold();
+    let cx: ext_ctxt = mk_ctxt(parse_sess, cfg);
+    let f_pre =
+        @{fold_expr: bind expand_expr(exts, cx, _, _, _, afp.fold_expr),
+          fold_mod: bind expand_mod_items(exts, cx, _, _, afp.fold_mod),
+          fold_item: bind expand_item(cx, _, _, afp.fold_item),
+          new_span: bind new_span(cx, _)
+          with *afp};
+    let f = make_fold(f_pre);
+    let cm = parse_expr_from_source_str("<core-macros>",
+                                        @core_macros(),
+                                        cfg,
+                                        parse_sess);
+
+    // This is run for its side-effects on the expander env,
+    // as it registers all the core macros as expanders.
+    f.fold_expr(cm);
+
+    let res = @f.fold_crate(*c);
+    ret res;
+}
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// End: