rustc: Introduce ext module. Move some things from parser to ext.

Introduce an ext_ctxt record to provide a span_err method for use while
expanding syntax extensions. Hopefully it will be useful for other things.

src/comp/front/ext.rs

@@ -0,0 +1,49 @@
+import std::option;
+import std::map::hashmap;
+
+import driver::session::session;
+import util::common::span;
+import util::common::new_str_hash;
+
+type syntax_expander = fn(&ext_ctxt, &parser::parser, span,
+                          &vec[@ast::expr],
+                          option::t[str]) -> @ast::expr;
+
+// Temporary: to introduce a tag in order to make a recursive type work
+tag syntax_extension {
+    x(syntax_expander);
+}
+
+// A temporary hard-coded map of methods for expanding syntax extension
+// AST nodes into full ASTs
+fn syntax_expander_table() -> hashmap[str, syntax_extension] {
+    auto syntax_expanders = new_str_hash[syntax_extension]();
+    syntax_expanders.insert("fmt", x(extfmt::expand_syntax_ext));
+    syntax_expanders.insert("env", x(extenv::expand_syntax_ext));
+    ret syntax_expanders;
+}
+
+type span_err_fn = fn (span sp, str msg) -> !;
+
+// Provides a limited set of services necessary for syntax extensions
+// to do their thing
+type ext_ctxt = rec(span_err_fn span_err);
+
+fn mk_ctxt(session sess) -> ext_ctxt {
+    fn ext_span_err_(session sess, span sp, str err) -> ! {
+        sess.span_err(sp, err);
+    }
+    auto ext_span_err = bind ext_span_err_(sess, _, _);
+    ret rec(span_err = ext_span_err);
+}
+
+//
+// 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:
+//

src/comp/front/extenv.rs

@@ -11,10 +11,13 @@ import std::vec;
 import std::option;
 import std::generic_os;
 
+import ext::*;
+
 export expand_syntax_ext;
 
 // FIXME: Need to thread parser through here to handle errors correctly
-fn expand_syntax_ext(&parser::parser p,
+fn expand_syntax_ext(&ext_ctxt cx,
+                     &parser::parser p,
                      common::span sp,
                      &vec[@ast::expr] args,
                      option::t[str] body) -> @ast::expr {

src/comp/front/extfmt.rs

@@ -15,9 +15,12 @@ import std::option::some;
 
 import std::extfmt::ct::*;
 
+import ext::*;
+
 export expand_syntax_ext;
 
-fn expand_syntax_ext(&parser p, common::span sp, 
+fn expand_syntax_ext(&ext_ctxt cx,
+                     &parser p, common::span sp, 
                      &vec[@ast::expr] args,
                      option::t[str] body) -> @ast::expr {
 

src/comp/front/parser.rs

@@ -27,11 +27,6 @@ tag file_type {
 
 type ty_or_bang = util::common::ty_or_bang[@ast::ty];
 
-// Temporary: to introduce a tag in order to make a recursive type work
-tag syntax_extension {
-    x(syntax_expander);
-}
-
 state type parser =
     state obj {
         fn peek() -> token::token;
@@ -53,15 +48,12 @@ state type parser =
         fn get_reader() -> lexer::reader;
         fn get_filemap() -> codemap::filemap;
         fn get_bad_expr_words() -> hashmap[str, ()];
-        fn get_syntax_expanders() -> hashmap[str, syntax_extension];
+        fn get_syntax_expanders() -> hashmap[str, ext::syntax_extension];
         fn get_chpos() -> uint;
         fn get_ann() -> ast::ann;
         fn next_ann_num() -> uint;
     };
 
-type syntax_expander = fn(&parser, common::span, &vec[@ast::expr], 
-                          option::t[str]) -> @ast::expr;
-
 fn new_parser(session::session sess,
                      eval::env env,
                      ast::def_id initial_def,
@@ -80,7 +72,8 @@ fn new_parser(session::session sess,
                            vec[op_spec] precs,
                            mutable uint next_ann_var,
                            hashmap[str, ()] bad_words,
-                           hashmap[str, syntax_extension] syntax_expanders)
+                           hashmap[str, ext::syntax_extension]
+                               syntax_expanders)
         {
             fn peek() -> token::token {
                 ret tok;
@@ -153,7 +146,7 @@ fn new_parser(session::session sess,
                 ret bad_words;
             }
 
-            fn get_syntax_expanders() -> hashmap[str, syntax_extension] {
+            fn get_syntax_expanders() -> hashmap[str, ext::syntax_extension] {
                 ret syntax_expanders;
             }
 
@@ -183,7 +176,7 @@ fn new_parser(session::session sess,
     ret stdio_parser(sess, env, ftype, lexer::next_token(rdr),
                      npos, npos, npos, initial_def._1, UNRESTRICTED,
                      initial_def._0, rdr, prec_table(), next_ann,
-                     bad_expr_word_table(), syntax_expander_table());
+                     bad_expr_word_table(), ext::syntax_expander_table());
 }
 
 // These are the words that shouldn't be allowed as value identifiers,
@@ -227,13 +220,6 @@ fn bad_expr_word_table() -> hashmap[str, ()] {
     ret words;
 }
 
-fn syntax_expander_table() -> hashmap[str, syntax_extension] {
-    auto syntax_expanders = new_str_hash[syntax_extension]();
-    syntax_expanders.insert("fmt", x(extfmt::expand_syntax_ext));
-    syntax_expanders.insert("env", x(extenv::expand_syntax_ext));
-    ret syntax_expanders;
-}
-
 fn unexpected(&parser p, token::token t) -> ! {
     let str s = "unexpected token: ";
     s += token::to_str(p.get_reader(), t);
@@ -1060,11 +1046,13 @@ fn expand_syntax_ext(&parser p, common::span sp,
     auto extname = path.node.idents.(0);
 
     alt (p.get_syntax_expanders().find(extname)) {
-        case (none[syntax_extension]) {
+        case (none) {
             p.err("unknown syntax expander: '" + extname + "'");
         }
-        case (some[syntax_extension](x(?ext))) {
-            ret ast::expr_ext(path, args, body, ext(p, sp, args, body), 
+        case (some(ext::x(?ext))) {
+            auto ext_cx = ext::mk_ctxt(p.get_session());
+            ret ast::expr_ext(path, args, body,
+                              ext(ext_cx, p, sp, args, body), 
                               p.get_ann());
         }
     }

src/comp/rustc.rc

@@ -38,6 +38,7 @@ mod pretty {
 mod front {
     mod ast;
     mod creader;
+    mod ext;
     mod extfmt;
     mod extenv;
     mod codemap;