auto merge of #6611 : huonw/rust/syntax-ext-no-dup, r=jbclements

Fixes #6578 by merging the 3 different ways to build an AST into a single `AstBuilder` trait, creating a more uniform and briefer interface.

Also, converts the `ext_ctxt` trait-object to be a plain struct, as well as renaming it to `ExtCtxt`.

Seems to make expansion slightly faster for the normal case (e.g. `libcore` and `libstd`), but slower for `librustc` (slightly) and `libsyntax` (0.3s -> 0.8s! I'm investigating this, but I'd prefer this patch to land relatively quickly.).

`git blame` suggests maybe @graydon or @erickt are familiar with this area of the code. r?

src/librustc/front/test.rs

@@ -17,7 +17,7 @@ use syntax::ast_util::*;
 use syntax::attr;
 use syntax::codemap::{dummy_sp, span, ExpandedFrom, CallInfo, NameAndSpan};
 use syntax::codemap;
-use syntax::ext::base::{mk_ctxt, ext_ctxt};
+use syntax::ext::base::ExtCtxt;
 use syntax::fold;
 use syntax::print::pprust;
 use syntax::{ast, ast_util};
@@ -36,7 +36,7 @@ struct TestCtxt {
     sess: session::Session,
     crate: @ast::crate,
     path: ~[ast::ident],
-    ext_cx: @ext_ctxt,
+    ext_cx: @ExtCtxt,
     testfns: ~[Test]
 }
 
@@ -64,7 +64,7 @@ fn generate_test_harness(sess: session::Session,
     let cx: @mut TestCtxt = @mut TestCtxt {
         sess: sess,
         crate: crate,
-        ext_cx: mk_ctxt(sess.parse_sess, copy sess.opts.cfg),
+        ext_cx: ExtCtxt::new(sess.parse_sess, copy sess.opts.cfg),
         path: ~[],
         testfns: ~[]
     };

src/librustpkg/util.rs

@@ -19,7 +19,7 @@ use std::semver;
 use std::term;
 use syntax::ast_util::*;
 use syntax::codemap::{dummy_sp, spanned, dummy_spanned};
-use syntax::ext::base::{mk_ctxt, ext_ctxt};
+use syntax::ext::base::ExtCtxt;
 use syntax::{ast, attr, codemap, diagnostic, fold};
 use syntax::ast::{meta_name_value, meta_list};
 use syntax::attr::{mk_attr};
@@ -178,7 +178,7 @@ struct ListenerFn {
 struct ReadyCtx {
     sess: session::Session,
     crate: @ast::crate,
-    ext_cx: @ext_ctxt,
+    ext_cx: @ExtCtxt,
     path: ~[ast::ident],
     fns: ~[ListenerFn]
 }
@@ -247,7 +247,7 @@ pub fn ready_crate(sess: session::Session,
     let ctx = @mut ReadyCtx {
         sess: sess,
         crate: crate,
-        ext_cx: mk_ctxt(sess.parse_sess, copy sess.opts.cfg),
+        ext_cx: ExtCtxt::new(sess.parse_sess, copy sess.opts.cfg),
         path: ~[],
         fns: ~[]
     };

src/libsyntax/ext/asm.rs

@@ -37,7 +37,7 @@ fn next_state(s: State) -> Option<State> {
     }
 }
 
-pub fn expand_asm(cx: @ext_ctxt, sp: span, tts: &[ast::token_tree])
+pub fn expand_asm(cx: @ExtCtxt, sp: span, tts: &[ast::token_tree])
                -> base::MacResult {
     let p = parse::new_parser_from_tts(cx.parse_sess(),
                                        cx.cfg(),

src/libsyntax/ext/auto_encode.rs

@@ -15,7 +15,7 @@ use codemap::span;
 use ext::base::*;
 
 pub fn expand_auto_encode(
-    cx: @ext_ctxt,
+    cx: @ExtCtxt,
     span: span,
     _mitem: @ast::meta_item,
     in_items: ~[@ast::item]
@@ -25,7 +25,7 @@ pub fn expand_auto_encode(
 }
 
 pub fn expand_auto_decode(
-    cx: @ext_ctxt,
+    cx: @ExtCtxt,
     span: span,
     _mitem: @ast::meta_item,
     in_items: ~[@ast::item]

src/libsyntax/ext/base.rs

@@ -33,7 +33,7 @@ pub struct MacroDef {
     ext: SyntaxExtension
 }
 
-pub type ItemDecorator = @fn(@ext_ctxt,
+pub type ItemDecorator = @fn(@ExtCtxt,
                              span,
                              @ast::meta_item,
                              ~[@ast::item])
@@ -44,7 +44,7 @@ pub struct SyntaxExpanderTT {
     span: Option<span>
 }
 
-pub type SyntaxExpanderTTFun = @fn(@ext_ctxt,
+pub type SyntaxExpanderTTFun = @fn(@ExtCtxt,
                                    span,
                                    &[ast::token_tree])
                                 -> MacResult;
@@ -54,7 +54,7 @@ pub struct SyntaxExpanderTTItem {
     span: Option<span>
 }
 
-pub type SyntaxExpanderTTItemFun = @fn(@ext_ctxt,
+pub type SyntaxExpanderTTItemFun = @fn(@ExtCtxt,
                                        span,
                                        ast::ident,
                                        ~[ast::token_tree])
@@ -202,134 +202,109 @@ pub fn syntax_expander_table() -> SyntaxEnv {
 // 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.
-pub trait ext_ctxt {
-    fn codemap(&self) -> @CodeMap;
-    fn parse_sess(&self) -> @mut parse::ParseSess;
-    fn cfg(&self) -> ast::crate_cfg;
-    fn call_site(&self) -> span;
-    fn print_backtrace(&self);
-    fn backtrace(&self) -> Option<@ExpnInfo>;
-    fn mod_push(&self, mod_name: ast::ident);
-    fn mod_pop(&self);
-    fn mod_path(&self) -> ~[ast::ident];
-    fn bt_push(&self, ei: codemap::ExpnInfo);
-    fn bt_pop(&self);
-    fn span_fatal(&self, sp: span, msg: &str) -> !;
-    fn span_err(&self, sp: span, msg: &str);
-    fn span_warn(&self, sp: span, msg: &str);
-    fn span_unimpl(&self, sp: span, msg: &str) -> !;
-    fn span_bug(&self, sp: span, msg: &str) -> !;
-    fn bug(&self, msg: &str) -> !;
-    fn next_id(&self) -> ast::node_id;
-    fn trace_macros(&self) -> bool;
-    fn set_trace_macros(&self, x: bool);
-    /* for unhygienic identifier transformation */
-    fn str_of(&self, id: ast::ident) -> ~str;
-    fn ident_of(&self, st: &str) -> ast::ident;
+pub struct ExtCtxt {
+    parse_sess: @mut parse::ParseSess,
+    cfg: ast::crate_cfg,
+    backtrace: @mut Option<@ExpnInfo>,
+
+    // These two @mut's should really not be here,
+    // but the self types for CtxtRepr are all wrong
+    // and there are bugs in the code for object
+    // types that make this hard to get right at the
+    // moment. - nmatsakis
+    mod_path: @mut ~[ast::ident],
+    trace_mac: @mut bool
 }
 
-pub fn mk_ctxt(parse_sess: @mut parse::ParseSess, cfg: ast::crate_cfg)
-            -> @ext_ctxt {
-    struct CtxtRepr {
-        parse_sess: @mut parse::ParseSess,
-        cfg: ast::crate_cfg,
-        backtrace: @mut Option<@ExpnInfo>,
-
-        // These two @mut's should really not be here,
-        // but the self types for CtxtRepr are all wrong
-        // and there are bugs in the code for object
-        // types that make this hard to get right at the
-        // moment. - nmatsakis
-        mod_path: @mut ~[ast::ident],
-        trace_mac: @mut bool
-    }
-    impl ext_ctxt for CtxtRepr {
-        fn codemap(&self) -> @CodeMap { self.parse_sess.cm }
-        fn parse_sess(&self) -> @mut parse::ParseSess { self.parse_sess }
-        fn cfg(&self) -> ast::crate_cfg { copy self.cfg }
-        fn call_site(&self) -> span {
-            match *self.backtrace {
-                Some(@ExpandedFrom(CallInfo {call_site: cs, _})) => cs,
-                None => self.bug("missing top span")
-            }
+pub impl ExtCtxt {
+    fn new(parse_sess: @mut parse::ParseSess, cfg: ast::crate_cfg) -> @ExtCtxt {
+        @ExtCtxt {
+            parse_sess: parse_sess,
+            cfg: cfg,
+            backtrace: @mut None,
+            mod_path: @mut ~[],
+            trace_mac: @mut false
+        }
+    }
+
+    fn codemap(&self) -> @CodeMap { self.parse_sess.cm }
+    fn parse_sess(&self) -> @mut parse::ParseSess { self.parse_sess }
+    fn cfg(&self) -> ast::crate_cfg { copy self.cfg }
+    fn call_site(&self) -> span {
+        match *self.backtrace {
+            Some(@ExpandedFrom(CallInfo {call_site: cs, _})) => cs,
+            None => self.bug("missing top span")
         }
-        fn print_backtrace(&self) { }
-        fn backtrace(&self) -> Option<@ExpnInfo> { *self.backtrace }
-        fn mod_push(&self, i: ast::ident) { self.mod_path.push(i); }
-        fn mod_pop(&self) { self.mod_path.pop(); }
-        fn mod_path(&self) -> ~[ast::ident] { copy *self.mod_path }
-        fn bt_push(&self, ei: codemap::ExpnInfo) {
-            match ei {
-              ExpandedFrom(CallInfo {call_site: cs, callee: ref callee}) => {
+    }
+    fn print_backtrace(&self) { }
+    fn backtrace(&self) -> Option<@ExpnInfo> { *self.backtrace }
+    fn mod_push(&self, i: ast::ident) { self.mod_path.push(i); }
+    fn mod_pop(&self) { self.mod_path.pop(); }
+    fn mod_path(&self) -> ~[ast::ident] { copy *self.mod_path }
+    fn bt_push(&self, ei: codemap::ExpnInfo) {
+        match ei {
+            ExpandedFrom(CallInfo {call_site: cs, callee: ref callee}) => {
                 *self.backtrace =
                     Some(@ExpandedFrom(CallInfo {
                         call_site: span {lo: cs.lo, hi: cs.hi,
                                          expn_info: *self.backtrace},
                         callee: copy *callee}));
-              }
             }
         }
-        fn bt_pop(&self) {
-            match *self.backtrace {
-              Some(@ExpandedFrom(CallInfo {
-                  call_site: span {expn_info: prev, _}, _
-              })) => {
+    }
+    fn bt_pop(&self) {
+        match *self.backtrace {
+            Some(@ExpandedFrom(
+                CallInfo {
+                    call_site: span {expn_info: prev, _}, _
+                })) => {
                 *self.backtrace = prev
-              }
-              _ => self.bug("tried to pop without a push")
             }
+            _ => self.bug("tried to pop without a push")
         }
-        fn span_fatal(&self, sp: span, msg: &str) -> ! {
-            self.print_backtrace();
-            self.parse_sess.span_diagnostic.span_fatal(sp, msg);
-        }
-        fn span_err(&self, sp: span, msg: &str) {
-            self.print_backtrace();
-            self.parse_sess.span_diagnostic.span_err(sp, msg);
-        }
-        fn span_warn(&self, sp: span, msg: &str) {
-            self.print_backtrace();
-            self.parse_sess.span_diagnostic.span_warn(sp, msg);
-        }
-        fn span_unimpl(&self, sp: span, msg: &str) -> ! {
-            self.print_backtrace();
-            self.parse_sess.span_diagnostic.span_unimpl(sp, msg);
-        }
-        fn span_bug(&self, sp: span, msg: &str) -> ! {
-            self.print_backtrace();
-            self.parse_sess.span_diagnostic.span_bug(sp, msg);
-        }
-        fn bug(&self, msg: &str) -> ! {
-            self.print_backtrace();
-            self.parse_sess.span_diagnostic.handler().bug(msg);
-        }
-        fn next_id(&self) -> ast::node_id {
-            return parse::next_node_id(self.parse_sess);
-        }
-        fn trace_macros(&self) -> bool {
-            *self.trace_mac
-        }
-        fn set_trace_macros(&self, x: bool) {
-            *self.trace_mac = x
-        }
-        fn str_of(&self, id: ast::ident) -> ~str {
-            copy *self.parse_sess.interner.get(id)
-        }
-        fn ident_of(&self, st: &str) -> ast::ident {
-            self.parse_sess.interner.intern(st)
-        }
     }
-    let imp: @CtxtRepr = @CtxtRepr {
-        parse_sess: parse_sess,
-        cfg: cfg,
-        backtrace: @mut None,
-        mod_path: @mut ~[],
-        trace_mac: @mut false
-    };
-    ((imp) as @ext_ctxt)
+    fn span_fatal(&self, sp: span, msg: &str) -> ! {
+        self.print_backtrace();
+        self.parse_sess.span_diagnostic.span_fatal(sp, msg);
+    }
+    fn span_err(&self, sp: span, msg: &str) {
+        self.print_backtrace();
+        self.parse_sess.span_diagnostic.span_err(sp, msg);
+    }
+    fn span_warn(&self, sp: span, msg: &str) {
+        self.print_backtrace();
+        self.parse_sess.span_diagnostic.span_warn(sp, msg);
+    }
+    fn span_unimpl(&self, sp: span, msg: &str) -> ! {
+        self.print_backtrace();
+        self.parse_sess.span_diagnostic.span_unimpl(sp, msg);
+    }
+    fn span_bug(&self, sp: span, msg: &str) -> ! {
+        self.print_backtrace();
+        self.parse_sess.span_diagnostic.span_bug(sp, msg);
+    }
+    fn bug(&self, msg: &str) -> ! {
+        self.print_backtrace();
+        self.parse_sess.span_diagnostic.handler().bug(msg);
+    }
+    fn next_id(&self) -> ast::node_id {
+        parse::next_node_id(self.parse_sess)
+    }
+    fn trace_macros(&self) -> bool {
+        *self.trace_mac
+    }
+    fn set_trace_macros(&self, x: bool) {
+        *self.trace_mac = x
+    }
+    fn str_of(&self, id: ast::ident) -> ~str {
+        copy *self.parse_sess.interner.get(id)
+    }
+    fn ident_of(&self, st: &str) -> ast::ident {
+        self.parse_sess.interner.intern(st)
+    }
 }
 
-pub fn expr_to_str(cx: @ext_ctxt, expr: @ast::expr, err_msg: ~str) -> ~str {
+pub fn expr_to_str(cx: @ExtCtxt, expr: @ast::expr, err_msg: ~str) -> ~str {
     match expr.node {
       ast::expr_lit(l) => match l.node {
         ast::lit_str(s) => copy *s,
@@ -339,7 +314,7 @@ pub fn expr_to_str(cx: @ext_ctxt, expr: @ast::expr, err_msg: ~str) -> ~str {
     }
 }
 
-pub fn expr_to_ident(cx: @ext_ctxt,
+pub fn expr_to_ident(cx: @ExtCtxt,
                      expr: @ast::expr,
                      err_msg: &str) -> ast::ident {
     match expr.node {
@@ -353,14 +328,14 @@ pub fn expr_to_ident(cx: @ext_ctxt,
     }
 }
 
-pub fn check_zero_tts(cx: @ext_ctxt, sp: span, tts: &[ast::token_tree],
+pub fn check_zero_tts(cx: @ExtCtxt, sp: span, tts: &[ast::token_tree],
                       name: &str) {
     if tts.len() != 0 {
         cx.span_fatal(sp, fmt!("%s takes no arguments", name));
     }
 }
 
-pub fn get_single_str_from_tts(cx: @ext_ctxt,
+pub fn get_single_str_from_tts(cx: @ExtCtxt,
                                sp: span,
                                tts: &[ast::token_tree],
                                name: &str) -> ~str {
@@ -375,7 +350,7 @@ pub fn get_single_str_from_tts(cx: @ext_ctxt,
     }
 }
 
-pub fn get_exprs_from_tts(cx: @ext_ctxt, tts: &[ast::token_tree])
+pub fn get_exprs_from_tts(cx: @ExtCtxt, tts: &[ast::token_tree])
                        -> ~[@ast::expr] {
     let p = parse::new_parser_from_tts(cx.parse_sess(),
                                        cx.cfg(),