Adds a ProcMacro form of syntax extension

This commit adds syntax extension forms matching the types for procedural macros 2.0 (RFC #1566), these still require the usual syntax extension boiler plate, but this is a first step towards proper implementation and should be useful for macros 1.1 stuff too.

Supports both attribute-like and function-like macros.

Author: Nick Cameron

src/librustc_plugin/registry.rs

@@ -111,6 +111,8 @@ impl<'a> Registry<'a> {
             }
             MultiDecorator(ext) => MultiDecorator(ext),
             MultiModifier(ext) => MultiModifier(ext),
+            SyntaxExtension::ProcMacro(ext) => SyntaxExtension::ProcMacro(ext),
+            SyntaxExtension::AttrProcMacro(ext) => SyntaxExtension::AttrProcMacro(ext),
         }));
     }
 

src/libsyntax/ext/base.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-pub use self::SyntaxExtension::*;
+pub use self::SyntaxExtension::{MultiDecorator, MultiModifier, NormalTT, IdentTT, MacroRulesTT};
 
 use ast::{self, Attribute, Name, PatKind};
 use attr::HasAttrs;
@@ -19,7 +19,7 @@ use ext::expand::{self, Invocation, Expansion};
 use ext::hygiene::Mark;
 use ext::tt::macro_rules;
 use parse;
-use parse::parser;
+use parse::parser::{self, Parser};
 use parse::token;
 use parse::token::{InternedString, str_to_ident};
 use ptr::P;
@@ -31,7 +31,8 @@ use feature_gate;
 use std::collections::HashMap;
 use std::path::PathBuf;
 use std::rc::Rc;
-use tokenstream;
+use std::default::Default;
+use tokenstream::{self, TokenStream};
 
 
 #[derive(Debug,Clone)]
@@ -60,6 +61,14 @@ impl HasAttrs for Annotatable {
 }
 
 impl Annotatable {
+    pub fn span(&self) -> Span {
+        match *self {
+            Annotatable::Item(ref item) => item.span,
+            Annotatable::TraitItem(ref trait_item) => trait_item.span,
+            Annotatable::ImplItem(ref impl_item) => impl_item.span,
+        }
+    }
+
     pub fn expect_item(self) -> P<ast::Item> {
         match self {
             Annotatable::Item(i) => i,
@@ -146,6 +155,173 @@ impl Into<Vec<Annotatable>> for Annotatable {
     }
 }
 
+pub trait ProcMacro {
+    fn expand<'cx>(&self,
+                   ecx: &'cx mut ExtCtxt,
+                   span: Span,
+                   ts: TokenStream)
+                   -> Box<MacResult+'cx>;
+}
+
+impl<F> ProcMacro for F
+    where F: Fn(TokenStream) -> TokenStream
+{
+    fn expand<'cx>(&self,
+                   ecx: &'cx mut ExtCtxt,
+                   span: Span,
+                   ts: TokenStream)
+                   -> Box<MacResult+'cx> {
+        let result = (*self)(ts);
+        // FIXME setup implicit context in TLS before calling self.
+        let parser = ecx.new_parser_from_tts(&result.to_tts());
+        Box::new(TokResult { parser: parser, span: span })
+    }
+}
+
+pub trait AttrProcMacro {
+    fn expand<'cx>(&self,
+                   ecx: &'cx mut ExtCtxt,
+                   span: Span,
+                   annotation: TokenStream,
+                   annotated: TokenStream)
+                   -> Box<MacResult+'cx>;
+}
+
+impl<F> AttrProcMacro for F
+    where F: Fn(TokenStream, TokenStream) -> TokenStream
+{
+    fn expand<'cx>(&self,
+                   ecx: &'cx mut ExtCtxt,
+                   span: Span,
+                   annotation: TokenStream,
+                   annotated: TokenStream)
+                   -> Box<MacResult+'cx> {
+        // FIXME setup implicit context in TLS before calling self.
+        let parser = ecx.new_parser_from_tts(&(*self)(annotation, annotated).to_tts());
+        Box::new(TokResult { parser: parser, span: span })
+    }
+}
+
+struct TokResult<'a> {
+    parser: Parser<'a>,
+    span: Span,
+}
+
+impl<'a> MacResult for TokResult<'a> {
+    fn make_items(mut self: Box<Self>) -> Option<SmallVector<P<ast::Item>>> {
+        if self.parser.sess.span_diagnostic.has_errors() {
+            return None;
+        }
+
+        let mut items = SmallVector::zero();
+        loop {
+            match self.parser.parse_item() {
+                Ok(Some(item)) => {
+                    // FIXME better span info.
+                    let mut item = item.unwrap();
+                    item.span = self.span;
+                    items.push(P(item));
+                }
+                Ok(None) => {
+                    return Some(items);
+                }
+                Err(mut e) => {
+                    e.emit();
+                    return None;
+                }
+            }
+        }
+    }
+
+    fn make_impl_items(mut self: Box<Self>) -> Option<SmallVector<ast::ImplItem>> {
+        let mut items = SmallVector::zero();
+        loop {
+            match self.parser.parse_impl_item() {
+                Ok(mut item) => {
+                    // FIXME better span info.
+                    item.span = self.span;
+                    items.push(item);
+
+                    return Some(items);
+                }
+                Err(mut e) => {
+                    e.emit();
+                    return None;
+                }
+            }
+        }
+    }
+
+    fn make_trait_items(mut self: Box<Self>) -> Option<SmallVector<ast::TraitItem>> {
+        let mut items = SmallVector::zero();
+        loop {
+            match self.parser.parse_trait_item() {
+                Ok(mut item) => {
+                    // FIXME better span info.
+                    item.span = self.span;
+                    items.push(item);
+
+                    return Some(items);
+                }
+                Err(mut e) => {
+                    e.emit();
+                    return None;
+                }
+            }
+        }
+    }
+
+    fn make_expr(mut self: Box<Self>) -> Option<P<ast::Expr>> {
+        match self.parser.parse_expr() {
+            Ok(e) => Some(e),
+            Err(mut e) => {
+                e.emit();
+                return None;
+            }
+        }
+    }
+
+    fn make_pat(mut self: Box<Self>) -> Option<P<ast::Pat>> {
+        match self.parser.parse_pat() {
+            Ok(e) => Some(e),
+            Err(mut e) => {
+                e.emit();
+                return None;
+            }
+        }
+    }
+
+    fn make_stmts(mut self: Box<Self>) -> Option<SmallVector<ast::Stmt>> {
+        let mut stmts = SmallVector::zero();
+        loop {
+            if self.parser.token == token::Eof {
+                return Some(stmts);
+            }
+            match self.parser.parse_full_stmt(true) {
+                Ok(Some(mut stmt)) => {
+                    stmt.span = self.span;
+                    stmts.push(stmt);
+                }
+                Ok(None) => { /* continue */ }
+                Err(mut e) => {
+                    e.emit();
+                    return None;
+                }
+            }
+        }
+    }
+
+    fn make_ty(mut self: Box<Self>) -> Option<P<ast::Ty>> {
+        match self.parser.parse_ty() {
+            Ok(e) => Some(e),
+            Err(mut e) => {
+                e.emit();
+                return None;
+            }
+        }
+    }
+}
+
 /// Represents a thing that maps token trees to Macro Results
 pub trait TTMacroExpander {
     fn expand<'cx>(&self,
@@ -439,24 +615,35 @@ pub enum SyntaxExtension {
     /// based upon it.
     ///
     /// `#[derive(...)]` is a `MultiItemDecorator`.
-    MultiDecorator(Box<MultiItemDecorator + 'static>),
+    ///
+    /// Prefer ProcMacro or MultiModifier since they are more flexible.
+    MultiDecorator(Box<MultiItemDecorator>),
 
     /// A syntax extension that is attached to an item and modifies it
-    /// in-place. More flexible version than Modifier.
-    MultiModifier(Box<MultiItemModifier + 'static>),
+    /// in-place. Also allows decoration, i.e., creating new items.
+    MultiModifier(Box<MultiItemModifier>),
+
+    /// A function-like procedural macro. TokenStream -> TokenStream.
+    ProcMacro(Box<ProcMacro>),
+
+    /// An attribute-like procedural macro. TokenStream, TokenStream -> TokenStream.
+    /// The first TokenSteam is the attribute, the second is the annotated item.
+    /// Allows modification of the input items and adding new items, similar to
+    /// MultiModifier, but uses TokenStreams, rather than AST nodes.
+    AttrProcMacro(Box<AttrProcMacro>),
 
     /// A normal, function-like syntax extension.
     ///
     /// `bytes!` is a `NormalTT`.
     ///
     /// The `bool` dictates whether the contents of the macro can
     /// directly use `#[unstable]` things (true == yes).
-    NormalTT(Box<TTMacroExpander + 'static>, Option<Span>, bool),
+    NormalTT(Box<TTMacroExpander>, Option<Span>, bool),
 
     /// A function-like syntax extension that has an extra ident before
     /// the block.
     ///
-    IdentTT(Box<IdentMacroExpander + 'static>, Option<Span>, bool),
+    IdentTT(Box<IdentMacroExpander>, Option<Span>, bool),
 }
 
 pub type NamedSyntaxExtension = (Name, SyntaxExtension);

src/libsyntax/ext/expand.rs

@@ -22,8 +22,9 @@ use feature_gate::{self, Features};
 use fold;
 use fold::*;
 use parse::token::{intern, keywords};
+use parse::span_to_tts;
 use ptr::P;
-use tokenstream::TokenTree;
+use tokenstream::{TokenTree, TokenStream};
 use util::small_vector::SmallVector;
 use visit::Visitor;
 
@@ -308,6 +309,31 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 items.push(item);
                 kind.expect_from_annotatables(items)
             }
+            SyntaxExtension::AttrProcMacro(ref mac) => {
+                let attr_toks = TokenStream::from_tts(span_to_tts(&fld.cx.parse_sess,
+                                                                  attr.span));
+                let item_toks = TokenStream::from_tts(span_to_tts(&fld.cx.parse_sess,
+                                                                  item.span()));
+                let result = mac.expand(self.cx, attr.span, attr_toks, item_toks);
+                let items = match item {
+                    Annotatable::Item(_) => result.make_items()
+                                                  .unwrap_or(SmallVector::zero())
+                                                  .into_iter()
+                                                  .map(|i| Annotatable::Item(i))
+                                                  .collect(),
+                    Annotatable::TraitItem(_) => result.make_trait_items()
+                                                       .unwrap_or(SmallVector::zero())
+                                                       .into_iter()
+                                                       .map(|i| Annotatable::TraitItem(P(i)))
+                                                       .collect(),
+                    Annotatable::ImplItem(_) => result.make_impl_items()
+                                                      .unwrap_or(SmallVector::zero())
+                                                      .into_iter()
+                                                      .map(|i| Annotatable::ImplItem(P(i)))
+                                                      .collect(),
+                };
+                kind.expect_from_annotatables(items)
+            }
             _ => unreachable!(),
         }
     }
@@ -377,11 +403,34 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 kind.make_from(expander.expand(self.cx, span, ident, marked_tts, attrs))
             }
 
-            MultiDecorator(..) | MultiModifier(..) => {
+            MultiDecorator(..) | MultiModifier(..) | SyntaxExtension::AttrProcMacro(..) => {
                 self.cx.span_err(path.span,
                                  &format!("`{}` can only be used in attributes", extname));
                 return kind.dummy(span);
             }
+
+            SyntaxExtension::ProcMacro(ref expandfun) => {
+                if ident.name != keywords::Invalid.name() {
+                    let msg =
+                        format!("macro {}! expects no ident argument, given '{}'", extname, ident);
+                    fld.cx.span_err(path.span, &msg);
+                    return None;
+                }
+
+                fld.cx.bt_push(ExpnInfo {
+                    call_site: call_site,
+                    callee: NameAndSpan {
+                        format: MacroBang(extname),
+                        // FIXME procedural macros do not have proper span info
+                        // yet, when they do, we should use it here.
+                        span: None,
+                        // FIXME probably want to follow macro_rules macros here.
+                        allow_internal_unstable: false,
+                    },
+                });
+
+                Some(expandfun.expand(fld.cx, call_site, TokenStream::from_tts(marked_tts)))
+            }
         };
 
         let expanded = if let Some(expanded) = opt_expanded {

src/libsyntax/ext/proc_macro_shim.rs

@@ -24,7 +24,9 @@ use ext::base::*;
 
 /// Take a `ExtCtxt`, `Span`, and `TokenStream`, and produce a Macro Result that parses
 /// the TokenStream as a block and returns it as an `Expr`.
-pub fn build_block_emitter<'cx>(cx: &'cx mut ExtCtxt, sp: Span, output: TokenStream)
+pub fn build_block_emitter<'cx>(cx: &'cx mut ExtCtxt,
+                                sp: Span,
+                                output: TokenStream)
                                 -> Box<MacResult + 'cx> {
     let parser = cx.new_parser_from_tts(&output.to_tts());
 
@@ -60,7 +62,7 @@ pub fn build_block_emitter<'cx>(cx: &'cx mut ExtCtxt, sp: Span, output: TokenStr
 }
 
 pub mod prelude {
-    pub use ext::proc_macro_shim::build_block_emitter;
+    pub use super::build_block_emitter;
     pub use ast::Ident;
     pub use codemap::{DUMMY_SP, Span};
     pub use ext::base::{ExtCtxt, MacResult};