772 lines
26 KiB
Rust
772 lines
26 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use ast;
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use ast::Name;
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use codemap;
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use codemap::{CodeMap, Span, ExpnId, ExpnInfo, NO_EXPANSION};
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use ext;
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use ext::expand;
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use parse;
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use parse::parser;
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use parse::token;
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use parse::token::{InternedString, intern, str_to_ident};
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use ptr::P;
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use util::small_vector::SmallVector;
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use ext::mtwt;
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use fold::Folder;
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use std::collections::HashMap;
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use std::rc::Rc;
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// new-style macro! tt code:
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//
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// MacResult, NormalTT, IdentTT
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//
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// also note that ast::Mac used to have a bunch of extraneous cases and
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// is now probably a redundant AST node, can be merged with
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// ast::MacInvocTT.
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pub struct MacroDef {
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pub name: String,
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pub ext: SyntaxExtension
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}
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pub trait ItemDecorator {
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fn expand(&self,
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ecx: &mut ExtCtxt,
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sp: Span,
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meta_item: &ast::MetaItem,
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item: &ast::Item,
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push: |P<ast::Item>|);
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}
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impl ItemDecorator for fn(&mut ExtCtxt, Span, &ast::MetaItem, &ast::Item, |P<ast::Item>|) {
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fn expand(&self,
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ecx: &mut ExtCtxt,
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sp: Span,
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meta_item: &ast::MetaItem,
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item: &ast::Item,
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push: |P<ast::Item>|) {
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(*self)(ecx, sp, meta_item, item, push)
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}
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}
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pub trait ItemModifier {
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fn expand(&self,
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ecx: &mut ExtCtxt,
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span: Span,
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meta_item: &ast::MetaItem,
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item: P<ast::Item>)
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-> P<ast::Item>;
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}
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impl ItemModifier for fn(&mut ExtCtxt, Span, &ast::MetaItem, P<ast::Item>) -> P<ast::Item> {
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fn expand(&self,
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ecx: &mut ExtCtxt,
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span: Span,
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meta_item: &ast::MetaItem,
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item: P<ast::Item>)
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-> P<ast::Item> {
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(*self)(ecx, span, meta_item, item)
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}
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}
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/// Represents a thing that maps token trees to Macro Results
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pub trait TTMacroExpander {
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fn expand<'cx>(&self,
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ecx: &'cx mut ExtCtxt,
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span: Span,
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token_tree: &[ast::TokenTree])
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-> Box<MacResult+'cx>;
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}
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pub type MacroExpanderFn =
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fn<'cx>(&'cx mut ExtCtxt, Span, &[ast::TokenTree]) -> Box<MacResult+'cx>;
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impl TTMacroExpander for MacroExpanderFn {
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fn expand<'cx>(&self,
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ecx: &'cx mut ExtCtxt,
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span: Span,
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token_tree: &[ast::TokenTree])
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-> Box<MacResult+'cx> {
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(*self)(ecx, span, token_tree)
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}
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}
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pub trait IdentMacroExpander {
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fn expand<'cx>(&self,
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cx: &'cx mut ExtCtxt,
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sp: Span,
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ident: ast::Ident,
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token_tree: Vec<ast::TokenTree> )
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-> Box<MacResult+'cx>;
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}
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pub type IdentMacroExpanderFn =
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fn<'cx>(&'cx mut ExtCtxt, Span, ast::Ident, Vec<ast::TokenTree>) -> Box<MacResult+'cx>;
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impl IdentMacroExpander for IdentMacroExpanderFn {
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fn expand<'cx>(&self,
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cx: &'cx mut ExtCtxt,
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sp: Span,
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ident: ast::Ident,
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token_tree: Vec<ast::TokenTree> )
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-> Box<MacResult+'cx> {
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(*self)(cx, sp, ident, token_tree)
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}
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}
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/// The result of a macro expansion. The return values of the various
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/// methods are spliced into the AST at the callsite of the macro (or
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/// just into the compiler's internal macro table, for `make_def`).
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pub trait MacResult {
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/// Attempt to define a new macro.
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// this should go away; the idea that a macro might expand into
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// either a macro definition or an expression, depending on what
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// the context wants, is kind of silly.
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fn make_def(&mut self) -> Option<MacroDef> {
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None
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}
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/// Create an expression.
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fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
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None
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}
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/// Create zero or more items.
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fn make_items(self: Box<Self>) -> Option<SmallVector<P<ast::Item>>> {
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None
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}
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/// Create zero or more methods.
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fn make_methods(self: Box<Self>) -> Option<SmallVector<P<ast::Method>>> {
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None
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}
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/// Create a pattern.
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fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
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None
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}
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/// Create a statement.
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///
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/// By default this attempts to create an expression statement,
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/// returning None if that fails.
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fn make_stmt(self: Box<Self>) -> Option<P<ast::Stmt>> {
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self.make_expr()
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.map(|e| P(codemap::respan(e.span, ast::StmtExpr(e, ast::DUMMY_NODE_ID))))
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}
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}
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/// A convenience type for macros that return a single expression.
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pub struct MacExpr {
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e: P<ast::Expr>
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}
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impl MacExpr {
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pub fn new(e: P<ast::Expr>) -> Box<MacResult+'static> {
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box MacExpr { e: e } as Box<MacResult+'static>
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}
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}
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impl MacResult for MacExpr {
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fn make_expr(self: Box<MacExpr>) -> Option<P<ast::Expr>> {
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Some(self.e)
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}
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fn make_pat(self: Box<MacExpr>) -> Option<P<ast::Pat>> {
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match self.e.node {
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ast::ExprLit(_) => Some(P(ast::Pat {
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id: ast::DUMMY_NODE_ID,
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span: self.e.span,
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node: ast::PatLit(self.e)
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})),
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_ => None
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}
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}
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}
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/// A convenience type for macros that return a single pattern.
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pub struct MacPat {
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p: P<ast::Pat>
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}
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impl MacPat {
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pub fn new(p: P<ast::Pat>) -> Box<MacResult+'static> {
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box MacPat { p: p } as Box<MacResult+'static>
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}
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}
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impl MacResult for MacPat {
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fn make_pat(self: Box<MacPat>) -> Option<P<ast::Pat>> {
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Some(self.p)
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}
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}
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/// A type for macros that return multiple items.
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pub struct MacItems {
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items: SmallVector<P<ast::Item>>
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}
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impl MacItems {
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pub fn new<I: Iterator<P<ast::Item>>>(mut it: I) -> Box<MacResult+'static> {
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box MacItems { items: it.collect() } as Box<MacResult+'static>
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}
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}
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impl MacResult for MacItems {
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fn make_items(self: Box<MacItems>) -> Option<SmallVector<P<ast::Item>>> {
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Some(self.items)
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}
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}
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/// Fill-in macro expansion result, to allow compilation to continue
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/// after hitting errors.
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pub struct DummyResult {
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expr_only: bool,
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span: Span
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}
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impl DummyResult {
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/// Create a default MacResult that can be anything.
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///
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/// Use this as a return value after hitting any errors and
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/// calling `span_err`.
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pub fn any(sp: Span) -> Box<MacResult+'static> {
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box DummyResult { expr_only: false, span: sp } as Box<MacResult+'static>
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}
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/// Create a default MacResult that can only be an expression.
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///
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/// Use this for macros that must expand to an expression, so even
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/// if an error is encountered internally, the user will receive
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/// an error that they also used it in the wrong place.
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pub fn expr(sp: Span) -> Box<MacResult+'static> {
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box DummyResult { expr_only: true, span: sp } as Box<MacResult+'static>
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}
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/// A plain dummy expression.
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pub fn raw_expr(sp: Span) -> P<ast::Expr> {
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P(ast::Expr {
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id: ast::DUMMY_NODE_ID,
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node: ast::ExprLit(P(codemap::respan(sp, ast::LitNil))),
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span: sp,
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})
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}
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/// A plain dummy pattern.
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pub fn raw_pat(sp: Span) -> ast::Pat {
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ast::Pat {
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id: ast::DUMMY_NODE_ID,
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node: ast::PatWild(ast::PatWildSingle),
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span: sp,
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}
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}
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}
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impl MacResult for DummyResult {
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fn make_expr(self: Box<DummyResult>) -> Option<P<ast::Expr>> {
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Some(DummyResult::raw_expr(self.span))
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}
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fn make_pat(self: Box<DummyResult>) -> Option<P<ast::Pat>> {
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Some(P(DummyResult::raw_pat(self.span)))
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}
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fn make_items(self: Box<DummyResult>) -> Option<SmallVector<P<ast::Item>>> {
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// this code needs a comment... why not always just return the Some() ?
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if self.expr_only {
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None
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} else {
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Some(SmallVector::zero())
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}
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}
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fn make_methods(self: Box<DummyResult>) -> Option<SmallVector<P<ast::Method>>> {
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if self.expr_only {
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None
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} else {
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Some(SmallVector::zero())
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}
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}
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fn make_stmt(self: Box<DummyResult>) -> Option<P<ast::Stmt>> {
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Some(P(codemap::respan(self.span,
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ast::StmtExpr(DummyResult::raw_expr(self.span),
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ast::DUMMY_NODE_ID))))
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}
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}
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/// An enum representing the different kinds of syntax extensions.
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pub enum SyntaxExtension {
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/// A syntax extension that is attached to an item and creates new items
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/// based upon it.
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///
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/// `#[deriving(...)]` is an `ItemDecorator`.
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Decorator(Box<ItemDecorator + 'static>),
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/// A syntax extension that is attached to an item and modifies it
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/// in-place.
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Modifier(Box<ItemModifier + 'static>),
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/// A normal, function-like syntax extension.
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///
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/// `bytes!` is a `NormalTT`.
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NormalTT(Box<TTMacroExpander + 'static>, Option<Span>),
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/// A function-like syntax extension that has an extra ident before
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/// the block.
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///
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IdentTT(Box<IdentMacroExpander + 'static>, Option<Span>),
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/// An ident macro that has two properties:
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/// - it adds a macro definition to the environment, and
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/// - the definition it adds doesn't introduce any new
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/// identifiers.
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///
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/// `macro_rules!` is a LetSyntaxTT
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LetSyntaxTT(Box<IdentMacroExpander + 'static>, Option<Span>),
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}
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pub type NamedSyntaxExtension = (Name, SyntaxExtension);
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pub struct BlockInfo {
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/// Should macros escape from this scope?
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pub macros_escape: bool,
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/// What are the pending renames?
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pub pending_renames: mtwt::RenameList,
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}
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impl BlockInfo {
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pub fn new() -> BlockInfo {
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BlockInfo {
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macros_escape: false,
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pending_renames: Vec::new(),
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}
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}
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}
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/// The base map of methods for expanding syntax extension
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/// AST nodes into full ASTs
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fn initial_syntax_expander_table() -> SyntaxEnv {
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// utility function to simplify creating NormalTT syntax extensions
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fn builtin_normal_expander(f: MacroExpanderFn) -> SyntaxExtension {
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NormalTT(box f, None)
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}
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let mut syntax_expanders = SyntaxEnv::new();
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syntax_expanders.insert(intern("macro_rules"),
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LetSyntaxTT(box ext::tt::macro_rules::add_new_extension, None));
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syntax_expanders.insert(intern("fmt"),
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builtin_normal_expander(
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ext::fmt::expand_syntax_ext));
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syntax_expanders.insert(intern("format_args"),
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builtin_normal_expander(
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ext::format::expand_format_args));
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syntax_expanders.insert(intern("format_args_method"),
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builtin_normal_expander(
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ext::format::expand_format_args_method));
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syntax_expanders.insert(intern("env"),
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builtin_normal_expander(
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ext::env::expand_env));
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syntax_expanders.insert(intern("option_env"),
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builtin_normal_expander(
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ext::env::expand_option_env));
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syntax_expanders.insert(intern("bytes"),
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builtin_normal_expander(
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ext::bytes::expand_syntax_ext));
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syntax_expanders.insert(intern("concat_idents"),
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builtin_normal_expander(
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ext::concat_idents::expand_syntax_ext));
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syntax_expanders.insert(intern("concat"),
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builtin_normal_expander(
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ext::concat::expand_syntax_ext));
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syntax_expanders.insert(intern("log_syntax"),
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builtin_normal_expander(
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ext::log_syntax::expand_syntax_ext));
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syntax_expanders.insert(intern("deriving"),
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Decorator(box ext::deriving::expand_meta_deriving));
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// Quasi-quoting expanders
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syntax_expanders.insert(intern("quote_tokens"),
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builtin_normal_expander(
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ext::quote::expand_quote_tokens));
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syntax_expanders.insert(intern("quote_expr"),
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builtin_normal_expander(
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ext::quote::expand_quote_expr));
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syntax_expanders.insert(intern("quote_ty"),
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builtin_normal_expander(
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ext::quote::expand_quote_ty));
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syntax_expanders.insert(intern("quote_method"),
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builtin_normal_expander(
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ext::quote::expand_quote_method));
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syntax_expanders.insert(intern("quote_item"),
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builtin_normal_expander(
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ext::quote::expand_quote_item));
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syntax_expanders.insert(intern("quote_pat"),
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builtin_normal_expander(
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ext::quote::expand_quote_pat));
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syntax_expanders.insert(intern("quote_arm"),
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builtin_normal_expander(
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ext::quote::expand_quote_arm));
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syntax_expanders.insert(intern("quote_stmt"),
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builtin_normal_expander(
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ext::quote::expand_quote_stmt));
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syntax_expanders.insert(intern("line"),
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builtin_normal_expander(
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ext::source_util::expand_line));
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syntax_expanders.insert(intern("col"),
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builtin_normal_expander(
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ext::source_util::expand_col));
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syntax_expanders.insert(intern("file"),
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builtin_normal_expander(
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ext::source_util::expand_file));
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syntax_expanders.insert(intern("stringify"),
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builtin_normal_expander(
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ext::source_util::expand_stringify));
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syntax_expanders.insert(intern("include"),
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builtin_normal_expander(
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ext::source_util::expand_include));
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syntax_expanders.insert(intern("include_str"),
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builtin_normal_expander(
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ext::source_util::expand_include_str));
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syntax_expanders.insert(intern("include_bin"),
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builtin_normal_expander(
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ext::source_util::expand_include_bin));
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syntax_expanders.insert(intern("module_path"),
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builtin_normal_expander(
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ext::source_util::expand_mod));
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syntax_expanders.insert(intern("asm"),
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builtin_normal_expander(
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ext::asm::expand_asm));
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syntax_expanders.insert(intern("cfg"),
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builtin_normal_expander(
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ext::cfg::expand_cfg));
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syntax_expanders.insert(intern("trace_macros"),
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builtin_normal_expander(
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ext::trace_macros::expand_trace_macros));
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syntax_expanders
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}
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/// One of these is made during expansion and incrementally updated as we go;
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/// when a macro expansion occurs, the resulting nodes have the backtrace()
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/// -> expn_info of their expansion context stored into their span.
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pub struct ExtCtxt<'a> {
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pub parse_sess: &'a parse::ParseSess,
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pub cfg: ast::CrateConfig,
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pub backtrace: ExpnId,
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pub ecfg: expand::ExpansionConfig,
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pub mod_path: Vec<ast::Ident> ,
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pub trace_mac: bool,
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pub exported_macros: Vec<P<ast::Item>>,
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pub syntax_env: SyntaxEnv,
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}
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impl<'a> ExtCtxt<'a> {
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pub fn new<'a>(parse_sess: &'a parse::ParseSess, cfg: ast::CrateConfig,
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ecfg: expand::ExpansionConfig) -> ExtCtxt<'a> {
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ExtCtxt {
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parse_sess: parse_sess,
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cfg: cfg,
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backtrace: NO_EXPANSION,
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mod_path: Vec::new(),
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ecfg: ecfg,
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trace_mac: false,
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exported_macros: Vec::new(),
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syntax_env: initial_syntax_expander_table(),
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}
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}
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#[deprecated = "Replaced with `expander().fold_expr()`"]
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pub fn expand_expr(&mut self, e: P<ast::Expr>) -> P<ast::Expr> {
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self.expander().fold_expr(e)
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}
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/// Returns a `Folder` for deeply expanding all macros in a AST node.
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pub fn expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
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expand::MacroExpander { cx: self }
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}
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pub fn new_parser_from_tts(&self, tts: &[ast::TokenTree])
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-> parser::Parser<'a> {
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parse::tts_to_parser(self.parse_sess, Vec::from_slice(tts), self.cfg())
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}
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pub fn codemap(&self) -> &'a CodeMap { &self.parse_sess.span_diagnostic.cm }
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pub fn parse_sess(&self) -> &'a parse::ParseSess { self.parse_sess }
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pub fn cfg(&self) -> ast::CrateConfig { self.cfg.clone() }
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pub fn call_site(&self) -> Span {
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self.codemap().with_expn_info(self.backtrace, |ei| match ei {
|
|
Some(expn_info) => expn_info.call_site,
|
|
None => self.bug("missing top span")
|
|
})
|
|
}
|
|
pub fn print_backtrace(&self) { }
|
|
pub fn backtrace(&self) -> ExpnId { self.backtrace }
|
|
pub fn original_span(&self) -> Span {
|
|
let mut expn_id = self.backtrace;
|
|
let mut call_site = None;
|
|
loop {
|
|
match self.codemap().with_expn_info(expn_id, |ei| ei.map(|ei| ei.call_site)) {
|
|
None => break,
|
|
Some(cs) => {
|
|
call_site = Some(cs);
|
|
expn_id = cs.expn_id;
|
|
}
|
|
}
|
|
}
|
|
call_site.expect("missing expansion backtrace")
|
|
}
|
|
pub fn original_span_in_file(&self) -> Span {
|
|
let mut expn_id = self.backtrace;
|
|
let mut call_site = None;
|
|
loop {
|
|
let expn_info = self.codemap().with_expn_info(expn_id, |ei| {
|
|
ei.map(|ei| (ei.call_site, ei.callee.name.as_slice() == "include"))
|
|
});
|
|
match expn_info {
|
|
None => break,
|
|
Some((cs, is_include)) => {
|
|
if is_include {
|
|
// Don't recurse into file using "include!".
|
|
break;
|
|
}
|
|
call_site = Some(cs);
|
|
expn_id = cs.expn_id;
|
|
}
|
|
}
|
|
}
|
|
call_site.expect("missing expansion backtrace")
|
|
}
|
|
|
|
pub fn mod_push(&mut self, i: ast::Ident) { self.mod_path.push(i); }
|
|
pub fn mod_pop(&mut self) { self.mod_path.pop().unwrap(); }
|
|
pub fn mod_path(&self) -> Vec<ast::Ident> {
|
|
let mut v = Vec::new();
|
|
v.push(token::str_to_ident(self.ecfg.crate_name.as_slice()));
|
|
v.extend(self.mod_path.iter().map(|a| *a));
|
|
return v;
|
|
}
|
|
pub fn bt_push(&mut self, ei: ExpnInfo) {
|
|
let mut call_site = ei.call_site;
|
|
call_site.expn_id = self.backtrace;
|
|
self.backtrace = self.codemap().record_expansion(ExpnInfo {
|
|
call_site: call_site,
|
|
callee: ei.callee
|
|
});
|
|
}
|
|
pub fn bt_pop(&mut self) {
|
|
match self.backtrace {
|
|
NO_EXPANSION => self.bug("tried to pop without a push"),
|
|
expn_id => {
|
|
self.backtrace = self.codemap().with_expn_info(expn_id, |expn_info| {
|
|
expn_info.map_or(NO_EXPANSION, |ei| ei.call_site.expn_id)
|
|
});
|
|
}
|
|
}
|
|
}
|
|
/// Emit `msg` attached to `sp`, and stop compilation immediately.
|
|
///
|
|
/// `span_err` should be strongly preferred where-ever possible:
|
|
/// this should *only* be used when
|
|
/// - continuing has a high risk of flow-on errors (e.g. errors in
|
|
/// declaring a macro would cause all uses of that macro to
|
|
/// complain about "undefined macro"), or
|
|
/// - there is literally nothing else that can be done (however,
|
|
/// in most cases one can construct a dummy expression/item to
|
|
/// substitute; we never hit resolve/type-checking so the dummy
|
|
/// value doesn't have to match anything)
|
|
pub fn span_fatal(&self, sp: Span, msg: &str) -> ! {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.span_fatal(sp, msg);
|
|
}
|
|
|
|
/// Emit `msg` attached to `sp`, without immediately stopping
|
|
/// compilation.
|
|
///
|
|
/// Compilation will be stopped in the near future (at the end of
|
|
/// the macro expansion phase).
|
|
pub fn span_err(&self, sp: Span, msg: &str) {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.span_err(sp, msg);
|
|
}
|
|
pub fn span_warn(&self, sp: Span, msg: &str) {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.span_warn(sp, msg);
|
|
}
|
|
pub fn span_unimpl(&self, sp: Span, msg: &str) -> ! {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.span_unimpl(sp, msg);
|
|
}
|
|
pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.span_bug(sp, msg);
|
|
}
|
|
pub fn span_note(&self, sp: Span, msg: &str) {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.span_note(sp, msg);
|
|
}
|
|
pub fn bug(&self, msg: &str) -> ! {
|
|
self.print_backtrace();
|
|
self.parse_sess.span_diagnostic.handler().bug(msg);
|
|
}
|
|
pub fn trace_macros(&self) -> bool {
|
|
self.trace_mac
|
|
}
|
|
pub fn set_trace_macros(&mut self, x: bool) {
|
|
self.trace_mac = x
|
|
}
|
|
pub fn ident_of(&self, st: &str) -> ast::Ident {
|
|
str_to_ident(st)
|
|
}
|
|
pub fn name_of(&self, st: &str) -> ast::Name {
|
|
token::intern(st)
|
|
}
|
|
}
|
|
|
|
/// Extract a string literal from the macro expanded version of `expr`,
|
|
/// emitting `err_msg` if `expr` is not a string literal. This does not stop
|
|
/// compilation on error, merely emits a non-fatal error and returns None.
|
|
pub fn expr_to_string(cx: &mut ExtCtxt, expr: P<ast::Expr>, err_msg: &str)
|
|
-> Option<(InternedString, ast::StrStyle)> {
|
|
// we want to be able to handle e.g. concat("foo", "bar")
|
|
let expr = cx.expander().fold_expr(expr);
|
|
match expr.node {
|
|
ast::ExprLit(ref l) => match l.node {
|
|
ast::LitStr(ref s, style) => return Some(((*s).clone(), style)),
|
|
_ => cx.span_err(l.span, err_msg)
|
|
},
|
|
_ => cx.span_err(expr.span, err_msg)
|
|
}
|
|
None
|
|
}
|
|
|
|
/// Non-fatally assert that `tts` is empty. Note that this function
|
|
/// returns even when `tts` is non-empty, macros that *need* to stop
|
|
/// compilation should call
|
|
/// `cx.parse_sess.span_diagnostic.abort_if_errors()` (this should be
|
|
/// done as rarely as possible).
|
|
pub fn check_zero_tts(cx: &ExtCtxt,
|
|
sp: Span,
|
|
tts: &[ast::TokenTree],
|
|
name: &str) {
|
|
if tts.len() != 0 {
|
|
cx.span_err(sp, format!("{} takes no arguments", name).as_slice());
|
|
}
|
|
}
|
|
|
|
/// Extract the string literal from the first token of `tts`. If this
|
|
/// is not a string literal, emit an error and return None.
|
|
pub fn get_single_str_from_tts(cx: &ExtCtxt,
|
|
sp: Span,
|
|
tts: &[ast::TokenTree],
|
|
name: &str)
|
|
-> Option<String> {
|
|
if tts.len() != 1 {
|
|
cx.span_err(sp, format!("{} takes 1 argument.", name).as_slice());
|
|
} else {
|
|
match tts[0] {
|
|
ast::TTTok(_, token::LIT_STR(ident)) => return Some(parse::str_lit(ident.as_str())),
|
|
ast::TTTok(_, token::LIT_STR_RAW(ident, _)) => {
|
|
return Some(parse::raw_str_lit(ident.as_str()))
|
|
}
|
|
_ => {
|
|
cx.span_err(sp,
|
|
format!("{} requires a string.", name).as_slice())
|
|
}
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
/// Extract comma-separated expressions from `tts`. If there is a
|
|
/// parsing error, emit a non-fatal error and return None.
|
|
pub fn get_exprs_from_tts(cx: &mut ExtCtxt,
|
|
sp: Span,
|
|
tts: &[ast::TokenTree]) -> Option<Vec<P<ast::Expr>>> {
|
|
let mut p = cx.new_parser_from_tts(tts);
|
|
let mut es = Vec::new();
|
|
while p.token != token::EOF {
|
|
es.push(cx.expander().fold_expr(p.parse_expr()));
|
|
if p.eat(&token::COMMA) {
|
|
continue;
|
|
}
|
|
if p.token != token::EOF {
|
|
cx.span_err(sp, "expected token: `,`");
|
|
return None;
|
|
}
|
|
}
|
|
Some(es)
|
|
}
|
|
|
|
/// In order to have some notion of scoping for macros,
|
|
/// we want to implement the notion of a transformation
|
|
/// environment.
|
|
///
|
|
/// This environment maps Names to SyntaxExtensions.
|
|
pub struct SyntaxEnv {
|
|
chain: Vec<MapChainFrame> ,
|
|
}
|
|
|
|
// impl question: how to implement it? Initially, the
|
|
// env will contain only macros, so it might be painful
|
|
// to add an empty frame for every context. Let's just
|
|
// get it working, first....
|
|
|
|
// NB! the mutability of the underlying maps means that
|
|
// if expansion is out-of-order, a deeper scope may be
|
|
// able to refer to a macro that was added to an enclosing
|
|
// scope lexically later than the deeper scope.
|
|
|
|
struct MapChainFrame {
|
|
info: BlockInfo,
|
|
map: HashMap<Name, Rc<SyntaxExtension>>,
|
|
}
|
|
|
|
impl SyntaxEnv {
|
|
fn new() -> SyntaxEnv {
|
|
let mut map = SyntaxEnv { chain: Vec::new() };
|
|
map.push_frame();
|
|
map
|
|
}
|
|
|
|
pub fn push_frame(&mut self) {
|
|
self.chain.push(MapChainFrame {
|
|
info: BlockInfo::new(),
|
|
map: HashMap::new(),
|
|
});
|
|
}
|
|
|
|
pub fn pop_frame(&mut self) {
|
|
assert!(self.chain.len() > 1, "too many pops on MapChain!");
|
|
self.chain.pop();
|
|
}
|
|
|
|
fn find_escape_frame<'a>(&'a mut self) -> &'a mut MapChainFrame {
|
|
for (i, frame) in self.chain.iter_mut().enumerate().rev() {
|
|
if !frame.info.macros_escape || i == 0 {
|
|
return frame
|
|
}
|
|
}
|
|
unreachable!()
|
|
}
|
|
|
|
pub fn find(&self, k: &Name) -> Option<Rc<SyntaxExtension>> {
|
|
for frame in self.chain.iter().rev() {
|
|
match frame.map.find(k) {
|
|
Some(v) => return Some(v.clone()),
|
|
None => {}
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
pub fn insert(&mut self, k: Name, v: SyntaxExtension) {
|
|
self.find_escape_frame().map.insert(k, Rc::new(v));
|
|
}
|
|
|
|
pub fn info<'a>(&'a mut self) -> &'a mut BlockInfo {
|
|
let last_chain_index = self.chain.len() - 1;
|
|
&mut self.chain.get_mut(last_chain_index).info
|
|
}
|
|
}
|