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Extended expand.rs to support alternate expansion behaviours (eg. stepwise expansion) #34811

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Merged
merged 1 commit into from
Aug 12, 2016
Merged

Extended expand.rs to support alternate expansion behaviours (eg. stepwise expansion) #34811

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6 changes: 2 additions & 4 deletions src/librustc_driver/driver.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -672,13 +672,11 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
cfg,
&mut loader);
syntax_ext::register_builtins(&mut ecx.syntax_env);
let (ret, macro_names) = syntax::ext::expand::expand_crate(ecx,
syntax_exts,
krate);
let ret = syntax::ext::expand::expand_crate(&mut ecx, syntax_exts, krate);
if cfg!(windows) {
env::set_var("PATH", &old_path);
}
*sess.available_macros.borrow_mut() = macro_names;
*sess.available_macros.borrow_mut() = ecx.syntax_env.names;
ret
});

Expand Down
2 changes: 1 addition & 1 deletion src/libsyntax/ext/base.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -633,7 +633,7 @@ impl<'a> ExtCtxt<'a> {

/// Returns a `Folder` for deeply expanding all macros in an AST node.
pub fn expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
expand::MacroExpander::new(self)
expand::MacroExpander::new(self, false, false)
}

pub fn new_parser_from_tts(&self, tts: &[tokenstream::TokenTree])
Expand Down
120 changes: 79 additions & 41 deletions src/libsyntax/ext/expand.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use ast::{Block, Crate, Ident, Mac_, Name, PatKind};
use ast::{Block, Crate, Ident, Mac_, PatKind};
use ast::{MacStmtStyle, Stmt, StmtKind, ItemKind};
use ast;
use ext::hygiene::Mark;
Expand All @@ -29,8 +29,6 @@ use visit;
use visit::Visitor;
use std_inject;

use std::collections::HashSet;

// A trait for AST nodes and AST node lists into which macro invocations may expand.
trait MacroGenerable: Sized {
// Expand the given MacResult using its appropriate `make_*` method.
Expand Down Expand Up @@ -218,8 +216,7 @@ fn expand_mac_invoc<T>(mac: ast::Mac, ident: Option<Ident>, attrs: Vec<ast::Attr
}
});

// DON'T mark before expansion.
fld.cx.insert_macro(ast::MacroDef {
let def = ast::MacroDef {
ident: ident,
id: ast::DUMMY_NODE_ID,
span: call_site,
Expand All @@ -229,10 +226,30 @@ fn expand_mac_invoc<T>(mac: ast::Mac, ident: Option<Ident>, attrs: Vec<ast::Attr
export: attr::contains_name(&attrs, "macro_export"),
allow_internal_unstable: attr::contains_name(&attrs, "allow_internal_unstable"),
attrs: attrs,
});
};

// macro_rules! has a side effect but expands to nothing.
Some(Box::new(MacroScopePlaceholder))
fld.cx.insert_macro(def.clone());

// macro_rules! has a side effect, but expands to nothing.
// If keep_macs is true, expands to a MacEager::items instead.
if fld.keep_macs {
Some(MacEager::items(SmallVector::one(P(ast::Item {
ident: def.ident,
attrs: def.attrs.clone(),
id: ast::DUMMY_NODE_ID,
node: ast::ItemKind::Mac(ast::Mac {
span: def.span,
node: ast::Mac_ {
path: path.clone(),
tts: def.body.clone(),
}
}),
vis: ast::Visibility::Inherited,
span: def.span,
}))))
} else {
Some(Box::new(MacroScopePlaceholder))
}
}

MultiDecorator(..) | MultiModifier(..) => {
Expand Down Expand Up @@ -260,7 +277,13 @@ fn expand_mac_invoc<T>(mac: ast::Mac, ident: Option<Ident>, attrs: Vec<ast::Attr
let marked = expanded.fold_with(&mut Marker { mark: mark, expn_id: Some(fld.cx.backtrace()) });
let configured = marked.fold_with(&mut fld.strip_unconfigured());
fld.load_macros(&configured);
let fully_expanded = configured.fold_with(fld);

let fully_expanded = if fld.single_step {
configured
} else {
configured.fold_with(fld)
};

fld.cx.bt_pop();
fully_expanded
}
Expand Down Expand Up @@ -491,11 +514,19 @@ pub fn expand_type(t: P<ast::Ty>, fld: &mut MacroExpander) -> P<ast::Ty> {
/// A tree-folder that performs macro expansion
pub struct MacroExpander<'a, 'b:'a> {
pub cx: &'a mut ExtCtxt<'b>,
pub single_step: bool,
pub keep_macs: bool,
}

impl<'a, 'b> MacroExpander<'a, 'b> {
pub fn new(cx: &'a mut ExtCtxt<'b>) -> MacroExpander<'a, 'b> {
MacroExpander { cx: cx }
pub fn new(cx: &'a mut ExtCtxt<'b>,
single_step: bool,
keep_macs: bool) -> MacroExpander<'a, 'b> {
MacroExpander {
cx: cx,
single_step: single_step,
keep_macs: keep_macs
}
}

fn strip_unconfigured(&mut self) -> StripUnconfigured {
Expand Down Expand Up @@ -673,38 +704,45 @@ impl<'feat> ExpansionConfig<'feat> {
}
}

pub fn expand_crate(mut cx: ExtCtxt,
pub fn expand_crate(cx: &mut ExtCtxt,
user_exts: Vec<NamedSyntaxExtension>,
mut c: Crate) -> (Crate, HashSet<Name>) {
c: Crate) -> Crate {
let mut expander = MacroExpander::new(cx, false, false);
expand_crate_with_expander(&mut expander, user_exts, c)
}

// Expands crate using supplied MacroExpander - allows for
// non-standard expansion behaviour (e.g. step-wise).
pub fn expand_crate_with_expander(expander: &mut MacroExpander,
user_exts: Vec<NamedSyntaxExtension>,
mut c: Crate) -> Crate {
if std_inject::no_core(&c) {
cx.crate_root = None;
expander.cx.crate_root = None;
} else if std_inject::no_std(&c) {
cx.crate_root = Some("core");
expander.cx.crate_root = Some("core");
} else {
cx.crate_root = Some("std");
expander.cx.crate_root = Some("std");
}
let ret = {
let mut expander = MacroExpander::new(&mut cx);

for (name, extension) in user_exts {
expander.cx.syntax_env.insert(name, extension);
}
// User extensions must be added before expander.load_macros is called,
// so that macros from external crates shadow user defined extensions.
for (name, extension) in user_exts {
expander.cx.syntax_env.insert(name, extension);
}

let items = SmallVector::many(c.module.items);
expander.load_macros(&items);
c.module.items = items.into();
let items = SmallVector::many(c.module.items);
expander.load_macros(&items);
c.module.items = items.into();

let err_count = cx.parse_sess.span_diagnostic.err_count();
let mut ret = expander.fold_crate(c);
ret.exported_macros = expander.cx.exported_macros.clone();
let err_count = expander.cx.parse_sess.span_diagnostic.err_count();
let mut ret = expander.fold_crate(c);
ret.exported_macros = expander.cx.exported_macros.clone();

if cx.parse_sess.span_diagnostic.err_count() > err_count {
cx.parse_sess.span_diagnostic.abort_if_errors();
}
if expander.cx.parse_sess.span_diagnostic.err_count() > err_count {
expander.cx.parse_sess.span_diagnostic.abort_if_errors();
}

ret
};
return (ret, cx.syntax_env.names);
ret
}

// A Marker adds the given mark to the syntax context and
Expand Down Expand Up @@ -780,8 +818,8 @@ mod tests {
Vec::new(), &sess).unwrap();
// should fail:
let mut loader = DummyMacroLoader;
let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut loader);
expand_crate(ecx, vec![], crate_ast);
let mut ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut loader);
expand_crate(&mut ecx, vec![], crate_ast);
}

// make sure that macros can't escape modules
Expand All @@ -795,8 +833,8 @@ mod tests {
src,
Vec::new(), &sess).unwrap();
let mut loader = DummyMacroLoader;
let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut loader);
expand_crate(ecx, vec![], crate_ast);
let mut ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut loader);
expand_crate(&mut ecx, vec![], crate_ast);
}

// macro_use modules should allow macros to escape
Expand All @@ -809,17 +847,17 @@ mod tests {
src,
Vec::new(), &sess).unwrap();
let mut loader = DummyMacroLoader;
let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut loader);
expand_crate(ecx, vec![], crate_ast);
let mut ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut loader);
expand_crate(&mut ecx, vec![], crate_ast);
}

fn expand_crate_str(crate_str: String) -> ast::Crate {
let ps = parse::ParseSess::new();
let crate_ast = panictry!(string_to_parser(&ps, crate_str).parse_crate_mod());
// the cfg argument actually does matter, here...
let mut loader = DummyMacroLoader;
let ecx = ExtCtxt::new(&ps, vec![], test_ecfg(), &mut loader);
expand_crate(ecx, vec![], crate_ast).0
let mut ecx = ExtCtxt::new(&ps, vec![], test_ecfg(), &mut loader);
expand_crate(&mut ecx, vec![], crate_ast)
}

#[test] fn macro_tokens_should_match(){
Expand Down