src/librustc_save_analysis/span_utils.rs - third_party/rust - Git at Google

 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 use rustc::session::Session;

 use generated_code;

 use std::cell::Cell;
 use std::env;
 use std::path::Path;

 use syntax::ast;
 use syntax::parse::lexer::{self, Reader, StringReader};
 use syntax::parse::token::{self, keywords, Token};
 use syntax_pos::*;

 #[derive(Clone)]
 pub struct SpanUtils<'a> {
     pub sess: &'a Session,
     // FIXME given that we clone SpanUtils all over the place, this err_count is
     // probably useless and any logic relying on it is bogus.
     pub err_count: Cell<isize>,
 }

 impl<'a> SpanUtils<'a> {
     pub fn new(sess: &'a Session) -> SpanUtils<'a> {
         SpanUtils {
             sess: sess,
             err_count: Cell::new(0),
         }
     }

     pub fn make_path_string(file_name: &str) -> String {
         let path = Path::new(file_name);
         if path.is_absolute() {
             path.clone().display().to_string()
         } else {
             env::current_dir().unwrap().join(&path).display().to_string()
         }
     }

     // sub_span starts at span.lo, so we need to adjust the positions etc.
     // If sub_span is None, we don't need to adjust.
     pub fn make_sub_span(&self, span: Span, sub_span: Option<Span>) -> Option<Span> {
         match sub_span {
             None => None,
             Some(sub) => {
                 let FileMapAndBytePos {fm, pos} = self.sess.codemap().lookup_byte_offset(span.lo);
                 let base = pos + fm.start_pos;
                 Some(Span {
                     lo: base + self.sess.codemap().lookup_byte_offset(sub.lo).pos,
                     hi: base + self.sess.codemap().lookup_byte_offset(sub.hi).pos,
                     expn_id: span.expn_id,
                 })
             }
         }
     }

     pub fn snippet(&self, span: Span) -> String {
         match self.sess.codemap().span_to_snippet(span) {
             Ok(s) => s,
             Err(_) => String::new(),
         }
     }

     pub fn retokenise_span(&self, span: Span) -> StringReader<'a> {
         // sadness - we don't have spans for sub-expressions nor access to the tokens
         // so in order to get extents for the function name itself (which dxr expects)
         // we need to re-tokenise the fn definition

         // Note: this is a bit awful - it adds the contents of span to the end of
         // the codemap as a new filemap. This is mostly OK, but means we should
         // not iterate over the codemap. Also, any spans over the new filemap
         // are incompatible with spans over other filemaps.
         let filemap = self.sess
                           .codemap()
                           .new_filemap(String::from("<anon-dxr>"), None, self.snippet(span));
         let s = self.sess;
         lexer::StringReader::new(s.diagnostic(), filemap)
     }

     // Re-parses a path and returns the span for the last identifier in the path
     pub fn span_for_last_ident(&self, span: Span) -> Option<Span> {
         let mut result = None;

         let mut toks = self.retokenise_span(span);
         let mut bracket_count = 0;
         loop {
             let ts = toks.real_token();
             if ts.tok == token::Eof {
                 return self.make_sub_span(span, result)
             }
             if bracket_count == 0 && (ts.tok.is_ident() || ts.tok.is_keyword(keywords::SelfValue)) {
                 result = Some(ts.sp);
             }

             bracket_count += match ts.tok {
                 token::Lt => 1,
                 token::Gt => -1,
                 token::BinOp(token::Shr) => -2,
                 _ => 0,
             }
         }
     }

     // Return the span for the first identifier in the path.
     pub fn span_for_first_ident(&self, span: Span) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         let mut bracket_count = 0;
         loop {
             let ts = toks.real_token();
             if ts.tok == token::Eof {
                 return None;
             }
             if bracket_count == 0 && (ts.tok.is_ident() || ts.tok.is_keyword(keywords::SelfValue)) {
                 return self.make_sub_span(span, Some(ts.sp));
             }

             bracket_count += match ts.tok {
                 token::Lt => 1,
                 token::Gt => -1,
                 token::BinOp(token::Shr) => -2,
                 _ => 0,
             }
         }
     }

     // Return the span for the last ident before a `(` or `<` or '::<' and outside any
     // any brackets, or the last span.
     pub fn sub_span_for_meth_name(&self, span: Span) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         let mut prev = toks.real_token();
         let mut result = None;
         let mut bracket_count = 0;
         let mut last_span = None;
         while prev.tok != token::Eof {
             last_span = None;
             let mut next = toks.real_token();

             if (next.tok == token::OpenDelim(token::Paren) || next.tok == token::Lt) &&
                bracket_count == 0 && prev.tok.is_ident() {
                 result = Some(prev.sp);
             }

             if bracket_count == 0 && next.tok == token::ModSep {
                 let old = prev;
                 prev = next;
                 next = toks.real_token();
                 if next.tok == token::Lt && old.tok.is_ident() {
                     result = Some(old.sp);
                 }
             }

             bracket_count += match prev.tok {
                 token::OpenDelim(token::Paren) | token::Lt => 1,
                 token::CloseDelim(token::Paren) | token::Gt => -1,
                 token::BinOp(token::Shr) => -2,
                 _ => 0,
             };

             if prev.tok.is_ident() && bracket_count == 0 {
                 last_span = Some(prev.sp);
             }
             prev = next;
         }
         if result.is_none() && last_span.is_some() {
             return self.make_sub_span(span, last_span);
         }
         return self.make_sub_span(span, result);
     }

     // Return the span for the last ident before a `<` and outside any
     // brackets, or the last span.
     pub fn sub_span_for_type_name(&self, span: Span) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         let mut prev = toks.real_token();
         let mut result = None;
         let mut bracket_count = 0;
         loop {
             let next = toks.real_token();

             if (next.tok == token::Lt || next.tok == token::Colon) && bracket_count == 0 &&
                prev.tok.is_ident() {
                 result = Some(prev.sp);
             }

             bracket_count += match prev.tok {
                 token::Lt => 1,
                 token::Gt => -1,
                 token::BinOp(token::Shl) => 2,
                 token::BinOp(token::Shr) => -2,
                 _ => 0,
             };

             if next.tok == token::Eof {
                 break;
             }
             prev = next;
         }
         if bracket_count != 0 {
             let loc = self.sess.codemap().lookup_char_pos(span.lo);
             span_bug!(span,
                       "Mis-counted brackets when breaking path? Parsing '{}' \
                        in {}, line {}",
                       self.snippet(span),
                       loc.file.name,
                       loc.line);
         }
         if result.is_none() && prev.tok.is_ident() && bracket_count == 0 {
             return self.make_sub_span(span, Some(prev.sp));
         }
         self.make_sub_span(span, result)
     }

     // Reparse span and return an owned vector of sub spans of the first limit
     // identifier tokens in the given nesting level.
     // example with Foo<Bar<T,V>, Bar<T,V>>
     // Nesting = 0: all idents outside of brackets: [Foo]
     // Nesting = 1: idents within one level of brackets: [Bar, Bar]
     pub fn spans_with_brackets(&self, span: Span, nesting: isize, limit: isize) -> Vec<Span> {
         let mut result: Vec<Span> = vec!();

         let mut toks = self.retokenise_span(span);
         // We keep track of how many brackets we're nested in
         let mut bracket_count: isize = 0;
         let mut found_ufcs_sep = false;
         loop {
             let ts = toks.real_token();
             if ts.tok == token::Eof {
                 if bracket_count != 0 {
                     if generated_code(span) {
                         return vec!();
                     }
                     let loc = self.sess.codemap().lookup_char_pos(span.lo);
                     span_bug!(span,
                               "Mis-counted brackets when breaking path? \
                                Parsing '{}' in {}, line {}",
                               self.snippet(span),
                               loc.file.name,
                               loc.line);
                 }
                 return result
             }
             if (result.len() as isize) == limit {
                 return result;
             }
             bracket_count += match ts.tok {
                 token::Lt => 1,
                 token::Gt => -1,
                 token::BinOp(token::Shl) => 2,
                 token::BinOp(token::Shr) => -2,
                 _ => 0,
             };

             // Ignore the `>::` in `<Type as Trait>::AssocTy`.

             // The root cause of this hack is that the AST representation of
             // qpaths is horrible. It treats <A as B>::C as a path with two
             // segments, B and C and notes that there is also a self type A at
             // position 0. Because we don't have spans for individual idents,
             // only the whole path, we have to iterate over the tokens in the
             // path, trying to pull out the non-nested idents (e.g., avoiding 'a
             // in `<A as B<'a>>::C`). So we end up with a span for `B>::C` from
             // the start of the first ident to the end of the path.
             if !found_ufcs_sep && bracket_count == -1 {
                 found_ufcs_sep = true;
                 bracket_count += 1;
             }
             if ts.tok.is_ident() && bracket_count == nesting {
                 result.push(self.make_sub_span(span, Some(ts.sp)).unwrap());
             }
         }
     }

     pub fn sub_span_before_token(&self, span: Span, tok: Token) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         let mut prev = toks.real_token();
         loop {
             if prev.tok == token::Eof {
                 return None;
             }
             let next = toks.real_token();
             if next.tok == tok {
                 return self.make_sub_span(span, Some(prev.sp));
             }
             prev = next;
         }
     }

     pub fn sub_span_of_token(&self, span: Span, tok: Token) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         loop {
             let next = toks.real_token();
             if next.tok == token::Eof {
                 return None;
             }
             if next.tok == tok {
                 return self.make_sub_span(span, Some(next.sp));
             }
         }
     }

     pub fn sub_span_after_keyword(&self, span: Span, keyword: keywords::Keyword) -> Option<Span> {
         self.sub_span_after(span, |t| t.is_keyword(keyword))
     }

     pub fn sub_span_after_token(&self, span: Span, tok: Token) -> Option<Span> {
         self.sub_span_after(span, |t| t == tok)
     }

     fn sub_span_after<F: Fn(Token) -> bool>(&self, span: Span, f: F) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         loop {
             let ts = toks.real_token();
             if ts.tok == token::Eof {
                 return None;
             }
             if f(ts.tok) {
                 let ts = toks.real_token();
                 if ts.tok == token::Eof {
                     return None
                 } else {
                     return self.make_sub_span(span, Some(ts.sp));
                 }
             }
         }
     }


     // Returns a list of the spans of idents in a path.
     // E.g., For foo::bar<x,t>::baz, we return [foo, bar, baz] (well, their spans)
     pub fn spans_for_path_segments(&self, path: &ast::Path) -> Vec<Span> {
         self.spans_with_brackets(path.span, 0, -1)
     }

     // Return an owned vector of the subspans of the param identifier
     // tokens found in span.
     pub fn spans_for_ty_params(&self, span: Span, number: isize) -> Vec<Span> {
         // Type params are nested within one level of brackets:
         // i.e. we want Vec<A, B> from Foo<A, B<T,U>>
         self.spans_with_brackets(span, 1, number)
     }

     pub fn report_span_err(&self, kind: &str, span: Span) {
         let loc = self.sess.codemap().lookup_char_pos(span.lo);
         info!("({}) Could not find sub_span in `{}` in {}, line {}",
               kind,
               self.snippet(span),
               loc.file.name,
               loc.line);
         self.err_count.set(self.err_count.get() + 1);
         if self.err_count.get() > 1000 {
             bug!("span errors reached 1000, giving up");
         }
     }

     // Return the name for a macro definition (identifier after first `!`)
     pub fn span_for_macro_def_name(&self, span: Span) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         loop {
             let ts = toks.real_token();
             if ts.tok == token::Eof {
                 return None;
             }
             if ts.tok == token::Not {
                 let ts = toks.real_token();
                 if ts.tok.is_ident() {
                     return self.make_sub_span(span, Some(ts.sp));
                 } else {
                     return None;
                 }
             }
         }
     }

     // Return the name for a macro use (identifier before first `!`).
     pub fn span_for_macro_use_name(&self, span:Span) -> Option<Span> {
         let mut toks = self.retokenise_span(span);
         let mut prev = toks.real_token();
         loop {
             if prev.tok == token::Eof {
                 return None;
             }
             let ts = toks.real_token();
             if ts.tok == token::Not {
                 if prev.tok.is_ident() {
                     return self.make_sub_span(span, Some(prev.sp));
                 } else {
                     return None;
                 }
             }
             prev = ts;
         }
     }

     /// Return true if the span is generated code, and
     /// it is not a subspan of the root callsite.
     ///
     /// Used to filter out spans of minimal value,
     /// such as references to macro internal variables.
     pub fn filter_generated(&self, sub_span: Option<Span>, parent: Span) -> bool {
         if !generated_code(parent) {
             if sub_span.is_none() {
                 // Edge case - this occurs on generated code with incorrect expansion info.
                 return true;
             }
             return false;
         }
         // If sub_span is none, filter out generated code.
         if sub_span.is_none() {
             return true;
         }

         //If the span comes from a fake filemap, filter it.
         if !self.sess.codemap().lookup_char_pos(parent.lo).file.is_real_file() {
             return true;
         }

         // Otherwise, a generated span is deemed invalid if it is not a sub-span of the root
         // callsite. This filters out macro internal variables and most malformed spans.
         let span = self.sess.codemap().source_callsite(parent);
         !(span.contains(parent))
     }
 }

 macro_rules! filter {
     ($util: expr, $span: ident, $parent: expr, None) => {
         if $util.filter_generated($span, $parent) {
             return None;
         }
     };
     ($util: expr, $span: ident, $parent: expr) => {
         if $util.filter_generated($span, $parent) {
             return;
         }
     };
 }
	// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	use rustc::session::Session;

	use generated_code;

	use std::cell::Cell;
	use std::env;
	use std::path::Path;

	use syntax::ast;
	use syntax::parse::lexer::{self, Reader, StringReader};
	use syntax::parse::token::{self, keywords, Token};
	use syntax_pos::*;

	#[derive(Clone)]
	pub struct SpanUtils<'a> {
	pub sess: &'a Session,
	// FIXME given that we clone SpanUtils all over the place, this err_count is
	// probably useless and any logic relying on it is bogus.
	pub err_count: Cell<isize>,
	}

	impl<'a> SpanUtils<'a> {
	pub fn new(sess: &'a Session) -> SpanUtils<'a> {
	SpanUtils {
	sess: sess,
	err_count: Cell::new(0),
	}
	}

	pub fn make_path_string(file_name: &str) -> String {
	let path = Path::new(file_name);
	if path.is_absolute() {
	path.clone().display().to_string()
	} else {
	env::current_dir().unwrap().join(&path).display().to_string()
	}
	}

	// sub_span starts at span.lo, so we need to adjust the positions etc.
	// If sub_span is None, we don't need to adjust.
	pub fn make_sub_span(&self, span: Span, sub_span: Option<Span>) -> Option<Span> {
	match sub_span {
	None => None,
	Some(sub) => {
	let FileMapAndBytePos {fm, pos} = self.sess.codemap().lookup_byte_offset(span.lo);
	let base = pos + fm.start_pos;
	Some(Span {
	lo: base + self.sess.codemap().lookup_byte_offset(sub.lo).pos,
	hi: base + self.sess.codemap().lookup_byte_offset(sub.hi).pos,
	expn_id: span.expn_id,
	})
	}
	}
	}

	pub fn snippet(&self, span: Span) -> String {
	match self.sess.codemap().span_to_snippet(span) {
	Ok(s) => s,
	Err(_) => String::new(),
	}
	}

	pub fn retokenise_span(&self, span: Span) -> StringReader<'a> {
	// sadness - we don't have spans for sub-expressions nor access to the tokens
	// so in order to get extents for the function name itself (which dxr expects)
	// we need to re-tokenise the fn definition

	// Note: this is a bit awful - it adds the contents of span to the end of
	// the codemap as a new filemap. This is mostly OK, but means we should
	// not iterate over the codemap. Also, any spans over the new filemap
	// are incompatible with spans over other filemaps.
	let filemap = self.sess
	.codemap()
	.new_filemap(String::from("<anon-dxr>"), None, self.snippet(span));
	let s = self.sess;
	lexer::StringReader::new(s.diagnostic(), filemap)
	}

	// Re-parses a path and returns the span for the last identifier in the path
	pub fn span_for_last_ident(&self, span: Span) -> Option<Span> {
	let mut result = None;

	let mut toks = self.retokenise_span(span);
	let mut bracket_count = 0;
	loop {
	let ts = toks.real_token();
	if ts.tok == token::Eof {
	return self.make_sub_span(span, result)
	}
	if bracket_count == 0 && (ts.tok.is_ident() \|\| ts.tok.is_keyword(keywords::SelfValue)) {
	result = Some(ts.sp);
	}

	bracket_count += match ts.tok {
	token::Lt => 1,
	token::Gt => -1,
	token::BinOp(token::Shr) => -2,
	_ => 0,
	}
	}
	}

	// Return the span for the first identifier in the path.
	pub fn span_for_first_ident(&self, span: Span) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	let mut bracket_count = 0;
	loop {
	let ts = toks.real_token();
	if ts.tok == token::Eof {
	return None;
	}
	if bracket_count == 0 && (ts.tok.is_ident() \|\| ts.tok.is_keyword(keywords::SelfValue)) {
	return self.make_sub_span(span, Some(ts.sp));
	}

	bracket_count += match ts.tok {
	token::Lt => 1,
	token::Gt => -1,
	token::BinOp(token::Shr) => -2,
	_ => 0,
	}
	}
	}

	// Return the span for the last ident before a `(` or `<` or '::<' and outside any
	// any brackets, or the last span.
	pub fn sub_span_for_meth_name(&self, span: Span) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	let mut prev = toks.real_token();
	let mut result = None;
	let mut bracket_count = 0;
	let mut last_span = None;
	while prev.tok != token::Eof {
	last_span = None;
	let mut next = toks.real_token();

	if (next.tok == token::OpenDelim(token::Paren) \|\| next.tok == token::Lt) &&
	bracket_count == 0 && prev.tok.is_ident() {
	result = Some(prev.sp);
	}

	if bracket_count == 0 && next.tok == token::ModSep {
	let old = prev;
	prev = next;
	next = toks.real_token();
	if next.tok == token::Lt && old.tok.is_ident() {
	result = Some(old.sp);
	}
	}

	bracket_count += match prev.tok {
	token::OpenDelim(token::Paren) \| token::Lt => 1,
	token::CloseDelim(token::Paren) \| token::Gt => -1,
	token::BinOp(token::Shr) => -2,
	_ => 0,
	};

	if prev.tok.is_ident() && bracket_count == 0 {
	last_span = Some(prev.sp);
	}
	prev = next;
	}
	if result.is_none() && last_span.is_some() {
	return self.make_sub_span(span, last_span);
	}
	return self.make_sub_span(span, result);
	}

	// Return the span for the last ident before a `<` and outside any
	// brackets, or the last span.
	pub fn sub_span_for_type_name(&self, span: Span) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	let mut prev = toks.real_token();
	let mut result = None;
	let mut bracket_count = 0;
	loop {
	let next = toks.real_token();

	if (next.tok == token::Lt \|\| next.tok == token::Colon) && bracket_count == 0 &&
	prev.tok.is_ident() {
	result = Some(prev.sp);
	}

	bracket_count += match prev.tok {
	token::Lt => 1,
	token::Gt => -1,
	token::BinOp(token::Shl) => 2,
	token::BinOp(token::Shr) => -2,
	_ => 0,
	};

	if next.tok == token::Eof {
	break;
	}
	prev = next;
	}
	if bracket_count != 0 {
	let loc = self.sess.codemap().lookup_char_pos(span.lo);
	span_bug!(span,
	"Mis-counted brackets when breaking path? Parsing '{}' \
	in {}, line {}",
	self.snippet(span),
	loc.file.name,
	loc.line);
	}
	if result.is_none() && prev.tok.is_ident() && bracket_count == 0 {
	return self.make_sub_span(span, Some(prev.sp));
	}
	self.make_sub_span(span, result)
	}

	// Reparse span and return an owned vector of sub spans of the first limit
	// identifier tokens in the given nesting level.
	// example with Foo<Bar<T,V>, Bar<T,V>>
	// Nesting = 0: all idents outside of brackets: [Foo]
	// Nesting = 1: idents within one level of brackets: [Bar, Bar]
	pub fn spans_with_brackets(&self, span: Span, nesting: isize, limit: isize) -> Vec<Span> {
	let mut result: Vec<Span> = vec!();

	let mut toks = self.retokenise_span(span);
	// We keep track of how many brackets we're nested in
	let mut bracket_count: isize = 0;
	let mut found_ufcs_sep = false;
	loop {
	let ts = toks.real_token();
	if ts.tok == token::Eof {
	if bracket_count != 0 {
	if generated_code(span) {
	return vec!();
	}
	let loc = self.sess.codemap().lookup_char_pos(span.lo);
	span_bug!(span,
	"Mis-counted brackets when breaking path? \
	Parsing '{}' in {}, line {}",
	self.snippet(span),
	loc.file.name,
	loc.line);
	}
	return result
	}
	if (result.len() as isize) == limit {
	return result;
	}
	bracket_count += match ts.tok {
	token::Lt => 1,
	token::Gt => -1,
	token::BinOp(token::Shl) => 2,
	token::BinOp(token::Shr) => -2,
	_ => 0,
	};

	// Ignore the `>::` in `<Type as Trait>::AssocTy`.

	// The root cause of this hack is that the AST representation of
	// qpaths is horrible. It treats <A as B>::C as a path with two
	// segments, B and C and notes that there is also a self type A at
	// position 0. Because we don't have spans for individual idents,
	// only the whole path, we have to iterate over the tokens in the
	// path, trying to pull out the non-nested idents (e.g., avoiding 'a
	// in `<A as B<'a>>::C`). So we end up with a span for `B>::C` from
	// the start of the first ident to the end of the path.
	if !found_ufcs_sep && bracket_count == -1 {
	found_ufcs_sep = true;
	bracket_count += 1;
	}
	if ts.tok.is_ident() && bracket_count == nesting {
	result.push(self.make_sub_span(span, Some(ts.sp)).unwrap());
	}
	}
	}

	pub fn sub_span_before_token(&self, span: Span, tok: Token) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	let mut prev = toks.real_token();
	loop {
	if prev.tok == token::Eof {
	return None;
	}
	let next = toks.real_token();
	if next.tok == tok {
	return self.make_sub_span(span, Some(prev.sp));
	}
	prev = next;
	}
	}

	pub fn sub_span_of_token(&self, span: Span, tok: Token) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	loop {
	let next = toks.real_token();
	if next.tok == token::Eof {
	return None;
	}
	if next.tok == tok {
	return self.make_sub_span(span, Some(next.sp));
	}
	}
	}

	pub fn sub_span_after_keyword(&self, span: Span, keyword: keywords::Keyword) -> Option<Span> {
	self.sub_span_after(span, \|t\| t.is_keyword(keyword))
	}

	pub fn sub_span_after_token(&self, span: Span, tok: Token) -> Option<Span> {
	self.sub_span_after(span, \|t\| t == tok)
	}

	fn sub_span_after<F: Fn(Token) -> bool>(&self, span: Span, f: F) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	loop {
	let ts = toks.real_token();
	if ts.tok == token::Eof {
	return None;
	}
	if f(ts.tok) {
	let ts = toks.real_token();
	if ts.tok == token::Eof {
	return None
	} else {
	return self.make_sub_span(span, Some(ts.sp));
	}
	}
	}
	}


	// Returns a list of the spans of idents in a path.
	// E.g., For foo::bar<x,t>::baz, we return [foo, bar, baz] (well, their spans)
	pub fn spans_for_path_segments(&self, path: &ast::Path) -> Vec<Span> {
	self.spans_with_brackets(path.span, 0, -1)
	}

	// Return an owned vector of the subspans of the param identifier
	// tokens found in span.
	pub fn spans_for_ty_params(&self, span: Span, number: isize) -> Vec<Span> {
	// Type params are nested within one level of brackets:
	// i.e. we want Vec<A, B> from Foo<A, B<T,U>>
	self.spans_with_brackets(span, 1, number)
	}

	pub fn report_span_err(&self, kind: &str, span: Span) {
	let loc = self.sess.codemap().lookup_char_pos(span.lo);
	info!("({}) Could not find sub_span in `{}` in {}, line {}",
	kind,
	self.snippet(span),
	loc.file.name,
	loc.line);
	self.err_count.set(self.err_count.get() + 1);
	if self.err_count.get() > 1000 {
	bug!("span errors reached 1000, giving up");
	}
	}

	// Return the name for a macro definition (identifier after first `!`)
	pub fn span_for_macro_def_name(&self, span: Span) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	loop {
	let ts = toks.real_token();
	if ts.tok == token::Eof {
	return None;
	}
	if ts.tok == token::Not {
	let ts = toks.real_token();
	if ts.tok.is_ident() {
	return self.make_sub_span(span, Some(ts.sp));
	} else {
	return None;
	}
	}
	}
	}

	// Return the name for a macro use (identifier before first `!`).
	pub fn span_for_macro_use_name(&self, span:Span) -> Option<Span> {
	let mut toks = self.retokenise_span(span);
	let mut prev = toks.real_token();
	loop {
	if prev.tok == token::Eof {
	return None;
	}
	let ts = toks.real_token();
	if ts.tok == token::Not {
	if prev.tok.is_ident() {
	return self.make_sub_span(span, Some(prev.sp));
	} else {
	return None;
	}
	}
	prev = ts;
	}
	}

	/// Return true if the span is generated code, and
	/// it is not a subspan of the root callsite.
	///
	/// Used to filter out spans of minimal value,
	/// such as references to macro internal variables.
	pub fn filter_generated(&self, sub_span: Option<Span>, parent: Span) -> bool {
	if !generated_code(parent) {
	if sub_span.is_none() {
	// Edge case - this occurs on generated code with incorrect expansion info.
	return true;
	}
	return false;
	}
	// If sub_span is none, filter out generated code.
	if sub_span.is_none() {
	return true;
	}

	//If the span comes from a fake filemap, filter it.
	if !self.sess.codemap().lookup_char_pos(parent.lo).file.is_real_file() {
	return true;
	}

	// Otherwise, a generated span is deemed invalid if it is not a sub-span of the root
	// callsite. This filters out macro internal variables and most malformed spans.
	let span = self.sess.codemap().source_callsite(parent);
	!(span.contains(parent))
	}
	}

	macro_rules! filter {
	($util: expr, $span: ident, $parent: expr, None) => {
	if $util.filter_generated($span, $parent) {
	return None;
	}
	};
	($util: expr, $span: ident, $parent: expr) => {
	if $util.filter_generated($span, $parent) {
	return;
	}
	};
	}