auto merge of #13985 : alexcrichton/rust/libfmt, r=brson

This code does not belong in libstd, and rather belongs in a dedicated crate. In
the future, the syntax::ext::format module should move to the fmt_macros crate
(hence the name of the crate), but for now the fmt_macros crate will only
contain the format string parser.

The entire fmt_macros crate is marked #[experimental] because it is not meant
for general consumption, only the format!() interface is officially supported,
not the internals.

This is a breaking change for anyone using the internals of std::fmt::parse.
Some of the flags have moved to std::fmt::rt, while the actual parsing support
has all moved to the fmt_macros library.

[breaking-change]

3 files changed, 80 insertions, 1009 deletions

diff --git a/src/libstd/fmt/mod.rs b/src/libstd/fmt/mod.rs
index 74ab874d319..8846fa3f6f3 100644
--- a/src/libstd/fmt/mod.rs
+++ b/src/libstd/fmt/mod.rs
@@ -510,9 +510,34 @@ pub use self::num::Radix;
 pub use self::num::RadixFmt;
 
 mod num;
-pub mod parse;
 pub mod rt;
 
+#[cfg(stage0)]
+#[allow(missing_doc)]
+pub mod parse {
+    #[deriving(Eq)]
+    pub enum Alignment {
+        AlignLeft,
+        AlignRight,
+        AlignUnknown,
+    }
+
+    pub enum PluralKeyword {
+        Zero,
+        One,
+        Two,
+        Few,
+        Many,
+    }
+
+    pub enum Flag {
+        FlagSignPlus,
+        FlagSignMinus,
+        FlagAlternate,
+        FlagSignAwareZeroPad,
+    }
+}
+
 pub type Result = io::IoResult<()>;
 
 /// A struct to represent both where to emit formatting strings to and how they
@@ -524,7 +549,7 @@ pub struct Formatter<'a> {
     /// Character used as 'fill' whenever there is alignment
     pub fill: char,
     /// Boolean indication of whether the output should be left-aligned
-    pub align: parse::Alignment,
+    pub align: rt::Alignment,
     /// Optionally specified integer width that the output should be
     pub width: Option<uint>,
     /// Optionally specified precision for numeric types
@@ -757,7 +782,7 @@ pub unsafe fn write_unsafe(output: &mut io::Writer,
         width: None,
         precision: None,
         buf: output,
-        align: parse::AlignUnknown,
+        align: rt::AlignUnknown,
         fill: ' ',
         args: args,
         curarg: args.iter(),
@@ -890,15 +915,15 @@ impl<'a> Formatter<'a> {
                 let value = value - match offset { Some(i) => i, None => 0 };
                 for s in selectors.iter() {
                     let run = match s.selector {
-                        rt::Keyword(parse::Zero) => value == 0,
-                        rt::Keyword(parse::One) => value == 1,
-                        rt::Keyword(parse::Two) => value == 2,
+                        rt::Keyword(rt::Zero) => value == 0,
+                        rt::Keyword(rt::One) => value == 1,
+                        rt::Keyword(rt::Two) => value == 2,
 
                         // FIXME: Few/Many should have a user-specified boundary
                         //      One possible option would be in the function
                         //      pointer of the 'arg: Argument' struct.
-                        rt::Keyword(parse::Few) => value < 8,
-                        rt::Keyword(parse::Many) => value >= 8,
+                        rt::Keyword(rt::Few) => value < 8,
+                        rt::Keyword(rt::Many) => value >= 8,
 
                         rt::Literal(..) => false
                     };
@@ -960,7 +985,7 @@ impl<'a> Formatter<'a> {
     /// This function will correctly account for the flags provided as well as
     /// the minimum width. It will not take precision into account.
     pub fn pad_integral(&mut self, is_positive: bool, prefix: &str, buf: &[u8]) -> Result {
-        use fmt::parse::{FlagAlternate, FlagSignPlus, FlagSignAwareZeroPad};
+        use fmt::rt::{FlagAlternate, FlagSignPlus, FlagSignAwareZeroPad};
 
         let mut width = buf.len();
 
@@ -1000,11 +1025,11 @@ impl<'a> Formatter<'a> {
             Some(min) if self.flags & (1 << (FlagSignAwareZeroPad as uint)) != 0 => {
                 self.fill = '0';
                 try!(write_prefix(self));
-                self.with_padding(min - width, parse::AlignRight, |f| f.buf.write(buf))
+                self.with_padding(min - width, rt::AlignRight, |f| f.buf.write(buf))
             }
             // Otherwise, the sign and prefix goes after the padding
             Some(min) => {
-                self.with_padding(min - width, parse::AlignRight, |f| {
+                self.with_padding(min - width, rt::AlignRight, |f| {
                     try!(write_prefix(f)); f.buf.write(buf)
                 })
             }
@@ -1055,7 +1080,7 @@ impl<'a> Formatter<'a> {
             // If we're under both the maximum and the minimum width, then fill
             // up the minimum width with the specified string + some alignment.
             Some(width) => {
-                self.with_padding(width - s.len(), parse::AlignLeft, |me| {
+                self.with_padding(width - s.len(), rt::AlignLeft, |me| {
                     me.buf.write(s.as_bytes())
                 })
             }
@@ -1066,13 +1091,13 @@ impl<'a> Formatter<'a> {
     /// afterwards depending on whether right or left alingment is requested.
     fn with_padding(&mut self,
                     padding: uint,
-                    default: parse::Alignment,
+                    default: rt::Alignment,
                     f: |&mut Formatter| -> Result) -> Result {
         let align = match self.align {
-            parse::AlignUnknown => default,
-            parse::AlignLeft | parse::AlignRight => self.align
+            rt::AlignUnknown => default,
+            rt::AlignLeft | rt::AlignRight => self.align
         };
-        if align == parse::AlignLeft {
+        if align == rt::AlignLeft {
             try!(f(self));
         }
         let mut fill = [0u8, ..4];
@@ -1080,7 +1105,7 @@ impl<'a> Formatter<'a> {
         for _ in range(0, padding) {
             try!(self.buf.write(fill.slice_to(len)));
         }
-        if align == parse::AlignRight {
+        if align == rt::AlignRight {
             try!(f(self));
         }
         Ok(())
@@ -1203,7 +1228,7 @@ impl<T> Poly for T {
 
 impl<T> Pointer for *T {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        f.flags |= 1 << (parse::FlagAlternate as uint);
+        f.flags |= 1 << (rt::FlagAlternate as uint);
         secret_lower_hex::<uint>(&(*self as uint), f)
     }
 }
@@ -1304,7 +1329,7 @@ impl<T: Show, U: Show> Show for ::result::Result<T, U> {
 
 impl<'a, T: Show> Show for &'a [T] {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        if f.flags & (1 << (parse::FlagAlternate as uint)) == 0 {
+        if f.flags & (1 << (rt::FlagAlternate as uint)) == 0 {
             try!(write!(f.buf, "["));
         }
         let mut is_first = true;
@@ -1316,7 +1341,7 @@ impl<'a, T: Show> Show for &'a [T] {
             }
             try!(write!(f.buf, "{}", *x))
         }
-        if f.flags & (1 << (parse::FlagAlternate as uint)) == 0 {
+        if f.flags & (1 << (rt::FlagAlternate as uint)) == 0 {
             try!(write!(f.buf, "]"));
         }
         Ok(())
diff --git a/src/libstd/fmt/parse.rs b/src/libstd/fmt/parse.rs
deleted file mode 100644
index ba126e00153..00000000000
--- a/src/libstd/fmt/parse.rs
+++ /dev/null
@@ -1,986 +0,0 @@
-// Copyright 2013 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.
-
-//! Parsing of format strings
-//!
-//! These structures are used when parsing format strings for the compiler.
-//! Parsing does not happen at runtime: structures of `std::fmt::rt` are
-//! generated instead.
-
-use prelude::*;
-
-use char;
-use owned::Box;
-use str;
-
-/// A piece is a portion of the format string which represents the next part
-/// to emit. These are emitted as a stream by the `Parser` class.
-#[deriving(Eq)]
-pub enum Piece<'a> {
-    /// A literal string which should directly be emitted
-    String(&'a str),
-    /// A back-reference to whatever the current argument is. This is used
-    /// inside of a method call to refer back to the original argument.
-    CurrentArgument,
-    /// This describes that formatting should process the next argument (as
-    /// specified inside) for emission.
-    Argument(Argument<'a>),
-}
-
-/// Representation of an argument specification.
-#[deriving(Eq)]
-pub struct Argument<'a> {
-    /// Where to find this argument
-    pub position: Position<'a>,
-    /// How to format the argument
-    pub format: FormatSpec<'a>,
-    /// If not `None`, what method to invoke on the argument
-    pub method: Option<Box<Method<'a>>>
-}
-
-/// Specification for the formatting of an argument in the format string.
-#[deriving(Eq)]
-pub struct FormatSpec<'a> {
-    /// Optionally specified character to fill alignment with
-    pub fill: Option<char>,
-    /// Optionally specified alignment
-    pub align: Alignment,
-    /// Packed version of various flags provided
-    pub flags: uint,
-    /// The integer precision to use
-    pub precision: Count<'a>,
-    /// The string width requested for the resulting format
-    pub width: Count<'a>,
-    /// The descriptor string representing the name of the format desired for
-    /// this argument, this can be empty or any number of characters, although
-    /// it is required to be one word.
-    pub ty: &'a str
-}
-
-/// Enum describing where an argument for a format can be located.
-#[deriving(Eq)]
-pub enum Position<'a> {
-    /// The argument will be in the next position. This is the default.
-    ArgumentNext,
-    /// The argument is located at a specific index.
-    ArgumentIs(uint),
-    /// The argument has a name.
-    ArgumentNamed(&'a str),
-}
-
-/// Enum of alignments which are supported.
-#[deriving(Eq)]
-pub enum Alignment {
-    /// The value will be aligned to the left.
-    AlignLeft,
-    /// The value will be aligned to the right.
-    AlignRight,
-    /// The value will take on a default alignment.
-    AlignUnknown,
-}
-
-/// Various flags which can be applied to format strings. The meaning of these
-/// flags is defined by the formatters themselves.
-#[deriving(Eq)]
-pub enum Flag {
-    /// A `+` will be used to denote positive numbers.
-    FlagSignPlus,
-    /// A `-` will be used to denote negative numbers. This is the default.
-    FlagSignMinus,
-    /// An alternate form will be used for the value. In the case of numbers,
-    /// this means that the number will be prefixed with the supplied string.
-    FlagAlternate,
-    /// For numbers, this means that the number will be padded with zeroes,
-    /// and the sign (`+` or `-`) will precede them.
-    FlagSignAwareZeroPad,
-}
-
-/// A count is used for the precision and width parameters of an integer, and
-/// can reference either an argument or a literal integer.
-#[deriving(Eq)]
-pub enum Count<'a> {
-    /// The count is specified explicitly.
-    CountIs(uint),
-    /// The count is specified by the argument with the given name.
-    CountIsName(&'a str),
-    /// The count is specified by the argument at the given index.
-    CountIsParam(uint),
-    /// The count is specified by the next parameter.
-    CountIsNextParam,
-    /// The count is implied and cannot be explicitly specified.
-    CountImplied,
-}
-
-/// Enum describing all of the possible methods which the formatting language
-/// currently supports.
-#[deriving(Eq)]
-pub enum Method<'a> {
-    /// A plural method selects on an integer over a list of either integer or
-    /// keyword-defined clauses. The meaning of the keywords is defined by the
-    /// current locale.
-    ///
-    /// An offset is optionally present at the beginning which is used to
-    /// match against keywords, but it is not matched against the literal
-    /// integers.
-    ///
-    /// The final element of this enum is the default "other" case which is
-    /// always required to be specified.
-    Plural(Option<uint>, Vec<PluralArm<'a>>, Vec<Piece<'a>>),
-
-    /// A select method selects over a string. Each arm is a different string
-    /// which can be selected for.
-    ///
-    /// As with `Plural`, a default "other" case is required as well.
-    Select(Vec<SelectArm<'a>>, Vec<Piece<'a>>),
-}
-
-/// A selector for what pluralization a plural method should take
-#[deriving(Eq, TotalEq, Hash)]
-pub enum PluralSelector {
-    /// One of the plural keywords should be used
-    Keyword(PluralKeyword),
-    /// A literal pluralization should be used
-    Literal(uint),
-}
-
-/// Structure representing one "arm" of the `plural` function.
-#[deriving(Eq)]
-pub struct PluralArm<'a> {
-    /// A selector can either be specified by a keyword or with an integer
-    /// literal.
-    pub selector: PluralSelector,
-    /// Array of pieces which are the format of this arm
-    pub result: Vec<Piece<'a>>,
-}
-
-/// Enum of the 5 CLDR plural keywords. There is one more, "other", but that
-/// is specially placed in the `Plural` variant of `Method`.
-///
-/// http://www.icu-project.org/apiref/icu4c/classicu_1_1PluralRules.html
-#[deriving(Eq, TotalEq, Hash)]
-#[allow(missing_doc)]
-pub enum PluralKeyword {
-    /// The plural form for zero objects.
-    Zero,
-    /// The plural form for one object.
-    One,
-    /// The plural form for two objects.
-    Two,
-    /// The plural form for few objects.
-    Few,
-    /// The plural form for many objects.
-    Many,
-}
-
-/// Structure representing one "arm" of the `select` function.
-#[deriving(Eq)]
-pub struct SelectArm<'a> {
-    /// String selector which guards this arm
-    pub selector: &'a str,
-    /// Array of pieces which are the format of this arm
-    pub result: Vec<Piece<'a>>,
-}
-
-/// The parser structure for interpreting the input format string. This is
-/// modelled as an iterator over `Piece` structures to form a stream of tokens
-/// being output.
-///
-/// This is a recursive-descent parser for the sake of simplicity, and if
-/// necessary there's probably lots of room for improvement performance-wise.
-pub struct Parser<'a> {
-    input: &'a str,
-    cur: str::CharOffsets<'a>,
-    depth: uint,
-    /// Error messages accumulated during parsing
-    pub errors: Vec<~str>,
-}
-
-impl<'a> Iterator<Piece<'a>> for Parser<'a> {
-    fn next(&mut self) -> Option<Piece<'a>> {
-        match self.cur.clone().next() {
-            Some((_, '#')) => { self.cur.next(); Some(CurrentArgument) }
-            Some((_, '{')) => {
-                self.cur.next();
-                let ret = Some(Argument(self.argument()));
-                self.must_consume('}');
-                ret
-            }
-            Some((pos, '\\')) => {
-                self.cur.next();
-                self.escape(); // ensure it's a valid escape sequence
-                Some(String(self.string(pos + 1))) // skip the '\' character
-            }
-            Some((_, '}')) if self.depth == 0 => {
-                self.cur.next();
-                self.err("unmatched `}` found");
-                None
-            }
-            Some((_, '}')) | None => { None }
-            Some((pos, _)) => {
-                Some(String(self.string(pos)))
-            }
-        }
-    }
-}
-
-impl<'a> Parser<'a> {
-    /// Creates a new parser for the given format string
-    pub fn new<'a>(s: &'a str) -> Parser<'a> {
-        Parser {
-            input: s,
-            cur: s.char_indices(),
-            depth: 0,
-            errors: vec!(),
-        }
-    }
-
-    /// Notifies of an error. The message doesn't actually need to be of type
-    /// ~str, but I think it does when this eventually uses conditions so it
-    /// might as well start using it now.
-    fn err(&mut self, msg: &str) {
-        self.errors.push(msg.to_owned());
-    }
-
-    /// Optionally consumes the specified character. If the character is not at
-    /// the current position, then the current iterator isn't moved and false is
-    /// returned, otherwise the character is consumed and true is returned.
-    fn consume(&mut self, c: char) -> bool {
-        match self.cur.clone().next() {
-            Some((_, maybe)) if c == maybe => {
-                self.cur.next();
-                true
-            }
-            Some(..) | None => false,
-        }
-    }
-
-    /// Forces consumption of the specified character. If the character is not
-    /// found, an error is emitted.
-    fn must_consume(&mut self, c: char) {
-        self.ws();
-        match self.cur.clone().next() {
-            Some((_, maybe)) if c == maybe => {
-                self.cur.next();
-            }
-            Some((_, other)) => {
-                self.err(
-                    format!("expected `{}` but found `{}`", c, other));
-            }
-            None => {
-                self.err(
-                    format!("expected `{}` but string was terminated", c));
-            }
-        }
-    }
-
-    /// Attempts to consume any amount of whitespace followed by a character
-    fn wsconsume(&mut self, c: char) -> bool {
-        self.ws(); self.consume(c)
-    }
-
-    /// Consumes all whitespace characters until the first non-whitespace
-    /// character
-    fn ws(&mut self) {
-        loop {
-            match self.cur.clone().next() {
-                Some((_, c)) if char::is_whitespace(c) => { self.cur.next(); }
-                Some(..) | None => { return }
-            }
-        }
-    }
-
-    /// Consumes an escape sequence, failing if there is not a valid character
-    /// to be escaped.
-    fn escape(&mut self) -> char {
-        match self.cur.next() {
-            Some((_, c @ '#')) | Some((_, c @ '{')) |
-            Some((_, c @ '\\')) | Some((_, c @ '}')) => { c }
-            Some((_, c)) => {
-                self.err(format!("invalid escape character `{}`", c));
-                c
-            }
-            None => {
-                self.err("expected an escape sequence, but format string was \
-                           terminated");
-                ' '
-            }
-        }
-    }
-
-    /// Parses all of a string which is to be considered a "raw literal" in a
-    /// format string. This is everything outside of the braces.
-    fn string(&mut self, start: uint) -> &'a str {
-        loop {
-            // we may not consume the character, so clone the iterator
-            match self.cur.clone().next() {
-                Some((pos, '\\')) | Some((pos, '#')) |
-                Some((pos, '}')) | Some((pos, '{')) => {
-                    return self.input.slice(start, pos);
-                }
-                Some(..) => { self.cur.next(); }
-                None => {
-                    self.cur.next();
-                    return self.input.slice(start, self.input.len());
-                }
-            }
-        }
-    }
-
-    /// Parses an Argument structure, or what's contained within braces inside
-    /// the format string
-    fn argument(&mut self) -> Argument<'a> {
-        Argument {
-            position: self.position(),
-            format: self.format(),
-            method: self.method(),
-        }
-    }
-
-    /// Parses a positional argument for a format. This could either be an
-    /// integer index of an argument, a named argument, or a blank string.
-    fn position(&mut self) -> Position<'a> {
-        match self.integer() {
-            Some(i) => { ArgumentIs(i) }
-            None => {
-                match self.cur.clone().next() {
-                    Some((_, c)) if char::is_alphabetic(c) => {
-                        ArgumentNamed(self.word())
-                    }
-                    _ => ArgumentNext
-                }
-            }
-        }
-    }
-
-    /// Parses a format specifier at the current position, returning all of the
-    /// relevant information in the FormatSpec struct.
-    fn format(&mut self) -> FormatSpec<'a> {
-        let mut spec = FormatSpec {
-            fill: None,
-            align: AlignUnknown,
-            flags: 0,
-            precision: CountImplied,
-            width: CountImplied,
-            ty: self.input.slice(0, 0),
-        };
-        if !self.consume(':') { return spec }
-
-        // fill character
-        match self.cur.clone().next() {
-            Some((_, c)) => {
-                match self.cur.clone().skip(1).next() {
-                    Some((_, '>')) | Some((_, '<')) => {
-                        spec.fill = Some(c);
-                        self.cur.next();
-                    }
-                    Some(..) | None => {}
-                }
-            }
-            None => {}
-        }
-        // Alignment
-        if self.consume('<') {
-            spec.align = AlignLeft;
-        } else if self.consume('>') {
-            spec.align = AlignRight;
-        }
-        // Sign flags
-        if self.consume('+') {
-            spec.flags |= 1 << (FlagSignPlus as uint);
-        } else if self.consume('-') {
-            spec.flags |= 1 << (FlagSignMinus as uint);
-        }
-        // Alternate marker
-        if self.consume('#') {
-            spec.flags |= 1 << (FlagAlternate as uint);
-        }
-        // Width and precision
-        let mut havewidth = false;
-        if self.consume('0') {
-            // small ambiguity with '0$' as a format string. In theory this is a
-            // '0' flag and then an ill-formatted format string with just a '$'
-            // and no count, but this is better if we instead interpret this as
-            // no '0' flag and '0$' as the width instead.
-            if self.consume('$') {
-                spec.width = CountIsParam(0);
-                havewidth = true;
-            } else {
-                spec.flags |= 1 << (FlagSignAwareZeroPad as uint);
-            }
-        }
-        if !havewidth {
-            spec.width = self.count();
-        }
-        if self.consume('.') {
-            if self.consume('*') {
-                spec.precision = CountIsNextParam;
-            } else {
-                spec.precision = self.count();
-            }
-        }
-        // Finally the actual format specifier
-        if self.consume('?') {
-            spec.ty = "?";
-        } else {
-            spec.ty = self.word();
-        }
-        return spec;
-    }
-
-    /// Parses a method to be applied to the previously specified argument and
-    /// its format. The two current supported methods are 'plural' and 'select'
-    fn method(&mut self) -> Option<Box<Method<'a>>> {
-        if !self.wsconsume(',') {
-            return None;
-        }
-        self.ws();
-        match self.word() {
-            "select" => {
-                self.must_consume(',');
-                Some(self.select())
-            }
-            "plural" => {
-                self.must_consume(',');
-                Some(self.plural())
-            }
-            "" => {
-                self.err("expected method after comma");
-                return None;
-            }
-            method => {
-                self.err(format!("unknown method: `{}`", method));
-                return None;
-            }
-        }
-    }
-
-    /// Parses a 'select' statement (after the initial 'select' word)
-    fn select(&mut self) -> Box<Method<'a>> {
-        let mut other = None;
-        let mut arms = vec!();
-        // Consume arms one at a time
-        loop {
-            self.ws();
-            let selector = self.word();
-            if selector == "" {
-                self.err("cannot have an empty selector");
-                break
-            }
-            self.must_consume('{');
-            self.depth += 1;
-            let pieces = self.collect();
-            self.depth -= 1;
-            self.must_consume('}');
-            if selector == "other" {
-                if !other.is_none() {
-                    self.err("multiple `other` statements in `select");
-                }
-                other = Some(pieces);
-            } else {
-                arms.push(SelectArm { selector: selector, result: pieces });
-            }
-            self.ws();
-            match self.cur.clone().next() {
-                Some((_, '}')) => { break }
-                Some(..) | None => {}
-            }
-        }
-        // The "other" selector must be present
-        let other = match other {
-            Some(arm) => { arm }
-            None => {
-                self.err("`select` statement must provide an `other` case");
-                vec!()
-            }
-        };
-        box Select(arms, other)
-    }
-
-    /// Parses a 'plural' statement (after the initial 'plural' word)
-    fn plural(&mut self) -> Box<Method<'a>> {
-        let mut offset = None;
-        let mut other = None;
-        let mut arms = vec!();
-
-        // First, attempt to parse the 'offset:' field. We know the set of
-        // selector words which can appear in plural arms, and the only ones
-        // which start with 'o' are "other" and "offset", hence look two
-        // characters deep to see if we can consume the word "offset"
-        self.ws();
-        let mut it = self.cur.clone();
-        match it.next() {
-            Some((_, 'o')) => {
-                match it.next() {
-                    Some((_, 'f')) => {
-                        let word = self.word();
-                        if word != "offset" {
-                            self.err(format!("expected `offset`, found `{}`",
-                                             word));
-                        } else {
-                            self.must_consume(':');
-                            match self.integer() {
-                                Some(i) => { offset = Some(i); }
-                                None => {
-                                    self.err("offset must be an integer");
-                                }
-                            }
-                        }
-                    }
-                    Some(..) | None => {}
-                }
-            }
-            Some(..) | None => {}
-        }
-
-        // Next, generate all the arms
-        loop {
-            let mut isother = false;
-            let selector = if self.wsconsume('=') {
-                match self.integer() {
-                    Some(i) => Literal(i),
-                    None => {
-                        self.err("plural `=` selectors must be followed by an \
-                                  integer");
-                        Literal(0)
-                    }
-                }
-            } else {
-                let word = self.word();
-                match word {
-                    "other" => { isother = true; Keyword(Zero) }
-                    "zero"  => Keyword(Zero),
-                    "one"   => Keyword(One),
-                    "two"   => Keyword(Two),
-                    "few"   => Keyword(Few),
-                    "many"  => Keyword(Many),
-                    word    => {
-                        self.err(format!("unexpected plural selector `{}`",
-                                         word));
-                        if word == "" {
-                            break
-                        } else {
-                            Keyword(Zero)
-                        }
-                    }
-                }
-            };
-            self.must_consume('{');
-            self.depth += 1;
-            let pieces = self.collect();
-            self.depth -= 1;
-            self.must_consume('}');
-            if isother {
-                if !other.is_none() {
-                    self.err("multiple `other` statements in `select");
-                }
-                other = Some(pieces);
-            } else {
-                arms.push(PluralArm { selector: selector, result: pieces });
-            }
-            self.ws();
-            match self.cur.clone().next() {
-                Some((_, '}')) => { break }
-                Some(..) | None => {}
-            }
-        }
-
-        let other = match other {
-            Some(arm) => { arm }
-            None => {
-                self.err("`plural` statement must provide an `other` case");
-                vec!()
-            }
-        };
-        box Plural(offset, arms, other)
-    }
-
-    /// Parses a Count parameter at the current position. This does not check
-    /// for 'CountIsNextParam' because that is only used in precision, not
-    /// width.
-    fn count(&mut self) -> Count<'a> {
-        match self.integer() {
-            Some(i) => {
-                if self.consume('$') {
-                    CountIsParam(i)
-                } else {
-                    CountIs(i)
-                }
-            }
-            None => {
-                let tmp = self.cur.clone();
-                match self.word() {
-                    word if word.len() > 0 && self.consume('$') => {
-                        CountIsName(word)
-                    }
-                    _ => {
-                        self.cur = tmp;
-                        CountImplied
-                    }
-                }
-            }
-        }
-    }
-
-    /// Parses a word starting at the current position. A word is considered to
-    /// be an alphabetic character followed by any number of alphanumeric
-    /// characters.
-    fn word(&mut self) -> &'a str {
-        let start = match self.cur.clone().next() {
-            Some((pos, c)) if char::is_XID_start(c) => {
-                self.cur.next();
-                pos
-            }
-            Some(..) | None => { return self.input.slice(0, 0); }
-        };
-        let mut end;
-        loop {
-            match self.cur.clone().next() {
-                Some((_, c)) if char::is_XID_continue(c) => {
-                    self.cur.next();
-                }
-                Some((pos, _)) => { end = pos; break }
-                None => { end = self.input.len(); break }
-            }
-        }
-        self.input.slice(start, end)
-    }
-
-    /// Optionally parses an integer at the current position. This doesn't deal
-    /// with overflow at all, it's just accumulating digits.
-    fn integer(&mut self) -> Option<uint> {
-        let mut cur = 0;
-        let mut found = false;
-        loop {
-            match self.cur.clone().next() {
-                Some((_, c)) => {
-                    match char::to_digit(c, 10) {
-                        Some(i) => {
-                            cur = cur * 10 + i;
-                            found = true;
-                            self.cur.next();
-                        }
-                        None => { break }
-                    }
-                }
-                None => { break }
-            }
-        }
-        if found {
-            return Some(cur);
-        } else {
-            return None;
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use prelude::*;
-
-    fn same(fmt: &'static str, p: &[Piece<'static>]) {
-        let mut parser = Parser::new(fmt);
-        assert!(p == parser.collect::<Vec<Piece<'static>>>().as_slice());
-    }
-
-    fn fmtdflt() -> FormatSpec<'static> {
-        return FormatSpec {
-            fill: None,
-            align: AlignUnknown,
-            flags: 0,
-            precision: CountImplied,
-            width: CountImplied,
-            ty: "",
-        }
-    }
-
-    fn musterr(s: &str) {
-        let mut p = Parser::new(s);
-        p.next();
-        assert!(p.errors.len() != 0);
-    }
-
-    #[test]
-    fn simple() {
-        same("asdf", [String("asdf")]);
-        same("a\\{b", [String("a"), String("{b")]);
-        same("a\\#b", [String("a"), String("#b")]);
-        same("a\\}b", [String("a"), String("}b")]);
-        same("a\\}", [String("a"), String("}")]);
-        same("\\}", [String("}")]);
-    }
-
-    #[test] fn invalid01() { musterr("{") }
-    #[test] fn invalid02() { musterr("\\") }
-    #[test] fn invalid03() { musterr("\\a") }
-    #[test] fn invalid04() { musterr("{3a}") }
-    #[test] fn invalid05() { musterr("{:|}") }
-    #[test] fn invalid06() { musterr("{:>>>}") }
-
-    #[test]
-    fn format_nothing() {
-        same("{}", [Argument(Argument {
-            position: ArgumentNext,
-            format: fmtdflt(),
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_position() {
-        same("{3}", [Argument(Argument {
-            position: ArgumentIs(3),
-            format: fmtdflt(),
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_position_nothing_else() {
-        same("{3:}", [Argument(Argument {
-            position: ArgumentIs(3),
-            format: fmtdflt(),
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_type() {
-        same("{3:a}", [Argument(Argument {
-            position: ArgumentIs(3),
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "a",
-            },
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_align_fill() {
-        same("{3:>}", [Argument(Argument {
-            position: ArgumentIs(3),
-            format: FormatSpec {
-                fill: None,
-                align: AlignRight,
-                flags: 0,
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "",
-            },
-            method: None,
-        })]);
-        same("{3:0<}", [Argument(Argument {
-            position: ArgumentIs(3),
-            format: FormatSpec {
-                fill: Some('0'),
-                align: AlignLeft,
-                flags: 0,
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "",
-            },
-            method: None,
-        })]);
-        same("{3:*<abcd}", [Argument(Argument {
-            position: ArgumentIs(3),
-            format: FormatSpec {
-                fill: Some('*'),
-                align: AlignLeft,
-                flags: 0,
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "abcd",
-            },
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_counts() {
-        same("{:10s}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountImplied,
-                width: CountIs(10),
-                ty: "s",
-            },
-            method: None,
-        })]);
-        same("{:10$.10s}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountIs(10),
-                width: CountIsParam(10),
-                ty: "s",
-            },
-            method: None,
-        })]);
-        same("{:.*s}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountIsNextParam,
-                width: CountImplied,
-                ty: "s",
-            },
-            method: None,
-        })]);
-        same("{:.10$s}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountIsParam(10),
-                width: CountImplied,
-                ty: "s",
-            },
-            method: None,
-        })]);
-        same("{:a$.b$s}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountIsName("b"),
-                width: CountIsName("a"),
-                ty: "s",
-            },
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_flags() {
-        same("{:-}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: (1 << FlagSignMinus as uint),
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "",
-            },
-            method: None,
-        })]);
-        same("{:+#}", [Argument(Argument {
-            position: ArgumentNext,
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: (1 << FlagSignPlus as uint) | (1 << FlagAlternate as uint),
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "",
-            },
-            method: None,
-        })]);
-    }
-    #[test]
-    fn format_mixture() {
-        same("abcd {3:a} efg", [String("abcd "), Argument(Argument {
-            position: ArgumentIs(3),
-            format: FormatSpec {
-                fill: None,
-                align: AlignUnknown,
-                flags: 0,
-                precision: CountImplied,
-                width: CountImplied,
-                ty: "a",
-            },
-            method: None,
-        }), String(" efg")]);
-    }
-
-    #[test]
-    fn select_simple() {
-        same("{, select, other { haha } }", [Argument(Argument{
-            position: ArgumentNext,
-            format: fmtdflt(),
-            method: Some(box Select(vec![], vec![String(" haha ")]))
-        })]);
-        same("{1, select, other { haha } }", [Argument(Argument{
-            position: ArgumentIs(1),
-            format: fmtdflt(),
-            method: Some(box Select(vec![], vec![String(" haha ")]))
-        })]);
-        same("{1, select, other {#} }", [Argument(Argument{
-            position: ArgumentIs(1),
-            format: fmtdflt(),
-            method: Some(box Select(vec![], vec![CurrentArgument]))
-        })]);
-        same("{1, select, other {{2, select, other {lol}}} }", [Argument(Argument{
-            position: ArgumentIs(1),
-            format: fmtdflt(),
-            method: Some(box Select(vec![], vec![Argument(Argument{
-                position: ArgumentIs(2),
-                format: fmtdflt(),
-                method: Some(box Select(vec![], vec![String("lol")]))
-            })])) // wat
-        })]);
-    }
-
-    #[test]
-    fn select_cases() {
-        same("{1, select, a{1} b{2} c{3} other{4} }", [Argument(Argument{
-            position: ArgumentIs(1),
-            format: fmtdflt(),
-            method: Some(box Select(vec![
-                SelectArm{ selector: "a", result: vec![String("1")] },
-                SelectArm{ selector: "b", result: vec![String("2")] },
-                SelectArm{ selector: "c", result: vec![String("3")] },
-            ], vec![String("4")]))
-        })]);
-    }
-
-    #[test] fn badselect01() { musterr("{select, }") }
-    #[test] fn badselect02() { musterr("{1, select}") }
-    #[test] fn badselect03() { musterr("{1, select, }") }
-    #[test] fn badselect04() { musterr("{1, select, a {}}") }
-    #[test] fn badselect05() { musterr("{1, select, other }}") }
-    #[test] fn badselect06() { musterr("{1, select, other {}") }
-    #[test] fn badselect07() { musterr("{select, other {}") }
-    #[test] fn badselect08() { musterr("{1 select, other {}") }
-    #[test] fn badselect09() { musterr("{:d select, other {}") }
-    #[test] fn badselect10() { musterr("{1:d select, other {}") }
-
-    #[test]
-    fn plural_simple() {
-        same("{, plural, other { haha } }", [Argument(Argument{
-            position: ArgumentNext,
-            format: fmtdflt(),
-            method: Some(box Plural(None, vec![], vec![String(" haha ")]))
-        })]);
-        same("{:, plural, other { haha } }", [Argument(Argument{
-            position: ArgumentNext,
-            format: fmtdflt(),
-            method: Some(box Plural(None, vec![], vec![String(" haha ")]))
-        })]);
-        same("{, plural, offset:1 =2{2} =3{3} many{yes} other{haha} }",
-        [Argument(Argument{
-            position: ArgumentNext,
-            format: fmtdflt(),
-            method: Some(box Plural(Some(1), vec![
-                PluralArm{ selector: Literal(2), result: vec![String("2")] },
-                PluralArm{ selector: Literal(3), result: vec![String("3")] },
-                PluralArm{ selector: Keyword(Many), result: vec![String("yes")] }
-            ], vec![String("haha")]))
-        })]);
-    }
-}
diff --git a/src/libstd/fmt/rt.rs b/src/libstd/fmt/rt.rs
index 01c2c06c3fb..33e86a4485b 100644
--- a/src/libstd/fmt/rt.rs
+++ b/src/libstd/fmt/rt.rs
@@ -17,9 +17,17 @@
 #![allow(missing_doc)]
 #![doc(hidden)]
 
-use fmt::parse;
 use option::Option;
 
+#[cfg(stage0)]
+pub use fmt::parse::{Alignment, AlignLeft, AlignRight, AlignUnknown};
+#[cfg(stage0)]
+pub use fmt::parse::{PluralKeyword, Zero, One, Two, Few, Many};
+#[cfg(stage0)]
+pub use fmt::parse::{Flag, FlagSignPlus, FlagSignMinus, FlagSignAwareZeroPad};
+#[cfg(stage0)]
+pub use fmt::parse::{FlagAlternate};
+
 pub enum Piece<'a> {
     String(&'a str),
     // FIXME(#8259): this shouldn't require the unit-value here
@@ -35,12 +43,20 @@ pub struct Argument<'a> {
 
 pub struct FormatSpec {
     pub fill: char,
-    pub align: parse::Alignment,
+    pub align: Alignment,
     pub flags: uint,
     pub precision: Count,
     pub width: Count,
 }
 
+#[cfg(not(stage0))]
+#[deriving(Eq)]
+pub enum Alignment {
+    AlignLeft,
+    AlignRight,
+    AlignUnknown,
+}
+
 pub enum Count {
     CountIs(uint), CountIsParam(uint), CountIsNextParam, CountImplied,
 }
@@ -49,16 +65,32 @@ pub enum Position {
     ArgumentNext, ArgumentIs(uint)
 }
 
+#[cfg(not(stage0))]
+pub enum Flag {
+    FlagSignPlus,
+    FlagSignMinus,
+    FlagAlternate,
+    FlagSignAwareZeroPad,
+}
+
 pub enum Method<'a> {
     Plural(Option<uint>, &'a [PluralArm<'a>], &'a [Piece<'a>]),
     Select(&'a [SelectArm<'a>], &'a [Piece<'a>]),
 }
 
 pub enum PluralSelector {
-    Keyword(parse::PluralKeyword),
+    Keyword(PluralKeyword),
     Literal(uint),
 }
 
+pub enum PluralKeyword {
+    Zero,
+    One,
+    Two,
+    Few,
+    Many,
+}
+
 pub struct PluralArm<'a> {
     pub selector: PluralSelector,
     pub result: &'a [Piece<'a>],