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Diffstat (limited to 'src/libstd/fmt/parse.rs')
| -rw-r--r-- | src/libstd/fmt/parse.rs | 896 |
1 files changed, 896 insertions, 0 deletions
diff --git a/src/libstd/fmt/parse.rs b/src/libstd/fmt/parse.rs new file mode 100644 index 00000000000..673ea1d3fa8 --- /dev/null +++ b/src/libstd/fmt/parse.rs @@ -0,0 +1,896 @@ +// 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. + +use prelude::*; + +use char; +use str; +use iterator; + +condition! { pub parse_error: ~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<'self> { + /// A literal string which should directly be emitted + String(&'self 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<'self>), +} + +/// Representation of an argument specification. +#[deriving(Eq)] +pub struct Argument<'self> { + /// Where to find this argument + position: Position<'self>, + /// How to format the argument + format: FormatSpec<'self>, + /// If not `None`, what method to invoke on the argument + method: Option<~Method<'self>> +} + +/// Specification for the formatting of an argument in the format string. +#[deriving(Eq)] +pub struct FormatSpec<'self> { + /// Optionally specified character to fill alignment with + fill: Option<char>, + /// Optionally specified alignment + align: Option<Alignment>, + /// Packed version of various flags provided + flags: uint, + /// The integer precision to use + precision: Count, + /// The string width requested for the resulting format + width: Count, + /// 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. + ty: &'self str +} + +/// Enum describing where an argument for a format can be located. +#[deriving(Eq)] +pub enum Position<'self> { + ArgumentNext, ArgumentIs(uint), ArgumentNamed(&'self str) +} + +/// Enum of alignments which are supoprted. +#[deriving(Eq)] +pub enum Alignment { AlignLeft, AlignRight } + +/// 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 { + FlagSignPlus, + FlagSignMinus, + FlagAlternate, +} + +/// 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 { + CountIs(uint), + CountIsParam(uint), + CountIsNextParam, + CountImplied, +} + +/// Enum describing all of the possible methods which the formatting language +/// currently supports. +#[deriving(Eq)] +pub enum Method<'self> { + /// 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>, ~[PluralArm<'self>], ~[Piece<'self>]), + + /// 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(~[SelectArm<'self>], ~[Piece<'self>]), +} + +/// Structure representing one "arm" of the `plural` function. +#[deriving(Eq)] +pub struct PluralArm<'self> { + /// A selector can either be specified by a keyword or with an integer + /// literal. + selector: Either<PluralKeyword, uint>, + /// Array of pieces which are the format of this arm + result: ~[Piece<'self>], +} + +/// 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, IterBytes)] +pub enum PluralKeyword { + Zero, One, Two, Few, Many +} + +/// Structure representing one "arm" of the `select` function. +#[deriving(Eq)] +pub struct SelectArm<'self> { + /// String selector which guards this arm + selector: &'self str, + /// Array of pieces which are the format of this arm + result: ~[Piece<'self>], +} + +/// 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<'self> { + priv input: &'self str, + priv cur: str::CharOffsetIterator<'self>, +} + +impl<'self> iterator::Iterator<Piece<'self>> for Parser<'self> { + fn next(&mut self) -> Option<Piece<'self>> { + match self.cur.clone().next() { + Some((_, '#')) => { self.cur.next(); Some(CurrentArgument) } + Some((_, '{')) => { + self.cur.next(); + let ret = Some(Argument(self.argument())); + if !self.consume('}') { + self.err(~"unterminated format string"); + } + 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((_, '}')) | None => { None } + Some((pos, _)) => { + Some(String(self.string(pos))) + } + } + } +} + +impl<'self> Parser<'self> { + /// Creates a new parser for the given format string + pub fn new<'a>(s: &'a str) -> Parser<'a> { + Parser { + input: s, + cur: s.char_offset_iter(), + } + } + + /// 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(&self, msg: ~str) { + parse_error::cond.raise(msg); + } + + /// 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, + } + } + + /// 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(fmt!("invalid escape character `%c`", 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) -> &'self 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<'self> { + 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<'self> { + 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<'self> { + let mut spec = FormatSpec { + fill: None, + align: None, + 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 = Some(AlignLeft); + } else if self.consume('>') { + spec.align = Some(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 + spec.width = self.count(); + if self.consume('.') { + if self.consume('*') { + spec.precision = CountIsNextParam; + } else { + spec.precision = self.count(); + } + } + // Finally the actual format specifier + 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<~Method<'self>> { + if !self.wsconsume(',') { + return None; + } + self.ws(); + match self.word() { + "select" => { + if !self.wsconsume(',') { + self.err(~"`select` must be followed by `,`"); + } + Some(self.select()) + } + "plural" => { + if !self.wsconsume(',') { + self.err(~"`plural` must be followed by `,`"); + } + Some(self.plural()) + } + "" => { + self.err(~"expected method after comma"); + return None; + } + method => { + self.err(fmt!("unknown method: `%s`", method)); + return None; + } + } + } + + /// Parses a 'select' statement (after the initial 'select' word) + fn select(&mut self) -> ~Method<'self> { + let mut other = None; + let mut arms = ~[]; + // Consume arms one at a time + loop { + self.ws(); + let selector = self.word(); + if selector == "" { + self.err(~"cannot have an empty selector"); + break + } + if !self.wsconsume('{') { + self.err(~"selector must be followed by `{`"); + } + let pieces = self.collect(); + if !self.wsconsume('}') { + self.err(~"selector case must be terminated by `}`"); + } + 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"); + ~[] + } + }; + ~Select(arms, other) + } + + /// Parses a 'plural' statement (after the initial 'plural' word) + fn plural(&mut self) -> ~Method<'self> { + let mut offset = None; + let mut other = None; + let mut arms = ~[]; + + // 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(fmt!("expected `offset`, found `%s`", + word)); + } else { + if !self.consume(':') { + self.err(~"`offset` must be followed by `:`"); + } + 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) => Right(i), + None => { + self.err(~"plural `=` selectors must be followed by an \ + integer"); + Right(0) + } + } + } else { + let word = self.word(); + match word { + "other" => { isother = true; Left(Zero) } + "zero" => Left(Zero), + "one" => Left(One), + "two" => Left(Two), + "few" => Left(Few), + "many" => Left(Many), + word => { + self.err(fmt!("unexpected plural selector `%s`", word)); + if word == "" { + break + } else { + Left(Zero) + } + } + } + }; + if !self.wsconsume('{') { + self.err(~"selector must be followed by `{`"); + } + let pieces = self.collect(); + if !self.wsconsume('}') { + self.err(~"selector case must be terminated by `}`"); + } + 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"); + ~[] + } + }; + ~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 { + match self.integer() { + Some(i) => { + if self.consume('$') { + CountIsParam(i) + } else { + CountIs(i) + } + } + None => { 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) -> &'self str { + let start = match self.cur.clone().next() { + Some((pos, c)) if char::is_alphabetic(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_alphanumeric(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::*; + use realstd::fmt::{String}; + + fn same(fmt: &'static str, p: ~[Piece<'static>]) { + let mut parser = Parser::new(fmt); + assert_eq!(p, parser.collect()); + } + + fn fmtdflt() -> FormatSpec<'static> { + return FormatSpec { + fill: None, + align: None, + flags: 0, + precision: CountImplied, + width: CountImplied, + ty: "", + } + } + + fn musterr(s: &str) { + Parser::new(s).next(); + } + + #[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] #[should_fail] fn invalid01() { musterr("{") } + #[test] #[should_fail] fn invalid02() { musterr("\\") } + #[test] #[should_fail] fn invalid03() { musterr("\\a") } + #[test] #[should_fail] fn invalid04() { musterr("{3a}") } + #[test] #[should_fail] fn invalid05() { musterr("{:|}") } + #[test] #[should_fail] 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: None, + 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: Some(AlignRight), + flags: 0, + precision: CountImplied, + width: CountImplied, + ty: "", + }, + method: None, + })]); + same("{3:0<}", ~[Argument(Argument { + position: ArgumentIs(3), + format: FormatSpec { + fill: Some('0'), + align: Some(AlignLeft), + flags: 0, + precision: CountImplied, + width: CountImplied, + ty: "", + }, + method: None, + })]); + same("{3:*<abcd}", ~[Argument(Argument { + position: ArgumentIs(3), + format: FormatSpec { + fill: Some('*'), + align: Some(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: None, + flags: 0, + precision: CountImplied, + width: CountIs(10), + ty: "s", + }, + method: None, + })]); + same("{:10$.10s}", ~[Argument(Argument { + position: ArgumentNext, + format: FormatSpec { + fill: None, + align: None, + flags: 0, + precision: CountIs(10), + width: CountIsParam(10), + ty: "s", + }, + method: None, + })]); + same("{:.*s}", ~[Argument(Argument { + position: ArgumentNext, + format: FormatSpec { + fill: None, + align: None, + flags: 0, + precision: CountIsNextParam, + width: CountImplied, + ty: "s", + }, + method: None, + })]); + same("{:.10$s}", ~[Argument(Argument { + position: ArgumentNext, + format: FormatSpec { + fill: None, + align: None, + flags: 0, + precision: CountIsParam(10), + width: CountImplied, + ty: "s", + }, + method: None, + })]); + } + #[test] + fn format_flags() { + same("{:-}", ~[Argument(Argument { + position: ArgumentNext, + format: FormatSpec { + fill: None, + align: None, + flags: (1 << FlagSignMinus as uint), + precision: CountImplied, + width: CountImplied, + ty: "", + }, + method: None, + })]); + same("{:+#}", ~[Argument(Argument { + position: ArgumentNext, + format: FormatSpec { + fill: None, + align: None, + 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: None, + 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(~Select(~[], ~[String(" haha ")])) + })]); + same("{1, select, other { haha } }", ~[Argument(Argument{ + position: ArgumentIs(1), + format: fmtdflt(), + method: Some(~Select(~[], ~[String(" haha ")])) + })]); + same("{1, select, other {#} }", ~[Argument(Argument{ + position: ArgumentIs(1), + format: fmtdflt(), + method: Some(~Select(~[], ~[CurrentArgument])) + })]); + same("{1, select, other {{2, select, other {lol}}} }", ~[Argument(Argument{ + position: ArgumentIs(1), + format: fmtdflt(), + method: Some(~Select(~[], ~[Argument(Argument{ + position: ArgumentIs(2), + format: fmtdflt(), + method: Some(~Select(~[], ~[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(~Select(~[ + SelectArm{ selector: "a", result: ~[String("1")] }, + SelectArm{ selector: "b", result: ~[String("2")] }, + SelectArm{ selector: "c", result: ~[String("3")] }, + ], ~[String("4")])) + })]); + } + + #[test] #[should_fail] fn badselect01() { + musterr("{select, }") + } + #[test] #[should_fail] fn badselect02() { + musterr("{1, select}") + } + #[test] #[should_fail] fn badselect03() { + musterr("{1, select, }") + } + #[test] #[should_fail] fn badselect04() { + musterr("{1, select, a {}}") + } + #[test] #[should_fail] fn badselect05() { + musterr("{1, select, other }}") + } + #[test] #[should_fail] fn badselect06() { + musterr("{1, select, other {}") + } + #[test] #[should_fail] fn badselect07() { + musterr("{select, other {}") + } + #[test] #[should_fail] fn badselect08() { + musterr("{1 select, other {}") + } + #[test] #[should_fail] fn badselect09() { + musterr("{:d select, other {}") + } + #[test] #[should_fail] fn badselect10() { + musterr("{1:d select, other {}") + } + + #[test] + fn plural_simple() { + same("{, plural, other { haha } }", ~[Argument(Argument{ + position: ArgumentNext, + format: fmtdflt(), + method: Some(~Plural(None, ~[], ~[String(" haha ")])) + })]); + same("{:, plural, other { haha } }", ~[Argument(Argument{ + position: ArgumentNext, + format: fmtdflt(), + method: Some(~Plural(None, ~[], ~[String(" haha ")])) + })]); + same("{, plural, offset:1 =2{2} =3{3} many{yes} other{haha} }", + ~[Argument(Argument{ + position: ArgumentNext, + format: fmtdflt(), + method: Some(~Plural(Some(1), ~[ + PluralArm{ selector: Right(2), result: ~[String("2")] }, + PluralArm{ selector: Right(3), result: ~[String("3")] }, + PluralArm{ selector: Left(Many), result: ~[String("yes")] } + ], ~[String("haha")])) + })]); + } +} |