656 lines
22 KiB
Rust
656 lines
22 KiB
Rust
//! Macro support for 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.
|
|
|
|
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/",
|
|
html_playground_url = "https://play.rust-lang.org/",
|
|
test(attr(deny(warnings))))]
|
|
|
|
#![feature(nll)]
|
|
#![feature(rustc_private)]
|
|
#![feature(unicode_internals)]
|
|
|
|
pub use Piece::*;
|
|
pub use Position::*;
|
|
pub use Alignment::*;
|
|
pub use Flag::*;
|
|
pub use Count::*;
|
|
|
|
use std::str;
|
|
use std::string;
|
|
use std::iter;
|
|
|
|
use syntax_pos::{InnerSpan, Symbol};
|
|
|
|
#[derive(Copy, Clone)]
|
|
struct InnerOffset(usize);
|
|
|
|
impl InnerOffset {
|
|
fn to(self, end: InnerOffset) -> InnerSpan {
|
|
InnerSpan::new(self.0, end.0)
|
|
}
|
|
}
|
|
|
|
/// 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.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
pub enum Piece<'a> {
|
|
/// A literal string which should directly be emitted
|
|
String(&'a str),
|
|
/// This describes that formatting should process the next argument (as
|
|
/// specified inside) for emission.
|
|
NextArgument(Argument<'a>),
|
|
}
|
|
|
|
/// Representation of an argument specification.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
pub struct Argument<'a> {
|
|
/// Where to find this argument
|
|
pub position: Position,
|
|
/// How to format the argument
|
|
pub format: FormatSpec<'a>,
|
|
}
|
|
|
|
/// Specification for the formatting of an argument in the format string.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
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: u32,
|
|
/// The integer precision to use.
|
|
pub precision: Count,
|
|
/// The span of the precision formatting flag (for diagnostics).
|
|
pub precision_span: Option<InnerSpan>,
|
|
/// The string width requested for the resulting format.
|
|
pub width: Count,
|
|
/// The span of the width formatting flag (for diagnostics).
|
|
pub width_span: Option<InnerSpan>,
|
|
/// 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,
|
|
/// The span of the descriptor string (for diagnostics).
|
|
pub ty_span: Option<InnerSpan>,
|
|
}
|
|
|
|
/// Enum describing where an argument for a format can be located.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
pub enum Position {
|
|
/// The argument is implied to be located at an index
|
|
ArgumentImplicitlyIs(usize),
|
|
/// The argument is located at a specific index given in the format
|
|
ArgumentIs(usize),
|
|
/// The argument has a name.
|
|
ArgumentNamed(Symbol),
|
|
}
|
|
|
|
impl Position {
|
|
pub fn index(&self) -> Option<usize> {
|
|
match self {
|
|
ArgumentIs(i) | ArgumentImplicitlyIs(i) => Some(*i),
|
|
_ => None,
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Enum of alignments which are supported.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
pub enum Alignment {
|
|
/// The value will be aligned to the left.
|
|
AlignLeft,
|
|
/// The value will be aligned to the right.
|
|
AlignRight,
|
|
/// The value will be aligned in the center.
|
|
AlignCenter,
|
|
/// 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.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
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,
|
|
/// For Debug / `?`, format integers in lower-case hexadecimal.
|
|
FlagDebugLowerHex,
|
|
/// For Debug / `?`, format integers in upper-case hexadecimal.
|
|
FlagDebugUpperHex,
|
|
}
|
|
|
|
/// A count is used for the precision and width parameters of an integer, and
|
|
/// can reference either an argument or a literal integer.
|
|
#[derive(Copy, Clone, Debug, PartialEq)]
|
|
pub enum Count {
|
|
/// The count is specified explicitly.
|
|
CountIs(usize),
|
|
/// The count is specified by the argument with the given name.
|
|
CountIsName(Symbol),
|
|
/// The count is specified by the argument at the given index.
|
|
CountIsParam(usize),
|
|
/// The count is implied and cannot be explicitly specified.
|
|
CountImplied,
|
|
}
|
|
|
|
pub struct ParseError {
|
|
pub description: string::String,
|
|
pub note: Option<string::String>,
|
|
pub label: string::String,
|
|
pub span: InnerSpan,
|
|
pub secondary_label: Option<(string::String, InnerSpan)>,
|
|
}
|
|
|
|
/// The parser structure for interpreting the input format string. This is
|
|
/// modeled 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: iter::Peekable<str::CharIndices<'a>>,
|
|
/// Error messages accumulated during parsing
|
|
pub errors: Vec<ParseError>,
|
|
/// Current position of implicit positional argument pointer
|
|
curarg: usize,
|
|
/// `Some(raw count)` when the string is "raw", used to position spans correctly
|
|
style: Option<usize>,
|
|
/// Start and end byte offset of every successfully parsed argument
|
|
pub arg_places: Vec<InnerSpan>,
|
|
/// Characters that need to be shifted
|
|
skips: Vec<usize>,
|
|
/// Span of the last opening brace seen, used for error reporting
|
|
last_opening_brace: Option<InnerSpan>,
|
|
/// Wether the source string is comes from `println!` as opposed to `format!` or `print!`
|
|
append_newline: bool,
|
|
}
|
|
|
|
impl<'a> Iterator for Parser<'a> {
|
|
type Item = Piece<'a>;
|
|
|
|
fn next(&mut self) -> Option<Piece<'a>> {
|
|
if let Some(&(pos, c)) = self.cur.peek() {
|
|
match c {
|
|
'{' => {
|
|
let curr_last_brace = self.last_opening_brace;
|
|
let byte_pos = self.to_span_index(pos);
|
|
self.last_opening_brace = Some(byte_pos.to(InnerOffset(byte_pos.0 + 1)));
|
|
self.cur.next();
|
|
if self.consume('{') {
|
|
self.last_opening_brace = curr_last_brace;
|
|
|
|
Some(String(self.string(pos + 1)))
|
|
} else {
|
|
let arg = self.argument();
|
|
if let Some(end) = self.must_consume('}') {
|
|
let start = self.to_span_index(pos);
|
|
let end = self.to_span_index(end + 1);
|
|
self.arg_places.push(start.to(end));
|
|
}
|
|
Some(NextArgument(arg))
|
|
}
|
|
}
|
|
'}' => {
|
|
self.cur.next();
|
|
if self.consume('}') {
|
|
Some(String(self.string(pos + 1)))
|
|
} else {
|
|
let err_pos = self.to_span_index(pos);
|
|
self.err_with_note(
|
|
"unmatched `}` found",
|
|
"unmatched `}`",
|
|
"if you intended to print `}`, you can escape it using `}}`",
|
|
err_pos.to(err_pos),
|
|
);
|
|
None
|
|
}
|
|
}
|
|
'\n' => {
|
|
Some(String(self.string(pos)))
|
|
}
|
|
_ => Some(String(self.string(pos))),
|
|
}
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a> Parser<'a> {
|
|
/// Creates a new parser for the given format string
|
|
pub fn new(
|
|
s: &'a str,
|
|
style: Option<usize>,
|
|
skips: Vec<usize>,
|
|
append_newline: bool,
|
|
) -> Parser<'a> {
|
|
Parser {
|
|
input: s,
|
|
cur: s.char_indices().peekable(),
|
|
errors: vec![],
|
|
curarg: 0,
|
|
style,
|
|
arg_places: vec![],
|
|
skips,
|
|
last_opening_brace: None,
|
|
append_newline,
|
|
}
|
|
}
|
|
|
|
/// Notifies of an error. The message doesn't actually need to be of type
|
|
/// String, but I think it does when this eventually uses conditions so it
|
|
/// might as well start using it now.
|
|
fn err<S1: Into<string::String>, S2: Into<string::String>>(
|
|
&mut self,
|
|
description: S1,
|
|
label: S2,
|
|
span: InnerSpan,
|
|
) {
|
|
self.errors.push(ParseError {
|
|
description: description.into(),
|
|
note: None,
|
|
label: label.into(),
|
|
span,
|
|
secondary_label: None,
|
|
});
|
|
}
|
|
|
|
/// Notifies of an error. The message doesn't actually need to be of type
|
|
/// String, but I think it does when this eventually uses conditions so it
|
|
/// might as well start using it now.
|
|
fn err_with_note<S1: Into<string::String>, S2: Into<string::String>, S3: Into<string::String>>(
|
|
&mut self,
|
|
description: S1,
|
|
label: S2,
|
|
note: S3,
|
|
span: InnerSpan,
|
|
) {
|
|
self.errors.push(ParseError {
|
|
description: description.into(),
|
|
note: Some(note.into()),
|
|
label: label.into(),
|
|
span,
|
|
secondary_label: None,
|
|
});
|
|
}
|
|
|
|
/// 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 {
|
|
self.consume_pos(c).is_some()
|
|
}
|
|
|
|
/// Optionally consumes the specified character. If the character is not at
|
|
/// the current position, then the current iterator isn't moved and `None` is
|
|
/// returned, otherwise the character is consumed and the current position is
|
|
/// returned.
|
|
fn consume_pos(&mut self, c: char) -> Option<usize> {
|
|
if let Some(&(pos, maybe)) = self.cur.peek() {
|
|
if c == maybe {
|
|
self.cur.next();
|
|
return Some(pos);
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
fn to_span_index(&self, pos: usize) -> InnerOffset {
|
|
let mut pos = pos;
|
|
// This handles the raw string case, the raw argument is the number of #
|
|
// in r###"..."### (we need to add one because of the `r`).
|
|
let raw = self.style.map(|raw| raw + 1).unwrap_or(0);
|
|
for skip in &self.skips {
|
|
if pos > *skip {
|
|
pos += 1;
|
|
} else if pos == *skip && raw == 0 {
|
|
pos += 1;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
InnerOffset(raw + pos + 1)
|
|
}
|
|
|
|
/// Forces consumption of the specified character. If the character is not
|
|
/// found, an error is emitted.
|
|
fn must_consume(&mut self, c: char) -> Option<usize> {
|
|
self.ws();
|
|
|
|
if let Some(&(pos, maybe)) = self.cur.peek() {
|
|
if c == maybe {
|
|
self.cur.next();
|
|
Some(pos)
|
|
} else {
|
|
let pos = self.to_span_index(pos);
|
|
let description = format!("expected `'}}'`, found `{:?}`", maybe);
|
|
let label = "expected `}`".to_owned();
|
|
let (note, secondary_label) = if c == '}' {
|
|
(Some("if you intended to print `{`, you can escape it using `{{`".to_owned()),
|
|
self.last_opening_brace.map(|sp| {
|
|
("because of this opening brace".to_owned(), sp)
|
|
}))
|
|
} else {
|
|
(None, None)
|
|
};
|
|
self.errors.push(ParseError {
|
|
description,
|
|
note,
|
|
label,
|
|
span: pos.to(pos),
|
|
secondary_label,
|
|
});
|
|
None
|
|
}
|
|
} else {
|
|
let description = format!("expected `{:?}` but string was terminated", c);
|
|
// point at closing `"`
|
|
let pos = self.input.len() - if self.append_newline { 1 } else { 0 };
|
|
let pos = self.to_span_index(pos);
|
|
if c == '}' {
|
|
let label = format!("expected `{:?}`", c);
|
|
let (note, secondary_label) = if c == '}' {
|
|
(Some("if you intended to print `{`, you can escape it using `{{`".to_owned()),
|
|
self.last_opening_brace.map(|sp| {
|
|
("because of this opening brace".to_owned(), sp)
|
|
}))
|
|
} else {
|
|
(None, None)
|
|
};
|
|
self.errors.push(ParseError {
|
|
description,
|
|
note,
|
|
label,
|
|
span: pos.to(pos),
|
|
secondary_label,
|
|
});
|
|
} else {
|
|
self.err(description, format!("expected `{:?}`", c), pos.to(pos));
|
|
}
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Consumes all whitespace characters until the first non-whitespace character
|
|
fn ws(&mut self) {
|
|
while let Some(&(_, c)) = self.cur.peek() {
|
|
if c.is_whitespace() {
|
|
self.cur.next();
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// 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: usize) -> &'a str {
|
|
// we may not consume the character, peek the iterator
|
|
while let Some(&(pos, c)) = self.cur.peek() {
|
|
match c {
|
|
'{' | '}' => {
|
|
return &self.input[start..pos];
|
|
}
|
|
_ => {
|
|
self.cur.next();
|
|
}
|
|
}
|
|
}
|
|
&self.input[start..self.input.len()]
|
|
}
|
|
|
|
/// Parses an `Argument` structure, or what's contained within braces inside the format string.
|
|
fn argument(&mut self) -> Argument<'a> {
|
|
let pos = self.position();
|
|
let format = self.format();
|
|
|
|
// Resolve position after parsing format spec.
|
|
let pos = match pos {
|
|
Some(position) => position,
|
|
None => {
|
|
let i = self.curarg;
|
|
self.curarg += 1;
|
|
ArgumentImplicitlyIs(i)
|
|
}
|
|
};
|
|
|
|
Argument {
|
|
position: pos,
|
|
format,
|
|
}
|
|
}
|
|
|
|
/// Parses a positional argument for a format. This could either be an
|
|
/// integer index of an argument, a named argument, or a blank string.
|
|
/// Returns `Some(parsed_position)` if the position is not implicitly
|
|
/// consuming a macro argument, `None` if it's the case.
|
|
fn position(&mut self) -> Option<Position> {
|
|
if let Some(i) = self.integer() {
|
|
Some(ArgumentIs(i))
|
|
} else {
|
|
match self.cur.peek() {
|
|
Some(&(_, c)) if c.is_alphabetic() => {
|
|
Some(ArgumentNamed(Symbol::intern(self.word())))
|
|
}
|
|
Some(&(pos, c)) if c == '_' => {
|
|
let invalid_name = self.string(pos);
|
|
self.err_with_note(format!("invalid argument name `{}`", invalid_name),
|
|
"invalid argument name",
|
|
"argument names cannot start with an underscore",
|
|
self.to_span_index(pos).to(
|
|
self.to_span_index(pos + invalid_name.len())
|
|
),
|
|
);
|
|
Some(ArgumentNamed(Symbol::intern(invalid_name)))
|
|
},
|
|
|
|
// This is an `ArgumentNext`.
|
|
// Record the fact and do the resolution after parsing the
|
|
// format spec, to make things like `{:.*}` work.
|
|
_ => None,
|
|
}
|
|
}
|
|
}
|
|
|
|
/// 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,
|
|
precision_span: None,
|
|
width: CountImplied,
|
|
width_span: None,
|
|
ty: &self.input[..0],
|
|
ty_span: None,
|
|
};
|
|
if !self.consume(':') {
|
|
return spec;
|
|
}
|
|
|
|
// fill character
|
|
if let Some(&(_, c)) = self.cur.peek() {
|
|
match self.cur.clone().nth(1) {
|
|
Some((_, '>')) | Some((_, '<')) | Some((_, '^')) => {
|
|
spec.fill = Some(c);
|
|
self.cur.next();
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
// Alignment
|
|
if self.consume('<') {
|
|
spec.align = AlignLeft;
|
|
} else if self.consume('>') {
|
|
spec.align = AlignRight;
|
|
} else if self.consume('^') {
|
|
spec.align = AlignCenter;
|
|
}
|
|
// Sign flags
|
|
if self.consume('+') {
|
|
spec.flags |= 1 << (FlagSignPlus as u32);
|
|
} else if self.consume('-') {
|
|
spec.flags |= 1 << (FlagSignMinus as u32);
|
|
}
|
|
// Alternate marker
|
|
if self.consume('#') {
|
|
spec.flags |= 1 << (FlagAlternate as u32);
|
|
}
|
|
// 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 u32);
|
|
}
|
|
}
|
|
if !havewidth {
|
|
let width_span_start = if let Some((pos, _)) = self.cur.peek() {
|
|
*pos
|
|
} else {
|
|
0
|
|
};
|
|
let (w, sp) = self.count(width_span_start);
|
|
spec.width = w;
|
|
spec.width_span = sp;
|
|
}
|
|
if let Some(start) = self.consume_pos('.') {
|
|
if let Some(end) = self.consume_pos('*') {
|
|
// Resolve `CountIsNextParam`.
|
|
// We can do this immediately as `position` is resolved later.
|
|
let i = self.curarg;
|
|
self.curarg += 1;
|
|
spec.precision = CountIsParam(i);
|
|
spec.precision_span =
|
|
Some(self.to_span_index(start).to(self.to_span_index(end + 1)));
|
|
} else {
|
|
let (p, sp) = self.count(start);
|
|
spec.precision = p;
|
|
spec.precision_span = sp;
|
|
}
|
|
}
|
|
let ty_span_start = self.cur.peek().map(|(pos, _)| *pos);
|
|
// Optional radix followed by the actual format specifier
|
|
if self.consume('x') {
|
|
if self.consume('?') {
|
|
spec.flags |= 1 << (FlagDebugLowerHex as u32);
|
|
spec.ty = "?";
|
|
} else {
|
|
spec.ty = "x";
|
|
}
|
|
} else if self.consume('X') {
|
|
if self.consume('?') {
|
|
spec.flags |= 1 << (FlagDebugUpperHex as u32);
|
|
spec.ty = "?";
|
|
} else {
|
|
spec.ty = "X";
|
|
}
|
|
} else if self.consume('?') {
|
|
spec.ty = "?";
|
|
} else {
|
|
spec.ty = self.word();
|
|
let ty_span_end = self.cur.peek().map(|(pos, _)| *pos);
|
|
if !spec.ty.is_empty() {
|
|
spec.ty_span = ty_span_start
|
|
.and_then(|s| ty_span_end.map(|e| (s, e)))
|
|
.map(|(start, end)| self.to_span_index(start).to(self.to_span_index(end)));
|
|
}
|
|
}
|
|
spec
|
|
}
|
|
|
|
/// 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, start: usize) -> (Count, Option<InnerSpan>) {
|
|
if let Some(i) = self.integer() {
|
|
if let Some(end) = self.consume_pos('$') {
|
|
let span = self.to_span_index(start).to(self.to_span_index(end + 1));
|
|
(CountIsParam(i), Some(span))
|
|
} else {
|
|
(CountIs(i), None)
|
|
}
|
|
} else {
|
|
let tmp = self.cur.clone();
|
|
let word = self.word();
|
|
if word.is_empty() {
|
|
self.cur = tmp;
|
|
(CountImplied, None)
|
|
} else if self.consume('$') {
|
|
(CountIsName(Symbol::intern(word)), None)
|
|
} else {
|
|
self.cur = tmp;
|
|
(CountImplied, None)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Parses a word starting at the current position. A word is the same as
|
|
/// Rust identifier, except that it can't start with `_` character.
|
|
fn word(&mut self) -> &'a str {
|
|
let start = match self.cur.peek() {
|
|
Some(&(pos, c)) if c != '_' && rustc_lexer::is_id_start(c) => {
|
|
self.cur.next();
|
|
pos
|
|
}
|
|
_ => {
|
|
return &self.input[..0];
|
|
}
|
|
};
|
|
while let Some(&(pos, c)) = self.cur.peek() {
|
|
if rustc_lexer::is_id_continue(c) {
|
|
self.cur.next();
|
|
} else {
|
|
return &self.input[start..pos];
|
|
}
|
|
}
|
|
&self.input[start..self.input.len()]
|
|
}
|
|
|
|
/// 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<usize> {
|
|
let mut cur = 0;
|
|
let mut found = false;
|
|
while let Some(&(_, c)) = self.cur.peek() {
|
|
if let Some(i) = c.to_digit(10) {
|
|
cur = cur * 10 + i as usize;
|
|
found = true;
|
|
self.cur.next();
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
if found {
|
|
Some(cur)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests;
|