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//! 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/nightly-rustc/",
html_playground_url = "https://play.rust-lang.org/",
test(attr(deny(warnings)))
)]
#![deny(rustc::untranslatable_diagnostic)]
#![deny(rustc::diagnostic_outside_of_impl)]
// We want to be able to build this crate with a stable compiler, so no
// `#![feature]` attributes should be added.
use rustc_lexer::unescape;
pub use Alignment::*;
pub use Count::*;
pub use Piece::*;
pub use Position::*;
use std::iter;
use std::str;
use std::string;
// Note: copied from rustc_span
/// Range inside of a `Span` used for diagnostics when we only have access to relative positions.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct InnerSpan {
pub start: usize,
pub end: usize,
}
impl InnerSpan {
pub fn new(start: usize, end: usize) -> InnerSpan {
InnerSpan { start, end }
}
}
/// The location and before/after width of a character whose width has changed from its source code
/// representation
#[derive(Copy, Clone, PartialEq, Eq)]
pub struct InnerWidthMapping {
/// Index of the character in the source
pub position: usize,
/// The inner width in characters
pub before: usize,
/// The transformed width in characters
pub after: usize,
}
impl InnerWidthMapping {
pub fn new(position: usize, before: usize, after: usize) -> InnerWidthMapping {
InnerWidthMapping { position, before, after }
}
}
/// Whether the input string is a literal. If yes, it contains the inner width mappings.
#[derive(Clone, PartialEq, Eq)]
enum InputStringKind {
NotALiteral,
Literal { width_mappings: Vec<InnerWidthMapping> },
}
/// The type of format string that we are parsing.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum ParseMode {
/// A normal format string as per `format_args!`.
Format,
/// An inline assembly template string for `asm!`.
InlineAsm,
}
#[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(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(Box<Argument<'a>>),
}
/// Representation of an argument specification.
#[derive(Copy, Clone, Debug, PartialEq)]
pub struct Argument<'a> {
/// Where to find this argument
pub position: Position<'a>,
/// The span of the position indicator. Includes any whitespace in implicit
/// positions (`{ }`).
pub position_span: InnerSpan,
/// 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>,
/// Span of the optionally specified fill character.
pub fill_span: Option<InnerSpan>,
/// Optionally specified alignment.
pub align: Alignment,
/// The `+` or `-` flag.
pub sign: Option<Sign>,
/// The `#` flag.
pub alternate: bool,
/// The `0` flag.
pub zero_pad: bool,
/// The `x` or `X` flag. (Only for `Debug`.)
pub debug_hex: Option<DebugHex>,
/// The integer precision to use.
pub precision: Count<'a>,
/// 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<'a>,
/// 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<'a> {
/// 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(&'a str),
}
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,
}
/// Enum for the sign flags.
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum Sign {
/// The `+` flag.
Plus,
/// The `-` flag.
Minus,
}
/// Enum for the debug hex flags.
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum DebugHex {
/// The `x` flag in `{:x?}`.
Lower,
/// The `X` flag in `{:X?}`.
Upper,
}
/// 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<'a> {
/// The count is specified explicitly.
CountIs(usize),
/// The count is specified by the argument with the given name.
CountIsName(&'a str, InnerSpan),
/// The count is specified by the argument at the given index.
CountIsParam(usize),
/// The count is specified by a star (like in `{:.*}`) that refers to the argument at the given index.
CountIsStar(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)>,
pub suggestion: Suggestion,
}
pub enum Suggestion {
None,
/// Replace inline argument with positional argument:
/// `format!("{foo.bar}")` -> `format!("{}", foo.bar)`
UsePositional,
/// Remove `r#` from identifier:
/// `format!("{r#foo}")` -> `format!("{foo}")`
RemoveRawIdent(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> {
mode: ParseMode,
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
pub 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 whose length has been changed from their in-code representation
width_map: Vec<InnerWidthMapping>,
/// Span of the last opening brace seen, used for error reporting
last_opening_brace: Option<InnerSpan>,
/// Whether the source string is comes from `println!` as opposed to `format!` or `print!`
append_newline: bool,
/// Whether this formatting string was written directly in the source. This controls whether we
/// can use spans to refer into it and give better error messages.
/// N.B: This does _not_ control whether implicit argument captures can be used.
pub is_source_literal: bool,
/// Start position of the current line.
cur_line_start: usize,
/// Start and end byte offset of every line of the format string. Excludes
/// newline characters and leading whitespace.
pub line_spans: Vec<InnerSpan>,
}
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);
let lbrace_end = InnerOffset(byte_pos.0 + self.to_span_width(pos));
self.last_opening_brace = Some(byte_pos.to(lbrace_end));
self.cur.next();
if self.consume('{') {
self.last_opening_brace = curr_last_brace;
Some(String(self.string(pos + 1)))
} else {
let arg = self.argument(lbrace_end);
if let Some(rbrace_pos) = self.consume_closing_brace(&arg) {
if self.is_source_literal {
let lbrace_byte_pos = self.to_span_index(pos);
let rbrace_byte_pos = self.to_span_index(rbrace_pos);
let width = self.to_span_width(rbrace_pos);
self.arg_places.push(
lbrace_byte_pos.to(InnerOffset(rbrace_byte_pos.0 + width)),
);
}
} else {
if let Some(&(_, maybe)) = self.cur.peek() {
if maybe == '?' {
self.suggest_format();
} else {
self.suggest_positional_arg_instead_of_captured_arg(arg);
}
}
}
Some(NextArgument(Box::new(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
}
}
_ => Some(String(self.string(pos))),
}
} else {
if self.is_source_literal {
let span = self.span(self.cur_line_start, self.input.len());
if self.line_spans.last() != Some(&span) {
self.line_spans.push(span);
}
}
None
}
}
}
impl<'a> Parser<'a> {
/// Creates a new parser for the given format string
pub fn new(
s: &'a str,
style: Option<usize>,
snippet: Option<string::String>,
append_newline: bool,
mode: ParseMode,
) -> Parser<'a> {
let input_string_kind = find_width_map_from_snippet(s, snippet, style);
let (width_map, is_source_literal) = match input_string_kind {
InputStringKind::Literal { width_mappings } => (width_mappings, true),
InputStringKind::NotALiteral => (Vec::new(), false),
};
Parser {
mode,
input: s,
cur: s.char_indices().peekable(),
errors: vec![],
curarg: 0,
style,
arg_places: vec![],
width_map,
last_opening_brace: None,
append_newline,
is_source_literal,
cur_line_start: 0,
line_spans: vec![],
}
}
/// 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,
suggestion: Suggestion::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,
suggestion: Suggestion::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 remap_pos(&self, mut pos: usize) -> InnerOffset {
for width in &self.width_map {
if pos > width.position {
pos += width.before - width.after;
} else if pos == width.position && width.after == 0 {
pos += width.before;
} else {
break;
}
}
InnerOffset(pos)
}
fn to_span_index(&self, pos: usize) -> InnerOffset {
// 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_or(0, |raw| raw + 1);
let pos = self.remap_pos(pos);
InnerOffset(raw + pos.0 + 1)
}
fn to_span_width(&self, pos: usize) -> usize {
let pos = self.remap_pos(pos);
match self.width_map.iter().find(|w| w.position == pos.0) {
Some(w) => w.before,
None => 1,
}
}
fn span(&self, start_pos: usize, end_pos: usize) -> InnerSpan {
let start = self.to_span_index(start_pos);
let end = self.to_span_index(end_pos);
start.to(end)
}
/// Forces consumption of the specified character. If the character is not
/// found, an error is emitted.
fn consume_closing_brace(&mut self, arg: &Argument<'_>) -> Option<usize> {
self.ws();
let pos;
let description;
if let Some(&(peek_pos, maybe)) = self.cur.peek() {
if maybe == '}' {
self.cur.next();
return Some(peek_pos);
}
pos = peek_pos;
description = format!("expected `'}}'`, found `{maybe:?}`");
} else {
description = "expected `'}'` but string was terminated".to_owned();
// point at closing `"`
pos = self.input.len() - if self.append_newline { 1 } else { 0 };
}
let pos = self.to_span_index(pos);
let label = "expected `'}'`".to_owned();
let (note, secondary_label) = if arg.format.fill == Some('}') {
(
Some("the character `'}'` is interpreted as a fill character because of the `:` that precedes it".to_owned()),
arg.format.fill_span.map(|sp| ("this is not interpreted as a formatting closing brace".to_owned(), sp)),
)
} else {
(
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)),
)
};
self.errors.push(ParseError {
description,
note,
label,
span: pos.to(pos),
secondary_label,
suggestion: Suggestion::None,
});
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];
}
'\n' if self.is_source_literal => {
self.line_spans.push(self.span(self.cur_line_start, pos));
self.cur_line_start = pos + 1;
self.cur.next();
}
_ => {
if self.is_source_literal && pos == self.cur_line_start && c.is_whitespace() {
self.cur_line_start = pos + c.len_utf8();
}
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, start: InnerOffset) -> Argument<'a> {
let pos = self.position();
let end = self
.cur
.clone()
.find(|(_, ch)| !ch.is_whitespace())
.map_or(start, |(end, _)| self.to_span_index(end));
let position_span = start.to(end);
let format = match self.mode {
ParseMode::Format => self.format(),
ParseMode::InlineAsm => self.inline_asm(),
};
// 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, position_span, 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<'a>> {
if let Some(i) = self.integer() {
Some(ArgumentIs(i))
} else {
match self.cur.peek() {
Some(&(lo, c)) if rustc_lexer::is_id_start(c) => {
let word = self.word();
// Recover from `r#ident` in format strings.
// FIXME: use a let chain
if word == "r" {
if let Some((pos, '#')) = self.cur.peek() {
if self.input[pos + 1..]
.chars()
.next()
.is_some_and(rustc_lexer::is_id_start)
{
self.cur.next();
let word = self.word();
let prefix_span = self.span(lo, lo + 2);
let full_span = self.span(lo, lo + 2 + word.len());
self.errors.insert(0, ParseError {
description: "raw identifiers are not supported".to_owned(),
note: Some("identifiers in format strings can be keywords and don't need to be prefixed with `r#`".to_string()),
label: "raw identifier used here".to_owned(),
span: full_span,
secondary_label: None,
suggestion: Suggestion::RemoveRawIdent(prefix_span),
});
return Some(ArgumentNamed(word));
}
}
}
Some(ArgumentNamed(word))
}
// This is an `ArgumentNext`.
// Record the fact and do the resolution after parsing the
// format spec, to make things like `{:.*}` work.
_ => None,
}
}
}
fn current_pos(&mut self) -> usize {
if let Some(&(pos, _)) = self.cur.peek() { pos } else { self.input.len() }
}
/// 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,
fill_span: None,
align: AlignUnknown,
sign: None,
alternate: false,
zero_pad: false,
debug_hex: None,
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(&(idx, c)) = self.cur.peek() {
if let Some((_, '>' | '<' | '^')) = self.cur.clone().nth(1) {
spec.fill = Some(c);
spec.fill_span = Some(self.span(idx, idx + 1));
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.sign = Some(Sign::Plus);
} else if self.consume('-') {
spec.sign = Some(Sign::Minus);
}
// Alternate marker
if self.consume('#') {
spec.alternate = true;
}
// 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$' as the width instead.
if let Some(end) = self.consume_pos('$') {
spec.width = CountIsParam(0);
spec.width_span = Some(self.span(end - 1, end + 1));
havewidth = true;
} else {
spec.zero_pad = true;
}
}
if !havewidth {
let start = self.current_pos();
spec.width = self.count(start);
if spec.width != CountImplied {
let end = self.current_pos();
spec.width_span = Some(self.span(start, end));
}
}
if let Some(start) = self.consume_pos('.') {
if self.consume('*') {
// Resolve `CountIsNextParam`.
// We can do this immediately as `position` is resolved later.
let i = self.curarg;
self.curarg += 1;
spec.precision = CountIsStar(i);
} else {
spec.precision = self.count(start + 1);
}
let end = self.current_pos();
spec.precision_span = Some(self.span(start, end));
}
let ty_span_start = self.current_pos();
// Optional radix followed by the actual format specifier
if self.consume('x') {
if self.consume('?') {
spec.debug_hex = Some(DebugHex::Lower);
spec.ty = "?";
} else {
spec.ty = "x";
}
} else if self.consume('X') {
if self.consume('?') {
spec.debug_hex = Some(DebugHex::Upper);
spec.ty = "?";
} else {
spec.ty = "X";
}
} else if self.consume('?') {
spec.ty = "?";
} else {
spec.ty = self.word();
if !spec.ty.is_empty() {
let ty_span_end = self.current_pos();
spec.ty_span = Some(self.span(ty_span_start, ty_span_end));
}
}
spec
}
/// Parses an inline assembly template modifier at the current position, returning the modifier
/// in the `ty` field of the `FormatSpec` struct.
fn inline_asm(&mut self) -> FormatSpec<'a> {
let mut spec = FormatSpec {
fill: None,
fill_span: None,
align: AlignUnknown,
sign: None,
alternate: false,
zero_pad: false,
debug_hex: None,
precision: CountImplied,
precision_span: None,
width: CountImplied,
width_span: None,
ty: &self.input[..0],
ty_span: None,
};
if !self.consume(':') {
return spec;
}
let ty_span_start = self.current_pos();
spec.ty = self.word();
if !spec.ty.is_empty() {
let ty_span_end = self.current_pos();
spec.ty_span = Some(self.span(ty_span_start, ty_span_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<'a> {
if let Some(i) = self.integer() {
if self.consume('$') { CountIsParam(i) } else { CountIs(i) }
} else {
let tmp = self.cur.clone();
let word = self.word();
if word.is_empty() {
self.cur = tmp;
CountImplied
} else if let Some(end) = self.consume_pos('$') {
let name_span = self.span(start, end);
CountIsName(word, name_span)
} else {
self.cur = tmp;
CountImplied
}
}
}
/// 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 rustc_lexer::is_id_start(c) => {
self.cur.next();
pos
}
_ => {
return "";
}
};
let mut end = None;
while let Some(&(pos, c)) = self.cur.peek() {
if rustc_lexer::is_id_continue(c) {
self.cur.next();
} else {
end = Some(pos);
break;
}
}
let end = end.unwrap_or(self.input.len());
let word = &self.input[start..end];
if word == "_" {
self.err_with_note(
"invalid argument name `_`",
"invalid argument name",
"argument name cannot be a single underscore",
self.span(start, end),
);
}
word
}
fn integer(&mut self) -> Option<usize> {
let mut cur: usize = 0;
let mut found = false;
let mut overflow = false;
let start = self.current_pos();
while let Some(&(_, c)) = self.cur.peek() {
if let Some(i) = c.to_digit(10) {
let (tmp, mul_overflow) = cur.overflowing_mul(10);
let (tmp, add_overflow) = tmp.overflowing_add(i as usize);
if mul_overflow || add_overflow {
overflow = true;
}
cur = tmp;
found = true;
self.cur.next();
} else {
break;
}
}
if overflow {
let end = self.current_pos();
let overflowed_int = &self.input[start..end];
self.err(
format!(
"integer `{}` does not fit into the type `usize` whose range is `0..={}`",
overflowed_int,
usize::MAX
),
"integer out of range for `usize`",
self.span(start, end),
);
}
found.then_some(cur)
}
fn suggest_format(&mut self) {
if let (Some(pos), Some(_)) = (self.consume_pos('?'), self.consume_pos(':')) {
let word = self.word();
let _end = self.current_pos();
let pos = self.to_span_index(pos);
self.errors.insert(
0,
ParseError {
description: "expected format parameter to occur after `:`".to_owned(),
note: Some(format!("`?` comes after `:`, try `{}:{}` instead", word, "?")),
label: "expected `?` to occur after `:`".to_owned(),
span: pos.to(pos),
secondary_label: None,
suggestion: Suggestion::None,
},
);
}
}
fn suggest_positional_arg_instead_of_captured_arg(&mut self, arg: Argument<'a>) {
if let Some(end) = self.consume_pos('.') {
let byte_pos = self.to_span_index(end);
let start = InnerOffset(byte_pos.0 + 1);
let field = self.argument(start);
// We can only parse `foo.bar` field access, any deeper nesting,
// or another type of expression, like method calls, are not supported
if !self.consume('}') {
return;
}
if let ArgumentNamed(_) = arg.position {
if let ArgumentNamed(_) = field.position {
self.errors.insert(
0,
ParseError {
description: "field access isn't supported".to_string(),
note: None,
label: "not supported".to_string(),
span: InnerSpan::new(arg.position_span.start, field.position_span.end),
secondary_label: None,
suggestion: Suggestion::UsePositional,
},
);
}
}
}
}
}
/// Finds the indices of all characters that have been processed and differ between the actual
/// written code (code snippet) and the `InternedString` that gets processed in the `Parser`
/// in order to properly synthesise the intra-string `Span`s for error diagnostics.
fn find_width_map_from_snippet(
input: &str,
snippet: Option<string::String>,
str_style: Option<usize>,
) -> InputStringKind {
let snippet = match snippet {
Some(ref s) if s.starts_with('"') || s.starts_with("r\"") || s.starts_with("r#") => s,
_ => return InputStringKind::NotALiteral,
};
if str_style.is_some() {
return InputStringKind::Literal { width_mappings: Vec::new() };
}
// Strip quotes.
let snippet = &snippet[1..snippet.len() - 1];
// Macros like `println` add a newline at the end. That technically doesn't make them "literals" anymore, but it's fine
// since we will never need to point our spans there, so we lie about it here by ignoring it.
// Since there might actually be newlines in the source code, we need to normalize away all trailing newlines.
// If we only trimmed it off the input, `format!("\n")` would cause a mismatch as here we they actually match up.
// Alternatively, we could just count the trailing newlines and only trim one from the input if they don't match up.
let input_no_nl = input.trim_end_matches('\n');
let Some(unescaped) = unescape_string(snippet) else {
return InputStringKind::NotALiteral;
};
let unescaped_no_nl = unescaped.trim_end_matches('\n');
if unescaped_no_nl != input_no_nl {
// The source string that we're pointing at isn't our input, so spans pointing at it will be incorrect.
// This can for example happen with proc macros that respan generated literals.
return InputStringKind::NotALiteral;
}
let mut s = snippet.char_indices();
let mut width_mappings = vec![];
while let Some((pos, c)) = s.next() {
match (c, s.clone().next()) {
// skip whitespace and empty lines ending in '\\'
('\\', Some((_, '\n'))) => {
let _ = s.next();
let mut width = 2;
while let Some((_, c)) = s.clone().next() {
if matches!(c, ' ' | '\n' | '\t') {
width += 1;
let _ = s.next();
} else {
break;
}
}
width_mappings.push(InnerWidthMapping::new(pos, width, 0));
}
('\\', Some((_, 'n' | 't' | 'r' | '0' | '\\' | '\'' | '\"'))) => {
width_mappings.push(InnerWidthMapping::new(pos, 2, 1));
let _ = s.next();
}
('\\', Some((_, 'x'))) => {
// consume `\xAB` literal
s.nth(2);
width_mappings.push(InnerWidthMapping::new(pos, 4, 1));
}
('\\', Some((_, 'u'))) => {
let mut width = 2;
let _ = s.next();
if let Some((_, next_c)) = s.next() {
if next_c == '{' {
// consume up to 6 hexanumeric chars
let digits_len =
s.clone().take(6).take_while(|(_, c)| c.is_digit(16)).count();
let len_utf8 = s
.as_str()
.get(..digits_len)
.and_then(|digits| u32::from_str_radix(digits, 16).ok())
.and_then(char::from_u32)
.map_or(1, char::len_utf8);
// Skip the digits, for chars that encode to more than 1 utf-8 byte
// exclude as many digits as it is greater than 1 byte
//
// So for a 3 byte character, exclude 2 digits
let required_skips = digits_len.saturating_sub(len_utf8.saturating_sub(1));
// skip '{' and '}' also
width += required_skips + 2;
s.nth(digits_len);
} else if next_c.is_digit(16) {
width += 1;
// We suggest adding `{` and `}` when appropriate, accept it here as if
// it were correct
let mut i = 0; // consume up to 6 hexanumeric chars
while let (Some((_, c)), _) = (s.next(), i < 6) {
if c.is_digit(16) {
width += 1;
} else {
break;
}
i += 1;
}
}
}
width_mappings.push(InnerWidthMapping::new(pos, width, 1));
}
_ => {}
}
}
InputStringKind::Literal { width_mappings }
}
fn unescape_string(string: &str) -> Option<string::String> {
let mut buf = string::String::new();
let mut ok = true;
unescape::unescape_literal(string, unescape::Mode::Str, &mut |_, unescaped_char| {
match unescaped_char {
Ok(c) => buf.push(c),
Err(_) => ok = false,
}
});
ok.then_some(buf)
}
// Assert a reasonable size for `Piece`
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
rustc_index::static_assert_size!(Piece<'_>, 16);
#[cfg(test)]
mod tests;