vendor/bitflags-2.6.0/src/parser.rs - toolchain/rustc - Git at Google

 /*!
 Parsing flags from text.

 Format and parse a flags value as text using the following grammar:

 - _Flags:_ (_Whitespace_ _Flag_ _Whitespace_)`|`*
 - _Flag:_ _Name_ | _Hex Number_
 - _Name:_ The name of any defined flag
 - _Hex Number_: `0x`([0-9a-fA-F])*
 - _Whitespace_: (\s)*

 As an example, this is how `Flags::A | Flags::B | 0x0c` can be represented as text:

 ```text
 A | B | 0x0c
 ```

 Alternatively, it could be represented without whitespace:

 ```text
 A|B|0x0C
 ```

 Note that identifiers are *case-sensitive*, so the following is *not equivalent*:

 ```text
 a|b|0x0C
 ```
 */

 #![allow(clippy::let_unit_value)]

 use core::fmt::{self, Write};

 use crate::{Bits, Flags};

 /**
 Write a flags value as text.

 Any bits that aren't part of a contained flag will be formatted as a hex number.
 */
 pub fn to_writer<B: Flags>(flags: &B, mut writer: impl Write) -> Result<(), fmt::Error>
 where
     B::Bits: WriteHex,
 {
     // A formatter for bitflags that produces text output like:
     //
     // A | B | 0xf6
     //
     // The names of set flags are written in a bar-separated-format,
     // followed by a hex number of any remaining bits that are set
     // but don't correspond to any flags.

     // Iterate over known flag values
     let mut first = true;
     let mut iter = flags.iter_names();
     for (name, _) in &mut iter {
         if !first {
             writer.write_str(" | ")?;
         }

         first = false;
         writer.write_str(name)?;
     }

     // Append any extra bits that correspond to flags to the end of the format
     let remaining = iter.remaining().bits();
     if remaining != B::Bits::EMPTY {
         if !first {
             writer.write_str(" | ")?;
         }

         writer.write_str("0x")?;
         remaining.write_hex(writer)?;
     }

     fmt::Result::Ok(())
 }

 #[cfg(feature = "serde")]
 pub(crate) struct AsDisplay<'a, B>(pub(crate) &'a B);

 #[cfg(feature = "serde")]
 impl<'a, B: Flags> fmt::Display for AsDisplay<'a, B>
 where
     B::Bits: WriteHex,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         to_writer(self.0, f)
     }
 }

 /**
 Parse a flags value from text.

 This function will fail on any names that don't correspond to defined flags.
 Unknown bits will be retained.
 */
 pub fn from_str<B: Flags>(input: &str) -> Result<B, ParseError>
 where
     B::Bits: ParseHex,
 {
     let mut parsed_flags = B::empty();

     // If the input is empty then return an empty set of flags
     if input.trim().is_empty() {
         return Ok(parsed_flags);
     }

     for flag in input.split('|') {
         let flag = flag.trim();

         // If the flag is empty then we've got missing input
         if flag.is_empty() {
             return Err(ParseError::empty_flag());
         }

         // If the flag starts with `0x` then it's a hex number
         // Parse it directly to the underlying bits type
         let parsed_flag = if let Some(flag) = flag.strip_prefix("0x") {
             let bits =
                 <B::Bits>::parse_hex(flag).map_err(|_| ParseError::invalid_hex_flag(flag))?;

             B::from_bits_retain(bits)
         }
         // Otherwise the flag is a name
         // The generated flags type will determine whether
         // or not it's a valid identifier
         else {
             B::from_name(flag).ok_or_else(|| ParseError::invalid_named_flag(flag))?
         };

         parsed_flags.insert(parsed_flag);
     }

     Ok(parsed_flags)
 }

 /**
 Write a flags value as text, ignoring any unknown bits.
 */
 pub fn to_writer_truncate<B: Flags>(flags: &B, writer: impl Write) -> Result<(), fmt::Error>
 where
     B::Bits: WriteHex,
 {
     to_writer(&B::from_bits_truncate(flags.bits()), writer)
 }

 /**
 Parse a flags value from text.

 This function will fail on any names that don't correspond to defined flags.
 Unknown bits will be ignored.
 */
 pub fn from_str_truncate<B: Flags>(input: &str) -> Result<B, ParseError>
 where
     B::Bits: ParseHex,
 {
     Ok(B::from_bits_truncate(from_str::<B>(input)?.bits()))
 }

 /**
 Write only the contained, defined, named flags in a flags value as text.
 */
 pub fn to_writer_strict<B: Flags>(flags: &B, mut writer: impl Write) -> Result<(), fmt::Error> {
     // This is a simplified version of `to_writer` that ignores
     // any bits not corresponding to a named flag

     let mut first = true;
     let mut iter = flags.iter_names();
     for (name, _) in &mut iter {
         if !first {
             writer.write_str(" | ")?;
         }

         first = false;
         writer.write_str(name)?;
     }

     fmt::Result::Ok(())
 }

 /**
 Parse a flags value from text.

 This function will fail on any names that don't correspond to defined flags.
 This function will fail to parse hex values.
 */
 pub fn from_str_strict<B: Flags>(input: &str) -> Result<B, ParseError> {
     // This is a simplified version of `from_str` that ignores
     // any bits not corresponding to a named flag

     let mut parsed_flags = B::empty();

     // If the input is empty then return an empty set of flags
     if input.trim().is_empty() {
         return Ok(parsed_flags);
     }

     for flag in input.split('|') {
         let flag = flag.trim();

         // If the flag is empty then we've got missing input
         if flag.is_empty() {
             return Err(ParseError::empty_flag());
         }

         // If the flag starts with `0x` then it's a hex number
         // These aren't supported in the strict parser
         if flag.starts_with("0x") {
             return Err(ParseError::invalid_hex_flag("unsupported hex flag value"));
         }

         let parsed_flag = B::from_name(flag).ok_or_else(|| ParseError::invalid_named_flag(flag))?;

         parsed_flags.insert(parsed_flag);
     }

     Ok(parsed_flags)
 }

 /**
 Encode a value as a hex string.

 Implementors of this trait should not write the `0x` prefix.
 */
 pub trait WriteHex {
     /// Write the value as hex.
     fn write_hex<W: fmt::Write>(&self, writer: W) -> fmt::Result;
 }

 /**
 Parse a value from a hex string.
 */
 pub trait ParseHex {
     /// Parse the value from hex.
     fn parse_hex(input: &str) -> Result<Self, ParseError>
     where
         Self: Sized;
 }

 /// An error encountered while parsing flags from text.
 #[derive(Debug)]
 pub struct ParseError(ParseErrorKind);

 #[derive(Debug)]
 #[allow(clippy::enum_variant_names)]
 enum ParseErrorKind {
     EmptyFlag,
     InvalidNamedFlag {
         #[cfg(not(feature = "std"))]
         got: (),
         #[cfg(feature = "std")]
         got: String,
     },
     InvalidHexFlag {
         #[cfg(not(feature = "std"))]
         got: (),
         #[cfg(feature = "std")]
         got: String,
     },
 }

 impl ParseError {
     /// An invalid hex flag was encountered.
     pub fn invalid_hex_flag(flag: impl fmt::Display) -> Self {
         let _flag = flag;

         let got = {
             #[cfg(feature = "std")]
             {
                 _flag.to_string()
             }
         };

         ParseError(ParseErrorKind::InvalidHexFlag { got })
     }

     /// A named flag that doesn't correspond to any on the flags type was encountered.
     pub fn invalid_named_flag(flag: impl fmt::Display) -> Self {
         let _flag = flag;

         let got = {
             #[cfg(feature = "std")]
             {
                 _flag.to_string()
             }
         };

         ParseError(ParseErrorKind::InvalidNamedFlag { got })
     }

     /// A hex or named flag wasn't found between separators.
     pub const fn empty_flag() -> Self {
         ParseError(ParseErrorKind::EmptyFlag)
     }
 }

 impl fmt::Display for ParseError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match &self.0 {
             ParseErrorKind::InvalidNamedFlag { got } => {
                 let _got = got;

                 write!(f, "unrecognized named flag")?;

                 #[cfg(feature = "std")]
                 {
                     write!(f, " `{}`", _got)?;
                 }
             }
             ParseErrorKind::InvalidHexFlag { got } => {
                 let _got = got;

                 write!(f, "invalid hex flag")?;

                 #[cfg(feature = "std")]
                 {
                     write!(f, " `{}`", _got)?;
                 }
             }
             ParseErrorKind::EmptyFlag => {
                 write!(f, "encountered empty flag")?;
             }
         }

         Ok(())
     }
 }

 #[cfg(feature = "std")]
 impl std::error::Error for ParseError {}
	/*!
	Parsing flags from text.

	Format and parse a flags value as text using the following grammar:

	- _Flags:_ (_Whitespace_ _Flag_ _Whitespace_)`\|`*
	- _Flag:_ _Name_ \| _Hex Number_
	- _Name:_ The name of any defined flag
	- _Hex Number_: `0x`([0-9a-fA-F])*
	- _Whitespace_: (\s)*

	As an example, this is how `Flags::A \| Flags::B \| 0x0c` can be represented as text:

	```text
	A \| B \| 0x0c
	```

	Alternatively, it could be represented without whitespace:

	```text
	A\|B\|0x0C
	```

	Note that identifiers are case-sensitive, so the following is not equivalent:

	```text
	a\|b\|0x0C
	```
	*/

	#![allow(clippy::let_unit_value)]

	use core::fmt::{self, Write};

	use crate::{Bits, Flags};

	/**
	Write a flags value as text.

	Any bits that aren't part of a contained flag will be formatted as a hex number.
	*/
	pub fn to_writer<B: Flags>(flags: &B, mut writer: impl Write) -> Result<(), fmt::Error>
	where
	B::Bits: WriteHex,
	{
	// A formatter for bitflags that produces text output like:
	//
	// A \| B \| 0xf6
	//
	// The names of set flags are written in a bar-separated-format,
	// followed by a hex number of any remaining bits that are set
	// but don't correspond to any flags.

	// Iterate over known flag values
	let mut first = true;
	let mut iter = flags.iter_names();
	for (name, _) in &mut iter {
	if !first {
	writer.write_str(" \| ")?;
	}

	first = false;
	writer.write_str(name)?;
	}

	// Append any extra bits that correspond to flags to the end of the format
	let remaining = iter.remaining().bits();
	if remaining != B::Bits::EMPTY {
	if !first {
	writer.write_str(" \| ")?;
	}

	writer.write_str("0x")?;
	remaining.write_hex(writer)?;
	}

	fmt::Result::Ok(())
	}

	#[cfg(feature = "serde")]
	pub(crate) struct AsDisplay<'a, B>(pub(crate) &'a B);

	#[cfg(feature = "serde")]
	impl<'a, B: Flags> fmt::Display for AsDisplay<'a, B>
	where
	B::Bits: WriteHex,
	{
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	to_writer(self.0, f)
	}
	}

	/**
	Parse a flags value from text.

	This function will fail on any names that don't correspond to defined flags.
	Unknown bits will be retained.
	*/
	pub fn from_str<B: Flags>(input: &str) -> Result<B, ParseError>
	where
	B::Bits: ParseHex,
	{
	let mut parsed_flags = B::empty();

	// If the input is empty then return an empty set of flags
	if input.trim().is_empty() {
	return Ok(parsed_flags);
	}

	for flag in input.split('\|') {
	let flag = flag.trim();

	// If the flag is empty then we've got missing input
	if flag.is_empty() {
	return Err(ParseError::empty_flag());
	}

	// If the flag starts with `0x` then it's a hex number
	// Parse it directly to the underlying bits type
	let parsed_flag = if let Some(flag) = flag.strip_prefix("0x") {
	let bits =
	<B::Bits>::parse_hex(flag).map_err(\|_\| ParseError::invalid_hex_flag(flag))?;

	B::from_bits_retain(bits)
	}
	// Otherwise the flag is a name
	// The generated flags type will determine whether
	// or not it's a valid identifier
	else {
	B::from_name(flag).ok_or_else(\|\| ParseError::invalid_named_flag(flag))?
	};

	parsed_flags.insert(parsed_flag);
	}

	Ok(parsed_flags)
	}

	/**
	Write a flags value as text, ignoring any unknown bits.
	*/
	pub fn to_writer_truncate<B: Flags>(flags: &B, writer: impl Write) -> Result<(), fmt::Error>
	where
	B::Bits: WriteHex,
	{
	to_writer(&B::from_bits_truncate(flags.bits()), writer)
	}

	/**
	Parse a flags value from text.

	This function will fail on any names that don't correspond to defined flags.
	Unknown bits will be ignored.
	*/
	pub fn from_str_truncate<B: Flags>(input: &str) -> Result<B, ParseError>
	where
	B::Bits: ParseHex,
	{
	Ok(B::from_bits_truncate(from_str::<B>(input)?.bits()))
	}

	/**
	Write only the contained, defined, named flags in a flags value as text.
	*/
	pub fn to_writer_strict<B: Flags>(flags: &B, mut writer: impl Write) -> Result<(), fmt::Error> {
	// This is a simplified version of `to_writer` that ignores
	// any bits not corresponding to a named flag

	let mut first = true;
	let mut iter = flags.iter_names();
	for (name, _) in &mut iter {
	if !first {
	writer.write_str(" \| ")?;
	}

	first = false;
	writer.write_str(name)?;
	}

	fmt::Result::Ok(())
	}

	/**
	Parse a flags value from text.

	This function will fail on any names that don't correspond to defined flags.
	This function will fail to parse hex values.
	*/
	pub fn from_str_strict<B: Flags>(input: &str) -> Result<B, ParseError> {
	// This is a simplified version of `from_str` that ignores
	// any bits not corresponding to a named flag

	let mut parsed_flags = B::empty();

	// If the input is empty then return an empty set of flags
	if input.trim().is_empty() {
	return Ok(parsed_flags);
	}

	for flag in input.split('\|') {
	let flag = flag.trim();

	// If the flag is empty then we've got missing input
	if flag.is_empty() {
	return Err(ParseError::empty_flag());
	}

	// If the flag starts with `0x` then it's a hex number
	// These aren't supported in the strict parser
	if flag.starts_with("0x") {
	return Err(ParseError::invalid_hex_flag("unsupported hex flag value"));
	}

	let parsed_flag = B::from_name(flag).ok_or_else(\|\| ParseError::invalid_named_flag(flag))?;

	parsed_flags.insert(parsed_flag);
	}

	Ok(parsed_flags)
	}

	/**
	Encode a value as a hex string.

	Implementors of this trait should not write the `0x` prefix.
	*/
	pub trait WriteHex {
	/// Write the value as hex.
	fn write_hex<W: fmt::Write>(&self, writer: W) -> fmt::Result;
	}

	/**
	Parse a value from a hex string.
	*/
	pub trait ParseHex {
	/// Parse the value from hex.
	fn parse_hex(input: &str) -> Result<Self, ParseError>
	where
	Self: Sized;
	}

	/// An error encountered while parsing flags from text.
	#[derive(Debug)]
	pub struct ParseError(ParseErrorKind);

	#[derive(Debug)]
	#[allow(clippy::enum_variant_names)]
	enum ParseErrorKind {
	EmptyFlag,
	InvalidNamedFlag {
	#[cfg(not(feature = "std"))]
	got: (),
	#[cfg(feature = "std")]
	got: String,
	},
	InvalidHexFlag {
	#[cfg(not(feature = "std"))]
	got: (),
	#[cfg(feature = "std")]
	got: String,
	},
	}

	impl ParseError {
	/// An invalid hex flag was encountered.
	pub fn invalid_hex_flag(flag: impl fmt::Display) -> Self {
	let _flag = flag;

	let got = {
	#[cfg(feature = "std")]
	{
	_flag.to_string()
	}
	};

	ParseError(ParseErrorKind::InvalidHexFlag { got })
	}

	/// A named flag that doesn't correspond to any on the flags type was encountered.
	pub fn invalid_named_flag(flag: impl fmt::Display) -> Self {
	let _flag = flag;

	let got = {
	#[cfg(feature = "std")]
	{
	_flag.to_string()
	}
	};

	ParseError(ParseErrorKind::InvalidNamedFlag { got })
	}

	/// A hex or named flag wasn't found between separators.
	pub const fn empty_flag() -> Self {
	ParseError(ParseErrorKind::EmptyFlag)
	}
	}

	impl fmt::Display for ParseError {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	match &self.0 {
	ParseErrorKind::InvalidNamedFlag { got } => {
	let _got = got;

	write!(f, "unrecognized named flag")?;

	#[cfg(feature = "std")]
	{
	write!(f, " `{}`", _got)?;
	}
	}
	ParseErrorKind::InvalidHexFlag { got } => {
	let _got = got;

	write!(f, "invalid hex flag")?;

	#[cfg(feature = "std")]
	{
	write!(f, " `{}`", _got)?;
	}
	}
	ParseErrorKind::EmptyFlag => {
	write!(f, "encountered empty flag")?;
	}
	}

	Ok(())
	}
	}

	#[cfg(feature = "std")]
	impl std::error::Error for ParseError {}