Enum Symbol

pub enum Symbol {
    Char(char),
    SimpleEscape(u8),
    DecimalEscape(u8),
}

The zone file representation of a single character.

This is either a regular character or an escape sequence. See the variants for more details.

Variants

Char(char)

An unescaped Unicode character.

SimpleEscape(u8)

A character escaped via a preceding backslash.

This escape sequence is only allowed for printable ASCII characters.

DecimalEscape(u8)

A raw octet escaped using the decimal escape sequence.

This escape sequence consists of a backslash followed by exactly three decimal digits with the value of the octets.

Implementations

impl Symbol

pub fn from_chars<C: Iterator<Item = char>>( chars: &mut C, ) -> Result<Option<Self>, SymbolCharsError>

Reads a symbol from a character source.

Returns the next symbol in the source, Ok(None) if the source has been exhausted, or an error if there wasn’t a valid symbol.

pub fn from_slice_index( octets: &[u8], pos: usize, ) -> Result<Option<(Symbol, usize)>, SymbolOctetsError>

Reads a symbol from the given position in an octets slice.

Returns the symbol and the index of the end of the symbol in the slice.

pub fn from_octet(ch: u8) -> Self

Provides the best symbol for an octet.

The function will use the simple escape sequence for octet values that represent ASCII spaces, quotes, backslashes, and semicolons and the plain ASCII value for all other printable ASCII characters. Any other value is escaped using the decimal escape sequence.

pub fn quoted_from_octet(ch: u8) -> Self

Provides the best symbol for an octet inside a quoted string.

The function will only escape a double quote and backslash using a simple escape and all non-printable characters using decimal escapes.

pub fn display_from_octet(ch: u8) -> Self

Provides the best symbol for an octet inside a Display impl.

The function will only escape a backslash using a simple escape and all non-printable characters using decimal escapes.

pub fn into_octet(self) -> Result<u8, BadSymbol>

Converts the symbol into an octet if it represents one.

Both domain names and character strings operate on bytes instead of (Unicode) characters. These bytes can be represented by printable ASCII characters (that is, U+0020 to U+007E), both plain or through a simple escape, or by a decimal escape.

This method returns such an octet or an error if the symbol doesn’t have value representing an octet. Note that it will succeed for an ASCII space character U+0020 which may be used as a word separator in some cases.

pub fn into_ascii(self) -> Result<u8, BadSymbol>

Converts the symbol into an octet if it is printable ASCII.

This is similar to into_octet but returns an error when the resulting octet is not a printable ASCII character, i.e., an octet of value 0x20 up to and including 0x7E.

pub fn into_char(self) -> Result<char, BadSymbol>

Converts the symbol into a char.

This will fail for a decimal escape sequence which doesn’t actually represent a character.

pub fn into_digit(self, base: u32) -> Result<u32, BadSymbol>

Converts the symbol representing a digit into its integer value.

pub fn is_word_char(self) -> bool

Returns whether the symbol can occur as part of a word.

This is true for all symbols other than unescaped ASCII space and horizontal tabs, opening and closing parentheses, semicolon, and double quote.

Trait Implementations

impl Clone for Symbol

fn clone(&self) -> Symbol

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Symbol

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Symbol

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<Symbol> for EntrySymbol

fn from(symbol: Symbol) -> Self

Converts to this type from the input type.

impl From<char> for Symbol

fn from(ch: char) -> Symbol

Converts to this type from the input type.

impl PartialEq for Symbol

fn eq(&self, other: &Symbol) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Symbol

impl Eq for Symbol

impl StructuralPartialEq for Symbol