Struct Scanner

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pub struct Scanner<C: CharSource> { /* private fields */ }

Expand description

Reader of master file tokens.

A scanner reads characters from a source and converts them into tokens or errors.

Implementations§

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impl<C: CharSource> Scanner<C>

§Creation

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pub fn new(chars: C) -> Self

Creates a new scanner.

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pub fn with_pos(chars: C, pos: Pos) -> Self

Creates a new scanner using the given character source and position.

The scanner will assume that the current position of chars corresponds to the human-friendly position pos.

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impl<C: CharSource> Scanner<C>

§Access to Origin

Domain names in a master file that do not end in a dot are relative to some origin. This origin is simply appened to them to form an absolute name.

Since domain names can appear all over the place and we don’t want to have to pass around the origin all the time, it is part of the scanner and can be set and retrieved any time.

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pub fn origin(&self) -> &Option<Dname>

Returns the current origin if any.

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pub fn set_origin(&mut self, origin: Option<Dname>)

Sets the origin to the given value.

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impl<C: CharSource> Scanner<C>

§Fundamental Scanning

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pub fn is_eof(&mut self) -> bool

Returns whether the scanner has reached the end of data.

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pub fn pos(&self) -> Pos

Returns the current position of the scanner.

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pub fn scan_word<T, U, F, G>( &mut self, target: T, symbolop: F, finalop: G, ) -> Result<U, ScanError>
where F: FnMut(&mut T, Symbol) -> Result<(), SyntaxError>, G: FnOnce(T) -> Result<U, SyntaxError>,

Scans a word token.

A word is a sequence of non-special characters and escape sequences followed by a non-empty sequence of space unless it is followed directly by a newline. If successful, the method will position at the end of the space sequence if it is required. That is, you can scan for two subsequent word tokens without worrying about the space between them.

The method starts out with a target value and two closures. The first closure, symbolop, is being fed symbols of the word one by one and should feed them into the target. Once the word ended, the second closure is called to convert the target into the final result. Both can error out at any time stopping processing and leading the scanner to revert to the beginning of the token.

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pub fn scan_string_word<U, G>(&mut self, finalop: G) -> Result<U, ScanError>
where G: FnOnce(String) -> Result<U, SyntaxError>,

Scans a word with Unicode text into a String.

The method scans a word that consists of characters and puts these into a String. Once the word ends, the caller is given a chance to convert the value into something else via the closure finalop. This closure can fail, resulting in an error and back-tracking to the beginning of the phrase.

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pub fn scan_quoted<T, U, F, G>( &mut self, target: T, symbolop: F, finalop: G, ) -> Result<U, ScanError>
where F: FnMut(&mut T, Symbol) -> Result<(), SyntaxError>, G: FnOnce(T) -> Result<U, SyntaxError>,

Scans a quoted word.

A quoted word starts with a double quote ", followed by all sorts of characters or escape sequences until the next (unescaped) double quote. It may contain line feeds. Like a regular word, a quoted word is followed by a non-empty space sequence unless it is directly followed by a newline. This space is not part of the content but quietly skipped over.

The method starts out with a target value and two closures. The first closure, symbolop, is being fed symbols of the word one by one and should feed them into the target. Once the word ended, the second closure is called to convert the target into the final result. Both can error out at any time stopping processing and leading the scanner to revert to the beginning of the token.

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pub fn scan_phrase<T, U, F, G>( &mut self, target: T, symbolop: F, finalop: G, ) -> Result<U, ScanError>
where F: FnMut(&mut T, Symbol) -> Result<(), SyntaxError>, G: FnOnce(T) -> Result<U, SyntaxError>,

Scans a phrase: a normal word or a quoted word.

This method behaves like scan_quoted() if the next character is a double quote or like scan_word() otherwise.

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pub fn scan_byte_phrase<U, G>(&mut self, finalop: G) -> Result<U, ScanError>
where G: FnOnce(Bytes) -> Result<U, SyntaxError>,

Scans a phrase with byte content into a Bytes value.

The method scans a phrase that consists of byte only and puts these bytes into a Bytes value. Once the phrase ends, the caller is given a chance to convert the value into something else via the closure finalop. This closure can fail, resulting in an error and back-tracking to the beginning of the phrase.

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pub fn scan_string_phrase<U, G>(&mut self, finalop: G) -> Result<U, ScanError>
where G: FnOnce(String) -> Result<U, SyntaxError>,

Scans a phrase with Unicode text into a String.

The method scans a phrase that consists of characters and puts these into a String. Once the phrase ends, the caller is given a chance to convert the value into something else via the closure finalop. This closure can fail, resulting in an error and back-tracking to the beginning of the phrase.

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pub fn scan_newline(&mut self) -> Result<(), ScanError>

Scans over a mandatory newline.

A newline is either an optional comment followed by a newline sequence or the end of file. The latter is so that a file lacking a line feed after its last line is still parsed successfully.

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pub fn scan_space(&mut self) -> Result<(), ScanError>

Scans over a mandatory sequence of space.

There are two flavors of space. The simple form is any sequence of a space character ' ' or a horizontal tab ’\t'. However, a parenthesis can be used to turn newlines into normal space. This method recognises parentheses and acts accordingly.

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pub fn scan_opt_space(&mut self) -> Result<(), ScanError>

Scans over an optional sequence of space.

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pub fn skip_entry(&mut self) -> Result<(), ScanError>

Skips over an entry.

Keeps reading until it successfully scans a newline. The method tries to be smart about that and considers parentheses, quotes, and escapes but also tries its best to not fail.

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