Struct Scanner

pub struct Scanner { /* private fields */ }

This is used to analyze string. It can be initialized using either Scanner::from or Scanner::new.

Example

use snob::Scanner;

let mut scanner = Scanner::new("Hello, world!");
if let Some(position) = scanner.starts_with("Hello") {
    scanner.goto(position);
}

Implementations

impl Scanner

pub fn new(source: impl AsRef<str>) -> Self

Create a new Scanner with a given source.

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");

pub fn source(&self) -> &[char]

Get the full source being used in this scanner, as a slice of characters

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
let source = scanner.source().iter().collect::<String>();
assert_eq!(scanner.source().iter().collect::<String>(), "Hello, world!");

pub fn len(&self) -> usize

Get the full length of the source being used in this scanner

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
assert_eq!(scanner.len(), 13);

pub fn is_empty(&self) -> bool

Returns true if the scanner’s source is an empty string

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
assert!(!scanner.is_empty());

pub fn char_at(&self, index: usize) -> Option<char>

Get the character at a given position in the string.

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
assert!(!scanner.is_empty());

pub fn position(&self) -> usize

Get the current position in the string. When the Scanner is created, this value is zero.

Example

use snob::Scanner;

let mut scanner = Scanner::new("Hello, world!");
assert_eq!(scanner.position(), 0);
scanner.advance(5);
assert_eq!(scanner.position(), 5);
scanner.goto(3);
assert_eq!(scanner.position(), 3);

pub fn is_at_end(&self) -> bool

Returns true if the scanner’s position has reached the end of its source.

Example

use snob::Scanner;

let mut scanner = Scanner::new("Hello, world!");
assert!(!scanner.is_at_end());

if let Some(position) = scanner.starts_with("Hello, world!") {
    scanner.goto(position);
}

assert!(scanner.is_at_end());

pub fn goto(&mut self, position: usize) -> Option<String>

Set the scanner’s position. If the position out of range out the source, then None is returned. Otherwise, the subslice from the old position to the new position is returned. If the latter is less than the former, then the string is reversed.

Example

use snob::Scanner;

let mut scanner = Scanner::new("Hello, world!");
scanner.goto(3);
assert_eq!(scanner.position(), 3);

pub fn advance(&mut self, amount: isize) -> Option<String>

Increase the position by the given amount. If the new position is out of the range of the source, then None is returned. Otherwise, the subslice from the old position to the new position is returned. If the latter is less than the former, then the string is reversed.

Example

use snob::Scanner;

let mut scanner = Scanner::new("Hello, world!");
scanner.advance(5);
assert_eq!(scanner.position(), 5);

pub fn find_substring(&self, substring: impl AsRef<str>) -> Option<usize>

Looks for the given substring in the remainder of the scanner. If the substring is found, the position of the first character in the substring is returned. Otherwise, None is returned.

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
let position = scanner.find_substring("lo")?;
assert_eq!(position, 3);

pub fn starts_with(&self, substring: impl AsRef<str>) -> Option<usize>

If source[position..] starts with the given string, then this returns the ending position of the substring. Otherwise, None is returned.

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
let position = scanner.starts_with("Hello")?;
assert_eq!(position, 5);

pub fn advance_if_starts_with( &mut self, substring: impl AsRef<str>, ) -> Option<String>

If source[position..] starts with the given string, then this returns a copy of the substring. Otherwise, None is returned. This is the equivalent of: self.goto(self.starts_with(substring)?).

Example

use snob::Scanner;

let mut scanner = Scanner::new("Hello, world!");
let substring = scanner.advance_if_starts_with("Hello")?;
assert_eq!(substring, "Hello");
assert_eq!(scanner.position(), 5);

pub fn any(&self, cset: impl CharacterSet) -> Option<usize>

If the next character in the scanner is contained in the given cset, then the position after the next character is returned. Otherwise, None is returned.

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
let position = scanner.any('H')?;
assert_eq!(position, 1);

pub fn many(&self, cset: impl CharacterSet) -> Option<usize>

If the next character in the scanner is contained in the given cset, then the position after the longest initial sequence of characters in cset is returned. Otherwise, None is returned.

Example

use snob::Scanner;
use snob::csets::AsciiLetters;

let scanner = Scanner::new("Hello, world!");
let position = scanner.many(AsciiLetters)?;
assert_eq!(position, 5);

pub fn upto(&self, cset: impl CharacterSet) -> Option<usize>

If the remainder of the scanner contains a character from the given cset, then the position of the aforementioned character is returned. Otherwise, None is returned.

Example

use snob::Scanner;

let scanner = Scanner::new("Hello, world!");
let position = scanner.upto(' ')?;
assert_eq!(position, 6);

Trait Implementations

impl AsRef<[char]> for Scanner

fn as_ref(&self) -> &[char]

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for Scanner

fn clone(&self) -> Scanner

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Scanner

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

Formats the value using the given formatter.

impl From<&str> for Scanner

fn from(value: &str) -> Self

Converts to this type from the input type.

impl From<Box<[char]>> for Scanner

fn from(value: Box<[char]>) -> Self

Converts to this type from the input type.