strings.textscanner #

fn new(input string) TextScanner

new returns a stack allocated instance of TextScanner.

struct TextScanner {
pub:
	input string
	ilen  int
pub mut:
	pos int // current position; pos is *always* kept in [0,ilen]
}

TextScanner simplifies writing small scanners/parsers. It helps by providing safe methods to scan texts character by character, peek for the next characters, go back, etc.

fn (mut ss TextScanner) free()

free frees all allocated resources.

fn (ss &TextScanner) remaining() int

remaining returns how many characters remain from current position.

fn (mut ss TextScanner) next() int

next returns the next character code from the input text. next returns -1 if it can't reach the next character. next advances the scanner position.

fn (mut ss TextScanner) skip()

skip skips one character ahead; skip() is slightly faster than .next(). skip() does not return a result.

fn (mut ss TextScanner) skip_n(n int)

skip_n skips ahead n characters, stopping at the end of the input.

fn (ss &TextScanner) peek() int

peek returns the next character code from the input text. peek returns -1 if it can't peek the next character. unlike next(), peek() does not change the state of the scanner.

fn (ss &TextScanner) peek_u8() u8

peek_u8 returns the next character code from the input text, as a byte/u8. unlike next(), peek_u8() does not change the state of the scanner.

Note: peek_u8 returns 0, if it can't peek the next character.

Note: use peek(), instead of peek_u8(), if your input itself can legitimately contain bytes with value 0.

fn (ss &TextScanner) peek_n(n int) int

peek_n returns the character code from the input text at position + n. peek_n returns -1 if it can't peek n characters ahead. ts.peek_n(0) == ts.current() . ts.peek_n(1) == ts.peek() .

fn (ss &TextScanner) peek_n_u8(n int) u8

peek_n_u8 returns the character code from the input text, at position + n, as a byte/u8.

Note: peek_n_u8 returns 0, if it can't peek the next character.

Note: use peek_n(), instead of peek_n_u8(), if your input itself can legitimately contain bytes with value 0.

fn (mut ss TextScanner) back()

back goes back one character from the current scanner position.

fn (mut ss TextScanner) back_n(n int)

back_n goes back n characters from the current scanner position.

fn (ss &TextScanner) peek_back() int

peek_back returns the previous character code from the input text. peek_back returns -1 if it can't peek the previous character. unlike back(), peek_back() does not change the state of the scanner.

fn (ss &TextScanner) peek_back_n(n int) int

peek_back_n returns the character code from the input text at position - n. peek_back_n returns -1 if it can't peek n characters back. ts.peek_back_n(0) == ts.current() ts.peek_back_n(1) == ts.peek_back()

fn (mut ss TextScanner) current() int

current returns the current character code from the input text. current returns -1 at the start of the input text.

Note: after c := ts.next(), ts.current() will also return c.

fn (mut ss TextScanner) reset()

reset resets the internal state of the scanner. After calling .reset(), .next() will start reading again from the start of the input text.

fn (mut ss TextScanner) goto_end()

goto_end has the same effect as for ts.next() != -1 {}. i.e. after calling .goto_end(), the scanner will be at the end of the input text. Further .next() calls will return -1, unless you go back.

fn (mut ss TextScanner) skip_whitespace()

skip_whitespace advances the scanner pass any space characters in the input.