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|
//! Utilities to deal with characters.
use crate::constant::TAB_SIZE;
use crate::event::{Event, Kind, Point};
use std::str;
/// A range between two points.
#[derive(Debug)]
pub struct Position<'a> {
pub start: &'a Point,
pub end: &'a Point,
}
impl<'a> Position<'a> {
/// Get a position from an exit event.
///
/// Looks backwards for the corresponding `enter` event.
/// This does not support nested events (such as lists in lists).
///
/// ## Panics
///
/// This function panics if an enter event is given.
/// When `micromark` is used, this function never panics.
pub fn from_exit_event(events: &'a [Event], index: usize) -> Position<'a> {
let exit = &events[index];
debug_assert_eq!(
exit.kind,
Kind::Exit,
"expected `from_exit_event` to be called on `exit` event"
);
let mut enter_index = index - 1;
loop {
let enter = &events[enter_index];
if enter.kind == Kind::Enter && enter.name == exit.name {
return Position {
start: &enter.point,
end: &exit.point,
};
}
enter_index -= 1;
}
}
/// Turn a position into indices.
///
/// Indices are places in `bytes` where this position starts and ends.
///
/// > 👉 **Note**: indices cannot represent virtual spaces.
pub fn to_indices(&self) -> (usize, usize) {
(self.start.index, self.end.index)
}
}
/// Bytes belonging to a range.
///
/// Includes information on virtual spaces before and after the bytes.
#[derive(Debug)]
pub struct Slice<'a> {
pub bytes: &'a [u8],
pub before: usize,
pub after: usize,
}
impl<'a> Slice<'a> {
/// Get a slice for a single point.
pub fn from_point(bytes: &'a [u8], point: &Point) -> Slice<'a> {
let mut before = point.vs;
let mut start = point.index;
let end = if start < bytes.len() {
start + 1
} else {
start
};
// If we have virtual spaces before, it means we are past the actual
// character at that index, and those virtual spaces.
if before > 0 {
before = TAB_SIZE - before;
start += 1;
};
Slice {
bytes: if start < end { &bytes[start..end] } else { &[] },
before,
after: 0,
}
}
/// Get a slice for a single index.
///
/// > 👉 **Note**: indices cannot represent virtual spaces.
pub fn from_index(bytes: &'a [u8], index: usize) -> Slice<'a> {
Slice::from_indices(bytes, index, index + 1)
}
/// Get a slice for a position.
pub fn from_position(bytes: &'a [u8], position: &Position) -> Slice<'a> {
let mut before = position.start.vs;
let mut after = position.end.vs;
let mut start = position.start.index;
let mut end = position.end.index;
// If we have virtual spaces before, it means we are past the actual
// character at that index, and those virtual spaces.
if before > 0 {
before = TAB_SIZE - before;
start += 1;
};
// If we have virtual spaces after, it means that character is included,
// and one less virtual space.
if after > 0 {
after -= 1;
end += 1;
}
Slice {
bytes: &bytes[start..end],
before,
after,
}
}
/// Get a slice for two indices.
///
/// > 👉 **Note**: indices cannot represent virtual spaces.
pub fn from_indices(bytes: &'a [u8], start: usize, end: usize) -> Slice<'a> {
Slice {
bytes: &bytes[start..end],
before: 0,
after: 0,
}
}
/// Get the size of this slice, including virtual spaces.
pub fn len(&self) -> usize {
self.bytes.len() + self.before + self.after
}
/// Get the first byte in this slice, representing a virtual space as a
/// space.
pub fn head(&self) -> Option<u8> {
if self.before > 0 {
Some(b' ')
} else if self.bytes.is_empty() {
None
} else {
Some(self.bytes[0])
}
}
/// Turn the slice into a `&str`.
///
/// > 👉 **Note**: cannot represent virtual spaces.
pub fn as_str(&self) -> &str {
str::from_utf8(self.bytes).unwrap()
}
/// Turn the slice into a `String`.
///
/// Support virtual spaces.
pub fn serialize(&self) -> String {
let mut string = String::with_capacity(self.len());
let mut index = self.before;
while index > 0 {
string.push(' ');
index -= 1;
}
string.push_str(self.as_str());
index = self.after;
while index > 0 {
string.push(' ');
index -= 1;
}
string
}
}
|
