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use internals::grammar::{is_vchar, is_ws};
use internals::MailType;
#[derive(Copy, Clone, Debug, Fail, PartialEq, Eq, Hash)]
#[fail(display = "text contained control characters")]
pub struct PartitionError;
#[derive(Copy, Clone)]
pub enum Partition<'a> {
//from -> to the start of the next block
SPACE(&'a str),
VCHAR(&'a str)
}
#[derive(Clone, Copy, PartialEq)]
enum Type { SPACE, VCHAR }
pub fn partition<'a>( text: &'a str ) -> Result<Vec<Partition<'a>>, PartitionError> {
use self::Type::*;
if text.len() == 0 {
return Ok( Vec::new() );
}
// unwrap is ok, as we return earlier if len == 0
let start_with_vchar = is_vchar( text.chars().next().unwrap(), MailType::Internationalized);
let mut partitions = Vec::new();
let mut current_type = if start_with_vchar { VCHAR } else { SPACE };
let mut start_of_current = 0;
for (idx, ch) in text.char_indices() {
if is_vchar(ch, MailType::Internationalized) {
if current_type == SPACE {
// idx is the start index of the current char, with is the
// (exclusive) end index of the previous char which is the
// last char of the Partition we want to push
partitions.push(Partition::SPACE(&text[start_of_current..idx]));
start_of_current = idx;
current_type = VCHAR
}
} else if is_ws(ch) || ch == '\r' || ch == '\n' {
if current_type == VCHAR {
partitions.push(Partition::VCHAR(&text[start_of_current..idx]));
start_of_current = idx;
current_type = SPACE
}
} else {
//TODO look into this error case and especially PartitionError's Display impl
return Err(PartitionError);
}
}
partitions.push( match current_type {
SPACE => Partition::SPACE(&text[start_of_current..]),
VCHAR => Partition::VCHAR(&text[start_of_current..])
} );
Ok( partitions )
}
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