zip.rs

use std::cmp;

/// Position within a line
pub type Pos = usize;

/// Text zipper
pub struct Zip<'a> {
    /// Lines before the current line
    prev: Vec<&'a str>,

    /// Position within a line
    pos: Pos,
    /// Current working line
    cur: String,

    /// Lines after the current line, reversed
    next: Vec<&'a str>
}

impl<'a> Zip<'a> {
    pub fn new() -> Self {
        Zip {
            prev: Vec::new(),

            pos: 0,
            cur: "".to_string(),

            next: Vec::new()
        }
    }

    pub fn print(&self, editor_line : Pos) {
        for str in (self.prev.iter().take(editor_line)) {
            println!("{}", str);
        }
    }

    pub fn to_string(&self) -> String {
        let mut str = self.prev.clone();
        str.push(&self.cur);
        str.extend(self.next.iter());

        str.join("\n")
    }

    pub fn from_string(str: &'a str) -> Self {
        let mut strs = str.split("\n");
        let cur = strs.next().unwrap().to_string();
        let mut next = Vec::new();

        for str in strs {
            next.push(str);
        }

        Zip {
            prev: Vec::new(),

            pos: 0,
            cur,

            next
        }
    }

    pub fn new_line_before(&mut self) {
        self.prev.push("");
    }

    pub fn new_line_after(&mut self) {
        self.next.push("");
    }

    pub fn insert(&mut self,
                  str: &str) {
        let mut strs = str.split("\n");
        let str = strs.next().unwrap();

        self.cur.insert_str(self.pos, str);
        self.pos += str.len();

//        let tail = &self.cur.split_off(self.pos);
//        for str in strs {
//            {
//                self.prev.push(&self.cur);
//            }
//            self.cur = str.to_string();
//            self.pos = str.len();
//        }
//        self.cur.insert_str(self.pos, tail);
    }

    pub fn down(&mut self) {
        match self.next.pop() {
            Some (cur_) => {
                self.cur = cur_.to_string();
            }
            _ => {}
        }
    }

    pub fn up(&'a mut self) {
        match self.prev.pop() {
            Some (cur_) => {
                self.next.push(&self.cur);
                self.cur = cur_.to_string();
                self.pos = cmp::min(self.pos, self.cur.len());
            }
            _ => {}
        }
    }

    pub fn left(&mut self) {
        if (self.pos == 0) { return; }

        self.pos -= 1;
    }

    pub fn right(&mut self) {
        if (self.pos == self.cur.len()) { return; }

        self.pos += 1;
    }
}