rust - 匹配运算符的可能未初始化变量的借用

Question

我正在设计一个库，该库可以将给定的字符串从乌克兰语译为英语，因此我决定使用“匹配”运算符来定义带有多个条件检查的语句。但是我碰到了Rust常见的编译器错误，但是在我的情况下是完全不可能的(至少我想是这样)。

   --> src/lib.rs:188:21
    |
188 |  origin_mutated[i] = 'Y';
    |  ^^^^^^^^^^^^^^ use of possibly-uninitialized `origin_mutated`

error: aborting due to previous error

这是库的完整代码。如果我没有发现明显的问题，请把我的 Nose 碰到一个问题(因为我怀疑这可能是编译器中的错误)

pub fn transliterate(mut origin: String) -> String {
    let counter: usize = origin.chars().count();
    let mut j: usize = 0;
    let mut i: usize = 0;
    let origin_vec: Vec<char> = origin.chars().collect();
    let mut origin_mutated: Vec<char>;
    if j <= counter{
        while j <= counter {
            match origin_vec[j] {
                'А' => {
                    origin_mutated[i] = 'A';
                    i+=1;
                    j+=1;
                    },
                'Б' => {
                    origin_mutated[i] = 'B';
                    j+=1;
                    i+=1;
                    },
                'В' => {
                    origin_mutated[i] = 'V';
                    i+=1;
                    j+=1;
                    },
                'Г' => {
                    origin_mutated[i] = 'H';
                    i+=1;
                    j+=1;
                    },
                'Ґ' => {
                    origin_mutated[i] = 'G';
                    i+=1;
                    j+=1;
                    },
                'Д' => {
                    origin_mutated[i] = 'D';
                    i+=1;
                    j+=1;
                    },
                'Е' => {
                    origin_mutated[i] = 'E';
                    i+=1;
                    j+=1;
                    },
                'Є' => {
                    origin_mutated[i] = 'Y';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'e';
                    i+=1;
                    },
                'Ж' => {
                    origin_mutated[i] = 'Z';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'h';
                    i+=1;
                    },
                'З' => {
                    origin_mutated[i] = 'Z';
                    i+=1;
                    j+=1;
                    },
                'И' => {
                    origin_mutated[i] = 'Y';
                    i+=1;
                    j+=1;
                    },
                'І' => {
                    origin_mutated[i] = 'I';
                    i+=1;
                    j+=1;
                    },
                'Ї' => {
                    origin_mutated[i] = 'Y';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'i';
                    i+=1;
                    },
                'Й' => {
                    origin_mutated[i] = 'Y';
                    i+=1;
                    j+=1;
                    },
                'К' => {
                    origin_mutated[i] = 'K';
                    i+=1;
                    j+=1;
                    },
                'Л' => {
                    origin_mutated[i] = 'L';
                    i+=1;
                    j+=1;
                    },
                'М' => {
                    origin_mutated[i] = 'M';
                    i+=1;
                    j+=1;
                    },
                'Н' => {
                    origin_mutated[i] = 'N';
                    i+=1;
                    j+=1;
                    },
                'О' => {
                    origin_mutated[i] = 'O';
                    i==1;
                    j+=1;
                    },
                'П' => {
                    origin_mutated[i] = 'P';
                    i+=1;
                    j+=1;
                    },
                'Р' => {
                    origin_mutated[i] = 'R';
                    i==1;
                    j+=1;
                    },
                'С' => {
                    origin_mutated[i] = 'S';
                    i==1;
                    j+=1;
                    },
                'Т' => {
                    origin_mutated[i] = 'T';
                    i==1;
                    j+=1;
                    },
                'У' => {
                    origin_mutated[i] = 'U';
                    i+=1;
                    j+=1;
                    },
                'Ф' => {
                    origin_mutated[i] = 'F';
                    i==1;
                    j+=1;
                    },
                'Х' => {
                    origin_mutated[i] = 'K';
                    i+=1;
                    j==1;
                    origin_mutated[i] = 'h';
                    i+=1;
                    },
                'Ц' => {
                    origin_mutated[i] = 'T';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 's';
                    i+=1;
                    },
                'Ч' => {
                    origin_mutated[i] = 'C';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'h';
                    i+=1;
                    },
                'Ш' => {
                    origin_mutated[i] = 'S';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'h';
                    i+=1;
                    },
                'Щ' => {
                    origin_mutated[i] = 'S';
                    i+=1;
                    j==1;
                    origin_mutated[i] = 'h';
                    i+=1;
                    origin_mutated[i] = 'c';
                    i+=1;
                    origin_mutated[i] = 'h';
                    i+=1;
                    },
                'Ю' => {
                    origin_mutated[i] = 'Y';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'u';
                    i+=1;
                    },
                'Я' => {
                    origin_mutated[i] = 'Y';
                    i+=1;
                    j+=1;
                    origin_mutated[i] = 'a';
                    i+=1;
                    },
                _ => {
                    j+=1;
                    }
                }
            }
        }
    else if j > counter{
        origin_mutated[i] = '\n'; 
    }
    else {
        origin = origin_mutated.into_iter().collect();
    }
    //origin = origin_mutated.into_iter().collect();
    (origin)
}

Answer 1

发生错误的原因是此行不会创建Vec:

let mut origin_mutated: Vec<char>;

它创建了一个可以容纳Vec的变量，但还没有，甚至没有零长度的变量。就像在说

let a: i32;

它没有值(value)。你可能是说

let mut origin_mutated: Vec<char> = Vec::new();