sourcemap 2.2.1

Basic sourcemap handling for Rust
Documentation 
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use errors::{Result, Error};

const B64_CHARS: &'static [u8] =
    b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const B64: [i8; 256] =
    [-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,
     -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5,
     6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1,
     -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
     47, 48, 49, 50, 51, -1, -1, -1, -1, -1 - 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1];

pub fn parse_vlq_segment(segment: &str) -> Result<Vec<i64>> {
    let mut rv = vec![];

    let mut cur = 0;
    let mut shift = 0;

    for c in segment.bytes() {
        let enc = B64[c as usize] as i64;
        let val = enc & 0b11111;
        let cont = enc >> 5;
        cur += val.checked_shl(shift).ok_or(Error::VlqOverflow)?;
        shift += 5;

        if cont == 0 {
            let sign = cur & 1;
            cur = cur >> 1;
            if sign != 0 {
                cur = -cur;
            }
            rv.push(cur);
            cur = 0;
            shift = 0;
        }
    }

    if cur != 0 || shift != 0 {
        Err(Error::VlqLeftover)
    } else if rv.len() == 0 {
        Err(Error::VlqNoValues)
    } else {
        Ok(rv)
    }
}

pub fn generate_vlq_segment(nums: &[i64]) -> Result<String> {
    let mut rv = String::new();
    for &num in nums {
        encode_vlq(&mut rv, num);
    }
    Ok(rv)
}

pub fn encode_vlq(out: &mut String, num: i64) {
    let mut num = if num < 0 { ((-num) << 1) + 1 } else { num << 1 };

    loop {
        let mut digit = num & 0b11111;
        num >>= 5;
        if num > 0 {
            digit |= 1 << 5;
        }
        out.push(B64_CHARS[digit as usize] as char);
        if num == 0 {
            break;
        }
    }
}