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
 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
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149

//! Encoder for EAN-8 barcodes.
//!
//! EAN-8 barcodes are EAN style barcodes for smaller packages on products like
//! cigaretts, chewing gum, etc where package space is limited.

use sym::{Parse, helpers};
use error::Result;
use sym::ean13::{ENCODINGS,
                 LEFT_GUARD,
                 MIDDLE_GUARD,
                 RIGHT_GUARD};
use std::ops::Range;
use std::char;

/// The EAN-8 barcode type.
#[derive(Debug)]
pub struct EAN8(Vec<u8>);

impl EAN8 {
    /// Creates a new barcode.
    /// Returns Result<EAN8, String> indicating parse success.
    pub fn new<T: AsRef<str>>(data: T) -> Result<EAN8> {
        EAN8::parse(data.as_ref()).and_then(|d| {
            let digits = d.chars()
                          .map(|c| c.to_digit(10).expect("Unknown character") as u8)
                          .collect();
            Ok(EAN8(digits))
        })
    }

    /// Calculates the checksum digit using a weighting algorithm.
    fn checksum_digit(&self) -> u8 {
        helpers::modulo_10_checksum(&self.0[..], false)
    }

    fn number_system_digits(&self) -> &[u8] {
        &self.0[0..2]
    }

    fn number_system_encoding(&self) -> Vec<u8> {
        let mut ns = vec![];

        for d in self.number_system_digits() {
            ns.extend(self.char_encoding(0, *d).iter().cloned());
        }

        ns
    }

    fn checksum_encoding(&self) -> [u8; 7] {
        self.char_encoding(2, self.checksum_digit())
    }

    fn char_encoding(&self, side: usize, d: u8) -> [u8; 7] {
        ENCODINGS[side][d as usize]
    }

    fn left_digits(&self) -> &[u8] {
        &self.0[2..4]
    }

    fn right_digits(&self) -> &[u8] {
        &self.0[4..]
    }

    fn left_payload(&self) -> Vec<u8> {
        let slices: Vec<[u8; 7]> = self.left_digits()
                                       .iter()
                                       .map(|d| self.char_encoding(0, *d))
                                       .collect();

        helpers::join_iters(slices.iter())
    }

    fn right_payload(&self) -> Vec<u8> {
        let slices: Vec<[u8; 7]> = self.right_digits()
                                       .iter()
                                       .map(|d| self.char_encoding(2, *d))
                                       .collect();

        helpers::join_iters(slices.iter())
    }

    /// Encodes the barcode.
    /// Returns a Vec<u8> of binary digits.
    pub fn encode(&self) -> Vec<u8> {
        helpers::join_slices(&[&LEFT_GUARD[..],
                               &self.number_system_encoding()[..],
                               &self.left_payload()[..],
                               &MIDDLE_GUARD[..],
                               &self.right_payload()[..],
                               &self.checksum_encoding()[..],
                               &RIGHT_GUARD[..]][..])
    }
}

impl Parse for EAN8 {
    /// Returns the valid length of data acceptable in this type of barcode.
    fn valid_len() -> Range<u32> {
        7..8
    }

    /// Returns the set of valid characters allowed in this type of barcode.
    fn valid_chars() -> Vec<char> {
        (0..10).map(|i| char::from_digit(i, 10).unwrap()).collect()
    }
}

#[cfg(test)]
mod tests {
    use sym::ean8::*;
    use error::Error;
    use std::char;

    fn collapse_vec(v: Vec<u8>) -> String {
        let chars = v.iter().map(|d| char::from_digit(*d as u32, 10).unwrap());
        chars.collect()
    }

    #[test]
    fn new_ean8() {
        let ean8 = EAN8::new("1234567");

        assert!(ean8.is_ok());
    }

    #[test]
    fn invalid_data_ean8() {
        let ean8 = EAN8::new("1234er1");

        assert_eq!(ean8.err().unwrap(), Error::Character);
    }

    #[test]
    fn invalid_len_ean8() {
        let ean8 = EAN8::new("1111112222222333333");

        assert_eq!(ean8.err().unwrap(), Error::Length);
    }

    #[test]
    fn ean8_encode() {
        let ean81 = EAN8::new("5512345").unwrap(); // Check digit: 7
        let ean82 = EAN8::new("9834651").unwrap(); // Check digit: 3

        assert_eq!(collapse_vec(ean81.encode()), "1010110001011000100110010010011010101000010101110010011101000100101");
        assert_eq!(collapse_vec(ean82.encode()), "1010001011011011101111010100011010101010000100111011001101010000101");
    }
}