hl7_parser/
chrono_parser.rs

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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
use crate::{parser::Span, TimeParseError};
use chrono::{DateTime, FixedOffset, LocalResult, NaiveDate, NaiveDateTime, NaiveTime};
use nom::{
    bytes::complete::{tag, take_while_m_n},
    character::complete::one_of,
    combinator::{map_res, opt},
    sequence::preceded,
    IResult,
};

/// Parse an HL7 timestamp
///
/// Any missing components from the timestamp will be substituted with the first of that time
/// period (for example, if the month is not provided, it will default to 1 (January),
/// hour will default to `0`, offset will default to _UTC_)
///
/// # Arguments
///
/// * `s` - A string slice representing the HL7 timestamp (format: `YYYY[MM[DD[HH[MM[SS[.S[S[S[S]]]]]]]]][+/-ZZZZ]`)
pub fn parse_timestamp_chrono<'s>(
    s: &'s str,
) -> Result<LocalResult<DateTime<FixedOffset>>, TimeParseError> {
    fn is_decimal_digit(c: char) -> bool {
        c.is_ascii_digit()
    }

    fn from_digits(i: Span) -> Result<usize, std::num::ParseIntError> {
        i.fragment().parse::<usize>()
    }

    fn digit2(input: Span) -> IResult<Span, usize> {
        map_res(take_while_m_n(2, 2, is_decimal_digit), from_digits)(input)
    }

    fn digit4(input: Span) -> IResult<Span, usize> {
        map_res(take_while_m_n(4, 4, is_decimal_digit), from_digits)(input)
    }

    let s = Span::new(s);
    let (s, year) = digit4(s).map_err(|_| TimeParseError::ParsingFailed("year"))?;
    let (s, month) = opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("month"))?;
    let (s, day) = opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("day"))?;
    let (s, hour) = opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("hour"))?;
    let (s, minute) = opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("minute"))?;
    let (s, second) = opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("second"))?;
    let (s, second_fracs) = opt(preceded(tag("."), take_while_m_n(1, 4, is_decimal_digit)))(s)
        .map_err(|_: nom::Err<nom::error::Error<Span<'s>>>| {
            TimeParseError::ParsingFailed("fractional seconds")
        })?;
    let (s, offset_dir) =
        opt(one_of("+-"))(s).map_err(|_: nom::Err<nom::error::Error<Span<'s>>>| {
            TimeParseError::ParsingFailed("offset direction")
        })?;
    let (s, offset_hours) =
        opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("offset hours"))?;
    let (_, offset_minutes) =
        opt(digit2)(s).map_err(|_| TimeParseError::ParsingFailed("offset minutes"))?;

    let month = month.unwrap_or(1);
    let day = day.unwrap_or(1);
    let date = NaiveDate::from_ymd_opt(year as i32, month as u32, day as u32)
        .ok_or(TimeParseError::InvalidComponentRange("date does not exist"))?;

    let hour = hour.unwrap_or(0);
    let minute = minute.unwrap_or(0);
    let second = second.unwrap_or(0);

    let second_fracs = second_fracs.unwrap_or(Span::new("0"));
    let fracs_multiplier = match second_fracs.len() {
        1 => 100_000,
        2 => 10_000,
        3 => 1_000,
        4 => 100,
        _ => panic!("second_fracs.len() not in 1..=4"),
    };
    let microseconds = second_fracs
        .fragment()
        .parse::<u32>()
        .expect("can parse fractional seconds as number")
        * fracs_multiplier;
    let time =
        NaiveTime::from_hms_micro_opt(hour as u32, minute as u32, second as u32, microseconds)
            .ok_or(TimeParseError::InvalidComponentRange("time does not exist"))?;

    let offset_dir = match offset_dir.unwrap_or('+') {
        '-' => -1,
        _ => 1,
    };
    let offset_hours = offset_hours.unwrap_or(0) as i32 * offset_dir;
    let offset_minutes = offset_minutes.unwrap_or(0) as i32;
    let offset = FixedOffset::east_opt(offset_hours * 3600 + offset_minutes * 60)
        .ok_or(TimeParseError::InvalidComponentRange("offset does not exist"))?;

    let datetime = NaiveDateTime::new(date, time);
    let datetime = datetime.and_local_timezone(offset);
    Ok(datetime)
}

#[cfg(test)]
mod test {
    use super::*;
    use chrono::{Datelike, Timelike};

    #[test]
    fn can_parse_time_with_offsets() {
        let ts = "20230312195905.1234-0700";
        let ts = parse_timestamp_chrono(ts)
            .expect("can parse timestamp")
            .earliest()
            .expect("can convert to datetime");

        assert_eq!(ts.year(), 2023);
        assert_eq!(ts.month(), 3);
        assert_eq!(ts.day(), 12);
        assert_eq!(ts.hour(), 19);
        assert_eq!(ts.minute(), 59);
        assert_eq!(ts.second(), 5);
        assert_eq!(ts.nanosecond(), 123_400_000);
        assert_eq!(ts.offset().local_minus_utc() / 3600, -7);
        assert_eq!(ts.offset().local_minus_utc() % 3600, 0);
    }

    #[test]
    fn can_parse_time_without_offsets() {
        let ts = "20230312195905.1234";
        let ts = parse_timestamp_chrono(ts)
            .expect("can parse timestamp")
            .earliest()
            .expect("can convert to datetime");

        assert_eq!(ts.year(), 2023);
        assert_eq!(ts.month(), 3);
        assert_eq!(ts.day(), 12);
        assert_eq!(ts.hour(), 19);
        assert_eq!(ts.minute(), 59);
        assert_eq!(ts.second(), 5);
        assert_eq!(ts.nanosecond(), 123_400_000);
        assert_eq!(ts.offset().local_minus_utc(), 0);
    }

    #[test]
    fn can_parse_time_without_offsets_or_fractional_seconds() {
        let ts = "20230312195905";
        let ts = parse_timestamp_chrono(ts)
            .expect("can parse timestamp")
            .earliest()
            .expect("can convert to datetime");

        assert_eq!(ts.year(), 2023);
        assert_eq!(ts.month(), 3);
        assert_eq!(ts.day(), 12);
        assert_eq!(ts.hour(), 19);
        assert_eq!(ts.minute(), 59);
        assert_eq!(ts.second(), 5);
        assert_eq!(ts.nanosecond(), 0);
        assert_eq!(ts.offset().local_minus_utc(), 0);
    }

    #[test]
    fn can_parse_time_with_offsets_without_fractional_seconds() {
        let ts = "20230312195905-0700";
        let ts = parse_timestamp_chrono(ts)
            .expect("can parse timestamp")
            .earliest()
            .expect("can convert to datetime");

        assert_eq!(ts.year(), 2023);
        assert_eq!(ts.month(), 3);
        assert_eq!(ts.day(), 12);
        assert_eq!(ts.hour(), 19);
        assert_eq!(ts.minute(), 59);
        assert_eq!(ts.second(), 5);
        assert_eq!(ts.nanosecond(), 0);
        assert_eq!(ts.offset().local_minus_utc() / 3600, -7);
        assert_eq!(ts.offset().local_minus_utc() % 3600, 0);
    }

    #[test]
    fn can_parse_time_with_only_year() {
        let ts = "2023";
        let ts = parse_timestamp_chrono(ts)
            .expect("can parse timestamp")
            .earliest()
            .expect("can convert to datetime");

        assert_eq!(ts.year(), 2023);
        assert_eq!(ts.month(), 1);
        assert_eq!(ts.day(), 1);
        assert_eq!(ts.hour(), 0);
        assert_eq!(ts.minute(), 0);
        assert_eq!(ts.second(), 00);
        assert_eq!(ts.nanosecond(), 0);
        assert_eq!(ts.offset().local_minus_utc(), 0);
    }

    #[test]
    fn cant_parse_bad_timestamps() {
        assert!(parse_timestamp_chrono("23").is_err());
        assert!(parse_timestamp_chrono("abcd").is_err());
        assert!(parse_timestamp_chrono("20230230").is_err());
    }
}