crontab 0.2.0

A lightweight crontab parser.
Documentation 
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#![allow(deprecated)]

use error::CrontabError;
use std::collections::HashSet;
use std::iter::FromIterator;

/// The components of a crontab schedule.
/// The values in each field are guaranteed to be both unique and ordered.
#[derive(Clone, Debug, Default)]
pub struct ScheduleComponents {
  /// Minutes in the schedule.
  /// Range [0,59] inclusive.
  pub minutes: Vec<u32>,

  /// Hours in the schedule.
  /// Range [0,23] inclusive.
  pub hours: Vec<u32>,

  /// Days of the month in the schedule.
  /// Range [1,31] inclusive.
  pub days: Vec<u32>,

  /// Months in the schedule.
  /// Range [1,12] inclusive.
  pub months: Vec<u32>,

  /// Days of the week in the schedule.
  /// Range [0,6] inclusive.
  pub weekdays: Vec<u32>,

  /// Seconds in the schedule.
  /// Not yet in use. Do not use.
  #[deprecated(since="0.2.0", note="Field is never set!")]
  pub seconds: Vec<u32>,
}

pub (crate) fn parse_cron(schedule: &str)
    -> Result<ScheduleComponents, CrontabError> {
  let fields : Vec<&str> = schedule.trim()
      .split_whitespace()
      .collect();

  if fields.len() != 5 {
    return Err(CrontabError::ErrCronFormat(
      format!("Invalid format: {}", schedule)));
  }

  let minutes = parse_field(fields[0], 0, 59)?;
  let hours = parse_field(fields[1], 0, 23)?;
  let days = parse_field(fields[2], 1, 31)?;
  let months = parse_field(fields[3], 1, 12)?;
  let weekdays = parse_field(fields[4], 0, 6)?;

  Ok(ScheduleComponents {
    minutes: minutes,
    hours: hours,
    days: days,
    months: months,
    weekdays: weekdays,
    seconds: Vec::new(), // FIXME: Implement (though nonstandard).
  })
}

fn parse_field(field: &str, field_min: u32, field_max: u32)
    -> Result<Vec<u32>, CrontabError> {

  let mut components = HashSet::<u32>::new();

  for part in field.split(",") {
    let mut min = field_min;
    let mut max = field_max;
    let mut step = 1;

    // stepped, eg. */2 or 1-45/3
    let stepped : Vec<&str> = part.splitn(2, "/").collect();

    // ranges, eg. 1-30
    let range : Vec<&str> = stepped[0].splitn(2, "-").collect();

    if stepped.len() == 2 {
      step = stepped[1].parse::<u32>()?;
    }

    if range.len() == 2 {
      min = range[0].parse::<u32>()?;
      max = range[1].parse::<u32>()?;
    }

    if stepped.len() == 1 && range.len() == 1 && part != "*" {
      min = part.parse::<u32>()?;
      max = min;
    }

    if min < field_min {
      return Err(CrontabError::FieldOutsideRange {
        description: format!("Value {} is less than minimum: {}", min, field_min)
      });
    }

    if max > field_max {
      return Err(CrontabError::FieldOutsideRange {
        description: format!("Value {} is greater than maximum: {}", max, field_max)
      });
    }

    let values = (min .. max + 1).filter(|i| i % step == 0)
        .collect::<Vec<u32>>();

    components.extend(values);
  }

  let mut components : Vec<u32> = Vec::from_iter(components.into_iter());
  components.sort();

  Ok(components)
}


#[cfg(test)]
mod tests {
  use super::*;
  use expectest::prelude::*;

  #[test]
  fn parse_fields() {
    // Precise number of fields
    expect!(parse_cron("* * * * *")).to(be_ok());
    // Incorrect number of fields
    expect!(parse_cron("")).to(be_err());
    expect!(parse_cron("* * * *")).to(be_err());
    expect!(parse_cron("* * * * * *")).to(be_err());
  }

  #[test]
  fn parse_whitespace() {
    // Allowed whitespace
    expect!(parse_cron("  * * * * *  ")).to(be_ok());
    expect!(parse_cron("\n\t* * * * *\n\t")).to(be_ok());
    expect!(parse_cron("\n\t*\n\t*\n\t*\n\t*\n\t*\n\t")).to(be_ok());
    expect!(parse_cron("    *    *    *    *    *    ")).to(be_ok());
    expect!(parse_cron("\r\r*\r\n*\t\t*\t\t*\n  *\n\r")).to(be_ok());
  }

  #[test]
  fn wildcards() {
    let parsed = parse_cron("* * * * *").unwrap();

    expect!(parsed.minutes).to(be_equal_to((0..60).collect::<Vec<u32>>()));
    expect!(parsed.hours).to(be_equal_to((0..24).collect::<Vec<u32>>()));
    expect!(parsed.days).to(be_equal_to((1..32).collect::<Vec<u32>>()));
    expect!(parsed.months).to(be_equal_to((1..13).collect::<Vec<u32>>()));
    expect!(parsed.weekdays).to(be_equal_to((0..7).collect::<Vec<u32>>()));
  }

  #[test]
  fn ranges() {
    let parsed = parse_cron("0-5 20-23 1-5 1-6 0-6").unwrap();

    expect!(parsed.minutes).to(be_equal_to(vec![0,1,2,3,4,5]));
    expect!(parsed.hours).to(be_equal_to(vec![20,21,22,23]));
    expect!(parsed.days).to(be_equal_to(vec![1,2,3,4,5]));
    expect!(parsed.months).to(be_equal_to(vec![1,2,3,4,5,6]));
    expect!(parsed.weekdays).to(be_equal_to(vec![0,1,2,3,4,5,6]));
  }

  #[test]
  fn step() {
    let parsed = parse_cron("*/15 */4 */10 */3 */2").unwrap();

    expect!(parsed.minutes).to(be_equal_to(vec![0,15,30,45]));
    expect!(parsed.hours).to(be_equal_to(vec![0,4,8,12,16,20]));
    expect!(parsed.days).to(be_equal_to(vec![10,20,30]));
    expect!(parsed.months).to(be_equal_to(vec![3,6,9,12]));
    expect!(parsed.weekdays).to(be_equal_to(vec![0,2,4,6]));
  }

  #[test]
  fn ranges_with_step() {
    let parsed = parse_cron("0-30/5 0-12/2 1-20/5 1-10/2 0-5/2").unwrap();

    expect!(parsed.minutes).to(be_equal_to(vec![0,5,10,15,20,25,30]));
    expect!(parsed.hours).to(be_equal_to(vec![0,2,4,6,8,10,12]));
    expect!(parsed.days).to(be_equal_to(vec![5,10,15,20]));
    expect!(parsed.months).to(be_equal_to(vec![2,4,6,8,10]));
    expect!(parsed.weekdays).to(be_equal_to(vec![0,2,4]));
  }

  #[test]
  fn comma_separated() {
    let parsed = parse_cron("0,5,15 0,12 1,15 1,3,6,9,12 0,1,2,3,4").unwrap();

    expect!(parsed.minutes).to(be_equal_to(vec![0,5,15]));
    expect!(parsed.hours).to(be_equal_to(vec![0,12]));
    expect!(parsed.days).to(be_equal_to(vec![1,15]));
    expect!(parsed.months).to(be_equal_to(vec![1,3,6,9,12]));
    expect!(parsed.weekdays).to(be_equal_to(vec![0,1,2,3,4]));
  }

  #[test]
  fn exact_minutes() {
    let parsed = parse_cron("0 * * * *").unwrap();
    expect!(parsed.minutes).to(be_equal_to(vec![0]));

    let parsed = parse_cron("5,10,15 * * * *").unwrap();
    expect!(parsed.minutes).to(be_equal_to(vec![5,10,15]));

    let parsed = parse_cron("59 * * * *").unwrap();
    expect!(parsed.minutes).to(be_equal_to(vec![59]));
  }

  #[test]
  fn exact_hours() {
    let parsed = parse_cron("* 0 * * *").unwrap();
    expect!(parsed.hours).to(be_equal_to(vec![0]));

    let parsed = parse_cron("* 1,12,20 * * *").unwrap();
    expect!(parsed.hours).to(be_equal_to(vec![1, 12, 20]));

    let parsed = parse_cron("* 23 * * *").unwrap();
    expect!(parsed.hours).to(be_equal_to(vec![23]));
  }

  #[test]
  fn exact_days() {
    let parsed = parse_cron("* * 1 * *").unwrap();
    expect!(parsed.days).to(be_equal_to(vec![1]));

    let parsed = parse_cron("* * 1,10,20,30 * *").unwrap();
    expect!(parsed.days).to(be_equal_to(vec![1, 10, 20, 30]));

    let parsed = parse_cron("* * 31 * *").unwrap();
    expect!(parsed.days).to(be_equal_to(vec![31]));
  }

  #[test]
  fn exact_months() {
    let parsed = parse_cron("* * * 1 *").unwrap();
    expect!(parsed.months).to(be_equal_to(vec![1]));

    let parsed = parse_cron("* * * 1,5,7,10 *").unwrap();
    expect!(parsed.months).to(be_equal_to(vec![1, 5, 7, 10]));

    let parsed = parse_cron("* * * 12 *").unwrap();
    expect!(parsed.months).to(be_equal_to(vec![12]));
  }

  #[test]
  fn exact_weekdays() {
    let parsed = parse_cron("* * * * 0").unwrap();
    expect!(parsed.weekdays).to(be_equal_to(vec![0]));

    let parsed = parse_cron("* * * * 1,2").unwrap();
    expect!(parsed.weekdays).to(be_equal_to(vec![1, 2]));

    let parsed = parse_cron("* * * * 6").unwrap();
    expect!(parsed.weekdays).to(be_equal_to(vec![6]));
  }

  #[test]
  fn exact_values_outside_range() {
    // Minutes
    expect!(parse_cron("60 * * * *")).to(be_err());
    expect!(parse_cron("-1 * * * *")).to(be_err());
    // Hours
    expect!(parse_cron("* 24 * * *")).to(be_err());
    expect!(parse_cron("* -1 * * *")).to(be_err());
    // Days
    expect!(parse_cron("* * 0 * *")).to(be_err());
    expect!(parse_cron("* * 32 * *")).to(be_err());
    expect!(parse_cron("* * -1 * *")).to(be_err());
    // Months
    expect!(parse_cron("* * * 0 *")).to(be_err());
    expect!(parse_cron("* * * 13 *")).to(be_err());
    expect!(parse_cron("* * * -1 *")).to(be_err());
    // Weekdays
    expect!(parse_cron("* * * * 7")).to(be_err());
    expect!(parse_cron("* * * * -1")).to(be_err());
  }

  #[test]
  fn ranges_outside_range() {
    // Minutes
    expect!(parse_cron("0-60 * * * *")).to(be_err());
    expect!(parse_cron("-1-0 * * * *")).to(be_err());
    // Hours
    expect!(parse_cron("* 0-24 * * *")).to(be_err());
    expect!(parse_cron("* -1-10 * * *")).to(be_err());
    // Days
    expect!(parse_cron("* * 0-5 * *")).to(be_err());
    expect!(parse_cron("* * 10-32 * *")).to(be_err());
    expect!(parse_cron("* * -1-20 * *")).to(be_err());
    // Months
    expect!(parse_cron("* * * 0-5 *")).to(be_err());
    expect!(parse_cron("* * * 6-13 *")).to(be_err());
    expect!(parse_cron("* * * -1-12 *")).to(be_err());
    // Weekdays
    expect!(parse_cron("* * * * 5-7")).to(be_err());
    expect!(parse_cron("* * * * -1-5")).to(be_err());
  }

  #[test]
  fn values_deduped() {
    let parsed = parse_cron("1,1,1,1 * * * *").unwrap();
    expect!(parsed.minutes).to(be_equal_to(vec![1]));

    let parsed = parse_cron("1,1-3 * * * *").unwrap();
    expect!(parsed.minutes).to(be_equal_to(vec![1,2,3]));

    let parsed = parse_cron("* * * 1-4,2,4,*/2 *").unwrap();
    expect!(parsed.months).to(be_equal_to(vec![1, 2, 3, 4, 6, 8, 10, 12]));
  }

  #[test]
  fn values_in_order() {
    let parsed = parse_cron("4,3,1,2 * * * *").unwrap();
    expect!(parsed.minutes).to(be_equal_to(vec![1,2,3,4]));
  }

  #[test]
  fn misc_parse_errors() {
    // Invalid values
    expect!(parse_cron("A B C D E")).to(be_err());
    expect!(parse_cron("*A *B *C *D *E")).to(be_err());

    // No numeric values
    expect!(parse_cron(", * * * *")).to(be_err());
    expect!(parse_cron(",,,, * * * *")).to(be_err());

    // No range
    expect!(parse_cron("- * * * *")).to(be_err());
    expect!(parse_cron(",- * * * *")).to(be_err());
    expect!(parse_cron("-,- * * * *")).to(be_err());
    expect!(parse_cron(",-,- * * * *")).to(be_err());
    expect!(parse_cron(",-,-, * * * *")).to(be_err());

    // Allowed whitespace, but incorrect number of fields
    expect!(parse_cron("   ")).to(be_err());
    expect!(parse_cron("  * * * *  ")).to(be_err());
    expect!(parse_cron("  * * * * * *  ")).to(be_err());
    expect!(parse_cron("\n\t")).to(be_err());
    expect!(parse_cron("\n\t* * * *\n\t")).to(be_err());
    expect!(parse_cron("\n\t* * * * * *\n\t")).to(be_err());
  }
}