This is an attempt to implement a Cron Parser. This codebase produces a script that parses and outputs the representation of the given cron command according to the task description. Invalid cron commands are rejected.
Running
Prerequisites
scala should be installed on the host machine to run the script. Ideally version 2.12.*.
sbt 0.13 should be installed on the host to run the tests and to run the script via sbt console.
Make Targets
Compile
make compile
Run
make run compiles and runs the script. Cron command should be provided in the CMD argument;
make run CMD="1 1 1 1 4 /usr/bin/find"
After the initial compilation you can use the run-without-compile target in the same manner to avoid compilation at each run.
Alternatively you can run make sbt (requires sbt) and in the sbt console you can use run command;
make sbt
run "1 1 1 1 4 /usr/bin/find"
Run the Tests
make test (requires sbt)
Supported Features
Single Numeric Values
Examples are;
1 1 1 1 4 /usr/bin/find
20 12 5 1 1 /usr/bin/find
Comma Separated Numeric Values
Examples are;
1,3,5,10 1 1 1 4 /usr/bin/find
1,3,5,10 1 1 1 1,2,3,4,5 /usr/bin/find
Numeric Ranges
Examples are;
1-10 1 1 1 4 /usr/bin/find
50 1-10 1-5 1 1 /usr/bin/find
Single Literal Values for Months and Day of Week
Examples are;
1 1 1 JAN 4 /usr/bin/find
1 1 1 MAY 4 /usr/bin/find
1 1 1 AUG 4 /usr/bin/find
1 1 1 JAN SUN /usr/bin/find
1 1 1 JAN MON /usr/bin/find
Comma Separated Literal Values for Months and Day of Week
Examples are;
1 1 1 JAN,FEB,MAR 4 /usr/bin/find
1 1 1 MAY,AUG,JAN 4 /usr/bin/find
1 1 1 JAN SUN,MON,FRI /usr/bin/find
Literal Ranges for Months and Day of Week
Examples are;
1 1 1 JAN-MAR 4 /usr/bin/find
1 1 1 MAY-AUG 4 /usr/bin/find
1 1 1 JAN SUN-FRI /usr/bin/find
Single Asterisk
Examples are;
* 1 1 1 1 /usr/bin/find
1 1 * 1 1 /usr/bin/find
1 1 1 1 * /usr/bin/find
Not Supported Features
Asterisk with Dividends
Expressions sunc as */15 are not supported, even though the task description expects it. This feature is left out in order to reduce the development time.
Non-standard Features
Non-standard expression such as @yearly, @monthly and other non-standard symbols such as ?,H,L,W are not supported as indicated in the task description. The non-standard Year field is also not supported.
Assumptions
Input values are strictly validated, there is no graceful degradation for the input values. Invalid inputs are rejected.
Improvements
At the moment the script doesn't give any indication as to why an input was deemed invalid. This is the most important feature that lacks at this version of the script.