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use std::collections::HashMap;
use serde_json::value::{Value, to_value, from_value};
use errors::Result;
pub type GlobalFn = Box<Fn(HashMap<String, Value>) -> Result<Value> + Sync + Send>;
pub fn make_range_fn() -> GlobalFn {
Box::new(move |args| -> Result<Value> {
let start = match args.get("start") {
Some(val) => match from_value::<usize>(val.clone()) {
Ok(v) => v,
Err(_) => bail!("Global function `range` received start={} but `start` can only be a number"),
},
None => 0,
};
let step_by = match args.get("step_by") {
Some(val) => match from_value::<usize>(val.clone()) {
Ok(v) => v,
Err(_) => bail!("Global function `range` received step_by={} but `step` can only be a number"),
},
None => 1,
};
let end = match args.get("end") {
Some(val) => match from_value::<usize>(val.clone()) {
Ok(v) => v,
Err(_) => bail!("Global function `range` received end={} but `end` can only be a number"),
},
None => bail!("Global function `range` was called without a `end` argument"),
};
if start > end {
bail!("Global function `range` was called without a `start` argument greater than the `end` one");
}
let mut i = start;
let mut res = vec![];
while i < end {
res.push(i);
i += step_by;
}
Ok(to_value(res).unwrap())
})
}
#[cfg(test)]
mod tests {
use std::collections::HashMap;
use serde_json::value::{to_value};
use super::{make_range_fn};
#[test]
fn test_range_default() {
let mut args = HashMap::new();
args.insert("end".to_string(), to_value(5).unwrap());
let res = make_range_fn()(args).unwrap();
assert_eq!(res, to_value(vec![0,1,2,3,4]).unwrap());
}
#[test]
fn test_range_start() {
let mut args = HashMap::new();
args.insert("end".to_string(), to_value(5).unwrap());
args.insert("start".to_string(), to_value(1).unwrap());
let res = make_range_fn()(args).unwrap();
assert_eq!(res, to_value(vec![1,2,3,4]).unwrap());
}
#[test]
fn test_range_start_greater_than_end() {
let mut args = HashMap::new();
args.insert("end".to_string(), to_value(5).unwrap());
args.insert("start".to_string(), to_value(6).unwrap());
assert!(make_range_fn()(args).is_err());
}
#[test]
fn test_range_step_by() {
let mut args = HashMap::new();
args.insert("end".to_string(), to_value(10).unwrap());
args.insert("step_by".to_string(), to_value(2).unwrap());
let res = make_range_fn()(args).unwrap();
assert_eq!(res, to_value(vec![0,2,4,6,8]).unwrap());
}
}