Added segment and filter enums and constructors and added keep and

lowest/highest options for keep/drop

src/lib.rs

@@ -1,9 +1,74 @@
 use regex::Regex;
+use thiserror::Error;
+use anyhow::Result;
 
 #[cfg(test)]
 mod lib_test;
 
-fn parse_dice_segments<'a>(cmd: &'a str) -> Vec<regex::Captures<'a>> {
+#[derive(Debug, PartialEq)]
+enum DiceFilter {
+  DropLowest(i32), DropHighest(i32), KeepLowest(i32), KeepHighest(i32),
+}
+
+#[derive(Debug, PartialEq)]
+enum Segment {
+  DiceRoll{
+    op: char,
+    count: i32,
+    size: i32,
+    filter: Option<DiceFilter>,
+  },
+  Modifier{
+    op: char,
+    amount: i32,
+  },
+}
+
+#[derive(Error, Debug, PartialEq)]
+enum SegmentError {
+  #[error("Invalid segment")]
+  InvalidSegment,
+  #[error("No dice size was given")]
+  SizeIsMissing,
+  #[error("Invalid filter operator: {op}")]
+  InvalidFilterOperator{op: String},
+  #[error("Incomplete filter")]
+  IncompleteFilter,
+}
+
+fn construct_dice_filter(op: &str, amount: i32) -> Result<DiceFilter> {
+  match op.to_lowercase().as_str() {
+    "d" | "dl" => Ok(DiceFilter::DropLowest(amount)),
+    "dh" => Ok(DiceFilter::DropHighest(amount)),
+    "k" | "kh" => Ok(DiceFilter::KeepHighest(amount)),
+    "kl" => Ok(DiceFilter::KeepLowest(amount)),
+    _ => Err(SegmentError::InvalidFilterOperator{op: op.to_owned()})?,
+  }
+}
+
+fn construct_dice_segment(cap: regex::Captures) -> Result<Segment> {
+  let op = cap.name("op").and_then(|i| i.as_str().chars().next()).unwrap_or('+');
+  let modifier = cap.name("mod").map(|i| i.as_str().parse()).transpose()?;
+
+  if let Some(amount) = modifier {
+    return Ok(Segment::Modifier{ op, amount });
+  }
+
+  let count:i32 = cap.name("count").map(|i| i.as_str().parse()).transpose()?.unwrap_or(1);
+  let size:i32 = cap.name("size").map(|i| i.as_str().parse()).transpose()?.ok_or(SegmentError::SizeIsMissing)?;
+  let filter_amount = cap.name("filter").map(|i| i.as_str().parse::<i32>()).transpose()?;
+  let filter_op = cap.name("filter_op").map(|op| op.as_str());
+  dbg!(filter_amount);
+  dbg!(filter_op);
+  if filter_amount.is_some() != filter_op.is_some() {
+    Err(SegmentError::IncompleteFilter)?;
+  }
+  let filter = filter_amount.and_then(|amount| (filter_op.map(|op| construct_dice_filter(op, amount)))).transpose()?;
+
+  Ok(Segment::DiceRoll{op, count, size, filter})
+}
+
+fn parse_dice_segments(cmd: &str) -> Result<Vec<Segment>> {
   let regex = Regex::new(r#"(?x)
     (?P<op>[+\-/*])?
     \s*
@@ -12,12 +77,13 @@ fn parse_dice_segments<'a>(cmd: &'a str) -> Vec<regex::Captures<'a>> {
         (?P<count>\d+)? # count (optional)
         d
         (?P<size>\d+) # dice size
-        (?:d(?P<drop>\d+))?
+        (?P<filter_op>[dk][hl]?)?
+        (?P<filter>\d+)?
       ) | (?:
         (?P<mod>\d+)
       )
     )
   "#).expect("Failed to compile regex");
 
-  regex.captures_iter(cmd).collect()
+  regex.captures_iter(cmd).map(construct_dice_segment).collect()
 }

src/lib_test.rs

@@ -2,27 +2,35 @@ use super::*;
 
 #[test]
 fn test_roll_dice() {
-  let mut results = parse_dice_segments("2d6");
+  let mut results = parse_dice_segments("2d6").expect("Failed to unpack results");
   
-  assert_eq!(results.len(), 1);
-  assert_eq!(results[0]["count"], *"2");
-  assert_eq!(results[0]["size"], *"6");
+  assert_eq!(results, vec![ Segment::DiceRoll{ op: '+', count: 2, size: 6, filter: None } ]);
   
-  results = parse_dice_segments("2d6 + 1d20");
+  results = parse_dice_segments("2d6 + 1d20").expect("Failed to unpack results");
   
-  assert_eq!(results.len(), 2);
-  assert_eq!(results[1].name("op").map(|i| i.as_str()), Some("+"));
-  assert_eq!(results[1].name("count").map(|i| i.as_str()), Some("1"));
-  assert_eq!(results[1]["size"], *"20");
+  assert_eq!(results, vec![ 
+    Segment::DiceRoll{ op: '+', count: 2, size: 6, filter: None },
+    Segment::DiceRoll{ op: '+', count: 1, size: 20, filter: None },
+  ]);
   
-  results = parse_dice_segments("4d6d1");
+  results = parse_dice_segments("4d6d1").expect("Failed to unpack results");
   
-  assert_eq!(results.len(), 1);
-  assert_eq!(results[0].name("drop").map(|i| i.as_str()), Some("1"));
+  assert_eq!(results, vec![ 
+    Segment::DiceRoll{ op: '+', count: 4, size: 6, filter: Some(DiceFilter::DropLowest(1)) },
+  ]);
     
-  results = parse_dice_segments("3d8+8");
+  results = parse_dice_segments("3d8+8").expect("Failed to unpack results");
 
-  assert_eq!(results.len(), 2);
-  assert_eq!(results[1].name("op").map(|i| i.as_str()), Some("+"));
-  assert_eq!(results[1].name("mod").map(|i| i.as_str()), Some("8"));
+  assert_eq!(results, vec![ 
+    Segment::DiceRoll{ op: '+', count: 3, size: 8, filter: None },
+    Segment::Modifier{ op: '+', amount: 8 },
+  ]);
+  
+  results = parse_dice_segments("3d8kl3 - 2d1dh1 / 2").expect("Failed to unpack results");
+  
+  assert_eq!(results, vec![ 
+    Segment::DiceRoll{ op: '+', count: 3, size: 8, filter: Some(DiceFilter::KeepLowest(3)) },
+    Segment::DiceRoll{ op: '-', count: 2, size: 1, filter: Some(DiceFilter::DropHighest(1)) },
+    Segment::Modifier{ op: '/', amount: 2 },
+  ]);
 }