fixed exploding dice bug

src/dice.rs

@@ -17,6 +17,7 @@ pub enum Expression {
     Mul(ExpBox, ExpBox),
     Div(ExpBox, ExpBox),
     IntDiv(ExpBox, ExpBox),
+    Pow(ExpBox, ExpBox),
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -121,9 +122,6 @@ impl Expression {
                 // Exploding dice are early, they add rolls
                 if let Some(fragments) = x {
                     write!(w, "x")?;
-                    if size < 2 {
-                        bail!("Infinite explosion.")
-                    }
                     let mut comparers = Vec::with_capacity(fragments.len());
                     for fragment in fragments {
                         comparers.push(fragment.comparer(rng, w)?);
@@ -265,6 +263,12 @@ impl Expression {
                 let rhs = rhs_node.evaluate(rng, w, precedence)?;
                 lhs.div_euclid(rhs)
             }
+            Pow(lhs_node, rhs_node) => {
+                let lhs = lhs_node.evaluate(rng, w, precedence)?;
+                write!(w, " ^ ")?;
+                let rhs = rhs_node.evaluate(rng, w, precedence)?;
+                lhs.powf(rhs)
+            }
         };
         if needs_parens {
             write!(w, ")")?;
@@ -294,7 +298,7 @@ impl Expression {
                 } else {
                     1
                 };
-                if count > 1_000_000 {
+                if count > DICE_POOL_LIMIT {
                     bail!("Too many dice.")
                 };
                 let size = size.avg()? as i64;
@@ -326,6 +330,7 @@ impl Expression {
             Expression::Mul(lhs, rhs) => lhs.avg()? * rhs.avg()?,
             Expression::Div(lhs, rhs) => lhs.avg()? / rhs.avg()?,
             Expression::IntDiv(lhs, rhs) => lhs.avg()?.div_euclid(rhs.avg()?),
+            Expression::Pow(lhs, rhs) => lhs.avg()?.powf(rhs.avg()?),
         };
         Ok(result)
     }
@@ -377,6 +382,7 @@ impl Expression {
         match self {
             Const(_) => 1,
             Dice { .. } => 2,
+            Pow(_, _) => 4,
             Neg(_) => 5,
             Mul(_, _) | Div(_, _) | IntDiv(_, _) => 7,
             Add(_, _) | Sub(_, _) => 8,
@@ -480,7 +486,7 @@ impl<'a> WitnessSet for DiscordMdWitnessSet<'a> {
     type Error = DiscordMdWitnessError;
 
     fn witness_roll(&mut self, dice: DiceRoll) -> Result<Self::Ok, Self::Error> {
-        if self.parent.dice_written >= 100 {
+        if self.parent.dice_written >= 50 {
             if !self.dice_elided {
                 write!(self.parent.buffer, "…")?;
                 self.dice_elided = true;

src/parsing.rs

@@ -1,5 +1,10 @@
-use crate::dice::{CompareFragment, DiceFormula, Expression::{self, Const}};
+use crate::dice::{
+    CompareFragment, DiceFormula,
+    Expression::{self, Const},
+};
 use Assoc::Left;
+use nom::character::complete::digit0;
+use nom::combinator::recognize;
 use nom::{
     Parser,
     branch::alt,
@@ -89,6 +94,7 @@ fn expr<'c, 'i>(
             complete(unary_op(5, tag("-"))),
             fail(),
             complete(alt((
+                binary_op(4, Left, spaced_op("^")),
                 binary_op(7, Left, spaced_op("*")),
                 binary_op(7, Left, spaced_op("//")),
                 binary_op(7, Left, spaced_op("/")),
@@ -101,6 +107,7 @@ fn expr<'c, 'i>(
 
                 Ok(match op {
                     Prefix("-", x) => Neg(Box::new(x)),
+                    Binary(lhs, "^", rhs) => Pow(Box::new(lhs), Box::new(rhs)),
                     Binary(lhs, "*", rhs) => Mul(Box::new(lhs), Box::new(rhs)),
                     Binary(lhs, "//", rhs) => IntDiv(Box::new(lhs), Box::new(rhs)),
                     Binary(lhs, "/", rhs) => Div(Box::new(lhs), Box::new(rhs)),
@@ -115,9 +122,12 @@ fn expr<'c, 'i>(
 }
 
 fn number(i: &str) -> IResult<&str, Expression> {
-    map_res(digit1(), |s: &str| s.parse::<f64>())
-        .map(Const)
-        .parse_complete(i)
+    map_res(
+        alt((recognize((digit0, tag("."), digit1())), digit1())),
+        |s: &str| s.parse::<f64>(),
+    )
+    .map(Const)
+    .parse_complete(i)
 }
 
 fn basic_operand<'c, 'i>(
@@ -128,7 +138,7 @@ fn basic_operand<'c, 'i>(
 
 fn compare_fragment<'c, 'i>(
     ctx: &'c Context,
-) -> impl Parser<&'i str, Output = CompareFragment, Error = InternalError<&'i str>> + use<'c, 'i>  {
+) -> impl Parser<&'i str, Output = CompareFragment, Error = InternalError<&'i str>> + use<'c, 'i> {
     use CompareFragment::*;
     alt((
         preceded(tag("="), basic_operand(ctx)).map(|x| Eq(Box::new(x))),
@@ -154,6 +164,18 @@ mod test {
         assert_matches!(expression, Expression::Dice { .. });
     }
 
+    #[test]
+    pub fn parse_decimal() {
+        let expression = parse("2.5+2.5").unwrap();
+        assert_matches!(expression, Expression::Add { .. });
+    }
+
+    #[test]
+    pub fn parse_decimal2() {
+        let expression = parse(".4*.8").unwrap();
+        assert_matches!(expression, Expression::Mul { .. });
+    }
+
     #[test]
     pub fn parse_bare_dice() {
         let expression = parse("d8").unwrap();
@@ -162,7 +184,7 @@ mod test {
 
     #[test]
     pub fn parse_math() {
-        let expression = parse("8 * 2 + 2 * 5").unwrap();
+        let expression = parse("8 * 2 + 2 * 5 ^ 4").unwrap();
         assert_matches!(expression, Expression::Add { .. });
     }