implement command parser fully

src/bin/dicebot-cmd.rs

@@ -1,14 +1,16 @@
 use axfive_matrix_dicebot::dice::parser::parse_element_expression;
 use axfive_matrix_dicebot::roll::{Roll, Rolled};
-use axfive_matrix_dicebot::commands::Command;
+use axfive_matrix_dicebot::commands::parse_command;
 use std::error::Error;
+use std::string::ToString;
 
 fn main() -> Result<(), String> {
     let command = std::env::args().skip(1).collect::<Vec<String>>().join(" ");
-    let command: Command = match Command::parse(&command) {
-        Ok(command) => command.1,
-        Err(e) => return Err(format!("{}", e)),
+    let command = match parse_command(&command) {
+        Some(Ok(command)) => command,
+        Some(Err(e)) => return Err(format!("Error parsing command: {}", e)),
+        None => return Err("Command not recognized".into()),
     };
-    println!("{}", command.execute());
+    println!("{}", command.execute().plain());
     Ok(())
 }

src/commands.rs

@@ -4,27 +4,44 @@ use nom::error::ErrorKind;
 use nom::IResult;
 pub mod parser;
 
+pub struct Execution {
+    plain: String,
+    html: String,
+}
+
+impl Execution {
+    pub fn plain(&self) -> &str {
+        &self.plain
+    }
+
+    pub fn html(&self) -> &str {
+        &self.html
+    }
+}
+
 pub struct RollCommand(ElementExpression);
 
-pub enum Command {
-    Roll(RollCommand),
+pub trait Command {
+    fn execute(&self) -> Execution;
 }
 
-impl Command {
-    pub fn parse<'a>(input: &'a str) -> IResult<&'a str, Command> {
-        parser::parse_command(input)
-    }
-
-    // Type subject to change
-    pub fn execute(self) -> String {
-        match self {
-            Command::Roll(command) => command.execute(),
+impl Command for RollCommand {
+    fn execute(&self) -> Execution {
+        let roll = self.0.roll();
+        let plain = format!("Dice: {}\nResult: {}", self.0, roll);
+        let html = format!("<strong>Dice:</strong> {}<br><strong>Result</strong>: {}", self.0, roll);
+        Execution {
+            plain,
+            html,
         }
     }
 }
 
-impl RollCommand {
-    pub fn execute(self) -> String {
-        self.0.roll().to_string()
+pub fn parse_command(s: &str) -> Option<Result<Box<dyn Command>, String>> {
+    // Ignore trailing input, if any.
+    match parser::parse_command(s) {
+        Ok((_, Some(command))) => Some(Ok(command)),
+        Ok((_, None)) => None,
+        Err(err) => Some(Err(err.to_string())),
     }
 }

src/commands/parser.rs

@@ -1,7 +1,10 @@
 use nom::{
-    alt,
+    tuple,
+    switch,
+    take_while,
     bytes::complete::{tag, take_while},
     character::complete::digit1,
+    character::is_alphabetic,
     complete, many0, named,
     sequence::tuple,
     tag, IResult,
@@ -12,104 +15,30 @@ use crate::commands::{Command, RollCommand};
 use crate::dice::parser::parse_element_expression;
 
 // Parse a roll expression.
-fn parse_roll(input: &str) -> IResult<&str, Command> {
-    named!(invocation(&str) -> &str, alt!(complete!(tag!("!r")) | complete!(tag!("!roll"))));
-    let (input, _) = eat_whitespace(input)?;
-    let (input, _) = invocation(input)?;
+fn parse_roll(input: &str) -> IResult<&str, RollCommand> {
     let (input, _) = eat_whitespace(input)?;
     let (input, expression) = parse_element_expression(input)?;
-    Ok((input, Command::Roll(RollCommand(expression))))
+    Ok((input, RollCommand(expression)))
 }
 
-// Parse a command expression.
-pub fn parse_command(input: &str) -> IResult<&str, Command> {
-    // Add new commands to alt!
-    named!(command(&str) -> Command, alt!(parse_roll));
-    command(input)
+// Potentially parse a command expression.  If we recognize the command, an error should be raised
+// if the command is misparsed.  If we don't recognize the command, ignore it.
+pub fn parse_command(original_input: &str) -> IResult<&str, Option<Box<dyn Command>>> {
+    let (input, _) = eat_whitespace(original_input)?;
+    named!(command(&str) -> (&str, &str), tuple!(complete!(tag!("!")), complete!(take_while!(char::is_alphabetic))));
+    let (input, command) = match command(input) {
+        // Strip the exclamation mark
+        Ok((input, (_, result))) => (input, result),
+        Err(e) => return Ok((original_input, None)),
+    };
+    let (input, command): (&str, Box<dyn Command>) = match command {
+        "r" | "roll" => {
+            let (input, command) = parse_roll(input)?;
+            let command: Box<dyn Command> = Box::new(command);
+            (input, command)
+        },
+        // No recognized command, ignore this.
+        _ => return Ok((original_input, None)),
+    };
+    Ok((input, Some(command)))
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    #[test]
-    fn dice_test() {
-        assert_eq!(parse_dice("2d4"), Ok(("", Dice::new(2, 4))));
-        assert_eq!(parse_dice("20d40"), Ok(("", Dice::new(20, 40))));
-        assert_eq!(parse_dice("8d7"), Ok(("", Dice::new(8, 7))));
-    }
-
-    #[test]
-    fn element_test() {
-        assert_eq!(
-            parse_element("  \t\n\r\n 8d7 \n"),
-            Ok((" \n", Element::Dice(Dice::new(8, 7))))
-        );
-        assert_eq!(
-            parse_element("  \t\n\r\n 8 \n"),
-            Ok((" \n", Element::Bonus(8)))
-        );
-    }
-
-    #[test]
-    fn signed_element_test() {
-        assert_eq!(
-            parse_signed_element("+ 7"),
-            Ok(("", SignedElement::Positive(Element::Bonus(7))))
-        );
-        assert_eq!(
-            parse_signed_element("  \t\n\r\n- 8 \n"),
-            Ok((" \n", SignedElement::Negative(Element::Bonus(8))))
-        );
-        assert_eq!(
-            parse_signed_element("  \t\n\r\n- 8d4 \n"),
-            Ok((
-                " \n",
-                SignedElement::Negative(Element::Dice(Dice::new(8, 4)))
-            ))
-        );
-        assert_eq!(
-            parse_signed_element("  \t\n\r\n+ 8d4 \n"),
-            Ok((
-                " \n",
-                SignedElement::Positive(Element::Dice(Dice::new(8, 4)))
-            ))
-        );
-    }
-
-    #[test]
-    fn element_expression_test() {
-        assert_eq!(
-            parse_element_expression("8d4"),
-            Ok((
-                "",
-                ElementExpression(vec![SignedElement::Positive(Element::Dice(Dice::new(
-                    8, 4
-                )))])
-            ))
-        );
-        assert_eq!(
-            parse_element_expression(" -  8d4 \n "),
-            Ok((
-                " \n ",
-                ElementExpression(vec![SignedElement::Negative(Element::Dice(Dice::new(
-                    8, 4
-                )))])
-            ))
-        );
-        assert_eq!(
-            parse_element_expression("\t3d4 + 7 - 5 - 6d12 + 1d1 + 53 1d5 "),
-            Ok((
-                " 1d5 ",
-                ElementExpression(vec![
-                    SignedElement::Positive(Element::Dice(Dice::new(3, 4))),
-                    SignedElement::Positive(Element::Bonus(7)),
-                    SignedElement::Negative(Element::Bonus(5)),
-                    SignedElement::Negative(Element::Dice(Dice::new(6, 12))),
-                    SignedElement::Positive(Element::Dice(Dice::new(1, 1))),
-                    SignedElement::Positive(Element::Bonus(53)),
-                ])
-            ))
-        );
-    }
-}
-

src/dice.rs

@@ -1,5 +1,6 @@
 pub mod parser;
 
+use std::fmt;
 use std::ops::{Deref, DerefMut};
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -8,6 +9,12 @@ pub struct Dice {
     pub(crate) sides: u32,
 }
 
+impl fmt::Display for Dice {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}d{}", self.count, self.sides)
+    }
+}
+
 impl Dice {
     fn new(count: u32, sides: u32) -> Dice {
         Dice { count, sides }
@@ -20,12 +27,30 @@ pub enum Element {
     Bonus(u32),
 }
 
+impl fmt::Display for Element {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Element::Dice(d) => write!(f, "{}", d),
+            Element::Bonus(b) => write!(f, "{}", b),
+        }
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum SignedElement {
     Positive(Element),
     Negative(Element),
 }
 
+impl fmt::Display for SignedElement {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            SignedElement::Positive(e) => write!(f, "{}", e),
+            SignedElement::Negative(e) => write!(f, "-{}", e),
+        }
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub struct ElementExpression(Vec<SignedElement>);
 
@@ -42,3 +67,20 @@ impl DerefMut for ElementExpression {
         &mut self.0
     }
 }
+
+impl fmt::Display for ElementExpression {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut iter = self.0.iter();
+        if let Some(first) = iter.next() {
+            write!(f, "{}", first)?;
+            for roll in iter {
+                match roll {
+                    SignedElement::Positive(e) => write!(f, " + {}", e)?,
+                    SignedElement::Negative(e) => write!(f, " - {}", e)?,
+                }
+            }
+        }
+        Ok(())
+    }
+}
+

src/lib.rs

@@ -4,3 +4,4 @@ pub mod matrix;
 pub mod roll;
 pub mod commands;
 mod parser;
+

src/parser.rs

@@ -7,7 +7,8 @@ fn is_whitespace(input: char) -> bool {
     input == ' ' || input == '\n' || input == '\t' || input == '\r'
 }
 
-pub fn eat_whitespace(input: &str) -> IResult<&str, ()> {
-    let (input, _) = take_while(is_whitespace)(input)?;
-    Ok((input, ()))
+/// Eat whitespace, returning it
+pub fn eat_whitespace(input: &str) -> IResult<&str, &str> {
+    let (input, whitespace) = take_while(is_whitespace)(input)?;
+    Ok((input, whitespace))
 }