Re-add Display trait on descriptors

src/descriptors.rs

@@ -1,4 +1,7 @@
-use std::borrow::Cow;
+use std::{
+    borrow::Cow,
+    fmt::{self, Write},
+};
 
 use crate::ParseError;
 
@@ -49,6 +52,12 @@ impl ClassName<'_> {
             .fold(0, |sum, segment| sum + segment.name.len() + 1)
     }
 }
+impl<'a> fmt::Display for ClassName<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        let segments: Vec<Cow<'a, str>> = self.segments.iter().map(|s| s.name.clone()).collect();
+        write!(f, "{};", segments.join("/"))
+    }
+}
 
 // Returns the classname descriptor at the start of the given data, and ignores anything following.
 // Returns an error if there was no such classname.
@@ -96,6 +105,22 @@ impl FieldType<'_> {
     }
 }
 
+impl fmt::Display for FieldType<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match self {
+            Self::Byte => write!(f, "B"),
+            Self::Char => write!(f, "C"),
+            Self::Double => write!(f, "D"),
+            Self::Float => write!(f, "F"),
+            Self::Integer => write!(f, "I"),
+            Self::Long => write!(f, "J"),
+            Self::Short => write!(f, "S"),
+            Self::Boolean => write!(f, "Z"),
+            Self::Object(obj) => write!(f, "L{};", obj),
+        }
+    }
+}
+
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct FieldDescriptor<'a> {
     pub dimensions: u8,
@@ -108,6 +133,17 @@ impl FieldDescriptor<'_> {
     }
 }
 
+impl fmt::Display for FieldDescriptor<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(
+            f,
+            "{}{}",
+            "[".repeat(self.dimensions as usize),
+            self.field_type
+        )
+    }
+}
+
 // Parse the field descriptor at the start of the given data, and ignores anything
 // following. Returns an error if the data don't start with a field descriptor.
 pub(crate) fn parse_field_descriptor<'a>(
@@ -148,6 +184,14 @@ pub enum ReturnDescriptor<'a> {
     Return(FieldDescriptor<'a>),
     Void,
 }
+impl fmt::Display for ReturnDescriptor<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match self {
+            Self::Void => f.write_char('V'),
+            Self::Return(field) => write!(f, "{}", field),
+        }
+    }
+}
 
 impl ReturnDescriptor<'_> {
     fn byte_len(&self) -> usize {
@@ -177,6 +221,18 @@ pub struct MethodDescriptor<'a> {
     pub return_type: ReturnDescriptor<'a>,
 }
 
+impl fmt::Display for MethodDescriptor<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        f.write_char('(')?;
+
+        for param in &self.parameters {
+            write!(f, "{}", param)?;
+        }
+
+        write!(f, "){}", self.return_type)
+    }
+}
+
 impl MethodDescriptor<'_> {
     fn byte_len(&self) -> usize {
         1 + self