util: optimize opaque string formatting

src/utils/activation_token.rs

@@ -1,5 +1,6 @@
 use {
-    crate::utils::opaque::{opaque, Opaque, OpaqueError},
+    crate::utils::opaque::{opaque, Opaque, OpaqueError, OPAQUE_LEN},
+    arrayvec::ArrayString,
     std::{
         fmt::{Display, Formatter},
         str::FromStr,
@@ -13,6 +14,12 @@ pub fn activation_token() -> ActivationToken {
     ActivationToken(opaque())
 }
 
+impl ActivationToken {
+    pub fn to_string(self) -> ArrayString<OPAQUE_LEN> {
+        self.0.to_string()
+    }
+}
+
 impl Display for ActivationToken {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         self.0.fmt(f)

src/utils/opaque.rs

@@ -1,4 +1,5 @@
 use {
+    arrayvec::ArrayString,
     rand::{thread_rng, Rng},
     std::{
         fmt::{Debug, Display, Formatter},
@@ -22,6 +23,15 @@ pub fn opaque() -> Opaque {
     }
 }
 
+impl Opaque {
+    pub fn to_string(self) -> ArrayString<OPAQUE_LEN> {
+        use std::fmt::Write;
+        let mut s = ArrayString::new();
+        write!(s, "{}", self).unwrap();
+        s
+    }
+}
+
 impl Display for Opaque {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         write!(f, "{:016x}", self.hi)?;
@@ -40,20 +50,20 @@ impl FromStr for Opaque {
     type Err = OpaqueError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        if s.len() != LEN {
+        if s.len() != OPAQUE_LEN {
             return Err(OpaqueError::InvalidLength);
         }
-        if !s.is_char_boundary(LEN / 2) {
+        if !s.is_char_boundary(OPAQUE_LEN / 2) {
             return Err(OpaqueError::NotAscii);
         }
-        let (hi, lo) = s.split_at(LEN / 2);
+        let (hi, lo) = s.split_at(OPAQUE_LEN / 2);
         let hi = u64::from_str_radix(hi, 16).map_err(OpaqueError::Parse)?;
         let lo = u64::from_str_radix(lo, 16).map_err(OpaqueError::Parse)?;
         Ok(Self { lo, hi })
     }
 }
 
-const LEN: usize = 32;
+pub const OPAQUE_LEN: usize = 32;
 
 #[derive(Debug, Error)]
 pub enum OpaqueError {

src/utils/toplevel_identifier.rs

@@ -1,5 +1,6 @@
 use {
-    crate::utils::opaque::{opaque, Opaque, OpaqueError},
+    crate::utils::opaque::{opaque, Opaque, OpaqueError, OPAQUE_LEN},
+    arrayvec::ArrayString,
     std::{
         fmt::{Display, Formatter},
         str::FromStr,
@@ -13,6 +14,12 @@ pub fn toplevel_identifier() -> ToplevelIdentifier {
     ToplevelIdentifier(opaque())
 }
 
+impl ToplevelIdentifier {
+    pub fn to_string(self) -> ArrayString<OPAQUE_LEN> {
+        self.0.to_string()
+    }
+}
+
 impl Display for ToplevelIdentifier {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         self.0.fmt(f)