Take prefix as Cow<'static, str> (#242)

src/builtins/help.rs

@@ -1,7 +1,7 @@
 //! Contains the built-in help command and surrounding infrastructure
 
 use crate::{serenity_prelude as serenity, CreateReply};
-use std::fmt::Write as _;
+use std::{borrow::Cow, fmt::Write as _};
 
 /// Optional configuration for how the help message from [`help()`] looks
 pub struct HelpConfiguration<'a> {
@@ -85,7 +85,9 @@ impl TwoColumnList {
 }
 
 /// Get the prefix from options
-pub(super) async fn get_prefix_from_options<U, E>(ctx: crate::Context<'_, U, E>) -> Option<String> {
+pub(super) async fn get_prefix_from_options<U, E>(
+    ctx: crate::Context<'_, U, E>,
+) -> Option<Cow<'static, str>> {
     let options = &ctx.framework().options().prefix_options;
     match &options.prefix {
         Some(fixed_prefix) => Some(fixed_prefix.clone()),
@@ -155,7 +157,7 @@ async fn help_single_command<U, E>(
                 // None can happen if the prefix is dynamic, and the callback
                 // fails due to help being invoked with slash or context menu
                 // commands. Not sure there's a better way to handle this.
-                None => String::from("<prefix>"),
+                None => Cow::Borrowed("<prefix>"),
             };
             invocations.push(format!("`{}{}`", prefix, command.name));
             if subprefix.is_none() {

src/builtins/pretty_help.rs

@@ -1,7 +1,7 @@
 //! Contains a built-in help command and surrounding infrastructure that uses embeds.
 
 use crate::{serenity_prelude as serenity, CreateReply};
-use std::fmt::Write as _;
+use std::{borrow::Cow, fmt::Write as _};
 
 /// Optional configuration for how the help message from [`pretty_help()`] looks
 pub struct PrettyHelpConfiguration<'a> {
@@ -81,7 +81,7 @@ async fn pretty_help_all_commands<U, E>(
 
             for cmd in cmds {
                 let name = cmd.context_menu_name.as_deref().unwrap_or(&cmd.name);
-                let prefix = format_cmd_prefix(cmd, &options_prefix);
+                let prefix = format_cmd_prefix(cmd, options_prefix.as_deref());
 
                 if let Some(description) = cmd.description.as_deref() {
                     writeln!(buffer, "{}{}`: *{}*", prefix, name, description).ok();
@@ -92,7 +92,7 @@ async fn pretty_help_all_commands<U, E>(
                 if config.show_subcommands {
                     for sbcmd in &cmd.subcommands {
                         let name = sbcmd.context_menu_name.as_deref().unwrap_or(&sbcmd.name);
-                        let prefix = format_cmd_prefix(sbcmd, &options_prefix);
+                        let prefix = format_cmd_prefix(sbcmd, options_prefix.as_deref());
 
                         if let Some(description) = sbcmd.description.as_deref() {
                             writeln!(buffer, "> {}{}`: *{}*", prefix, name, description).ok();
@@ -127,11 +127,11 @@ async fn pretty_help_all_commands<U, E>(
 }
 
 /// Figures out which prefix a command should have
-fn format_cmd_prefix<U, E>(cmd: &crate::Command<U, E>, options_prefix: &Option<String>) -> String {
+fn format_cmd_prefix<U, E>(cmd: &crate::Command<U, E>, options_prefix: Option<&str>) -> String {
     if cmd.slash_action.is_some() {
         "`/".into()
     } else if cmd.prefix_action.is_some() {
-        format!("`{}", options_prefix.as_deref().unwrap_or_default())
+        format!("`{}", options_prefix.unwrap_or_default())
     } else if cmd.context_menu_action.is_some() {
         match cmd.context_menu_action {
             Some(crate::ContextMenuCommandAction::Message(_)) => "Message menu: `".into(),
@@ -187,7 +187,7 @@ async fn pretty_help_single_command<U, E>(
             .await
             // This can happen if the prefix is dynamic, and the callback fails
             // due to help being invoked with slash or context menu commands.
-            .unwrap_or_else(|| String::from("<prefix>"));
+            .unwrap_or(Cow::Borrowed("<prefix>"));
         invocations.push(format!("`{}{}`", prefix, command.name));
         subprefix = subprefix.or(Some(format!("> `{}{}`", prefix, command.name)));
     }
@@ -247,7 +247,7 @@ async fn pretty_help_single_command<U, E>(
         .subcommands
         .iter()
         .map(|sbcmd| {
-            let prefix = format_cmd_prefix(sbcmd, &subprefix); // i have no idea about this really
+            let prefix = format_cmd_prefix(sbcmd, subprefix.as_deref()); // i have no idea about this really
             let name = sbcmd.context_menu_name.as_deref().unwrap_or(&sbcmd.name);
             if let Some(description) = sbcmd.description.as_deref() {
                 format!("> {}{}`: *{} *", prefix, name, description)

src/dispatch/prefix.rs

@@ -21,7 +21,7 @@ async fn strip_prefix<'a, U, E>(
         match dynamic_prefix(partial_ctx).await {
             Ok(prefix) => {
                 if let Some(prefix) = prefix {
-                    if msg.content.starts_with(&prefix) {
+                    if msg.content.starts_with(prefix.as_ref()) {
                         return Some(msg.content.split_at(prefix.len()));
                     }
                 }
@@ -37,7 +37,7 @@ async fn strip_prefix<'a, U, E>(
         }
     }
 
-    if let Some(prefix) = &framework.options.prefix_options.prefix {
+    if let Some(prefix) = framework.options.prefix_options.prefix.as_deref() {
         if let Some(content) = msg.content.strip_prefix(prefix) {
             return Some((prefix, content));
         }

src/structs/prefix.rs

@@ -1,5 +1,7 @@
 //! Holds prefix-command definition structs.
 
+use std::borrow::Cow;
+
 use crate::{serenity_prelude as serenity, BoxFuture};
 
 /// The event that triggered a prefix command execution
@@ -82,7 +84,7 @@ pub enum Prefix {
 pub struct PrefixFrameworkOptions<U, E> {
     /// The main bot prefix. Can be set to None if the bot supports only
     /// [dynamic prefixes](Self::dynamic_prefix).
-    pub prefix: Option<String>,
+    pub prefix: Option<Cow<'static, str>>,
     /// List of additional bot prefixes
     // TODO: maybe it would be nicer to have separate fields for literal and regex prefixes
     // That way, you don't need to wrap every single literal prefix in a long path which looks ugly
@@ -93,8 +95,9 @@ pub struct PrefixFrameworkOptions<U, E> {
     ///
     /// For more advanced dynamic prefixes, see [`Self::stripped_dynamic_prefix`]
     #[derivative(Debug = "ignore")]
-    pub dynamic_prefix:
-        Option<fn(crate::PartialContext<'_, U, E>) -> BoxFuture<'_, Result<Option<String>, E>>>,
+    pub dynamic_prefix: Option<
+        fn(crate::PartialContext<'_, U, E>) -> BoxFuture<'_, Result<Option<Cow<'static, str>>, E>>,
+    >,
     /// Callback invoked on every message to strip the prefix off an incoming message.
     ///
     /// Override this field for advanced dynamic prefixes which change depending on guild or user.