Remove content and prefix from PrefixContext

src/builtins/mod.rs

@@ -179,10 +179,9 @@ pub async fn on_error<U, E: std::fmt::Display + std::fmt::Debug>(
  );
  }
  crate::FrameworkError::UnknownCommand {
- msg_content,
- prefix,
- ..
+ msg, content_start, ..
  } => {
+ let (prefix, msg_content) = msg.content.split_at(content_start.into());
  tracing::warn!(
  "Recognized prefix `{}`, but didn't recognize command name in `{}`",
  prefix,

src/dispatch/prefix.rs

@@ -1,14 +1,24 @@
 //! Dispatches incoming messages and message edits onto framework commands
 
+use std::convert::TryInto as _;
+
 use crate::serenity_prelude as serenity;
 
+/// Converts a prefix string's length into u16, panicking if it doesn't fit.
+fn prefix_len_to_u16(prefix: &str) -> u16 {
+ prefix
+ .len()
+ .try_into()
+ .expect("messages should not be more than 64k bytes, let alone a prefix")
+}
+
 /// Checks if this message is a bot invocation by attempting to strip the prefix
 ///
 /// Returns tuple of stripped prefix and rest of the message, if any prefix matches
 async fn strip_prefix<'a, U, E>(
  framework: crate::FrameworkContext<'a, U, E>,
  msg: &'a serenity::Message,
-) -> Option<(&'a str, &'a str)> {
+) -> Option<u16> {
  let partial_ctx = crate::PartialContext {
  guild_id: msg.guild_id,
  channel_id: msg.channel_id,
@@ -22,7 +32,7 @@ async fn strip_prefix<'a, U, E>(
  Ok(prefix) => {
  if let Some(prefix) = prefix {
  if msg.content.starts_with(prefix.as_ref()) {
- return Some(msg.content.split_at(prefix.len()));
+ return Some(prefix_len_to_u16(&prefix));
  }
  }
  }
@@ -38,39 +48,36 @@ async fn strip_prefix<'a, U, E>(
  }
 
  if let Some(prefix) = framework.options.prefix_options.prefix.as_deref() {
- if let Some(content) = msg.content.strip_prefix(prefix) {
- return Some((prefix, content));
+ if msg.content.starts_with(prefix) {
+ return Some(prefix_len_to_u16(prefix));
  }
  }
 
- if let Some((prefix, content)) = framework
+ if let Some(prefix) = framework
  .options
  .prefix_options
  .additional_prefixes
  .iter()
  .find_map(|prefix| match prefix {
- &crate::Prefix::Literal(prefix) => Some((prefix, msg.content.strip_prefix(prefix)?)),
+ &crate::Prefix::Literal(prefix) => Some(prefix),
  crate::Prefix::Regex(prefix) => {
  let regex_match = prefix.find(&msg.content)?;
  if regex_match.start() == 0 {
- Some(msg.content.split_at(regex_match.end()))
+ Some(&msg.content[..regex_match.end()])
  } else {
  None
  }
  }
  crate::Prefix::__NonExhaustive => unreachable!(),
  })
  {
- return Some((prefix, content));
+ return Some(prefix_len_to_u16(prefix));
  }
 
  if let Some(dynamic_prefix) = framework.options.prefix_options.stripped_dynamic_prefix {
  match dynamic_prefix(framework.serenity_context, msg, framework.user_data).await {
- Ok(result) => {
- if let Some((prefix, content)) = result {
- return Some((prefix, content));
- }
- }
+ Ok(Some(prefix)) => return Some(prefix_len_to_u16(prefix)),
+ Ok(None) => {}
  Err(error) => {
  (framework.options.on_error)(crate::FrameworkError::DynamicPrefix {
  error,
@@ -92,7 +99,7 @@ async fn strip_prefix<'a, U, E>(
  .strip_prefix('>')
  })() {
  let mention_prefix = &msg.content[..(msg.content.len() - stripped_content.len())];
- return Some((mention_prefix, stripped_content));
+ return Some(prefix_len_to_u16(mention_prefix));
  }
  }
 
@@ -242,11 +249,11 @@ pub async fn parse_invocation<'a, U: Send + Sync, E>(
  }
 
  // Strip prefix, trim whitespace between prefix and rest, split rest into command name and args
- let (prefix, msg_content) = match strip_prefix(framework, msg).await {
- Some(x) => x,
- None => return Ok(None),
+ let Some(content_start) = strip_prefix(framework, msg).await else {
+ return Ok(None);
  };
- let msg_content = msg_content.trim_start();
+
+ let msg_content = msg.content[content_start.into()..].trim_start();
 
  let (command, invoked_command_name, args) = find_command(
  &framework.options.commands,
@@ -256,8 +263,7 @@ pub async fn parse_invocation<'a, U: Send + Sync, E>(
  )
  .ok_or(crate::FrameworkError::UnknownCommand {
  msg,
- prefix,
- msg_content,
+ content_start,
  framework,
  invocation_data,
  trigger,
@@ -269,7 +275,7 @@ pub async fn parse_invocation<'a, U: Send + Sync, E>(
 
  Ok(Some(crate::PrefixContext {
  msg,
- prefix,
+ content_start,
  invoked_command_name,
  args,
  framework,

src/structs/context.rs

@@ -348,7 +348,7 @@ context_methods! {
  (prefix self)
  (pub fn prefix(self) -> &'a str) {
  match self {
- Context::Prefix(ctx) => ctx.prefix,
+ Context::Prefix(ctx) => &ctx.msg.content[..ctx.content_start.into()],
  Context::Application(_) => "/",
  }
  }

src/structs/framework_error.rs

@@ -164,12 +164,8 @@ pub enum FrameworkError<'a, U, E> {
  UnknownCommand {
  /// The message in question
  msg: &'a serenity::Message,
- /// The prefix that was recognized
- prefix: &'a str,
- /// The rest of the message (after the prefix) which was not recognized as a command
- ///
- /// This is a single field instead of two fields (command name and args) due to subcommands
- msg_content: &'a str,
+ /// The position in the message that the prefix ends.
+ content_start: u16,
  /// Framework context
  #[derivative(Debug = "ignore")]
  framework: crate::FrameworkContext<'a, U, E>,
@@ -403,7 +399,10 @@ impl<U, E: std::fmt::Display> std::fmt::Display for FrameworkError<'_, U, E> {
  msg.content
  )
  }
- Self::UnknownCommand { msg_content, .. } => {
+ Self::UnknownCommand {
+ content_start, msg, ..
+ } => {
+ let msg_content = &msg.content[(*content_start).into()..];
  write!(f, "unknown command `{}`", msg_content)
  }
  Self::UnknownInteraction { interaction, .. } => {

src/structs/prefix.rs

@@ -26,8 +26,8 @@ pub enum MessageDispatchTrigger {
 pub struct PrefixContext<'a, U, E> {
  /// The invoking user message
  pub msg: &'a serenity::Message,
- /// Prefix used by the user to invoke this command
- pub prefix: &'a str,
+ /// Position in the string that the prefix used by the user to invoke this command ends.
+ pub content_start: u16,
  /// Command name used by the user to invoke this command
  pub invoked_command_name: &'a str,
  /// Entire argument string
@@ -97,12 +97,12 @@ pub struct PrefixFrameworkOptions<U, E> {
  ///
  /// Override this field for advanced dynamic prefixes which change depending on guild or user.
  ///
- /// Return value is a tuple of the prefix and the rest of the message:
+ /// Return value is the prefix found
  /// ```rust,no_run
  /// # poise::PrefixFrameworkOptions::<(), ()> { stripped_dynamic_prefix: Some(|_, msg, _| Box::pin(async move {
  /// let my_cool_prefix = "$";
  /// if msg.content.starts_with(my_cool_prefix) {
- /// return Ok(Some(msg.content.split_at(my_cool_prefix.len())));
+ /// return Ok(Some(msg.content[..my_cool_prefix.len()]));
  /// }
  /// Ok(None)
  /// # })), ..Default::default() };
@@ -113,7 +113,7 @@ pub struct PrefixFrameworkOptions<U, E> {
  &'a serenity::Context,
  &'a serenity::Message,
  &'a U,
- ) -> BoxFuture<'a, Result<Option<(&'a str, &'a str)>, E>>,
+ ) -> BoxFuture<'a, Result<Option<&'a str>, E>>,
  >,
  /// Treat a bot mention (a ping) like a prefix
  pub mention_as_prefix: bool,