Crate ircv3_parse_derive 

Derive macros for FromMessage and ToMessage traits from ircv3_parse.

---

Attributes

When no explicit key is specified, the field name is used as the key, converted to kebab-case.

#[irc(command = "CMD")] is optional for structs and unit structs.

Struct

#[derive(FromMessage, ToMessage)]
#[irc(command = "PRIVMSG")]
struct PrivMsg<'a> {
    #[irc(tag = "id")]
    id: &'a str,
    #[irc(source)]
    nick: &'a str,
    #[irc(param)]
    channel: &'a str,
    #[irc(trailing)]
    text: &'a str,
}

The container attribute #[irc(command = "CMD")] checks the command on deserialization and writes it on serialization.

Tags

Tag

#[irc(tag)]
#[irc(tag = "key")]

Tag Flag

#[irc(tag_flag)]
#[irc(tag_flag = "key")]

Supports bool, Option<T>, or a nested type.

Source

#[irc(source)]              // source.name
#[irc(source = "name")]
#[irc(source = "user")]
#[irc(source = "host")]

Param

#[irc(param)]         // first param (index 0)
#[irc(param = 1)]     // second param
#[irc(params)]        // all params

Vec<T> is only valid with #[irc(params)].

Trailing

#[irc(trailing)]

• &str/String never fails - yields an empty string when absent.
• Option<T> yields None when absent or empty (empty string is treated as None).

Command

#[irc(command)]

Does not support Option.

Nested

A field with no #[irc(...)] attribute delegates to that type’s own FromMessage/ToMessage implementation.

---

Unit Struct

Unit structs validate that a message matches expected values without extracting data, and write those values on serialization.

#[derive(FromMessage, ToMessage)]
#[irc(command = "PING", tag = "src", value = "server")]
struct PingFromServer;

• #[irc(command = "CMD")] - matches/writes the command
• #[irc(tag = "key")], #[irc(param)], etc. - matches/writes a specific component value
• #[irc(value = "...")] - overrides the expected value (default: kebab-case of the struct name)

---

Enum

Enums match a single IRC component value against variant patterns.

#[derive(FromMessage, ToMessage)]
#[irc(command)]
enum Command {
    PrivMsg,
    Join,
    Part,
}

Container Attributes

#[irc(command)]
#[irc(tag)]
#[irc(tag = "key")]
#[irc(tag_flag)]
#[irc(tag_flag = "key")]
#[irc(source)]
#[irc(source = "name|user|host")]
#[irc(param)]
#[irc(param = N)]
#[irc(trailing)]

• #[irc(rename_all = "lowercase|UPPERCASE|kebab-case")] - rename all variants (default: kebab-case, except command which defaults to UPPERCASE)

When no key is specified, the enum name is used as the tag key (always kebab-case, independent of rename_all).

Variant Attributes

• #[irc(value = "...")] - override the match/serialization value (can appear multiple times. see pick for serialization with multiple values)
• #[irc(present)] - for tag_flag enums, marks the variant matched when the flag is present

#[derive(FromMessage, ToMessage)]
#[irc(tag = "badge-info")]
enum Badge {
    #[irc(value = "subscriber", pick)]
    #[irc(value = "sub")]
    Subscriber,
    Moderator,
}

#[derive(FromMessage, ToMessage)]
#[irc(tag_flag = "mod")]
enum Mod {
    #[irc(present)]
    Moderator,
    Regular,
}

tag_flag enums require exactly two variants:

• one marked #[irc(present)] - matched when the flag is present
• one absent variant - matched when the flag is absent. must be a unit variant

Enum Fields

Variants can carry fields that extract additional IRC components.

#[derive(FromMessage, ToMessage)]
#[irc(command)]
enum Command {
    PrivMsg {
        #[irc(param)]
        channel: String,
        #[irc(trailing)]
        text: String,
    },
    Join(#[irc(param)] String),
    Part,
}

When a variant has a single unnamed field with no #[irc(...)] attribute, the field carries the matched component value directly.

#[derive(FromMessage, ToMessage)]
#[irc(tag = "color")]
enum Color {
    Red,
    Blue,
    Other(String),
}

---

Deserialization (FromMessage)

Field Options

with

Provides a custom deserializer function. The function receives the raw component input.

#[irc(tag = "ts", with = "parse_timestamp")]
timestamp: u64,

fn parse_timestamp(value: Option<&str>) -> u64 {
    value.and_then(|s| s.parse().ok()).unwrap_or(0)
}

default

Uses a fallback value when the component is absent instead of returning an error.

#[irc(tag = "color", default)]             // Default::default()
#[irc(tag = "color", default = "red_fn")]  // red_fn()

Enum

• #[irc(default = "VariantName")] - catch-all unit variant for unrecognized values

---

Serialization (ToMessage)

Container

• #[irc(crlf)] - appends \r\n and validates the message is complete:
  • command must be set (#[irc(command = "...")] or #[irc(command)] field)
  • #[irc(source = "user")] or #[irc(source = "host")] requires #[irc(source)] to also be present

Field Options

skip

Always skip this field during serialization.

#[irc(tag = "internal", skip)]

skip_none

Skip the tag entirely when the value is None. Only allowed on #[irc(tag)] fields with Option<String> or Option<&str> type.

Without skip_none, None writes key= (tag present with no value). With skip_none, None omits the tag entirely.

#[irc(tag = "msgid", skip_none)]
id: Option<String>,    // None -> tag absent, Some(v) -> @msgid=v

#[irc(tag = "msgid")]
id: Option<String>,    // None -> @msgid=

Enum Variant

• #[irc(pick)] - when a variant has multiple #[irc(value)], selects which one to use for serialization

#[derive(ToMessage)]
#[irc(command)]
enum Command {
    #[irc(value = "PRIVMSG", pick)]
    #[irc(value = "NOTICE")]
    Message,                          // serializes as PRIVMSG
}

Derive Macros

FromMessage

ToMessage