nushell/crates/nu-protocol/src/engine/command.rs

use crate::{ast::Call, BlockId, Example, ShellError, Signature, Value};

use super::EvaluationContext;

pub trait Command {
    fn name(&self) -> &str;

    fn signature(&self) -> Signature {
        Signature::new(self.name()).desc(self.usage()).filter()
    }

    fn usage(&self) -> &str;

    fn extra_usage(&self) -> &str {
        ""
    }

    fn run(
        &self,
        context: &EvaluationContext,
        call: &Call,
        input: Value,
    ) -> Result<Value, ShellError>;

    fn is_binary(&self) -> bool {
        false
    }

    // Commands that are not meant to be run by users
    fn is_private(&self) -> bool {
        false
    }

    fn examples(&self) -> Vec<Example> {
        Vec::new()
    }

    // This is a built-in command
    fn is_builtin(&self) -> bool {
        true
    }

    // Is a sub command
    fn is_sub(&self) -> bool {
        self.name().contains(' ')
    }

    // Is a plugin command
    fn is_plugin(&self) -> bool {
        false
    }

    // If command is a block i.e. def blah [] { }, get the block id
    fn get_block_id(&self) -> Option<BlockId> {
        None
    }
}