nushell/src/commands/help.rs

use crate::commands::command::CommandAction;
use crate::commands::PerItemCommand;
use crate::errors::ShellError;
use crate::data::{command_dict, TaggedDictBuilder};
use crate::parser::registry;
use crate::prelude::*;

pub struct Help;

impl PerItemCommand for Help {
    fn name(&self) -> &str {
        "help"
    }

    fn signature(&self) -> registry::Signature {
        Signature::build("help").rest(SyntaxType::Any)
    }

    fn usage(&self) -> &str {
        "Display help information about commands."
    }

    fn run(
        &self,
        call_info: &CallInfo,
        registry: &CommandRegistry,
        _raw_args: &RawCommandArgs,
        _input: Tagged<Value>,
    ) -> Result<OutputStream, ShellError> {
        let span = call_info.name_span;

        if call_info.args.len() == 0 {
            return Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
                Tagged::from_simple_spanned_item(Value::nothing(), span),
            )))]
            .into());
        }

        match call_info.args.expect_nth(0)? {
            Tagged {
                item: Value::Primitive(Primitive::String(document)),
                tag,
            } => {
                if document == "commands" {
                    let mut specs = VecDeque::new();

                    for cmd in registry.names() {
                        let mut spec = TaggedDictBuilder::new(tag.clone());
                        let value = command_dict(registry.get_command(&cmd).unwrap(), tag.clone());

                        spec.insert("name", cmd);
                        spec.insert(
                            "description",
                            value.get_data_by_key("usage").unwrap().as_string().unwrap(),
                        );
                        spec.insert_tagged("details", value);

                        specs.push_back(ReturnSuccess::value(spec.into_tagged_value()));
                    }

                    return Ok(specs.to_output_stream());
                }

                Ok(OutputStream::empty())
            }
            x => Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
                x.clone(),
            )))]
            .into()),
        }
    }
}