//! Different variants of an `Item` in our intermediate representation.

use super::function::Function;
use super::module::Module;
use super::ty::Type;
use super::var::Var;

/// A item we parse and translate.
#[derive(Debug)]
pub enum ItemKind {
    /// A module, created implicitly once (the root module), or via C++
    /// namespaces.
    Module(Module),

    /// A type declared in any of the multiple ways it can be declared.
    Type(Type),

    /// A function or method declaration.
    Function(Function),

    /// A variable declaration, most likely a static.
    Var(Var),
}

impl ItemKind {
    /// Get a reference to this `ItemKind`'s underying `Module`, or `None` if it
    /// is some other kind.
    pub fn as_module(&self) -> Option<&Module> {
        match *self {
            ItemKind::Module(ref module) => Some(module),
            _ => None,
        }
    }

    /// Transform our `ItemKind` into a string.
    pub fn kind_name(&self) -> &'static str {
        match *self {
            ItemKind::Module(..) => "Module",
            ItemKind::Type(..) => "Type",
            ItemKind::Function(..) => "Function",
            ItemKind::Var(..) => "Var"
        }        
    }

    /// Is this a module?
    pub fn is_module(&self) -> bool {
        self.as_module().is_some()
    }

    /// Get a reference to this `ItemKind`'s underying `Module`, or panic if it
    /// is some other kind.
    pub fn expect_module(&self) -> &Module {
        self.as_module().expect("Not a module")
    }

    /// Get a reference to this `ItemKind`'s underying `Function`, or `None` if
    /// it is some other kind.
    pub fn as_function(&self) -> Option<&Function> {
        match *self {
            ItemKind::Function(ref func) => Some(func),
            _ => None,
        }
    }

    /// Is this a function?
    pub fn is_function(&self) -> bool {
        self.as_function().is_some()
    }

    /// Get a reference to this `ItemKind`'s underying `Function`, or panic if
    /// it is some other kind.
    pub fn expect_function(&self) -> &Function {
        self.as_function().expect("Not a function")
    }

    /// Get a reference to this `ItemKind`'s underying `Type`, or `None` if
    /// it is some other kind.
    pub fn as_type(&self) -> Option<&Type> {
        match *self {
            ItemKind::Type(ref ty) => Some(ty),
            _ => None,
        }
    }

    /// Get a mutable reference to this `ItemKind`'s underying `Type`, or `None`
    /// if it is some other kind.
    pub fn as_type_mut(&mut self) -> Option<&mut Type> {
        match *self {
            ItemKind::Type(ref mut ty) => Some(ty),
            _ => None,
        }
    }

    /// Is this a type?
    pub fn is_type(&self) -> bool {
        self.as_type().is_some()
    }

    /// Get a reference to this `ItemKind`'s underying `Type`, or panic if it is
    /// some other kind.
    pub fn expect_type(&self) -> &Type {
        self.as_type().expect("Not a type")
    }

    /// Get a reference to this `ItemKind`'s underying `Var`, or `None` if it is
    /// some other kind.
    pub fn as_var(&self) -> Option<&Var> {
        match *self {
            ItemKind::Var(ref v) => Some(v),
            _ => None,
        }
    }

    /// Is this a variable?
    pub fn is_var(&self) -> bool {
        self.as_var().is_some()
    }

    /// Get a reference to this `ItemKind`'s underying `Var`, or panic if it is
    /// some other kind.
    pub fn expect_var(&self) -> &Var {
        self.as_var().expect("Not a var")
    }
}