xsd_parser/code/

ident_path.rs

use std::ops::{Deref, DerefMut};
use std::str::FromStr;

use proc_macro2::{Ident as Ident2, TokenStream};
use quote::{format_ident, quote, ToTokens};
use smallvec::SmallVec;

use crate::{schema::NamespaceId, types::Types};

use super::format_module_ident;

/// Represents a identifier path.
///
/// A identifier path is the full path of a specific identifier in the code,
/// like `std::str::FromStr`. The identified object can be a constant, a type,
/// a trait or any thing else that is define within a module.
///
/// The identifier path contains two parts:
/// - The identifier itself, which is more or less the name of the object to identify, and
/// - the math of the module the object is provided at.
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct IdentPath {
    path: Option<ModulePath>,
    ident: Ident2,
}

/// Represents a path of a module.
///
/// The module path is a chain ob module names separated by a double colon like
/// `std::str`. It is used to identify modules inside the code.
#[derive(Default, Debug, Clone, Eq, PartialEq)]
pub struct ModulePath(pub SmallVec<[Ident2; 2]>);

impl IdentPath {
    /// Crates a new [`IdentPath`] instance from the passed module `path` and the
    /// `ident`ifier of the object to refer to.
    #[must_use]
    pub fn from_parts<I>(path: I, ident: Ident2) -> Self
    where
        I: IntoIterator<Item = Ident2>,
    {
        Self::from_ident(ident).with_path(path)
    }

    /// Creates a new [`IdentPath`] from the passed object `ident`ifier without a
    /// module path.
    #[must_use]
    pub fn from_ident(ident: Ident2) -> Self {
        Self { ident, path: None }
    }

    /// Changes the identifier of this identifier path to the passed `ident`.
    #[must_use]
    pub fn with_ident(mut self, ident: Ident2) -> Self {
        self.ident = ident;

        self
    }

    /// Changes the module path of this identifier path to the passed `path`.
    #[must_use]
    pub fn with_path<I>(mut self, path: I) -> Self
    where
        I: IntoIterator<Item = Ident2>,
    {
        self.path = Some(ModulePath(path.into_iter().collect()));

        self
    }

    /// Splits this identifier path into it's two main parts, the identifier
    /// and the module path.
    #[must_use]
    pub fn into_parts(self) -> (Ident2, Option<ModulePath>) {
        let Self { ident, path } = self;

        (ident, path)
    }

    /// Returns the identifier of this identifier path.
    #[must_use]
    pub fn ident(&self) -> &Ident2 {
        &self.ident
    }

    /// Creates a new [`IdentPath`] that is relative to the passed `dst` module path.
    ///
    /// This uses the `super` keyword to create a relative path from the passed `dst` module path
    /// and this identifier path. The relative path is returned as token stream.
    #[must_use]
    pub fn relative_to(&self, dst: &ModulePath) -> TokenStream {
        let ident = &self.ident;

        let Some(src) = &self.path else {
            return quote!(#ident);
        };

        let mut ret = TokenStream::new();
        let mut src = src.0.iter().fuse();
        let mut dst = dst.0.iter().fuse();

        macro_rules! push {
            ($x:expr) => {{
                let x = $x;
                if ret.is_empty() {
                    ret.extend(x)
                } else {
                    ret.extend(quote!(::#x))
                }
            }};
        }

        loop {
            match (src.next(), dst.next()) {
                (Some(a), Some(b)) if a == b => {}
                (Some(a), Some(_)) => {
                    push!(quote!(super));
                    while dst.next().is_some() {
                        push!(quote!(super));
                    }

                    push!(quote!(#a));
                    for a in src {
                        push!(quote!(#a));
                    }

                    push!(quote!(#ident));

                    return ret;
                }
                (Some(a), None) => push!(quote!(#a)),
                (None, Some(_)) => push!(quote!(super)),
                (None, None) => {
                    push!(quote!(#ident));
                    return ret;
                }
            }
        }
    }
}

impl FromStr for IdentPath {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut ident = None;
        let mut path = ModulePath::default();

        for part in s.split("::") {
            let part = part.trim();
            if part.is_empty() {
                continue;
            }

            if let Some(ident) = ident.take() {
                path.0.push(ident);
            }

            ident = Some(format_ident!("{part}"));
        }

        Ok(Self {
            ident: ident.ok_or(())?,
            path: Some(path),
        })
    }
}

impl ToTokens for IdentPath {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        if let Some(path) = &self.path {
            for module in &path.0 {
                tokens.extend(quote!(#module::));
            }
        }

        let ident = self.ident();

        tokens.extend(quote!(#ident));
    }
}

impl ModulePath {
    /// Create a new [`ModulePath`] instance from the passed namespace id `ns` and the
    /// `types` information.
    ///
    /// This tries to look up the passed namespace id in the types information and create
    /// a module path for it.
    #[must_use]
    pub fn from_namespace(ns: Option<NamespaceId>, types: &Types) -> Self {
        let ident = ns
            .and_then(|id| types.modules.get(&id))
            .and_then(|module| module.name.as_ref())
            .map(format_module_ident);

        Self(ident.into_iter().collect())
    }

    /// Add a module to the module
    #[must_use]
    pub fn join(mut self, other: Ident2) -> Self {
        self.0.push(other);

        self
    }
}

impl Deref for ModulePath {
    type Target = SmallVec<[Ident2; 2]>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl DerefMut for ModulePath {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

#[cfg(test)]
mod tests {
    use quote::{format_ident, quote};

    use super::{IdentPath, ModulePath};

    #[test]
    #[rustfmt::skip]
    fn type_path() {
        let string = IdentPath::from_ident(format_ident!("String"));
        let my_type = IdentPath::from_parts(
            [format_ident!("my_module")],
            format_ident!("MyType"),
        );
        let serializer = IdentPath::from_parts(
            [
                format_ident!("my_module"),
                format_ident!("quick_xml_serialize"),
            ],
            format_ident!("MyTypeSerializer"),
        );
        let deserializer = IdentPath::from_parts(
            [
                format_ident!("my_module"),
                format_ident!("quick_xml_deserialize"),
            ],
            format_ident!("MyTypeDeserializer"),
        );

        let empty_path = ModulePath::default();
        let module_path = ModulePath::default().join(format_ident!("my_module"));
        let other_module_path = ModulePath::default().join(format_ident!("other_module"));
        let serializer_path = module_path.clone().join(format_ident!("quick_xml_serialize"));
        let deserializer_path = module_path.clone().join(format_ident!("quick_xml_deserialize"));

        macro_rules! test {
            ($actual:expr, $( $expected:tt )*) => {{
                let a = $actual.to_string();
                let b = quote!($( $expected )*).to_string();

                assert_eq!(a, b);
            }};
        }

        /* With modules */

        test!(string.relative_to(&empty_path), String);
        test!(string.relative_to(&module_path), String);
        test!(string.relative_to(&other_module_path), String);
        test!(string.relative_to(&serializer_path), String);
        test!(string.relative_to(&deserializer_path), String);

        test!(my_type.relative_to(&empty_path), my_module::MyType);
        test!(my_type.relative_to(&module_path), MyType);
        test!(my_type.relative_to(&other_module_path), super::my_module::MyType);
        test!(my_type.relative_to(&serializer_path), super::MyType);
        test!(my_type.relative_to(&deserializer_path), super::MyType);

        test!(serializer.relative_to(&empty_path), my_module::quick_xml_serialize::MyTypeSerializer);
        test!(serializer.relative_to(&module_path), quick_xml_serialize::MyTypeSerializer);
        test!(serializer.relative_to(&other_module_path), super::my_module::quick_xml_serialize::MyTypeSerializer);
        test!(serializer.relative_to(&serializer_path), MyTypeSerializer);
        test!(serializer.relative_to(&deserializer_path), super::quick_xml_serialize::MyTypeSerializer);

        test!(deserializer.relative_to(&empty_path), my_module::quick_xml_deserialize::MyTypeDeserializer);
        test!(deserializer.relative_to(&module_path), quick_xml_deserialize::MyTypeDeserializer);
        test!(deserializer.relative_to(&other_module_path), super::my_module::quick_xml_deserialize::MyTypeDeserializer);
        test!(deserializer.relative_to(&serializer_path), super::quick_xml_deserialize::MyTypeDeserializer);
        test!(deserializer.relative_to(&deserializer_path), MyTypeDeserializer);
    }
}