lofty_attr: Generate internal write modules

lofty_attr/src/internal.rs

@@ -0,0 +1,121 @@
+// Items that only pertain to internal usage of lofty_attr
+
+use crate::FieldContents;
+
+use std::collections::HashMap;
+
+use quote::quote;
+
+pub(crate) fn opt_internal_file_type(
+	struct_name: String,
+) -> Option<(proc_macro2::TokenStream, bool)> {
+	const LOFTY_FILE_TYPES: [&str; 10] = [
+		"AIFF", "APE", "FLAC", "MPEG", "MP4", "Opus", "Vorbis", "Speex", "WAV", "WavPack",
+	];
+
+	const ID3V2_STRIPPABLE: [&str; 1] = ["APE"];
+
+	let stripped = struct_name.strip_suffix("File");
+	if let Some(prefix) = stripped {
+		if let Some(pos) = LOFTY_FILE_TYPES
+			.iter()
+			.position(|p| p.eq_ignore_ascii_case(prefix))
+		{
+			let file_ty = LOFTY_FILE_TYPES[pos];
+			let tt = file_ty.parse::<proc_macro2::TokenStream>().unwrap();
+
+			return Some((tt, ID3V2_STRIPPABLE.contains(&file_ty)));
+		}
+	}
+
+	None
+}
+
+pub(crate) fn init_write_lookup(
+	id3v2_strippable: bool,
+) -> HashMap<&'static str, proc_macro2::TokenStream> {
+	let mut map = HashMap::new();
+
+	macro_rules! insert {
+		($map:ident, $key:path, $val:block) => {
+			$map.insert(stringify!($key), quote! { $val })
+		};
+	}
+
+	insert!(map, APE, {
+		crate::ape::tag::ApeTagRef {
+			read_only: false,
+			items: crate::ape::tag::tagitems_into_ape(tag.items()),
+		}
+		.write_to(data)
+	});
+
+	insert!(map, ID3v1, {
+		Into::<crate::id3::v1::tag::Id3v1TagRef<'_>>::into(tag).write_to(data)
+	});
+
+	if id3v2_strippable {
+		insert!(map, ID3v2, {
+			crate::id3::v2::tag::Id3v2TagRef::empty().write_to(data)
+		});
+	} else {
+		insert!(map, ID3v2, {
+			crate::id3::v2::tag::Id3v2TagRef {
+				flags: crate::id3::v2::ID3v2TagFlags::default(),
+				frames: crate::id3::v2::tag::tag_frames(tag),
+			}
+			.write_to(data)
+		});
+	}
+
+	insert!(map, RIFFInfo, {
+		crate::iff::wav::tag::RIFFInfoListRef::new(crate::iff::wav::tag::tagitems_into_riff(
+			tag.items(),
+		))
+		.write_to(data)
+	});
+
+	insert!(map, AIFFText, {
+		crate::iff::aiff::tag::AiffTextChunksRef {
+			name: tag.get_string(&crate::tag::item::ItemKey::TrackTitle),
+			author: tag.get_string(&crate::tag::item::ItemKey::TrackArtist),
+			copyright: tag.get_string(&crate::tag::item::ItemKey::CopyrightMessage),
+			annotations: Some(tag.get_strings(&crate::tag::item::ItemKey::Comment)),
+			comments: None,
+		}
+		.write_to(data)
+	});
+
+	map
+}
+
+pub(crate) fn write_module(
+	fields: &[FieldContents],
+	lookup: HashMap<&'static str, proc_macro2::TokenStream>,
+) -> proc_macro2::TokenStream {
+	let applicable_formats = fields.iter().map(|f| {
+		let tag_ty =
+			syn::parse_str::<syn::Path>(&format!("crate::tag::TagType::{}", &f.tag_type)).unwrap();
+
+		let features = f.cfg_features.iter();
+
+		let block = lookup.get(&*tag_ty.segments[3].ident.to_string()).unwrap();
+
+		quote! {
+			#( #features )*
+			#tag_ty => #block,
+		}
+	});
+
+	quote! {
+		pub(crate) mod write {
+			#[allow(unused_variables)]
+			pub(crate) fn write_to(data: &mut std::fs::File, tag: &crate::tag::Tag) -> crate::error::Result<()> {
+				match tag.tag_type() {
+					#( #applicable_formats )*
+					_ => crate::macros::err!(UnsupportedTag),
+				}
+			}
+		}
+	}
+}

lofty_attr/src/lib.rs

@@ -1,3 +1,4 @@
+mod internal;
 mod util;
 
 use proc_macro::TokenStream;
@@ -6,10 +7,6 @@ use quote::{format_ident, quote, quote_spanned, ToTokens};
 use syn::spanned::Spanned;
 use syn::{parse_macro_input, Attribute, Data, DataStruct, DeriveInput, Fields, Ident, Type};
 
-const LOFTY_FILE_TYPES: [&str; 10] = [
-	"AIFF", "APE", "FLAC", "MPEG", "MP4", "Opus", "Vorbis", "Speex", "WAV", "WavPack",
-];
-
 /// Creates a file usable by Lofty
 ///
 /// See [here](https://github.com/Serial-ATA/lofty-rs/tree/main/examples/custom_resolver) for an example of how to use it.
@@ -68,9 +65,30 @@ fn parse(input: DeriveInput, errors: &mut Vec<syn::Error>) -> proc_macro2::Token
 	};
 
 	let struct_name = input.ident.clone();
+	let is_internal = input
+		.attrs
+		.iter()
+		.any(|attr| util::has_path_attr(attr, "internal_write_module_do_not_use_anywhere_else"));
 
-	let file_type = match opt_file_type(struct_name.to_string()) {
-		Some(ft) => ft,
+	// TODO: This is not readable in the slightest
+
+	let opt_file_type = internal::opt_internal_file_type(struct_name.to_string());
+	if opt_file_type.is_none() && is_internal {
+		// TODO: This is the best check we can do for now I think?
+		//       Definitely needs some work when a better solution comes out.
+		bail!(
+			errors,
+			input.ident.span(),
+			"Attempted to use an internal attribute externally"
+		);
+	}
+
+	let mut id3v2_strippable = false;
+	let file_type = match opt_file_type {
+		Some((ft, id3v2_strip)) => {
+			id3v2_strippable = id3v2_strip;
+			ft
+		},
 		_ => match util::get_attr("file_type", &input.attrs) {
 			Some(rfn) => rfn,
 			_ => {
@@ -168,7 +186,7 @@ fn parse(input: DeriveInput, errors: &mut Vec<syn::Error>) -> proc_macro2::Token
 
 	let getters = get_getters(&tag_fields, &struct_name);
 
-	quote! {
+	let mut ret = quote! {
 		#assert_properties_impl
 
 		#( #assert_tag_impl_into )*
@@ -191,7 +209,21 @@ fn parse(input: DeriveInput, errors: &mut Vec<syn::Error>) -> proc_macro2::Token
 		}
 
 		#( #getters )*
+	};
+
+	// Create `write` module if internal
+	if is_internal {
+		let lookup = internal::init_write_lookup(id3v2_strippable);
+		let write_mod = internal::write_module(&tag_fields, lookup);
+
+		ret = quote! {
+			#ret
+
+			#write_mod
+		}
 	}
+
+	ret
 }
 
 struct FieldContents {
@@ -252,24 +284,6 @@ fn get_fields<'a>(
 	Some((tag_fields, properties_field))
 }
 
-fn opt_file_type(struct_name: String) -> Option<proc_macro2::TokenStream> {
-	let stripped = struct_name.strip_suffix("File");
-	if let Some(prefix) = stripped {
-		if let Some(pos) = LOFTY_FILE_TYPES
-			.iter()
-			.position(|p| p.eq_ignore_ascii_case(prefix))
-		{
-			return Some(
-				LOFTY_FILE_TYPES[pos]
-					.parse::<proc_macro2::TokenStream>()
-					.unwrap(),
-			);
-		}
-	}
-
-	None
-}
-
 fn should_impl_audiofile(attrs: &[Attribute]) -> bool {
 	for attr in attrs {
 		if util::has_path_attr(attr, "no_audiofile_impl") {

src/ape/mod.rs

@@ -9,7 +9,6 @@ pub(crate) mod constants;
 pub(crate) mod header;
 mod properties;
 mod read;
-pub(crate) mod write;
 
 #[cfg(feature = "id3v1")]
 use crate::id3::v1::tag::ID3v1Tag;
@@ -35,6 +34,7 @@ pub use properties::ApeProperties;
 /// An APE file
 #[derive(LoftyFile)]
 #[lofty(read_fn = "read::read_from")]
+#[lofty(internal_write_module_do_not_use_anywhere_else)]
 pub struct ApeFile {
 	/// An ID3v1 tag
 	#[cfg(feature = "id3v1")]

src/ape/write.rs

@@ -1,30 +0,0 @@
-#[cfg(feature = "ape")]
-use crate::ape;
-use crate::error::Result;
-#[cfg(feature = "id3v1")]
-use crate::id3::v1;
-#[cfg(feature = "id3v2")]
-use crate::id3::v2;
-use crate::macros::err;
-#[allow(unused_imports)]
-use crate::tag::{Tag, TagType};
-
-use std::fs::File;
-
-#[allow(unused_variables)]
-pub(crate) fn write_to(data: &mut File, tag: &Tag) -> Result<()> {
-	match tag.tag_type() {
-		#[cfg(feature = "ape")]
-		TagType::APE => ape::tag::ApeTagRef {
-			read_only: false,
-			items: ape::tag::tagitems_into_ape(tag.items()),
-		}
-		.write_to(data),
-		// This tag can *only* be removed in this format
-		#[cfg(feature = "id3v2")]
-		TagType::ID3v2 => v2::tag::Id3v2TagRef::empty().write_to(data),
-		#[cfg(feature = "id3v1")]
-		TagType::ID3v1 => Into::<v1::tag::Id3v1TagRef<'_>>::into(tag).write_to(data),
-		_ => err!(UnsupportedTag),
-	}
-}

src/iff/aiff/mod.rs

@@ -1,6 +1,5 @@
 mod properties;
 mod read;
-pub(crate) mod write;
 
 #[cfg(feature = "id3v2")]
 use crate::id3::v2::tag::ID3v2Tag;
@@ -18,6 +17,7 @@ cfg_if::cfg_if! {
 /// An AIFF file
 #[derive(LoftyFile)]
 #[lofty(read_fn = "read::read_from")]
+#[lofty(internal_write_module_do_not_use_anywhere_else)]
 pub struct AiffFile {
 	/// Any text chunks included in the file
 	#[cfg(feature = "aiff_text_chunks")]

src/iff/aiff/write.rs

@@ -1,34 +0,0 @@
-use crate::error::Result;
-#[cfg(feature = "id3v2")]
-use crate::id3::v2;
-use crate::macros::err;
-#[allow(unused_imports)]
-use crate::tag::{Tag, TagType};
-
-use std::fs::File;
-
-#[allow(unused_variables)]
-pub(crate) fn write_to(data: &mut File, tag: &Tag) -> Result<()> {
-	match tag.tag_type() {
-		#[cfg(feature = "aiff_text_chunks")]
-		TagType::AIFFText => {
-			use crate::tag::item::ItemKey;
-
-			super::tag::AiffTextChunksRef {
-				name: tag.get_string(&ItemKey::TrackTitle),
-				author: tag.get_string(&ItemKey::TrackArtist),
-				copyright: tag.get_string(&ItemKey::CopyrightMessage),
-				annotations: Some(tag.get_strings(&ItemKey::Comment)),
-				comments: None,
-			}
-		}
-		.write_to(data),
-		#[cfg(feature = "id3v2")]
-		TagType::ID3v2 => v2::tag::Id3v2TagRef {
-			flags: v2::ID3v2TagFlags::default(),
-			frames: v2::tag::tag_frames(tag),
-		}
-		.write_to(data),
-		_ => err!(UnsupportedTag),
-	}
-}

src/iff/wav/mod.rs

@@ -1,6 +1,5 @@
 mod properties;
 mod read;
-pub(crate) mod write;
 
 #[cfg(feature = "id3v2")]
 use crate::id3::v2::tag::ID3v2Tag;
@@ -20,6 +19,7 @@ pub use crate::iff::wav::properties::{WavFormat, WavProperties};
 /// A WAV file
 #[derive(LoftyFile)]
 #[lofty(read_fn = "read::read_from")]
+#[lofty(internal_write_module_do_not_use_anywhere_else)]
 pub struct WavFile {
 	/// A RIFF INFO LIST
 	#[cfg(feature = "riff_info_list")]

src/iff/wav/write.rs

@@ -1,26 +0,0 @@
-use crate::error::Result;
-#[cfg(feature = "id3v2")]
-use crate::id3::v2;
-use crate::macros::err;
-#[allow(unused_imports)]
-use crate::tag::{Tag, TagType};
-
-use std::fs::File;
-
-#[allow(unused_variables)]
-pub(crate) fn write_to(data: &mut File, tag: &Tag) -> Result<()> {
-	match tag.tag_type() {
-		#[cfg(feature = "riff_info_list")]
-		TagType::RIFFInfo => {
-			super::tag::RIFFInfoListRef::new(super::tag::tagitems_into_riff(tag.items()))
-				.write_to(data)
-		},
-		#[cfg(feature = "id3v2")]
-		TagType::ID3v2 => v2::tag::Id3v2TagRef {
-			flags: v2::ID3v2TagFlags::default(),
-			frames: v2::tag::tag_frames(tag),
-		}
-		.write_to(data),
-		_ => err!(UnsupportedTag),
-	}
-}

src/wavpack/mod.rs

@@ -1,7 +1,6 @@
 //! WavPack specific items
 mod properties;
 mod read;
-pub(crate) mod write;
 
 #[cfg(feature = "ape")]
 use crate::ape::tag::ApeTag;
@@ -14,8 +13,9 @@ use lofty_attr::LoftyFile;
 pub use properties::WavPackProperties;
 
 /// A WavPack file
-#[derive(Default, LoftyFile)]
+#[derive(LoftyFile, Default)]
 #[lofty(read_fn = "read::read_from")]
+#[lofty(internal_write_module_do_not_use_anywhere_else)]
 pub struct WavPackFile {
 	/// An ID3v1 tag
 	#[cfg(feature = "id3v1")]

src/wavpack/write.rs

@@ -1,25 +0,0 @@
-#[cfg(feature = "ape")]
-use crate::ape;
-use crate::error::Result;
-#[cfg(feature = "id3v1")]
-use crate::id3::v1;
-use crate::macros::err;
-#[allow(unused_imports)]
-use crate::tag::{Tag, TagType};
-
-use std::fs::File;
-
-#[allow(unused_variables)]
-pub(crate) fn write_to(data: &mut File, tag: &Tag) -> Result<()> {
-	match tag.tag_type() {
-		#[cfg(feature = "ape")]
-		TagType::APE => ape::tag::ApeTagRef {
-			read_only: false,
-			items: ape::tag::tagitems_into_ape(tag.items()),
-		}
-		.write_to(data),
-		#[cfg(feature = "id3v1")]
-		TagType::ID3v1 => Into::<v1::tag::Id3v1TagRef<'_>>::into(tag).write_to(data),
-		_ => err!(UnsupportedTag),
-	}
-}