procmacro2 example

Chapter09/Cargo.toml

@@ -8,6 +8,7 @@ rand = "0.4.2"
 requests = "0.0.30"
 rusty-machine = "0.5.4"
 procmacro = { path = "procmacro" }
+procmacro2 = { path = "procmacro2" }
 
 [[bin]]
 name = "performance_release_mode"
@@ -96,3 +97,7 @@ path = "metaprogramming_ebnf.rs"
 [[bin]]
 name = "metaprogramming_procmacro"
 path = "metaprogramming_procmacro.rs"
+
+[[bin]]
+name = "metaprogramming_procmacro2"
+path = "metaprogramming_procmacro2.rs"

Chapter09/metaprogramming_procmacro2.rs

@@ -0,0 +1,9 @@
+#![feature(proc_macro_non_items)]
+#![feature(use_extern_macros)]
+extern crate procmacro2;
+
+fn main() {
+   procmacro2::misc_syntax!(
+      where while abcd : u64 >> 1 + 2 * 3; where T: 'x + A<B='y+C+D>;[M];A::f
+   );
+}

Chapter09/procmacro2/.gitignore

@@ -0,0 +1,2 @@
+Cargo.lock
+target

Chapter09/procmacro2/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "procmacro2"
+version = "1.0.0"
+
+[dependencies]
+syn = "0.12"
+quote = "0.4"
+
+[lib]
+proc-macro = true

Chapter09/procmacro2/src/lib.rs

@@ -0,0 +1,48 @@
+#![feature(proc_macro)]
+#![crate_type = "proc-macro"]
+extern crate proc_macro;
+#[macro_use] extern crate syn;
+#[macro_use] extern crate quote;
+
+use proc_macro::TokenStream;
+use syn::{Ident, Type, Expr, WhereClause, TypeSlice, Path};
+use syn::synom::Synom;
+
+struct MiscSyntax {
+   id: Ident,
+   ty: Type,
+   expr: Expr,
+   where_clause: WhereClause,
+   type_slice: TypeSlice,
+   path: Path
+}
+
+impl Synom for MiscSyntax {
+    named!(parse -> Self, do_parse!(
+        keyword!(where) >>
+        keyword!(while) >>
+        id: syn!(Ident) >>
+        punct!(:) >>
+        ty: syn!(Type) >>
+        punct!(>>) >>
+        expr: syn!(Expr) >>
+        punct!(;) >>
+        where_clause: syn!(WhereClause) >>
+        punct!(;) >>
+        type_slice: syn!(TypeSlice) >>
+        punct!(;) >>
+        path: syn!(Path) >>
+        (MiscSyntax { id, ty, expr, where_clause, type_slice, path })
+    ));
+}
+
+#[proc_macro]
+pub fn misc_syntax(input: TokenStream) -> TokenStream {
+    let m: MiscSyntax = syn::parse(input).expect("expected Miscellaneous Syntax");
+    let MiscSyntax { id, ty, expr, where_clause, type_slice, path } = m;
+
+    (quote! {
+       let #id: #ty = #expr;
+       println!("variable = {}", #id);
+    }).into()
+}