From a1cadd00299efe13e2a1f88273e484944344beb8 Mon Sep 17 00:00:00 2001
From: Per <Per Lindgren>
Date: Thu, 15 Mar 2018 12:35:48 +0100
Subject: [PATCH] error handling
---
examples/ex1.rs | 14 +++++++++----
src/lib.rs | 52 +++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 60 insertions(+), 6 deletions(-)
diff --git a/examples/ex1.rs b/examples/ex1.rs
index e85065a..cb65f1f 100644
--- a/examples/ex1.rs
+++ b/examples/ex1.rs
@@ -1,14 +1,20 @@
#![feature(proc_macro)]
extern crate parsetest;
-use parsetest::mylit;
+use parsetest::{mylit, mylitp};
fn main() {
println!("here");
- let v = mylit!(99);
- println!("v {}", v);
+ // let v = mylit!(99);
+ // println!("v {}", v);
+
+ // let v = mylit!(102);
+ // println!("v {}", v);
- let v = mylit!(102);
+ let v = mylitp!((99));
println!("v {}", v);
+
+ // let v = mylitp!(9o9);
+ // println!("v {}", v);
}
diff --git a/src/lib.rs b/src/lib.rs
index 66d0fe2..0594a34 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,13 +7,14 @@ extern crate quote;
extern crate syn;
use proc_macro::TokenStream;
-use syn::punctuated::Punctuated;
+// use syn::punctuated::Punctuated;
use syn::spanned::Spanned;
use syn::synom::Synom;
-use syn::{Expr, ExprArray, Ident, LitInt};
+use syn::LitInt;
use quote::ToTokens;
use std::convert::From;
+use std::error::Error;
/// MyLit
struct MyLit {
@@ -39,3 +40,50 @@ pub fn mylit(input: TokenStream) -> TokenStream {
}
From::from(v.val.into_tokens())
}
+
+/// MyLit
+struct MyLitP {
+ val: LitInt,
+}
+
+impl Synom for MyLitP {
+ named!(parse -> Self, do_parse!(
+ val: call!(LitInt::parse) >> (MyLitP { val })
+ ));
+}
+
+#[proc_macro]
+pub fn mylitp(input: TokenStream) -> TokenStream {
+ match syn::parse::<MyLitP>(input) {
+ Ok(v) => {
+ let value: u32 = v.val.value() as u32;
+ if !(10 <= value && value < 100) {
+ v.val
+ .span()
+ .unstable()
+ .error(format!(
+ "expected literal 10 <= x < 100, got {}",
+ value,
+ ))
+ .emit();
+ }
+ From::from(v.val.into_tokens())
+ }
+ Err(err) => {
+ //let desc = format!("could not parse {:?}", err);
+ let desc = err.description();
+ // println!(
+ // "here -----------------------------------------desc {:?}",
+ // desc
+ // );
+ let tokens = quote! {
+ compile_error!(#desc)
+ };
+
+ return tokens.into();
+ }
+ }
+}
+
+//panic!("here {}", err),
+//let desc = syn::synom::Synom::description(err);
--
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