48 lines
1.5 KiB
Rust
48 lines
1.5 KiB
Rust
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// no-prefer-dynamic
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#![crate_type = "proc-macro"]
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#![feature(proc_macro_diagnostic, proc_macro_span)]
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extern crate proc_macro;
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use proc_macro::{TokenStream, TokenTree, Span, Diagnostic};
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fn parse(input: TokenStream) -> Result<(), Diagnostic> {
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if let Some(TokenTree::Literal(lit)) = input.into_iter().next() {
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let mut spans = vec![];
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let string = lit.to_string();
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for hi in string.matches("hi") {
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let index = hi.as_ptr() as usize - string.as_ptr() as usize;
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let subspan = lit.subspan(index..(index + hi.len())).unwrap();
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spans.push(subspan);
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}
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if !spans.is_empty() {
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Err(Span::call_site().error("found 'hi's").span_note(spans, "here"))
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} else {
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Ok(())
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}
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} else {
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Err(Span::call_site().error("invalid input: expected string literal"))
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}
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}
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#[proc_macro]
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pub fn subspan(input: TokenStream) -> TokenStream {
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if let Err(diag) = parse(input) {
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diag.emit();
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}
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TokenStream::new()
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}
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