# codespan_preprocessed
[](https://crates.io/crates/codespan_preprocessed)
[](https://crates.io/crates/codespan_preprocessed)
[](https://crates.io/crates/codespan_preprocessed)
[](https://docs.rs/codespan_preprocessed)
This is an extension for the very useful crate `codespan_reporting`
to deal with preprocessed file through the well-known`m4` or `cpp`.
Using such a preprocessor allows, among a lost of things, the
inclusion of many files which are identified in the bytes sequence
with preprecessor directive as:
`#line 42 "/my/preprocessed/file"`
This directive breaks the location of the source and so
should be correctly processed to make correct location
for error reporting.
This is the purpose of this crate: taking a preprocessor
output and managing the different underlying locations
inside it.
# Example
```rust
use codespan_reporting::diagnostic::Diagnostic;
use codespan_reporting::term;
use codespan_reporting::term::termcolor::{ColorChoice, StandardStream};
use codespan_preprocessed::PreprocessedFile;
fn main()
{
let file = PreprocessedFile::new(
unindent::unindent(
r#"
#line 1 "top_file"
a first statement;
another one
#line 1 "included_file"
continue...
#line 5
another line
the last one
"#,
),
);
let diagnostic = Diagnostic::note()
.with_message("this is just an example")
.with_labels(vec![
file.primary_label(113..117).with_message("do you see that ?"),
file.secondary_label(21..26).with_message("is it related to this ?")
]);
// We now set up the writer and configuration, and then finally render the
// diagnostic to standard error.
// (see `codespan_reporting` documention for more details)
let writer = StandardStream::stderr(ColorChoice::Always);
let config = codespan_reporting::term::Config::default();
term::emit(&mut writer.lock(), &config, &file, &diagnostic);
}
```
The previous code will produce:
```text
note: this is just an example
┌─ included_file:6:5
│
6 │ the last one
│ ^^^^ do you see that ?
│
┌─ top_file:1:3
│
1 │ a first statement;
│ ----- is it related to this ?
```