codespan_preprocessed

这是一个针对非常有用的crate codespan_reporting 的扩展，用于通过众所周知的m4 或 cpp处理预处理的文件。

使用此类预处理器可以使许多文件被包含，这些文件通过预处理指令在字节序列中标识为

#行42 "/my/preprocessed/file"

此指令破坏了源位置，因此应该正确处理以生成错误报告的正确位置。

这正是此crate的目的：接收预处理器输出并管理其内部的不同基本位置。

示例

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);
}

前面的代码将生成

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 ?