build(rust): vendor rnix parser crate

third_party/crates/rnix-0.14.0/examples/error-report.rs

@@ -0,0 +1,67 @@
+use rnix::ParseError;
+use std::{env, fs};
+
+fn main() {
+    let file = match env::args().nth(1) {
+        Some(file) => file,
+        None => {
+            eprintln!("Usage: error-report <file>");
+            return;
+        }
+    };
+    let content = match fs::read_to_string(&file) {
+        Ok(content) => content,
+        Err(err) => {
+            eprintln!("error reading file: {}", err);
+            return;
+        }
+    };
+    let ast = rnix::Root::parse(&content);
+    for error in ast.errors() {
+        let range = match error {
+            ParseError::Unexpected(range) => range,
+            ParseError::UnexpectedExtra(range) => range,
+            ParseError::UnexpectedWanted(_, range, _) => range,
+            ParseError::UnexpectedDoubleBind(range) => range,
+            ParseError::DuplicatedArgs(range, _) => range,
+            err => {
+                eprintln!("error: {}", err);
+                continue;
+            }
+        };
+        eprintln!("----- ERROR -----");
+        eprintln!("{}", error);
+        let start = usize::from(range.start());
+        let start_row = content[..start].lines().count() - 1;
+        let start_line = content[..start].rfind('\n').map(|i| i + 1).unwrap_or(0);
+        let start_col = content[start_line..start].chars().count();
+        let end = usize::from(range.end());
+        let end_row = content[..end].lines().count() - 1;
+        let end_line = content[..end].rfind('\n').map(|i| i + 1).unwrap_or(0);
+        let end_col = content[end_line..end].chars().count();
+
+        let mut line_len = 1;
+        let mut line = end_row;
+        while line >= 10 {
+            line /= 10;
+            line_len += 1;
+        }
+
+        let i = start_row.saturating_sub(1);
+        for (i, line) in content.lines().enumerate().skip(i).take(end_row - i + 1) {
+            println!("{:line_len$} {}", i + 1, line, line_len = line_len);
+            if i >= start_row && i <= end_row {
+                print!("{:line_len$} ", "", line_len = line_len);
+                let mut end_col = if i == end_row { end_col } else { line.chars().count() };
+                if i == start_row {
+                    print!("{:indent$}", "", indent = start_col);
+                    end_col -= start_col;
+                }
+                for _ in 0..end_col {
+                    print!("^");
+                }
+                println!();
+            }
+        }
+    }
+}