prometheus-parser 0.4.3-alpha9

a Rust library for parsing and validating Prometheus query expressions
Documentation 
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// (C) Copyright 2019-2020 Hewlett Packard Enterprise Development LP

use std::env;

use prometheus_parser;

use prometheus_parser::ReturnKind;

fn main() {
    let args: Vec<String> = env::args().collect();

    let expr = &args[1];
    let label = &args[2];
    let res = prometheus_parser::parse_expr(expr);

    match res {
        Ok(r) => {
            let return_value = r.return_value();

            if let ReturnKind::Unknown(cause) = &return_value.kind {
                println!("note: expression return type is unknown, result may be inaccurate");
                println!("  reason:     {}", cause.message);
                println!("  expression: {}", cause.expression);
                println!();
            }

            if let Some(drops) = return_value.drops(label) {
                println!("label '{}' is dropped:\n", label);

                if let Some(span) = drops.span {
                    println!("{}", expr);
                    println!(
                        "{}{}",
                        " ".repeat(span.start),
                        "-".repeat(span.end - span.start)
                    );
                }

                println!();
                println!("parent expression: {}", drops.expression);
            } else {
                println!("label '{}' is not dropped", label);
            }
        }
        Err(e) => {
            eprintln!("error: {}", e);
        }
    };
}