Working with references in Rust

main.rs

use std::cell::RefCell;
use std::rc::Rc;

struct InternalWriter {
    indent_count: u32,
    stringwriter: String
}

impl InternalWriter {
    fn new() -> InternalWriter {
        InternalWriter {
            indent_count: 0,
            stringwriter: String::new()
        }
    }
}

#[derive(Clone)]
struct Writer {
    internalwriter: Rc<RefCell<InternalWriter>>
}

impl Writer {
    fn new() -> Writer {
        Writer {
            internalwriter: Rc::new(RefCell::new(InternalWriter::new()))
        }
    }

    fn write(&self, s: &str) {
        let mut writer = self.internalwriter.borrow_mut();

        for _ in 0..writer.indent_count {
            writer.stringwriter.push_str("    ");
        }
        writer.stringwriter.push_str(s);
    }

    fn writeline(&self, s: &str) {
        self.write(s);
        self.write("\n");
        // self.write(format!("{}{}", s, "\n").as_str());
    }

    fn indent(&self) {
        let mut writer = self.internalwriter.borrow_mut();
        writer.indent_count += 1;
    }

    fn dedent(&self) {
        let mut writer = self.internalwriter.borrow_mut();
        writer.indent_count -= 1;
    }

    fn context(&self) -> Context {
        Context::new(self.clone())
    }
}

struct Context {
    writer: Writer
}

impl Context {
    // Open context
    fn new(writer: Writer) -> Context {
        writer.writeline("{");
        writer.indent();

        Context {
            writer: writer
        }
    }
}

// Close context
impl Drop for Context {
    fn drop(&mut self) {
        self.writer.dedent();
        self.writer.writeline("}");
    }
}

fn main() {
    let writer = Writer::new();

    writer.writeline("let x = 1;");
    writer.writeline("let y = 2;");

    { // Opens context
        let _context = writer.context(); //Context::new(writer.clone());
        writer.writeline("let z = 3;");
    } // Closes context

    {
        let iwriter = writer.internalwriter.borrow();
        println!("{}", iwriter.stringwriter);

        // Output:
        // let x = 1;
        // let y = 2;
        // {
        //     let z = 3;
        // }
    }
}