monty 0.0.21

A sandboxed, snapshotable Python interpreter written in Rust.
Documentation 
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//! Implementation of the chr() builtin function.

use crate::{
    args::ArgValues,
    bytecode::VM,
    defer_drop,
    exception_private::{ExcType, RunResult, SimpleException},
    types::str::allocate_char,
    value::Value,
};

/// Implementation of the chr() builtin function.
///
/// Returns a string representing a character whose Unicode code point is the integer.
/// The valid range for the argument is from 0 through 1,114,111 (0x10FFFF).
pub fn builtin_chr(vm: &mut VM<'_>, args: ArgValues) -> RunResult<Value> {
    let value = args.get_one_arg("chr", vm.heap)?;
    defer_drop!(value, vm);

    match value {
        Value::Int(n) => {
            if *n < 0 || *n > 0x0010_FFFF {
                Err(SimpleException::new_msg(ExcType::ValueError, "chr() arg not in range(0x110000)").into())
            } else if let Some(c) = char::from_u32(
                #[expect(
                    clippy::cast_possible_truncation,
                    clippy::cast_sign_loss,
                    reason = "range of n already validated in the first if condition"
                )]
                {
                    *n as u32
                },
            ) {
                Ok(allocate_char(c, vm.heap))
            } else {
                // This shouldn't happen for valid Unicode range, but handle it
                Err(SimpleException::new_msg(ExcType::ValueError, "chr() arg not in range(0x110000)").into())
            }
        }
        Value::Bool(b) => {
            // bool is subclass of int
            let c = if *b { '\x01' } else { '\x00' };
            Ok(allocate_char(c, vm.heap))
        }
        _ => {
            let type_name = value.py_type_name(vm);
            Err(SimpleException::new_msg(
                ExcType::TypeError,
                format!("an integer is required (got type {type_name})"),
            )
            .into())
        }
    }
}