Remove line and block comments from a &str in Rust

main.rs

fn main() {
    let decommented = decomment(INPUT);
    println!("{}", decommented);
}

/// Removes both c-style block comments and c++-style line comments from a str.
pub fn decomment(src: &str) -> String {
    let mut in_line_comment = false;
    let mut in_block_comment = false;
    let mut decommented = String::with_capacity(src.len());
    let mut itr = src.chars().peekable();
    while let Some(ch) = itr.next() {
        match (ch, itr.peek()) {
            ('/', Some('*')) => {
                assert!(!in_line_comment);
                assert!(!in_block_comment);
                let _ = itr.next();
                in_block_comment = true;
            }
            ('*', Some('/')) => {
                assert!(in_block_comment);
                let _ = itr.next();
                in_block_comment = false;
            }
            ('/', Some('/')) => {
                assert!(!in_line_comment);
                assert!(!in_block_comment);
                let _ = itr.next();
                in_line_comment = true;
            }
            ('\r', Some('\n')) if in_line_comment => {
                let _ = itr.next();
                in_line_comment = false;
            }
            ('\n', _) if in_line_comment => {
                in_line_comment = false;
            }
            _ if in_block_comment || in_line_comment || ch.is_whitespace() => (),
            _ => decommented.push(ch),
        }
    }
    assert!(!in_block_comment);
    decommented
}

static INPUT: &str = r#"
{
    "SX130x_conf": { /* multiline
    * comment */ "spidev_path": "/dev/spidev0.0",
        "lorawan_public": true,
        "clksrc": 0,
        "antenna_gain": 0, /* antenna gain, in dBi */
        "full_duplex": false,
        "precision_timestamp": {
            "enable": false,
            "max_ts_metrics": 255,
            "nb_symbols": 1
        },
        "radio_0": {
            "enable": true,
            "type": "SX1250",
            "freq": 868100000,
            "rssi_offset": -215.4,
            "rssi_tcomp": {"coeff_a": 0, "coeff_b": 0, "coeff_c": 20.41, "coeff_d": 2162.56, "coeff_e": 0},
            "tx_enable": true,
            "tx_freq_min": 863000000,
            "tx_freq_max": 870000000,
            "tx_gain_lut":[
                {"rf_power": 12, "pa_gain": 1, "pwr_idx": 4},
                {"rf_power": 13, "pa_gain": 1, "pwr_idx": 5},
                {"rf_power": 14, "pa_gain": 1, "pwr_idx": 6},
                {"rf_power": 15, "pa_gain": 1, "pwr_idx": 7},
                {"rf_power": 16, "pa_gain": 1, "pwr_idx": 8},
                {"rf_power": 17, "pa_gain": 1, "pwr_idx": 9},
                {"rf_power": 18, "pa_gain": 1, "pwr_idx": 10},
                {"rf_power": 19, "pa_gain": 1, "pwr_idx": 11},
                {"rf_power": 20, "pa_gain": 1, "pwr_idx": 12},
                {"rf_power": 21, "pa_gain": 1, "pwr_idx": 13},
                {"rf_power": 22, "pa_gain": 1, "pwr_idx": 14},
                {"rf_power": 23, "pa_gain": 1, "pwr_idx": 15},
                {"rf_power": 24, "pa_gain": 1, "pwr_idx": 16},
                {"rf_power": 25, "pa_gain": 1, "pwr_idx": 17},
                {"rf_power": 26, "pa_gain": 1, "pwr_idx": 19},
                {"rf_power": 27, "pa_gain": 1, "pwr_idx": 20}
            ]
        },
        "radio_1": {
            "enable": true,
            "type": "SX1250",
            "freq": 869400000,
            "rssi_offset": -215.4,
            "rssi_tcomp": {"coeff_a": 0, "coeff_b": 0, "coeff_c": 20.41, "coeff_d": 2162.56, "coeff_e": 0},
            "tx_enable": false
        },
        "chan_multiSF_0": { //868.9, 25mW, 0.1% DC
            "enable": true,
            "radio": 1,
            "if": -500000
        },
        "chan_multiSF_1": { //869.1, 25mW, 0.1% DC
            "enable": true,
            "radio": 1,
            "if": -300000
        },
        "chan_multiSF_2": { //869.4, 500mW, 10% DC
            "enable": true,
            "radio": 1,
            "if": 0
        },
        "chan_multiSF_3": { //867.7, 25mW, 1% DC
            "enable": true,
            "radio": 0,
            "if": -400000
        },
        "chan_multiSF_4": { //867.9, 25mW, 1% DC
            "enable": true,
            "radio": 0,
            "if": -200000
        },
        "chan_multiSF_5": { //868.1, 25mW, 1% DC
            "enable": true,
            "radio": 0,
            "if": 0
        },
        "chan_multiSF_6": { //868.3, 25mW, 1% DC
            "enable": true,
            "radio": 0,
            "if": 200000
        },
        "chan_multiSF_7": { //868.5, 25mW, 1% DC
            "enable": true,
            "radio": 0,
            "if": 400000
        },
        "chan_Lora_std": {
            "enable": true,
            "radio": 1,
            "if": -200000,
            "bandwidth": 250000,
            "spread_factor": 7
        },
        "chan_FSK": {
            /* disabled */
            "enable": false,
            "radio": 0,
            "if": 300000,
            "bandwidth": 250000,
            "datarate": 100000
        }
    },
    "gateway_conf": {
        "gps_i2c_path": "/dev/i2c-1",
        "gateway_ID": "AA555A0000000000",
        /* change with default server address/ports */
        "server_address": "localhost",
        "serv_port_up": 1680,
        "serv_port_down": 1680,
        /* adjust the following parameters for your network */
        "keepalive_interval": 10,
        "stat_interval": 30,
        "push_timeout_ms": 100,
        /* forward only valid packets */
        "forward_crc_valid": true,
        "forward_crc_error": false,
        "forward_crc_disabled": false
    }
}
"#;