Using nom for parsing Json path

Cargo.toml

[package]
name = "nom-test"
version = "0.1.0"
authors = ["ducaale <sharaf.13@hotmail.com>"]
edition = "2018"

[dependencies]
nom="6"

main.rs

use nom::{IResult, combinator::map};
use nom::combinator::recognize;
use nom::bytes::complete::{take_while, take_till1, tag};
use nom::sequence::{preceded, pair, delimited};
use nom::character::complete::{satisfy, char};
use nom::multi::many0;
use nom::branch::alt;

fn main() {
    let input = "key.abc[hello.everyone.3.2][].world";
    json_path(input).unwrap();
    println!("Hello, world!");
}

fn start_identifier(c: char) -> bool {
    c.is_ascii_alphabetic() || c == '$' || c == '_'
}

fn part_identifier(c: char) -> bool {
    c.is_ascii_alphanumeric() || c == '$' || c == '_'
}

fn valid_identifier(input: &str) -> IResult<&str, &str> {
    recognize(
        pair(
            satisfy(start_identifier),
            take_while(part_identifier)
        )
    )
    (input)
}

fn dot_access(input: &str) -> IResult<&str, &str> {
    preceded(char('.'), valid_identifier)(input)
}

fn bracket_access(input: &str) -> IResult<&str, &str> {
    delimited(char('['), take_till1(|c| c == ']'), char(']'))(input)
}

fn array_access(input: &str) -> IResult<&str, &str> {
    tag("[]")(input)
}

fn json_path(input: &str) -> IResult<&str, Vec<&str>> {
    let parser = pair(
        valid_identifier,
        many0(alt((dot_access, bracket_access, array_access)))
    );

    map(parser, |(head, mut tail)| {
        let mut t = vec![head];
        t.append(&mut tail);
        t
    })(input)
}

#[test]
fn test_bool() {
    let input = "key.abc[hello\\=world][].world";
    assert_eq!(
        json_path(input),
        Ok(("", vec!["key", "abc", "hello\\=world", "[]", "world"]))
    );
}