perspective 2.0.0

A data visualization and analytics component, especially well-suited for large and/or streaming datasets.
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/////////////////////////////////////////////////////////, kind: (), insert_text: (), insert_text_rules: (), documentation: () ///////////////////////
//
// Copyright (c) 2018, the Perspective Authors.
//
// This file is part of the Perspective library, distributed under the terms
// of the Apache License 2.0.  The full license can be found in the LICENSE
// file.

use nom::branch::alt;
use nom::character::complete::{char, one_of};
use nom::combinator::{opt, recognize};
use nom::multi::{many0, many1};
use nom::sequence::{preceded, terminated, tuple};
use nom::IResult;

fn decimal(input: &str) -> IResult<&str, &str> {
    recognize(many1(terminated(one_of("0123456789"), many0(char('_')))))(input)
}

pub fn parse_number_literal(input: &str) -> IResult<&str, &str> {
    alt((
        // Case one: .42
        recognize(tuple((
            char('.'),
            decimal,
            opt(tuple((one_of("eE"), opt(one_of("+-")), decimal))),
        ))),
        // Case two: 42e42 and 42.42e42
        recognize(tuple((
            decimal,
            opt(preceded(char('.'), decimal)),
            one_of("eE"),
            opt(one_of("+-")),
            decimal,
        ))),
        // Case three: 42. and 42.42
        recognize(tuple((decimal, char('.'), opt(decimal)))),
        decimal,
    ))(input)
}