openethereum/util/src/from_json.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! Coversion from json.
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use standard::*;
use bigint::prelude::*;
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#[macro_export]
macro_rules! xjson {
( $x:expr ) => {
FromJson::from_json($x)
}
}
/// Trait allowing conversion from a JSON value.
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pub trait FromJson {
/// Convert a JSON value to an instance of this type.
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fn from_json(json: &Json) -> Self;
}
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impl FromJson for U256 {
fn from_json(json: &Json) -> Self {
match *json {
Json::String(ref s) => {
if s.len() >= 2 && &s[0..2] == "0x" {
FromStr::from_str(&s[2..]).unwrap_or_else(|_| Default::default())
} else {
Uint::from_dec_str(s).unwrap_or_else(|_| Default::default())
}
},
Json::U64(u) => From::from(u),
Json::I64(i) => From::from(i as u64),
_ => Uint::zero(),
}
}
}