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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Boolean logic
#[cfg(not(test))]
use cmp::{Eq, Ord, TotalOrd, Ordering};
use option::{None, Option, Some};
use from_str::FromStr;
/// Negation / inverse
pub fn not(v: bool) -> bool { !v }
/// Conjunction
pub fn and(a: bool, b: bool) -> bool { a && b }
/// Disjunction
pub fn or(a: bool, b: bool) -> bool { a || b }
/**
* Exclusive or
*
* Identical to `or(and(a, not(b)), and(not(a), b))`
*/
pub fn xor(a: bool, b: bool) -> bool { (a && !b) || (!a && b) }
/// Implication in the logic, i.e. from `a` follows `b`
pub fn implies(a: bool, b: bool) -> bool { !a || b }
/// true if truth values `a` and `b` are indistinguishable in the logic
pub fn eq(a: bool, b: bool) -> bool { a == b }
/// true if truth values `a` and `b` are distinguishable in the logic
pub fn ne(a: bool, b: bool) -> bool { a != b }
/// true if `v` represents truth in the logic
pub fn is_true(v: bool) -> bool { v }
/// true if `v` represents falsehood in the logic
pub fn is_false(v: bool) -> bool { !v }
/// Parse logic value from `s`
impl FromStr for bool {
fn from_str(s: &str) -> Option<bool> {
if s == "true" {
Some(true)
} else if s == "false" {
Some(false)
} else {
None
}
}
}
/// Convert `v` into a string
pub fn to_str(v: bool) -> ~str { if v { ~"true" } else { ~"false" } }
/**
* Iterates over all truth values by passing them to `blk` in an unspecified
* order
*/
pub fn all_values(blk: &fn(v: bool)) {
blk(true);
blk(false);
}
/// converts truth value to an 8 bit byte
#[inline(always)]
pub fn to_bit(v: bool) -> u8 { if v { 1u8 } else { 0u8 } }
#[cfg(not(test))]
impl Ord for bool {
#[inline(always)]
fn lt(&self, other: &bool) -> bool { to_bit(*self) < to_bit(*other) }
#[inline(always)]
fn le(&self, other: &bool) -> bool { to_bit(*self) <= to_bit(*other) }
#[inline(always)]
fn gt(&self, other: &bool) -> bool { to_bit(*self) > to_bit(*other) }
#[inline(always)]
fn ge(&self, other: &bool) -> bool { to_bit(*self) >= to_bit(*other) }
}
#[cfg(not(test))]
impl TotalOrd for bool {
#[inline(always)]
fn cmp(&self, other: &bool) -> Ordering { to_bit(*self).cmp(&to_bit(*other)) }
}
#[cfg(not(test))]
impl Eq for bool {
#[inline(always)]
fn eq(&self, other: &bool) -> bool { (*self) == (*other) }
#[inline(always)]
fn ne(&self, other: &bool) -> bool { (*self) != (*other) }
}
#[cfg(test)]
mod tests {
use super::*;
use prelude::*;
#[test]
fn test_bool_from_str() {
do all_values |v| {
assert!(Some(v) == FromStr::from_str(to_str(v)))
}
}
#[test]
fn test_bool_to_str() {
assert!(to_str(false) == ~"false");
assert!(to_str(true) == ~"true");
}
#[test]
fn test_bool_to_bit() {
do all_values |v| {
assert!(to_bit(v) == if is_true(v) { 1u8 } else { 0u8 });
}
}
#[test]
fn test_bool_ord() {
assert!(true > false);
assert!(!(false > true));
assert!(false < true);
assert!(!(true < false));
assert!(false <= false);
assert!(false >= false);
assert!(true <= true);
assert!(true >= true);
assert!(false <= true);
assert!(!(false >= true));
assert!(true >= false);
assert!(!(true <= false));
}
#[test]
fn test_bool_totalord() {
assert_eq!(true.cmp(&true), Equal);
assert_eq!(false.cmp(&false), Equal);
assert_eq!(true.cmp(&false), Greater);
assert_eq!(false.cmp(&true), Less);
}
}
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