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