101 lines
2.3 KiB
Rust
101 lines
2.3 KiB
Rust
// -*- rust -*-
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// NB: transitionary, de-mode-ing.
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#[forbid(deprecated_mode)];
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#[forbid(deprecated_pattern)];
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//! Boolean logic
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use cmp::Eq;
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/// Negation / inverse
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pub pure fn not(v: bool) -> bool { !v }
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/// Conjunction
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pub pure fn and(a: bool, b: bool) -> bool { a && b }
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/// Disjunction
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pub pure 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 pure 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 pure 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 pure 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 pure 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 pure fn is_true(v: bool) -> bool { v }
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/// true if `v` represents falsehood in the logic
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pub pure fn is_false(v: bool) -> bool { !v }
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/// Parse logic value from `s`
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pub pure fn from_str(s: &str) -> Option<bool> {
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if s == "true" {
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Some(true)
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} else if s == "false" {
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Some(false)
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} else {
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None
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}
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}
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/// Convert `v` into a string
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pub pure 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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pub pure fn to_bit(v: bool) -> u8 { if v { 1u8 } else { 0u8 } }
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#[cfg(notest)]
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impl bool : cmp::Eq {
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pure fn eq(&self, other: &bool) -> bool { (*self) == (*other) }
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pure fn ne(&self, other: &bool) -> bool { (*self) != (*other) }
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}
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#[test]
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pub fn test_bool_from_str() {
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do all_values |v| {
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assert Some(v) == from_str(bool::to_str(v))
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}
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}
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#[test]
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pub fn test_bool_to_str() {
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assert to_str(false) == ~"false";
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assert to_str(true) == ~"true";
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}
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#[test]
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pub fn test_bool_to_bit() {
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do all_values |v| {
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assert to_bit(v) == if is_true(v) { 1u8 } else { 0u8 };
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}
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}
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// Local Variables:
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// mode: rust;
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// fill-column: 78;
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// indent-tabs-mode: nil
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// c-basic-offset: 4
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// buffer-file-coding-system: utf-8-unix
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// End:
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