113 lines
2.5 KiB
Rust
113 lines
2.5 KiB
Rust
use std::fmt::Display;
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pub type Variable = String;
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#[derive(Clone, Debug)]
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pub struct Module
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{
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pub clauses: Vec<Clause>,
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}
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#[derive(Clone, Debug)]
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pub struct Clause
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{
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pub head: Predicate,
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pub body: Option<Body>,
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}
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#[derive(Clone, Debug)]
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pub enum Body
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{
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Term(Predicate),
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And(Vec<Body>),
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Or(Vec<Body>),
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}
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#[derive(Clone, Debug, PartialEq)]
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pub enum Predicate
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{
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Variable(Variable), // Upercase variable like X
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Fixed(String, Vec<Predicate>),
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}
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impl Display for Body
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{
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
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{
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match self
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{
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Body::Term(predicate) => write!(f, "{}", predicate),
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Body::And(items) | Body::Or(items) =>
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{
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let len = items.len();
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for (i, item) in items.iter().enumerate()
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{
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write!(f, "{}", item)?;
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if i != len - 1
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{
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write!(f, ",")?;
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}
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}
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Ok(())
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}
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}
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}
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}
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impl Display for Predicate
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{
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
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{
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match self
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{
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Predicate::Variable(variable) => write!(f, "{}", variable),
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Predicate::Fixed(name, predicates) =>
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{
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write!(f, "{}", name)?;
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if !predicates.is_empty()
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{
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write!(f, "(")?;
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let len = predicates.len();
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for (i, predicate) in predicates.iter().enumerate()
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{
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write!(f, "{}", predicate)?;
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if i != len - 1
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{
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write!(f, ", ")?;
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}
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}
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write!(f, ")")
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}
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else
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{
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Ok(())
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}
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}
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}
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}
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}
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impl Display for Clause
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{
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
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{
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write!(f, "{}", self.head)?;
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self.body
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.as_ref()
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.map_or_else(|| Ok(()), |body| write!(f, ":- {}", body))?;
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write!(f, ".")
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}
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}
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impl Display for Module
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{
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
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{
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for clause in self.clauses.iter()
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{
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writeln!(f, "{}", clause)?;
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}
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Ok(())
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}
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}
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