Merge pull request #137 from lixitrixi/rule-definition

Rule definition

conjure_oxide/src/lib.rs

@@ -1,6 +1,7 @@
 pub mod error;
 pub mod find_conjure;
 pub mod parse;
+pub mod rules;
 mod solvers;
 
 pub use conjure_core::ast; // re-export core::ast as conjure_oxide::ast

conjure_oxide/src/rules/mod.rs

@@ -0,0 +1,11 @@
+use conjure_core::ast::Expression;
+use conjure_core::rule::{Rule, RuleApplicationError};
+
+fn identity(expr: &Expression) -> Result<Expression, RuleApplicationError> {
+ Ok(expr.clone())
+}
+
+pub static IDENTITY_RULE: Rule = Rule {
+ name: "identity",
+ application: identity,
+};

crates/conjure_core/src/lib.rs

@@ -1,4 +1,5 @@
 pub mod ast;
+pub mod rule;
 
 pub mod solvers;
 pub use solvers::Solver;

crates/conjure_core/src/rule.rs

@@ -0,0 +1,36 @@
+use std::fmt::{self, Display, Formatter};
+
+use thiserror::Error;
+
+use crate::ast::Expression;
+
+#[derive(Debug, Error)]
+pub enum RuleApplicationError {
+ #[error("Rule is not applicable")]
+ RuleNotApplicable,
+}
+
+#[derive(Clone, Debug)]
+pub struct Rule<'a> {
+ pub name: &'a str,
+ pub application: fn(&Expression) -> Result<Expression, RuleApplicationError>,
+}
+
+impl<'a> Rule<'a> {
+ pub fn new(
+ name: &'a str,
+ application: fn(&Expression) -> Result<Expression, RuleApplicationError>,
+ ) -> Self {
+ Self { name, application }
+ }
+
+ pub fn apply(&self, expr: &Expression) -> Result<Expression, RuleApplicationError> {
+ (self.application)(expr)
+ }
+}
+
+impl<'a> Display for Rule<'a> {
+ fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+ write!(f, "{}", self.name)
+ }
+}