Model builder pattern

src/common/ast/ast.rs

@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 pub struct Model {
  pub variables: HashMap<Name, DecisionVariable>,
  pub constraints: Vec<Expression>,

src/common/ast/mod.rs

@@ -1,2 +1,5 @@
 mod ast;
 pub use ast::*;
+
+mod model_builder;
+pub use model_builder::*;

src/common/ast/model_builder.rs

@@ -0,0 +1,48 @@
+use std::collections::HashMap;
+use super::ast::*;
+
+pub struct ModelBuilder {
+ pub variables: HashMap<Name, DecisionVariable>,
+ pub constraints: Vec<Expression>,
+}
+
+impl ModelBuilder {
+ pub fn new() -> ModelBuilder {
+ ModelBuilder {
+ variables: HashMap::new(),
+ constraints: Vec::new(),
+ }
+ }
+
+ pub fn add_constraint(mut self, constraint: Expression) -> Self {
+ self.constraints.push(constraint);
+ self
+ }
+
+ pub fn add_var(mut self, name: Name, domain: Domain) -> Self {
+ self.variables.insert(
+ name,
+ DecisionVariable {
+ domain,
+ },
+ );
+ self
+ }
+
+ pub fn add_var_str(mut self, name: &str, domain: Domain) -> Self {
+ self.variables.insert(
+ Name::UserName(String::from(name)),
+ DecisionVariable {
+ domain,
+ },
+ );
+ self
+ }
+
+ pub fn build(self) -> Model {
+ Model {
+ variables: self.variables,
+ constraints: self.constraints,
+ }
+ }
+}

tests/builder_tests.rs

@@ -0,0 +1,68 @@
+use std::collections::HashMap;
+
+use conjure_oxide::ast::*;
+
+#[test]
+fn abc_equality() {
+ let a = Name::UserName(String::from("a"));
+ let b = Name::UserName(String::from("b"));
+ let c = Name::UserName(String::from("c"));
+
+ let mut variables = HashMap::new();
+ variables.insert(
+ a.clone(),
+ DecisionVariable {
+ domain: Domain::IntDomain(vec![Range::Bounded(1, 3)]),
+ },
+ );
+ variables.insert(
+ b.clone(),
+ DecisionVariable {
+ domain: Domain::IntDomain(vec![Range::Bounded(1, 3)]),
+ },
+ );
+ variables.insert(
+ c.clone(),
+ DecisionVariable {
+ domain: Domain::IntDomain(vec![Range::Bounded(1, 3)]),
+ },
+ );
+
+ let m1 = Model {
+ variables,
+ constraints: vec![
+ Expression::Eq(
+ Box::new(Expression::Sum(vec![
+ Expression::Reference(a.clone()),
+ Expression::Reference(b.clone()),
+ Expression::Reference(c.clone()),
+ ])),
+ Box::new(Expression::ConstantInt(4)),
+ ),
+ Expression::Geq(
+ Box::new(Expression::Reference(a.clone())),
+ Box::new(Expression::Reference(b.clone())),
+ ),
+ ],
+ };
+
+ let m2 = ModelBuilder::new()
+ .add_var_str("a", Domain::IntDomain(vec![Range::Bounded(1, 3)]))
+ .add_var_str("b", Domain::IntDomain(vec![Range::Bounded(1, 3)]))
+ .add_var_str("c", Domain::IntDomain(vec![Range::Bounded(1, 3)]))
+ .add_constraint(Expression::Eq(
+ Box::new(Expression::Sum(vec![
+ Expression::Reference(a.clone()),
+ Expression::Reference(b.clone()),
+ Expression::Reference(c.clone()),
+ ])),
+ Box::new(Expression::ConstantInt(4)),
+ ))
+ .add_constraint(Expression::Geq(
+ Box::new(Expression::Reference(a.clone())),
+ Box::new(Expression::Reference(b.clone())),
+ ))
+ .build();
+
+ assert!(m1 == m2);
+}