Grcov report - model.rs

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use std::cell::RefCell;

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use std::fmt::Debug;

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use std::sync::{Arc, RwLock};

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use derivative::Derivative;

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use serde::{Deserialize, Serialize};

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use serde_with::serde_as;

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use crate::ast::{DecisionVariable, Domain, Expression, Name, SymbolTable};

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use crate::context::Context;

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use crate::metadata::Metadata;

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/// Represents a computational model containing variables, constraints, and a shared context.

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///

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/// The `Model` struct holds a set of variables and constraints for manipulating and evaluating symbolic expressions.

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///

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/// # Fields

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/// - `variables`:

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///   - Type: `SymbolTable`

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///   - A table that links each variable's name to its corresponding `DecisionVariable`.

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///   - For example, the name `x` might be linked to a `DecisionVariable` that says `x` can only take values between 1 and 10.

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///

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/// - `constraints`:

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///   - Type: `Expression`

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///   - Represents the logical constraints applied to the model's variables.

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///   - Can be a single constraint or a combination of various expressions, such as logical operations (e.g., `AND`, `OR`),

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///     arithmetic operations (e.g., `SafeDiv`, `UnsafeDiv`), or specialized constraints like `SumEq`.

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///

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/// - `context`:

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///   - Type: `Arc<RwLock<Context<'static>>>`

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///   - A shared object that stores global settings and state for the model.

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///   - Can be safely read or changed by multiple parts of the program at the same time, making it good for multi-threaded use.

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///

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/// - `next_var`:

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///   - Type: `RefCell<i32>`

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///   - A counter used to create new, unique variable names.

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///   - Allows updating the counter inside the model without making the whole model mutable.

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///

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/// # Usage

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/// This struct is typically used to:

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/// - Define a set of variables and constraints for rule-based evaluation.

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/// - Have transformations, optimizations, and simplifications applied to it using a set of rules.

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#[serde_as]

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#[derive(Derivative, Clone, Debug, Serialize, Deserialize)]

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#[derivative(PartialEq, Eq)]

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pub struct Model {

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    #[serde_as(as = "Vec<(_, _)>")]

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    pub variables: SymbolTable,

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    pub constraints: Expression,

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    #[serde(skip)]

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    #[derivative(PartialEq = "ignore")]

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    pub context: Arc<RwLock<Context<'static>>>,

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    next_var: RefCell<i32>,

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impl Model {

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    pub fn new(

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        variables: SymbolTable,

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        constraints: Expression,

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        context: Arc<RwLock<Context<'static>>>,

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    ) -> Model {

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        Model {

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            variables,

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            constraints,

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            context,

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            next_var: RefCell::new(0),

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    pub fn new_empty(context: Arc<RwLock<Context<'static>>>) -> Model {

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        Model::new(

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            Default::default(),

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            Expression::And(Metadata::new(), Vec::new()),

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            context,

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    // Function to update a DecisionVariable based on its Name

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    pub fn update_domain(&mut self, name: &Name, new_domain: Domain) {

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        if let Some(decision_var) = self.variables.get_mut(name) {

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            decision_var.domain = new_domain;

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    pub fn get_domain(&self, name: &Name) -> Option<&Domain> {

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        self.variables.get(name).map(|v| &v.domain)

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    // Function to add a new DecisionVariable to the Model

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    pub fn add_variable(&mut self, name: Name, decision_var: DecisionVariable) {

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        self.variables.insert(name, decision_var);

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    pub fn get_constraints_vec(&self) -> Vec<Expression> {

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        match &self.constraints {

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            Expression::And(_, constraints) => constraints.clone(),

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            _ => vec![self.constraints.clone()],

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    pub fn set_constraints(&mut self, constraints: Vec<Expression>) {

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        if constraints.is_empty() {

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            self.constraints = Expression::And(Metadata::new(), Vec::new());

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        } else if constraints.len() == 1 {

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            self.constraints = constraints[0].clone();

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        } else {

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            self.constraints = Expression::And(Metadata::new(), constraints);

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    pub fn set_context(&mut self, context: Arc<RwLock<Context<'static>>>) {

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        self.context = context;

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    pub fn add_constraint(&mut self, expression: Expression) {

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        // ToDo (gs248) - there is no checking whatsoever

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        // We need to properly validate the expression but this is just for testing

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        let mut constraints = self.get_constraints_vec();

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        constraints.push(expression);

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        self.set_constraints(constraints);

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    pub fn add_constraints(&mut self, expressions: Vec<Expression>) {

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        let mut constraints = self.get_constraints_vec();

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        constraints.extend(expressions);

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        self.set_constraints(constraints);

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    /// Returns an arbitrary variable name that is not in the model.

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    pub fn gensym(&self) -> Name {

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        let num = *self.next_var.borrow();

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        *(self.next_var.borrow_mut()) += 1;

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        Name::MachineName(num) // incremented when inserted

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