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extern crate modelica_parser;
use std::clone::Clone;
use std::collections::HashMap;
use std::collections::HashSet;
use self::modelica_parser::ast::*;
//// Helpers
pub trait ModelicaModelExt {
fn get_constant_vars(&self) -> HashMap<String,Option<Expr>>;
fn get_free_vars(&self) -> Vec<String>;
fn solve_for(&self, indep_vars: Vec<String>, dep_vars: Vec<String>) -> Result<ModelicaModel,String>;
}
impl ModelicaModelExt for ModelicaModel {
fn get_constant_vars(&self) -> HashMap<String,Option<Expr>> {
let mut binds = HashMap::new();
// XXX: actually implement this...
for c in &self.components {
match c.prefix {
Some(ComponentPrefix::Constant) => { binds.insert(c.name.clone(), Some(Expr::Integer(123))); },
Some(ComponentPrefix::Parameter) => { binds.insert(c.name.clone(), Some(Expr::Float(4.56))); },
_ => (),
}
}
binds
}
// This crude function finds "unbound" variables: those which are not constants, parameters, or
// the sole element on the LHS of an equation.
// Bugs:
// if a var is on LHS and RHS of same equation
fn get_free_vars(&self) -> Vec<String> {
// Start with components, and remove constants and parameters
let vars = self.components.iter().filter(|v| match v.prefix {
Some(ComponentPrefix::Constant) | Some(ComponentPrefix::Parameter) => false,
_ => true,
});
// Remove LHS (bound) vars
let mut outputs = vec![];
for eq in self.equations.iter() {
// TODO:
if let Expr::Ident(ref symb) = eq.lhs {
outputs.push(symb.to_string());
}
}
let vars = vars.filter(|v| !outputs.contains(&v.name));
vars.map(|c| c.name.clone()).collect()
}
// V variables
// Q constants (become kwargs)
// P bound vars (independent, inputs/passed, become like constants)
// M unknowns (dependent, outputs)
// N' total equations
// N equations with unknowns
//
// TODO: allow passing in Q
fn solve_for(&self, indep_vars: Vec<String>, dep_vars: Vec<String>) -> Result<ModelicaModel,String> {
let constants = self.get_constant_vars();
let mut all_vars: HashSet<String> = HashSet::new();
for eqn in &self.equations {
all_vars.extend(eqn.identifiers());
}
// check that all dep and indep are in equations
let mut passed_vars = indep_vars.clone();
passed_vars.extend(dep_vars.clone());
for var in passed_vars {
if !all_vars.contains(&var) {
return Err(format!("Variable not found in equations: {}", var));
}
}
// check that V = Q + P + M
if all_vars.len() != (constants.len() + indep_vars.len() + dep_vars.len()) {
return Err(format!("Variable counts don't add up (V={} Q={} P={} M={})",
all_vars.len(),
constants.len(),
indep_vars.len(),
dep_vars.len()));
}
// check that all constants are bound and simple
for (name, value) in &constants {
match *value {
None => return Err(format!("UnderSpecifiedConstant: {}", name)),
Some(Expr::Integer(_)) | Some(Expr::Float(_)) => (), // Ok,
Some(_) => return Err(format!("NaiveImplementation: can't handle constant: {}", name)),
}
}
// check that there is a depdendent variable in each equation
for eqn in &self.equations {
if intersect_strings(&dep_vars, &eqn.identifiers()).len() == 0 {
return Err("NaiveImplementation/OverConstrained: at least one equation is missing a dependent variable".to_string());
}
}
// check N >= M
if self.equations.len() < dep_vars.len() {
return Err("UnderConstrained: more dependent variables than equations".to_string());
}
println!("Soliving for {:?} in terms of params {:?} and constants {:?}, with {} equations",
dep_vars, indep_vars, constants, self.equations.len());
let mut unsolved_eqns = self.equations.clone();
let mut solved: Vec<SimpleEquation> = vec![];
let mut unsolved_vars = dep_vars.clone();
while unsolved_eqns.len() > 0 {
let next_i = unsolved_eqns
.iter()
.position(|ref x| intersect_strings(&unsolved_vars, &x.identifiers()).len() == 1);
let eqn = match next_i {
None => { return Err("NaiveImplementation (or poor equation selection?)".to_string()); },
Some(i) => unsolved_eqns.remove(i),
};
let ref var = intersect_strings(&unsolved_vars, &eqn.identifiers())[0];
let eqn = eqn.rebalance_for(var.to_string()).expect("rebalance for success");
solved.push(eqn);
let var_i = unsolved_vars.iter().position(|ref x| x == &var).unwrap();
unsolved_vars.remove(var_i);
};
// TODO: sort output equations by LHS
Ok(ModelicaModel{
name: self.name.clone(),
description: self.description.clone(),
components: self.components.clone(),
connections: vec![],
equations: solved,
})
}
}
fn intersect_strings(a: &Vec<String>, b: &Vec<String>) -> Vec<String> {
let mut both = vec![];
for e in a {
if b.contains(&e) {
both.push(e.clone());
}
}
both
}
pub trait SimpleEquationExt {
fn rebalance_for(&self, ident: String) -> Result<SimpleEquation,String>;
fn simplify_lhs(&self, ident: &str) -> Result<SimpleEquation,String>;
}
impl SimpleEquationExt for SimpleEquation {
fn rebalance_for(&self, ident: String) -> Result<SimpleEquation,String> {
let lvars = self.lhs.identifiers();
let rvars = self.rhs.identifiers();
let ret = match (lvars.contains(&ident), rvars.contains(&ident)) {
(true, true) => Err("SymbolicError: NaiveImplementation".to_string()),
(false, false) => Err("SymbolicError: VariableNotFound".to_string()),
(true, false) => self.simplify_lhs(&ident),
(false, true) =>
SimpleEquation{lhs: self.rhs.clone(),
rhs: self.lhs.clone()}.simplify_lhs(&ident),
};
match ret {
Ok(eqn) => {
if eqn.rhs.contains(&ident) {
Err("SymbolicError: NaiveImplementation".to_string())
} else {
Ok(eqn)
}},
Err(_) => ret,
}
}
fn simplify_lhs(&self, ident: &str) -> Result<SimpleEquation,String> {
use modelica_parser::ast::Expr::*;
use modelica_parser::ast::BinOperator::*;
match self.lhs {
Ident(ref s) if s == ident => Ok((*self).clone()),
Ident(_) | Integer(_) | Float(_) | Boolean(_) | StringLiteral(_) =>
Err("SymbolicError: InternalError: expected var on LHS".to_string()),
Der(_) | MathUnaryExpr(_,_) | Sign(_) | Array(_) =>
Err("SymbolicError: NaiveImplementation: can't simplify".to_string()),
// TODO: create a macro for the below...
BinExpr(Multiply, ref a, ref b) if a.contains(ident) => {
SimpleEquation{
lhs: *a.clone(),
rhs: BinExpr(Divide, Box::new(self.rhs.clone()), b.clone())}.simplify_lhs(&ident) },
BinExpr(Multiply, ref a, ref b) if b.contains(ident) => {
SimpleEquation{
lhs: *b.clone(),
rhs: BinExpr(Divide, Box::new(self.rhs.clone()), a.clone())}.simplify_lhs(&ident) },
BinExpr(Divide, ref a, ref b) if a.contains(ident) => {
SimpleEquation{
lhs: *a.clone(),
rhs: BinExpr(Multiply, Box::new(self.rhs.clone()), b.clone())}.simplify_lhs(&ident) },
BinExpr(Divide, ref a, ref b) if b.contains(ident) => {
SimpleEquation{
lhs: *b.clone(),
rhs: BinExpr(Divide, a.clone(), Box::new(self.rhs.clone()))}.simplify_lhs(&ident) },
BinExpr(Add, ref a, ref b) if a.contains(ident) => {
SimpleEquation{
lhs: *a.clone(),
rhs: BinExpr(Subtract, Box::new(self.rhs.clone()), b.clone())}.simplify_lhs(&ident) },
BinExpr(Add, ref a, ref b) if b.contains(ident) => {
SimpleEquation{
lhs: *b.clone(),
rhs: BinExpr(Subtract, Box::new(self.rhs.clone()), a.clone())}.simplify_lhs(&ident) },
BinExpr(Subtract, ref a, ref b) if a.contains(ident) => {
SimpleEquation{
lhs: *a.clone(),
rhs: BinExpr(Add, Box::new(self.rhs.clone()), b.clone())}.simplify_lhs(&ident) },
BinExpr(Subtract, ref a, ref b) if b.contains(ident) => {
SimpleEquation{
lhs: *b.clone(),
rhs: BinExpr(Subtract, a.clone(), Box::new(self.rhs.clone()))}.simplify_lhs(&ident) },
BinExpr(_, _, _) => Err("SymbolicError: NotImplemented BinOperator (or else couldn't find var...)".to_string()),
// in case we add opers: _ => Err("NotImplemented".to_string()),
}
}
}
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