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/*
* Canonical Expressions
*
* AKA, simplified, normalized algebraic expressions.
*
*/
use crate::sexpr::SExpr;
pub enum NumericConstant {
Pi, // 3.141592...
E, // 2.718281...
Infinity,
}
#[derive(Clone, PartialEq)]
pub enum CNumber {
Integer(i64),
Rational(i64, u64),
// Float
// Constant
}
impl CNumber {
pub fn to_sexpr(&self) -> Result<SExpr, String> {
match self {
CNumber::Integer(v) => Ok(SExpr::SInteger(*v)),
CNumber::Rational(a, b) => Ok(SExpr::SList(vec![
SExpr::SBuiltin("/".to_string()),
SExpr::SInteger(*a),
SExpr::SInteger(*b as i64),
])),
}
}
}
#[derive(Clone, PartialEq)]
pub enum CExpr {
Symbol(String),
Number(CNumber),
Sum(Option<CNumber>, Vec<CExpr>),
Product(Option<CNumber>, Vec<CExpr>),
Power(Box<CExpr>, Box<CExpr>),
Factorial(Box<CExpr>),
UnaryFunction(String, Box<CExpr>),
// TODO: Infinity?
// TODO: Limit?
// TODO: Vector?
}
impl CExpr {
pub fn from_sexpr(sexpr: &SExpr) -> Result<CExpr, String> {
// not all cases are handled; some atoms are covered trivialy
match sexpr {
SExpr::SNull => Err("null not handled".to_string()),
SExpr::STrue | SExpr::SFalse => Err("booleans not handled".to_string()),
SExpr::SInteger(v) => Ok(CExpr::Number(CNumber::Integer(*v))),
SExpr::SFloat(v) => Err("floats not handled".to_string()),
SExpr::SBuiltin(v) => Ok(CExpr::Symbol(v.to_string())),
SExpr::SSymbol(v) => Err(format!("symbols (quoted identifiers) not handled: {}", v)),
SExpr::SIdentifier(v) => Ok(CExpr::Symbol(v.to_string())),
SExpr::SString(_) => Err("null not handled".to_string()),
SExpr::SList(_) => Err("null not handled".to_string()),
//SExpr::SList(l) => CExpr::from_sexpr_list(l),
}
}
/*
pub fn from_sexpr_list(list: &Vec<SExpr>) -> Result<CExpr, String> {
if list.is_empty() {
unimplemented!()
}
match list[0] {
SExpr::SBuiltin("+") => {
Ok(CExpr::Sum(
// XXX
None,
list[1..].iter().map(|v| CExpr::from_sexpr(v)).collect::<Result<Vec<SExpr>, String>>()?,
))
},
SExpr::SBuiltin("*") => {
},
SExpr::SBuiltin("^") => {
},
_ => {
unimplemented!()
}
}
}
*/
pub fn new_sum(list: &Vec<SExpr>) -> Result<CExpr, String> {
unimplemented!()
}
pub fn new_product(list: &Vec<SExpr>) -> Result<CExpr, String> {
unimplemented!()
}
pub fn to_sexpr(&self) -> Result<SExpr, String> {
match self {
CExpr::Symbol(s) => Ok(SExpr::SIdentifier(s.to_string())),
CExpr::Number(n) => n.to_sexpr(),
CExpr::Sum(n, l) => Ok(SExpr::SList(vec![
SExpr::SBuiltin("+".to_string()),
SExpr::SList(l.iter().map(|v| v.to_sexpr()).collect::<Result<Vec<SExpr>, String>>()?),
// XXX: n
])),
CExpr::Product(n, l) => Ok(SExpr::SList(vec![
SExpr::SBuiltin("*".to_string()),
SExpr::SList(l.iter().map(|v| v.to_sexpr()).collect::<Result<Vec<SExpr>, String>>()?),
// XXX: n
])),
CExpr::Power(a, b) => Ok(SExpr::SList(vec![
SExpr::SBuiltin("^".to_string()),
a.to_sexpr()?,
b.to_sexpr()?,
])),
CExpr::Factorial(v) => Ok(SExpr::SList(vec![
SExpr::SIdentifier("factorial".to_string()),
v.to_sexpr()?,
])),
CExpr::UnaryFunction(s, v) => Ok(SExpr::SList(vec![
SExpr::SIdentifier(s.to_string()),
v.to_sexpr()?,
])),
}
}
}
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