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//! Static analysis - compile time expression evaluation
use crate::ast::pl::{BinOp, Expr, ExprKind, Literal, UnOp};
pub fn static_analysis(expr: Expr) -> Expr {
// let is_const = match &expr.kind {
// ExprKind::Ident(_) => Some(false),
// ExprKind::Literal(_) => Some(true),
// ExprKind::Pipeline(pipeline) => pipeline.exprs.iter().map(|e| &e.is_const).all_true(),
// ExprKind::List(items) => items.iter().map(|e| &e.is_const).all_true(),
// ExprKind::Range(r) => {
// let exprs = r.start.iter().chain(r.end.iter());
// exprs.map(|e| &e.is_const).all_true()
// }
// ExprKind::Binary { left, op: _, right } => {
// let exprs = [left, right];
// exprs.iter().map(|e| &e.is_const).all_true()
// }
// ExprKind::Unary { op: _, expr } => expr.is_const.clone(),
// _ => None,
// };
let kind = eval(expr.kind);
Expr { kind, ..expr }
}
fn eval(kind: ExprKind) -> ExprKind {
match kind {
ExprKind::Unary { op, expr } => {
let res = if let ExprKind::Literal(lit) = &expr.kind {
match (op, lit) {
(UnOp::Not, Literal::Boolean(val)) => Some(Literal::Boolean(!val)),
(UnOp::Neg, Literal::Integer(val)) => Some(Literal::Integer(-val)),
(UnOp::Neg, Literal::Float(val)) => Some(Literal::Float(-val)),
_ => None,
}
} else {
None
};
if let Some(lit) = res {
ExprKind::Literal(lit)
} else {
ExprKind::Unary { op, expr }
}
}
ExprKind::Binary { left, op, right } => {
let res = if let (ExprKind::Literal(left), ExprKind::Literal(right)) =
(&left.kind, &right.kind)
{
match (op, left, right) {
(BinOp::Mul, Literal::Integer(left), Literal::Integer(right)) => {
Some(Literal::Integer(left * right))
}
(BinOp::Mul, Literal::Float(left), Literal::Float(right)) => {
Some(Literal::Float(left * right))
}
(BinOp::Div, Literal::Integer(left), Literal::Integer(right)) => {
Some(Literal::Integer(left / right))
}
(BinOp::Div, Literal::Float(left), Literal::Float(right)) => {
Some(Literal::Float(left / right))
}
(BinOp::Mod, Literal::Integer(left), Literal::Integer(right)) => {
Some(Literal::Integer(left % right))
}
(BinOp::Mod, Literal::Float(left), Literal::Float(right)) => {
Some(Literal::Float(left % right))
}
(BinOp::Add, Literal::Integer(left), Literal::Integer(right)) => {
Some(Literal::Integer(left + right))
}
(BinOp::Add, Literal::Float(left), Literal::Float(right)) => {
Some(Literal::Float(left + right))
}
(BinOp::Sub, Literal::Integer(left), Literal::Integer(right)) => {
Some(Literal::Integer(left - right))
}
(BinOp::Sub, Literal::Float(left), Literal::Float(right)) => {
Some(Literal::Float(left - right))
}
(BinOp::Eq, left, right) => {
// don't eval comparisons between different types of literals
if left.as_ref() != right.as_ref() {
None
} else {
Some(Literal::Boolean(left == right))
}
}
(BinOp::Ne, left, right) => {
// don't eval comparisons between different types of literals
if left.as_ref() != right.as_ref() {
None
} else {
Some(Literal::Boolean(left == right))
}
}
(BinOp::Gt, _, _) => None,
(BinOp::Lt, _, _) => None,
(BinOp::Gte, _, _) => None,
(BinOp::Lte, _, _) => None,
(BinOp::And, Literal::Boolean(left), Literal::Boolean(right)) => {
Some(Literal::Boolean(*left && *right))
}
(BinOp::Or, Literal::Boolean(left), Literal::Boolean(right)) => {
Some(Literal::Boolean(*left || *right))
}
_ => None,
}
} else {
None
};
if let Some(lit) = res {
ExprKind::Literal(lit)
} else if let (BinOp::Coalesce, ExprKind::Literal(Literal::Null)) = (op, &left.kind) {
right.kind
} else {
ExprKind::Binary { left, op, right }
}
}
ExprKind::Switch(items) => {
let mut res = Vec::with_capacity(items.len());
for item in items {
if let ExprKind::Literal(Literal::Boolean(condition)) = item.condition.kind {
if condition {
res.push(item);
break;
} else {
// this case can be removed
continue;
}
} else {
res.push(item);
}
}
if res.is_empty() {
return ExprKind::Literal(Literal::Null);
}
if res.len() == 1 {
let is_true = matches!(
res[0].condition.kind,
ExprKind::Literal(Literal::Boolean(true))
);
if is_true {
return res.remove(0).value.kind;
}
}
ExprKind::Switch(res)
}
k => k,
}
}