Function plan_case

src/sql/src/plan/query.rs:5744–5781

(
    ecx: &ExprContext,
    operand: &'a Option<Box<Expr<Aug>>>,
    conditions: &'a [Expr<Aug>],
    results: &'a [Expr<Aug>],
    else_result: &'a Option<Box<Expr<Aug>>>,
)

}

fn plan_case<'a>(
    ecx: &ExprContext,
    operand: &'a Option<Box<Expr<Aug>>>,
    conditions: &'a [Expr<Aug>],
    results: &'a [Expr<Aug>],
    else_result: &'a Option<Box<Expr<Aug>>>,
) -> Result<HirScalarExpr, PlanError> {
    let mut cond_exprs = Vec::new();
    let mut result_exprs = Vec::new();
    for (c, r) in conditions.iter().zip_eq(results) {
        let c = match operand {
            Some(operand) => operand.clone().equals(c.clone()),
            None => c.clone(),
        };
        let cexpr = plan_expr(ecx, &c)?.type_as(ecx, &SqlScalarType::Bool)?;
        cond_exprs.push(cexpr);
        result_exprs.push(r);
    }
    result_exprs.push(match else_result {
        Some(else_result) => else_result,
        None => &Expr::Value(Value::Null),
    });
    let mut result_exprs = coerce_homogeneous_exprs(
        &ecx.with_name("CASE"),
        plan_exprs(ecx, &result_exprs)?,
        None,
    )?;
    let mut expr = result_exprs.pop().unwrap();
    assert_eq!(cond_exprs.len(), result_exprs.len());
    for (cexpr, rexpr) in cond_exprs
        .into_iter()
        .rev()
        .zip_eq(result_exprs.into_iter().rev())
    {
        expr = HirScalarExpr::if_then_else(cexpr, rexpr, expr);
    }
    Ok(expr)
}

fn plan_literal<'a>(l: &'a Value) -> Result<CoercibleScalarExpr, PlanError> {
    let (datum, scalar_type) = match l {