Function resolve_func

src/sql/src/plan/query.rs:5645–5684

Resolves the name to a set of function implementations. If the name does not specify a known built-in function, returns an error.

(
    ecx: &ExprContext,
    name: &ResolvedItemName,
    args: &mz_sql_parser::ast::FunctionArgs<Aug>,
)

///
/// If the name does not specify a known built-in function, returns an error.
pub fn resolve_func(
    ecx: &ExprContext,
    name: &ResolvedItemName,
    args: &mz_sql_parser::ast::FunctionArgs<Aug>,
) -> Result<&'static Func, PlanError> {
    if let Ok(i) = ecx.qcx.scx.get_item_by_resolved_name(name) {
        if let Ok(f) = i.func() {
            return Ok(f);
        }
    }

    // Couldn't resolve function with this name, so generate verbose error
    // message.
    let cexprs = match args {
        mz_sql_parser::ast::FunctionArgs::Star => vec![],
        mz_sql_parser::ast::FunctionArgs::Args { args, order_by } => {
            if !order_by.is_empty() {
                sql_bail!(
                    "ORDER BY specified, but {} is not an aggregate function",
                    name
                );
            }
            plan_exprs(ecx, args)?
        }
    };

    let arg_types: Vec<_> = cexprs
        .into_iter()
        .map(|ty| match ecx.scalar_type(&ty) {
            CoercibleScalarType::Coerced(ty) => ecx.humanize_sql_scalar_type(&ty, false),
            CoercibleScalarType::Record(_) => "record".to_string(),
            CoercibleScalarType::Uncoerced => "unknown".to_string(),
        })
        .collect();

    Err(PlanError::UnknownFunction {
        name: name.to_string(),
        arg_types,
    })
}

fn plan_is_expr<'a>(
    ecx: &ExprContext,