name.rs

#[cfg(feature = "dtype-struct")]
use polars_utils::pl_str::PlSmallStr;

use super::*;

/// Specialized expressions for modifying the name of existing expressions.
pub struct ExprNameNameSpace(pub(crate) Expr);

impl ExprNameNameSpace {
    /// Keep the original root name
    ///
    /// ```rust,no_run
    /// # use polars_core::prelude::*;
    /// # use polars_plan::prelude::*;
    /// fn example(df: LazyFrame) -> LazyFrame {
    ///     df.select([
    /// // even thought the alias yields a different column name,
    /// // `keep` will make sure that the original column name is used
    ///         col("*").alias("foo").name().keep()
    /// ])
    /// }
    /// ```
    pub fn keep(self) -> Expr {
        Expr::KeepName(Arc::new(self.0))
    }

    /// Define an alias by mapping a function over the original root column name.
    pub fn map(self, function: PlanCallback<PlSmallStr, PlSmallStr>) -> Expr {
        Expr::RenameAlias {
            expr: Arc::new(self.0),
            function: RenameAliasFn::Map(function),
        }
    }

    /// Add a prefix to the root column name.
    pub fn prefix(self, prefix: &str) -> Expr {
        Expr::RenameAlias {
            expr: Arc::new(self.0),
            function: RenameAliasFn::Prefix(prefix.into()),
        }
    }

    /// Add a suffix to the root column name.
    pub fn suffix(self, suffix: &str) -> Expr {
        Expr::RenameAlias {
            expr: Arc::new(self.0),
            function: RenameAliasFn::Suffix(suffix.into()),
        }
    }

    /// Replace matching string pattern in the root column name with a new value.
    #[cfg(feature = "regex")]
    pub fn replace(self, pattern: &str, value: &str, literal: bool) -> Expr {
        Expr::RenameAlias {
            expr: Arc::new(self.0),
            function: RenameAliasFn::Replace {
                pattern: pattern.into(),
                value: value.into(),
                literal,
            },
        }
    }

    /// Update the root column name to use lowercase characters.
    #[allow(clippy::wrong_self_convention)]
    pub fn to_lowercase(self) -> Expr {
        Expr::RenameAlias {
            expr: Arc::new(self.0),
            function: RenameAliasFn::ToLowercase,
        }
    }

    /// Update the root column name to use uppercase characters.
    #[allow(clippy::wrong_self_convention)]
    pub fn to_uppercase(self) -> Expr {
        Expr::RenameAlias {
            expr: Arc::new(self.0),
            function: RenameAliasFn::ToUppercase,
        }
    }

    #[cfg(feature = "dtype-struct")]
    pub fn map_fields(self, function: PlanCallback<PlSmallStr, PlSmallStr>) -> Expr {
        self.0
            .map_unary(FunctionExpr::StructExpr(StructFunction::MapFieldNames(
                function,
            )))
    }

    #[cfg(feature = "dtype-struct")]
    pub fn prefix_fields(self, prefix: &str) -> Expr {
        self.0
            .map_unary(FunctionExpr::StructExpr(StructFunction::PrefixFields(
                PlSmallStr::from_str(prefix),
            )))
    }

    #[cfg(feature = "dtype-struct")]
    pub fn suffix_fields(self, suffix: &str) -> Expr {
        self.0
            .map_unary(FunctionExpr::StructExpr(StructFunction::SuffixFields(
                PlSmallStr::from_str(suffix),
            )))
    }
}

#[cfg(feature = "dtype-struct")]
pub type FieldsNameMapper = Arc<dyn Fn(&str) -> PlSmallStr + Send + Sync>;