`is_expression`

Header: <pressio/expressions.hpp>

This page summarizes the main type traits for detecting Pressio expressions and how they interact with native containers from supported backends.

Core Expression Type Traits

Trait	Description
`pressio::is_expression<T>`	Checks if `T` is any recognized Pressio expression (span, diagonal, subspan, or column).
`pressio::is_expression_span<T>`	True if `T` is a SpanExpr.
`pressio::is_expression_diagonal<T>`	True if `T` is a DiagonalExpr.
`pressio::is_expression_subspan<T>`	True if `T` is a SubspanExpr.
`pressio::is_expression_column<T>`	True if `T` is a ColumnExpr.

These traits refine the detection to check whether a recognized expression type wraps a native container from a specific backend.

Trait	Description
`pressio::is_expression_acting_on_eigen<T>`	True if `T` is a supported expression whose underlying container is an Eigen type.
`pressio::is_expression_acting_on_kokkos<T>`	True if `T` is a supported expression whose underlying container is a Kokkos type.
`pressio::is_expression_acting_on_tpetra<T>`	True if `T` is a ColumnExpr that wraps a Tpetra MultiVector.
`pressio::is_expression_column_acting_on_tpetra<T>`	True if `T` is both a ColumnExpr and acts on a Tpetra MultiVector.
`pressio::is_expression_acting_on_tpetra_block<T>`	True if `T` is a ColumnExpr that wraps a Tpetra Block MultiVector.
`pressio::is_expression_column_acting_on_tpetra_block<T>`	True if `T` is both a ColumnExpr and acts on a Tpetra Block MultiVector.

Each trait inherits from std::true_type or std::false_type and exposes a .value member for compile-time checks.
These traits automatically handle const-qualified types.