dasmig::core::layered_table Class Reference

A table assembled from layers of TSV data. More...

#include <table.hpp>

Public Member Functions
	layered_table (table_schema schema)
	An empty table.
const layer_info &	extend (tsv_document doc, layer_mode mode=layer_mode::override, const std::function< void(const tsv_row &)> &validate={})
	Apply a layer.
void	clear () noexcept
	Remove every row and layer.
const std::vector< tsv_row > &	rows () const noexcept
	The rows in effect, in order.
std::size_t	size () const noexcept
	Number of rows in effect.
bool	empty () const noexcept
	Whether no rows are in effect.
std::optional< tsv_row >	find (std::initializer_list< std::string_view > key) const
	Find a row by key.
const std::vector< layer_info > &	layers () const noexcept
	The layers in effect, in order: the last replace layer and those after it.
std::uint64_t	data_hash () const noexcept
	Hash of the loaded layers: their content hashes and modes, in order. 0 when nothing is loaded.
const table_schema &	schema () const noexcept
	The schema.

Static Public Attributes
static constexpr std::string_view	disabled_column = "disabled"
	Name of the column that removes a key when set to 1.

Detailed Description

A table assembled from layers of TSV data.

• Layers apply in the order loaded; later layers win.
• Rows keep the order they first appeared in: an overriding row takes the place of the row it replaces, new rows are appended. Row order is part of the output (weighted choices depend on it).
• A row with disabled set to 1 removes its key (override and replace modes). A layer needs the key columns; the other required columns are needed only by rows that add or replace data, so a layer that only removes rows can be just key and disabled.
• A layer is validated completely before it is applied; when it fails, the table is unchanged.

dasmig::core::layered_table table{{.key = {"country_code"},
                                   .required = {"male_height_cm"}}};
table.extend(dasmig::core::tsv_document::load("resources/lite/biodata.tsv"),
             dasmig::core::layer_mode::replace);
table.extend(dasmig::core::tsv_document::load("mods/tall_people.tsv"));
for (const auto& row : table.rows()) { ... row.get<double>("male_height_cm") ... }

Definition at line 94 of file table.hpp.

Constructor & Destructor Documentation

layered_table()

dasmig::core::layered_table::layered_table ( table_schema  schema )

inlineexplicit

An empty table.

Parameters

schema

The columns.

Exceptions

std::invalid_argument

If the schema has no key column.

Definition at line 103 of file table.hpp.

Member Function Documentation

clear()

void dasmig::core::layered_table::clear ( )

inlinenoexcept

Remove every row and layer.

Definition at line 185 of file table.hpp.

data_hash()

std::uint64_t dasmig::core::layered_table::data_hash ( ) const

inlinenoexcept

Hash of the loaded layers: their content hashes and modes, in order. 0 when nothing is loaded.

Put it in the seed_signature of results so a replay can tell whether it runs against the same data.

Returns

The hash.

Definition at line 240 of file table.hpp.

empty()

bool dasmig::core::layered_table::empty ( ) const

inlinenoexcept

Whether no rows are in effect.

Returns

True when empty.

Definition at line 203 of file table.hpp.

extend()

const layer_info & dasmig::core::layered_table::extend ( tsv_document  doc, layer_mode  mode = layer_mode::override, const std::function< void(const tsv_row &)> &  validate = {}  )

inline

Apply a layer.

validate is called for every row the layer adds or replaces (not for disabled rows) before anything changes; it should parse the row the way the library will and throw tsv_error on bad data.

Parameters

doc	The layer's data.
mode	How it combines with the rows loaded before.
validate	Optional void(const tsv_row&) row check.

Returns

What the layer did.

Exceptions

tsv_error

On a missing key column, a missing required column (for a row that adds or replaces data), an empty or repeated key, an invalid disabled value, a clash in add mode, or an error from validate. The table is then unchanged.

Definition at line 125 of file table.hpp.

find()

std::optional< tsv_row > dasmig::core::layered_table::find ( std::initializer_list< std::string_view >  key ) const

inline

Find a row by key.

Parameters

key	The key cells, in schema key order.

Returns

The row, or empty.

Exceptions

std::invalid_argument

If the number of cells is not the number of key columns.

Definition at line 210 of file table.hpp.

layers()

const std::vector< layer_info > & dasmig::core::layered_table::layers ( ) const

inlinenoexcept

The layers in effect, in order: the last replace layer and those after it.

Returns

The layer records.

Definition at line 231 of file table.hpp.

rows()

const std::vector< tsv_row > & dasmig::core::layered_table::rows ( ) const

inlinenoexcept

The rows in effect, in order.

Returns

The rows.

Definition at line 195 of file table.hpp.

schema()

const table_schema & dasmig::core::layered_table::schema ( ) const

inlinenoexcept

The schema.

Returns

The columns.

Definition at line 252 of file table.hpp.

size()

std::size_t dasmig::core::layered_table::size ( ) const

inlinenoexcept

Number of rows in effect.

Returns

The count.

Definition at line 199 of file table.hpp.

Member Data Documentation

disabled_column

constexpr std::string_view dasmig::core::layered_table::disabled_column = "disabled"

staticconstexpr

Name of the column that removes a key when set to 1.

Definition at line 98 of file table.hpp.

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The documentation for this class was generated from the following file:

• dasmig/core/table.hpp