A filter that maps values from one set to another. More...

#include <filter.h>

Inheritance diagram for esphome::text_sensor::MapFilter:

Public Member Functions
	MapFilter (const std::initializer_list< Substitution > &mappings)

bool	new_value (std::string &value) override

Public Member Functions inherited from esphome::text_sensor::Filter
virtual void	initialize (TextSensor parent, Filter next)
	Initialize this filter, please note this can be called more than once.

void	input (std::string value)

void	output (std::string &value)

Protected Attributes
FixedVector< Substitution >	mappings_

Protected Attributes inherited from esphome::text_sensor::Filter
friend	TextSensor

Filter *	next_ {nullptr}

TextSensor *	parent_ {nullptr}

Detailed Description

A filter that maps values from one set to another.

Uses linear search instead of std::map for typical small datasets (2-20 mappings). Linear search on contiguous memory is faster than red-black tree lookups when:

Dataset is small (< ~30 items)
Memory is contiguous (cache-friendly, better CPU cache utilization)
No pointer chasing overhead (tree node traversal)
String comparison cost dominates lookup time

Benchmark results (see benchmark_map_filter.cpp):

2 mappings: Linear 1.26x faster than std::map
5 mappings: Linear 2.25x faster than std::map
10 mappings: Linear 1.83x faster than std::map
20 mappings: Linear 1.59x faster than std::map
30 mappings: Linear 1.09x faster than std::map
40 mappings: std::map 1.27x faster than Linear (break-even)

Benefits over std::map:

~2KB smaller flash (no red-black tree code)
~24-32 bytes less RAM per mapping (no tree node overhead)
Faster for typical ESPHome usage (2-10 mappings common, 20+ rare)

Break-even point: ~35-40 mappings, but ESPHome configs rarely exceed 20

Definition at line 156 of file filter.h.

Constructor & Destructor Documentation

◆ MapFilter()

esphome::text_sensor::MapFilter::MapFilter ( const std::initializer_list< Substitution > & mappings )

explicit

Definition at line 95 of file filter.cpp.

Member Function Documentation

◆ new_value()

bool esphome::text_sensor::MapFilter::new_value ( std::string & value )

overridevirtual

Implements esphome::text_sensor::Filter.

Definition at line 97 of file filter.cpp.

Field Documentation

◆ mappings_

FixedVector<Substitution> esphome::text_sensor::MapFilter::mappings_

protected

Definition at line 162 of file filter.h.

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

esphome/components/text_sensor/filter.h
esphome/components/text_sensor/filter.cpp

Public Member Functions