Characterdepending

Characterdepending is a term used to describe rules or mechanisms whose behavior varies with the value of the input character itself. It contrasts with rules that are driven by position in a sequence or by broader system state. In characterdependent processing, the decision at each step depends on the specific character being processed.

In computing and text processing, characterdependent behavior appears in normalization, encoding, and rendering. For example, Unicode normalization can decompose certain characters into alternative forms, and the choice of whether to use a composed or decomposed form may depend on the identity of the character (such as ligatures or diacritics). The ligature fi or the ligature ff illustrate characterdependent transformations when a system chooses, under certain forms, to map a single character to multiple code points or vice versa.

Typography and font rendering also exhibit characterdependent behavior, as glyph substitution or shaping decisions can depend on the exact character being drawn. A font may apply a diacritic or ligature differently for a specific character than for others, especially when advanced font features are enabled.

Locale-aware case mapping is another example: in Turkish, the uppercase i maps to İ and the lowercase I maps to ı, a rule that depends on the character and the active locale. This shows how cultural and linguistic context can introduce characterdependent rules into software behavior.

Applications and domains include text normalization, tokenization, rendering, input validation, and localization. Challenges arise from the need to document precise character-specific rules and to test behavior across fonts, encodings, and locales to avoid inconsistencies.

See also: Unicode normalization, ligature, kerning, locale, tokenization.