PatternSettings class

How df_config recognises a placeholder in a string.

A placeholder is bounded by opening and closing and contains a default <delimiter> key body, where delimiter separates the fallback text from the lookup key. separator joins the parts of a dotted key (user.profile.name).

Case-folding applies to keys (never to the default value, which is returned verbatim). When caseSensitive is false the lookup key is passed through caseFold — by default String.toLowerCase. For Turkish/Azerbaijani or other locales where the Unicode default lowering produces the wrong result, supply a locale-aware folder. caseFold is also a natural place to hang Unicode normalisation (NFC) or bidirectional-control-character stripping for RTL scripts.

Direction-agnostic. All matching operates on UTF-16 code units, not on visual order. Arabic, Hebrew, Persian and Urdu content works out of the box; the only practical concern is making sure your keys are byte-for-byte stable (no stray bidi-control characters, no inconsistent precomposed-vs-combining diacritics).

Two canonical configurations are provided as constants:

• primary — {{ default || key }} with . separator.
• secondary — { default | key } with . separator.

tr() runs both passes by default: primary against translations, secondary against ad-hoc args.

Implementers

• PrimaryPatternSettings
• SecondaryPatternSettings

Constructors

PatternSettings({String opening = '{{', String closing = '}}', String separator = '.', String delimiter = '||', bool caseSensitive = false, String? callback(String key, dynamic suggestedReplacementValue, String defaultValue)?, String caseFold(String input)?})

const

Properties

callback → String? Function(String key, dynamic suggestedReplacementValue, String defaultValue)?

User-supplied callback invoked for every successful pattern match. Receives the parsed key, the value from the lookup map (or null if not present), and the parsed default value. Return the desired replacement, or null to fall back to the standard value ?? default chain.

final

caseFold → String Function(String input)?

Optional custom case-folding function. Used in place of String.toLowerCase when caseSensitive is false. Pass a locale-aware folder here for Turkish (İ ↔ i), Azerbaijani, or other special locales — and/or chain in Unicode normalisation (NFC) and bidi-control stripping for RTL languages.

final

caseSensitive → bool

final

closing → String

final

delimiter → String

final

hashCode → int

The hash code for this object.

no setter, inherited

opening → String

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

separator → String

final

Methods

foldKey(String input) → String

Applies the active case-folding strategy to input.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Constants

primary → const PatternSettings

The primary placeholder syntax: {{ default || key }}.

secondary → const PatternSettings

The secondary placeholder syntax: { default | key }. Used by tr() for the second pass so args can be interpolated with single braces without colliding with translation keys.