Return Chain instead of FormatterBuilder in mixin interfaces

The Builder and Chain mixin interfaces were declaring return types as
FormatterBuilder, which is the concrete class. Since FormatterBuilder
implements Chain, and Chain extends Formatter, returning Chain is more
accurate for the mixin type declarations.

Without this change, static analysis tools (e.g., PHPStan, Psalm)
interpret calls like `Sf::date()->uppercase()` as invoking a static
method (`Builder::uppercase()`) as a non-static method on a
FormatterBuilder instance. By returning Chain—which declares instance
methods—static analysis correctly resolves chained calls as non-static
method invocations.

Assisted-by: Claude Code (claude-opus-4-6)

Author: henriquemoody

src/Mixin/Builder.php

@@ -16,40 +16,40 @@
 /** @mixin FormatterBuilder */
 interface Builder
 {
-    public static function area(string $unit): FormatterBuilder;
+    public static function area(string $unit): Chain;
 
-    public static function creditCard(): FormatterBuilder;
+    public static function creditCard(): Chain;
 
-    public static function secureCreditCard(string $maskChar = '*'): FormatterBuilder;
+    public static function secureCreditCard(string $maskChar = '*'): Chain;
 
-    public static function imperialArea(string $unit): FormatterBuilder;
+    public static function imperialArea(string $unit): Chain;
 
-    public static function imperialLength(string $unit): FormatterBuilder;
+    public static function imperialLength(string $unit): Chain;
 
-    public static function imperialMass(string $unit): FormatterBuilder;
+    public static function imperialMass(string $unit): Chain;
 
-    public static function date(string $format = 'Y-m-d H:i:s'): FormatterBuilder;
+    public static function date(string $format = 'Y-m-d H:i:s'): Chain;
 
-    public static function lowercase(): FormatterBuilder;
+    public static function lowercase(): Chain;
 
-    public static function mask(string $range, string $replacement = '*'): FormatterBuilder;
+    public static function mask(string $range, string $replacement = '*'): Chain;
 
-    public static function metric(string $unit): FormatterBuilder;
+    public static function metric(string $unit): Chain;
 
     public static function number(
         int $decimals = 0,
         string $decimalSeparator = '.',
         string $thousandsSeparator = ',',
-    ): FormatterBuilder;
+    ): Chain;
 
-    public static function metricMass(string $unit): FormatterBuilder;
+    public static function metricMass(string $unit): Chain;
 
-    public static function pattern(string $pattern): FormatterBuilder;
+    public static function pattern(string $pattern): Chain;
 
     /** @param array<string, mixed> $parameters */
-    public static function placeholder(array $parameters): FormatterBuilder;
+    public static function placeholder(array $parameters): Chain;
 
-    public static function time(string $unit): FormatterBuilder;
+    public static function time(string $unit): Chain;
 
-    public static function uppercase(): FormatterBuilder;
+    public static function uppercase(): Chain;
 }

src/Mixin/Chain.php

@@ -11,45 +11,45 @@
 
 namespace Respect\StringFormatter\Mixin;
 
+use Respect\StringFormatter\Chain;
 use Respect\StringFormatter\Formatter;
-use Respect\StringFormatter\FormatterBuilder;
 
 interface Chain extends Formatter
 {
-    public function area(string $unit): FormatterBuilder;
+    public function area(string $unit): Chain;
 
-    public function creditCard(): FormatterBuilder;
+    public function creditCard(): Chain;
 
-    public function secureCreditCard(string $maskChar = '*'): FormatterBuilder;
+    public function secureCreditCard(string $maskChar = '*'): Chain;
 
-    public function imperialArea(string $unit): FormatterBuilder;
+    public function imperialArea(string $unit): Chain;
 
-    public function imperialLength(string $unit): FormatterBuilder;
+    public function imperialLength(string $unit): Chain;
 
-    public function imperialMass(string $unit): FormatterBuilder;
+    public function imperialMass(string $unit): Chain;
 
-    public function date(string $format = 'Y-m-d H:i:s'): FormatterBuilder;
+    public function date(string $format = 'Y-m-d H:i:s'): Chain;
 
-    public function lowercase(): FormatterBuilder;
+    public function lowercase(): Chain;
 
-    public function mask(string $range, string $replacement = '*'): FormatterBuilder;
+    public function mask(string $range, string $replacement = '*'): Chain;
 
-    public function metric(string $unit): FormatterBuilder;
+    public function metric(string $unit): Chain;
 
     public function number(
         int $decimals = 0,
         string $decimalSeparator = '.',
         string $thousandsSeparator = ',',
-    ): FormatterBuilder;
+    ): Chain;
 
-    public function metricMass(string $unit): FormatterBuilder;
+    public function metricMass(string $unit): Chain;
 
-    public function pattern(string $pattern): FormatterBuilder;
+    public function pattern(string $pattern): Chain;
 
     /** @param array<string, mixed> $parameters */
-    public function placeholder(array $parameters): FormatterBuilder;
+    public function placeholder(array $parameters): Chain;
 
-    public function time(string $unit): FormatterBuilder;
+    public function time(string $unit): Chain;
 
-    public function uppercase(): FormatterBuilder;
+    public function uppercase(): Chain;
 }