[Type] add non-empty-string type (#116)

src/Psl/Internal/Loader.php

@@ -318,6 +318,7 @@ final class Loader
         'Psl\Type\object',
         'Psl\Type\resource',
         'Psl\Type\string',
+        'Psl\Type\non_empty_string',
         'Psl\Type\scalar',
         'Psl\Type\union',
         'Psl\Type\is_array',
@@ -432,6 +433,7 @@ final class Loader
         'Psl\Type\Internal\ObjectType',
         'Psl\Type\Internal\ResourceType',
         'Psl\Type\Internal\StringType',
+        'Psl\Type\Internal\NonEmptyStringType',
         'Psl\Type\Internal\UnionType',
         'Psl\Type\Exception\TypeTrace',
         'Psl\Type\Exception\AssertException',

src/Psl/Iter/flat_map.php

@@ -12,7 +12,7 @@
  * @psalm-param iterable<Tk, Tv>            $iterable Iterable to be mapped over
  * @psalm-param (callable(Tv): iterable<T>) $mapper
  *
- * @psalm-return iterable<array-key, T>
+ * @psalm-return iterable<int, T>
  */
 function flat_map(iterable $iterable, callable $mapper): iterable
 {

src/Psl/Type/Internal/NonEmptyStringType.php

@@ -0,0 +1,72 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Type\Internal;
+
+use Psl\Str;
+use Psl\Type;
+use Psl\Type\Exception\AssertException;
+use Psl\Type\Exception\CoercionException;
+
+/**
+ * @extends Type\Type<non-empty-string>
+ *
+ * @internal
+ */
+final class NonEmptyStringType extends Type\Type
+{
+    /**
+     * @psalm-param mixed $value
+     *
+     * @psalm-return non-empty-string
+     *
+     * @throws CoercionException
+     */
+    public function coerce($value): string
+    {
+        if (Type\is_string($value) && !Str\is_empty($value)) {
+            return $value;
+        }
+
+        if (Type\is_int($value)) {
+            $str = (string) $value;
+            if (!Str\is_empty($str)) {
+                /** @var non-empty-string $str */
+                return $str;
+            }
+        }
+
+        if (Type\is_object($value) && method_exists($value, '__toString')) {
+            $str = (string)$value;
+            if (!Str\is_empty($str)) {
+                return $str;
+            }
+        }
+
+        throw CoercionException::withValue($value, $this->toString(), $this->getTrace());
+    }
+
+    /**
+     * @psalm-param mixed $value
+     *
+     * @psalm-return non-empty-string
+     *
+     * @psalm-assert non-empty-string $value
+     *
+     * @throws AssertException
+     */
+    public function assert($value): string
+    {
+        if (Type\is_string($value) && !Str\is_empty($value)) {
+            return $value;
+        }
+
+        throw AssertException::withValue($value, $this->toString(), $this->getTrace());
+    }
+
+    public function toString(): string
+    {
+        return 'non-empty-string';
+    }
+}

src/Psl/Type/non_empty_string.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Type;
+
+/**
+ * @psalm-return Type<non-empty-string>
+ */
+function non_empty_string(): Type
+{
+    return new Internal\NonEmptyStringType();
+}

tests/Psl/Type/NonEmptyStringTypeTest.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Type;
+
+use Psl\Type;
+
+/**
+ * @extends TypeTest<non-empty-string>
+ */
+final class NonEmptyStringTypeTest extends TypeTest
+{
+    /**
+     * @return Type\Type<non-empty-string>
+     */
+    public function getType(): Type\Type
+    {
+        return Type\non_empty_string();
+    }
+
+    public function getValidCoercions(): iterable
+    {
+        yield ['hello', 'hello'];
+        yield [$this->stringable('hello'), 'hello'];
+        yield [123, '123'];
+        yield [0, '0'];
+        yield ['0', '0'];
+        yield ['123', '123'];
+        yield ['1e23', '1e23'];
+        yield [$this->stringable('123'), '123'];
+    }
+
+    public function getInvalidCoercions(): iterable
+    {
+        yield [''];
+        yield [1.0];
+        yield [1.23];
+        yield [[]];
+        yield [[1]];
+        yield [Type\bool()];
+        yield [null];
+        yield [false];
+        yield [true];
+        yield [STDIN];
+    }
+
+    public function getToStringExamples(): iterable
+    {
+        yield [$this->getType(), 'non-empty-string'];
+    }
+}