Treat objects which are convertible to strings the same as actual strings in ValueInfo

lib/Misc/ValueInfo.php

@@ -18,9 +18,10 @@ class ValueInfo {
         if (is_null($value)) {
             // check if the input is null
             return self::NULL;
-        } elseif (is_string($value)) {
+        } elseif (is_string($value) || (is_object($value) && method_exists($value, "__toString"))) {
+            $value = (string) $value;
             // normalize a string an integer or float if possible
-            if (!strlen((string) $value)) {
+            if (!strlen($value)) {
                 // the empty string is equivalent to null when evaluating an integer
                 return self::NULL;
             } elseif (filter_var($value, \FILTER_VALIDATE_FLOAT) !== false && !fmod((float) $value, 1)) {
@@ -55,8 +56,11 @@ class ValueInfo {
         if (is_null($value)) {
             $out += self::NULL;
         }
-        // if the value is not scalar, is a boolean, or is infinity or NaN, it cannot be valid
-        if (!is_scalar($value) || is_bool($value) || (is_float($value) && !is_finite($value))) {
+        if (is_object($value) && method_exists($value, "__toString")) {
+            // if the value is an object which has a __toString method, this is acceptable
+            $value = (string) $value;
+        } elseif (!is_scalar($value) || is_bool($value) || (is_float($value) && !is_finite($value))) {
+            // otherwise if the value is not scalar, is a boolean, or is infinity or NaN, it cannot be valid
             return $out;
         }
         // mark validity

tests/Misc/TestValueInfo.php

@@ -3,6 +3,7 @@ declare(strict_types=1);
 namespace JKingWeb\Arsse;
 
 use JKingWeb\Arsse\Misc\ValueInfo as I;
+use JKingWeb\Arsse\Test\Misc\StrClass;
 
 /** @covers \JKingWeb\Arsse\Misc\ValueInfo */
 class TestValueInfo extends Test\AbstractTest {
@@ -58,6 +59,12 @@ class TestValueInfo extends Test\AbstractTest {
             ["some string", 0],
             ["           ", 0],
             [new \StdClass, 0],
+            [new StrClass(""),    I::NULL],
+            [new StrClass("1"),   I::VALID],
+            [new StrClass("0"),   I::VALID | I::ZERO],
+            [new StrClass("-1"),  I::VALID | I::NEG],
+            [new StrClass("Msg"), 0],
+            [new StrClass("   "), 0],
         ];
         foreach ($tests as $test) {
             list($value, $exp) = $test;
@@ -116,6 +123,12 @@ class TestValueInfo extends Test\AbstractTest {
             ["some string", I::VALID],
             ["           ", I::VALID | I::WHITE],
             [new \StdClass, 0],
+            [new StrClass(""),    I::VALID | I::EMPTY],
+            [new StrClass("1"),   I::VALID],
+            [new StrClass("0"),   I::VALID],
+            [new StrClass("-1"),  I::VALID],
+            [new StrClass("Msg"), I::VALID],
+            [new StrClass("   "), I::VALID | I::WHITE],
         ];
         foreach ($tests as $test) {
             list($value, $exp) = $test;
@@ -175,6 +188,12 @@ class TestValueInfo extends Test\AbstractTest {
             ["some string", false, false],
             ["           ", false, false],
             [new \StdClass, false, false],
+            [new StrClass(""),    false, true],
+            [new StrClass("1"),   true,  true],
+            [new StrClass("0"),   false, true],
+            [new StrClass("-1"),  false, false],
+            [new StrClass("Msg"), false, false],
+            [new StrClass("   "), false, false],
         ];
         foreach ($tests as $test) {
             list($value, $exp, $expNull) = $test;

tests/lib/Misc/StrClass.php

@@ -0,0 +1,15 @@
+<?php
+declare(strict_types=1);
+namespace JKingWeb\Arsse\Test\Misc;
+
+class StrClass {
+    public $str = "";
+
+    public function __construct($str) {
+        $this->str = (string) $str;
+    }
+
+    public function __toString() {
+        return $this->str;
+    }
+}