Is the value valid

@param  mixed $value
@return bool
546316
public function isValid($value) {
		if (! is_string($value)) {
			$this->addMessage('Value must be a string');
		
			return false;
		}
		
		if ($this->lengthMin !== null && $this->lengthMax !== null && $this->lengthMin >= $this->lengthMax) {
			throw new ValidationFailure('Min length cannot be equal or greater than max length');
		}
		
		if ($this->encoding === null) {
			$length = mb_strlen($value);
		} else {
			$length = mb_strlen($value, $this->encoding);
		}
		
		if ($this->lengthMin !== null && $length < $this->lengthMin) {
			$this->addMessage('Must be not less than %s symbols', $this->lengthMin);
		
			return false;
		}
		
		if ($this->lengthMax !== null && $length > $this->lengthMax) {
			$this->addMessage('Must be not more than %s symbols', $this->lengthMax);
		
			return false;
		}
		
		return true;
	}
706179
public function isValueValid($value) {
		return $value instanceof DataType\DateTimeType || $value instanceof DataType\TextType || $value instanceof DataType\URLType;
	}
31424
public function isValid($value)
    {
        $this->_setValue($value);

        if (!is_string($value)) {
            return false;
        }

        return Zend_Uri::check($value);
    }
111836
public function isValueValid($value) {
		return $value instanceof Type\Place || $value instanceof Type\PostalAddress || $value instanceof DataType\TextType;
	}
505905
public function isValueValid($value) {
		return $value instanceof Type\DataFeedItemType || $value instanceof DataType\TextType || $value instanceof Type\ThingType;
	}
770299
public function isValueValid($value) {
		return $value instanceof Type\CreativeWorkType || $value instanceof Type\ProductType || $value instanceof DataType\URLType;
	}
1215652
public function isValueValid($value) {
		return $value instanceof Type\PropertyValueType || $value instanceof DataType\TextType || $value instanceof DataType\URLType;
	}
851213
public function isValid($value)
    {
        $result = preg_match('/(.+)/i', $value);
        if (!$result) {
            $this->addMessage('notEmpty');
        }
        return (boolean) $result;
    }
379250
public function isValueValid($value) {
		return $value instanceof Type\PropertyValue || $value instanceof DataType\TextType || $value instanceof DataType\URLType;
	}
872394
public function isValid($value)
    {
        $valueString = (string) $value;

        $this->_setValue($valueString);

        $locale = localeconv();

        $valueFiltered = str_replace($locale['thousands_sep'], '', $valueString);
        $valueFiltered = str_replace($locale['decimal_point'], '.', $valueFiltered);

        if (strval(floatval($valueFiltered)) != $valueFiltered) {
            $this->_error();
            return false;
        }

        return true;
    }
253515
public function isValueValid($value) {
		return $value instanceof Type\AlignmentObject || $value instanceof Type\Course || $value instanceof DataType\TextType;
	}
1280346
public function isValueValid($value) {
		return $value instanceof Type\ProductType || $value instanceof DataType\TextType || $value instanceof DataType\URLType;
	}
135337
public function isValid($value)
    {
        $result = filter_var($value, FILTER_VALIDATE_INT);
        if (!$result) {
            $this->addMessage('number');
        }
        return ($result === false) ? false : true;
    }
1319912
public function isValid($value)
    {
        $valueString = (string) $value;

        $this->_setValue($valueString);

        if (ip2long($valueString) === false) {
            $this->_error();
            return false;
        }

        return true;
    }
333365
public function isValid($value)
    {
        $this->_setValue($value);

        if (!$value || !is_string($value) && !is_int($value) && !is_float($value)) {
            $this->_error(self::INVALID_PRICE);
            return false;
        }

        if (false === $this->_options['negative'] && '-' === $value[0]) {
            $this->_error(self::PRICE_NEGATIVE, $value);
            return false;
        }

        $status = @preg_match($this->_pattern, $value);
        if (false === $status) {
            $this->_error(self::INVALID_PRICE);
            return false;
        }

        if (!$status) {
            $this->_error(self::INVALID_PRICE);
            return false;
        }

        return true;
    }
1257041
public function isValueValid($value) {
		return $value instanceof Type\CreativeWork || $value instanceof Type\HowToSection || $value instanceof Type\HowToStep || $value instanceof DataType\TextType;
	}
403016
public function isValid(&$value)
    {
        // skip empty value
        if (is_string($value) && 0 === strlen($value)) {
            return false;
        }
        // found exact match
        if (in_array($value, $this->choices)) {
            return true;
        }
        // compare by ignoring case
        foreach ($this->choices as $choice) {
            if (!is_string($choice)) {
                continue;
            }
            if (strtoupper($value) == strtoupper($choice)) {
                $value = $choice;
                return true;
            }
        }
        // compare by match prefix
        foreach ($this->choices as $choice) {
            if (!is_string($choice)) {
                continue;
            }
            if (0 === strpos(strtoupper($choice), strtoupper($value))) {
                $value = $choice;
                return true;
            }
        }

        return false;
    }