Structure provides a set of classes to check the data type and format of your variables.

0.6-alpha2 2015-09-16 22:35 UTC


Structure provides a set of classes to check the data type and format of your variables.

Table of Contents

Static shortcuts
Class ScalarS
Class NumericS
Classes IntegerS and FloatS
Class StringS
Class ArrayS
Working with Value Sets
Further info
Planned features


Structure is provided under the MIT License.


You can install Structure into your project using Composer. Using the latest release is highly recommendable. You can start using it by adding the following to your composer.json:

    "3nr1c/structure": "0.*"

You can also use the "dev-master" version at your own risk. The code in this version may change at any time.


Have you ever had to check the structure of some variable? (maybe it's an array that must have certain keys and value types, or an integer that must be within a certain range). If so, you probably have written some code like this:

if (!is_array($c)) {
    throw new \Exception();
} else if (!isset($c["profile"])) {
    throw new \Exception();
} else if (!is_array($c["profile"])) {
    throw new \Exception();
} //...

And that's only the beginning! I suppose that for each key, you also have to check for other keys, and data types. Structure helps you with these issues. The previous code becomes:

$arrayCheck = new \Structure\ArrayS();
$arrayCheck->setFormat(array("profile" => "array");
if (!$arrayCheck->check($c)) {
    throw new \Exception();
} //...

Here are some more examples:

$arrayCheck = new \Structure\ArrayS();
    "id" => "int",
    "rating" => "float[0,10]",
    "title" => array(
        "en" => "str",
        "es" => "str"
    "links" => "string[]",
    "subtitles" => "bool"
$arrayCheck = new \Structure\ArrayS();
    "name" => "string",
    "customer_id" => "int",
    "is_admin" => "bool",
    "last_session" => "string"


All Structure classes have the same constructor:

public function __construct($data = null, $null = false);

The $null argument allows the data to be null when running the check method. All classes have also the following methods:

public function setData($data);
public function getData();

// to avoid the data to be null:
public function setNull($null);
public function getNull();

// to check everything (type and range/format)
public function check($data = null, &$failed = null);

// to format things (specially powerfull in ArrayS)
public function format($data = null);

public static function getLastFail();
public static function clearLastFail();

The &$failed argument of check lets you create a variable that will tell you why this method returned false. You can access to the last error information, and erase it, with the static methods getLastFail and clearLastFail. The possible values for this failure variables are specified in their section below.

Static shortcuts

The main Structure class provides four static methods to quickly generate checkers:

public static function ArrayS($format = null, $data = null, $countStrict = true, $null = false);
public static function NumericS($range = null, $data = null, $null = false);
public static function IntegerS($range = null, $data = null, $null = false);
public static function FloatS($range = null, $data = null, $null = false);
public static function StringS($data = null, $null = false);

All these methods return respectively an ArrayS, NumericS, IntegerS, FloatS or StringS object, with the properties set as passed by the arguments.

Class ScalarS

This class runs the is_scalar() test to a variable. If the result is false, the $failed var will show the type of the tested variable.


$scalar = new \Structure\ScalarS();
if (!$scalar->check($var, $failed)) {
  print "Error: expected _scalar_, got " . $failed;

This class and all its children have the setValueSet method, which lets you define possible values for the data to be checked. This method can take either a variable number of arguments, or a string with values separated by commas between curly brackets { and }:

$scalar->setFormat("value1", "value2", 10, 11, 12);
// or
$scalar->setFormat("{value1, value2, 10, 11, 12, commas and brackets can be escaped: \{\,}");

true and false tokens evaluate to booleans If you need the strings "true" and "false", escape them

$scalar->setFormat("{true, false}");
$scalar->check(true); //true
$scalar->check(false); //true
$scalar->check("true"); //false
$scalar->check("false"); //false

$scalar->setFormat("{\\true, \\false}");
$scalar->check(true); //false
$scalar->check(false); //false
$scalar->check("true"); //true
$scalar->check("false"); //true

If the tested variable is scalar but isn't in the defined set, the $failed var will be "scalar:value".

Class NumericS

This class runs the is_numeric() test against a variable. A range property can be defined, with the following syntax:


That is, it uses the mathematical notation:

  • The '(' character indicates a strict (<) lower bound
  • The '[' character indicates a non-strict (<=) lower bound
  • The ')' character indicates a strict (>) upper bound
  • The ']' character indicates a non-strict (>=) upper bound

The term inf is used to indicate infinities. It has limitations: the left value can only be -inf, and the right value either inf or +inf.

The parser will raise an \Exception if the syntax is not correct. Here are a couple of examples:

$numeric = new \Structure\NumericS();

$numeric->check(-4.2);// false
$numeric->check(-2);// false
$numeric->check(0.33);// true
$numeric->check(3);// true
$numeric->check(5);// true
$numeric->check(10.42);// false

The left number must be less than or equal to the right number.

If the type of the tested variable is correct, but the range isn't, the $failed variable will have the value "numeric:range".

Classes IntegerS and FloatS

They both inherit from NumericS. The only difference is that the check method of IntegerS uses is_integer (is stricter), and FloatS uses is_float. Notice this:

$numeric = new \Structure\NumericS();
$numeric->check("3.2");// true
$numeric->check("5");// true

$float = new \Structure\FloatS();
$float->check("3.2");// false

$integer = new \Structure\IntegerS();
$integer->check("5");// false

As you can see in the examples above, FloatS and IntegerS are strict regarding strings of numbers. You can use the attribute $numeric (set to false by default) to avoid this strictness:

$float = new \Structure\FloatS();
$integer = new \Structure\IntegerS();


$float->check("3.2");// true
$integer->check("5");// true

If the type of the tested variable is correct, but the range isn't, the $failed variable will be either "integer:range" or "float:range".

Class StringS

This class runs the is_string() test against a variable.


$string = new \Structure\StringS();

Min and max length can be required using setLength:

$string->setLength(4); // 4 characters or more
$string->setLength(4, 10); // 4 to 10 characters
$string->setLength(0, 10); // up to 10 characters
$string->setLength("(4..10)"); // 4 to 10 characters

If the test data is a string but does not match the length, the $fail var will have the value "string:length".

Class ArrayS

This class has the following methods (plus all the methods inherited from Structure):

public function setFormat($format);
public function getFormat();
public function setCountStrict();
public function isCountStrict();

public static function isAssociative($data);


The $format argument can have many forms. The type must always be array or string. The string type is used to define simple arrays, such as


The characters + and * can also be used to test simple arrays. Something like "[3..5]" can be used to express variable array size. The following expressions are valid:

$array->setFormat("string[*]"); // checks for 0 or more strings
$array->setFormat("integer[+]"); // checks for 1 or more integers
$array->setFormat("scalar[5+]"); // checks for 5 or more scalars

$array->setFormat("float[3..5]"); // checks for 3 to 5 floats
$array->setFormat("float[..5]"); // checks for a maximum of 5 floats
$array->setFormat("float[3..]"); // checks for at least 3 floats

Types can be mixed using the vertical bar |:


And the token [] can be "nested", to define multidimensional arrays


// Beware of dimensions. This:
// Would check true with this:
  array(1, 2),
  array(3, 4),
  array(5, 6)
)); // true

// this:
// is different from:

The array type is used to represent more complex array structures. If you expect an array to be sequential (i.e., not key-value), the format should be an array of types. Again, if all array elements have to be of the same type, the syntax above is recommended.

$array->setFormat(array("integer", "string", "array"));
    array("bool", "int", "float"),

Finally, you can define required keys for an associative array. Warning: if the array has some keys you do not want to check, make sure you run the $array->setCountStrict(false) command.

    "foo" => "string",
    "foo2" => "string{hello, bye}[]",
    "bar" => "int[3,10)",
    "bar2" => "int[3,10)[4+]",
    "abc" => "array",
    "xyz" => array(
            "hello" => "bool"

As you can see, it has a recursive definition.

Working with Value Sets

Sometimes you want to check if a variable has a value that you know. Let's imagine that we want to check if a number is 3 or 7. It's not possible using the mathematical notation supported by Structure (we'd need to use unions and intersections of mathematical entities). Value Sets in Structure provide this feature.

$numeric = new \Structure\NumericS();
$numeric->setValueSet(3, 7);

$numeric->check(3); //true
$numeric->check(7); //true
$numeric->check(542); //false

// Less efficient, but valid (and needed for ArrayS):
//  $numeric->setValueSet("{3,7}");

This feature is available for all Structure types. When ScalarS (StringS, NumericS, IntegerS, FloatS, and BooleanS) is inherited a setValueSet() method is available.

When working with arrays, the Value Set information can be embedded within the format declaration.

$format = array(
    "integer{2, 4, 6}"

$array = \Structure\Structure::ArrayS($format);

$arrayA = array("a", 2);
$arrayB = array("a", 6);
$arrayC = array("c", 2);
$arrayD = array("f", 2);

$array->check($arrayA); //correct
$array->check($arrayB); //correct
$array->check($arrayC); //correct
$array->check($arrayD); //incorrect

This feature can also be used to check whether a variable matches a single value, which can be quite useful in an array context. For example, you could check bools, or integers:

$format = array(
    "logged" => "bool{true}",
    "status" => "integer{0}"
$array = \Structure\Structure::ArrayS($format);

$test1 = array("logged" => true, "status" => 0);
$test2 = array("logged" => true, "status" => 1); //the status indicates some error code here


Further info

You can read more documentation by running composer doc (phpdoc needed) and by looking at the test cases.



  • ArrayS: arrays can be of variable length! "integer[1..5]", "string[..4]", "numeric[3..]"
  • ArrayS: format can be defined with a JSON string
  • ArrayS: format can be defined with a path to a file containing a format in JSON
  • ArrayS: fixed a bug with formats of the type "null|string[]"
  • ArrayS: literal null can be used in place of the "null" string
  • ArrayS: an array item can be "(string{a,b,c}|integer[3,10])[]"
  • ArrayS: "string[3]" can now be used to describe an associative array
  • Structure::typeof is now a public method


  • Compilation of strings for ArrayS, ScalarS (value sets) and NumericS (integer ranges) to avoid re-parsing
  • Failure reporting: all check methods accept as second argument a variable to be created to return what failed, if the test evaluates to false. The last occurred error can be retrieved with Structure::getLastFail() and removed with Structure::clearLastFail()
  • ArrayS: quantifiers for simple array description: "type[*]", "type[+]", "type[10+]"
  • ArrayS: multiple types for a value: "integer|float", "string|null"
  • ArrayS: mixed simple arrays: "(integer|float)[]"
  • ArrayS: nested simple arrays: "integer[][]", "(integer[]|string[])[]"
  • ScalarS: true and false tokens can be escaped to become strings: "{\\true, \\false}"
  • StringS: length test. It can be defined with setLength. For arrays, the syntax is "string(min..max)"

Planned features

  • Date formats: timestamp, mysql date/time/datetime, standard times
  • Email, ip, hash formats
  • Objects: attributes (name, visibility) and methods (name, visibility, parameters)
  • Regexp for strings
  • ArrayS: mark some keys as optional