3_types.md

Types

Recki-CT uses a series of system types to represent variables. These are represented by the ReckiCT\Type class.

Unknown (Type::TYPE_UNKNOWN)

This is the default type. All new variables that aren't parameters are initialized using this type. It also will prevent compilation if present in output IR.

Void (Type::TYPE_VOID)

A type that specifies the lack of a type. This is different from Unknown in that we know the type.

Null (Type::TYPE_NULL):

A type that's similar to Void, except where Void never allocates a variable, Null will always allocate one.

Numeric (Type::TYPE_NUMERIC)

This is a pseudo-type that "wraps" both long and double types. It represents any number that could be either an integer or a float. This allows delaying the decision on which exact type to use as late as possible.

Long (Type::TYPE_LONG)

This type represents integer values. It is always 64 bit.

Double (Type::TYPE_DOUBLE)

This type represents floating point values.

Typing Rules

• Addition, Subtraction and Multiplication (+, - and *):

  Longs are always generalized into numeric results (so long + numeric === numeric and long + long === numeric).

  Doubles are always specified into double results (so long + double === double and numeric + double === double).

• Division (/):

  Division always results in a double

• Bitwise Operations and Shifts (|, &, ^, <<, >>):

  With few exceptions (string inputs, etc), Bitwise operations always result in Long typed results.

String (Type::TYPE_STRING):

Represents a variable holding a string...

Boolean (Type::TYPE_BOOLEAN):

Represents a variable holding a boolean. In practice, this will be compiled into a long, but for analysis reasons it's considered a separate type.

Mixed (Type::TYPE_ZVAL):

Represents a variable of runtime-determined type. Support is presently limited.

User (Type::TYPE_USER):

Represents the name of a class.

Array (Type::TYPE_ARRAY):

Represents a numerically indexed array of something. Always requires a sub-type, which are the types of values.

Note that this is a literal array, not a PHP array. String keys are not supported, nor are sparse arrays.

Hash (Type::TYPE_HASH):

Represents a PHP array. Values are always mixed.