SPECS Translator

1. SPECS Translator A Aniruddha

2. Introduction SPECS (Significantly Prettier and Easier C++ Syntax) • Alternate syntactic binding for C++. • Reduces syntactic errors. • Includes new syntax for declaration/definition for types, functions and objects. • Changes operators and control structures. • Better syntactic differentiation of dissimilar constructs.

3. SPECS syntactic design principles • Syntactic consistency. • Syntactic differentiation of dissimilar constructs. • Better readability.

4. Syntactic consistency Creation of types in C++: Class Base {…} ; typedef struct {…} vector; typedef int (*fp) (); enum result {…} ; In SPECS: type Base : class {…} type vector : class {[public] …} type fp : ^((void)->int); type result : enum {…}

5. Syntactic differentiation of dissimilar constructs C++ - insufficient differentiation Declaration of functions and objects: int (f) (int, char); int (*fp) (int, char); In SPECS: func f : ((int, char) -> int); obj fp : ^((int, char) -> int);

6. Syntax : class (pure virtual functions) SPECS : type Base : class { func print_func : abstract ((& ostream) -> void) ; } // Note : no ; C++ : Class Base { virtual void print_func (ostream&) = 0; };

7. Syntax : class(inheritance and static members) type Derived : class inherits public Base { obj a : common int; } class Derived : public Base { static int a; }

8. Syntax: class (access control, constructors, destructors and friends) type TestClass : class { [private] obj a : int ; [friend] func operator << : ((& ostream, & TestClass) -> & ostream ); [public] func ctor : (int) ; func dtor : (void); }

9. Syntax: class(Operators and cast) type MyInt : class { [public] func operator pre ++ : ((void)-> & MyInt); func operator post ++ : ((void)-> & MyInt); funcdefined_cast : ((void) -> int); } class MyInt { public: MyInt & operator ++ (); // pre MyInt & operator ++ (int); // Dummy int for post operator int (); };

10. Syntax: Templates type GenericClass <[class X]> : class {…} template <class X> class GenericClass {…}; Advantages: • Keyword ‘template’ not required. • C++: TemplateClass<(1>2)> // Parens required SPECS: TemplateClass<[1>2]> • C++ : array<auto_ptr<X> > // Space required SPECS: array<[auto_ptr<[X]>]>

11. Syntax: Operators

12. Syntax: Statements • Loop body must be block. • switch • No break required. • No default fall-through. • case can have a list of constant-expression. • case/defaultmust be followed by a block. Example: switch (i) { case 1,2,3 : { cout << “1/2/3” ;} case 4: {cout << “4”; } }

13. Commonalities with C++ • All inbuilt types are identically named. Literal values are specified in exactly the same way. • The operators have the same precedence and associativity. • Scope rules, function call resolution, implicit conversion, access default and control structure semantics(except switch) are identical. • The same preprocessor and standard libraries are used for both languages. • RTTI, namespaces, exception handling are identical in syntax and semantics.

14. Implementation • Implemented using TXL(Turing Xtender/Tree Transformation Language). • Parse : construct parse tree based on input grammar. • Transform : based on defined rules. • Unparse : In-order traverse of parse tree with formatting. • Can convert • Simple object and type declarations. • Simple Function declaration and definitions. • Assignment statements. • Switch and class syntax.

15. Thank You