Changeset 8f13c98


Ignore:
Timestamp:
Feb 22, 2018, 4:53:01 PM (4 years ago)
Author:
Peter A. Buhr <pabuhr@…>
Branches:
aaron-thesis, arm-eh, cleanup-dtors, deferred_resn, demangler, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, resolv-new, with_gc
Children:
c27fb59
Parents:
2a8427c6 (diff), d2887f7 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.
Message:

Merge branch 'master' of plg2:software/cfa/cfa-cc

Files:
2 added
2 edited

Legend:

Unmodified
Added
Removed
  • doc/papers/general/Paper.tex

    r2a8427c6 r8f13c98  
    4141
    4242\newcommand{\Textbf}[2][red]{{\color{#1}{\textbf{#2}}}}
    43 \newcommand{\TODO}[1]{\textbf{TODO}: {\itshape #1}} % TODO included
    44 %\newcommand{\TODO}[1]{} % TODO elided
     43%\newcommand{\TODO}[1]{\textbf{TODO}: {\itshape #1}} % TODO included
     44\newcommand{\TODO}[1]{} % TODO elided
    4545
    4646% Default underscore is too low and wide. Cannot use lstlisting "literate" as replacing underscore
     
    260260\Celeven did add @_Generic@ expressions, which can be used in preprocessor macros to provide a form of ad-hoc polymorphism; however, this polymorphism is both functionally and ergonomically inferior to \CFA name overloading.
    261261The macro wrapping the generic expression imposes some limitations; as an example, it could not implement the example above, because the variables @max@ would collide with the functions @max@.
    262 Ergonomic limitations of @_Generic@ include the necessity to put a fixed list of supported types in a single place and manually dispatch to appropriate overloads, as well as possible namespace pollution from the functions dispatched to, which must all have distinct names.
     262Ergonomic limitations of @_Generic@ include the necessity to put a fixed list of supported types in a single place and manually dispatch to appropriate overloads, as well as possible namespace pollution from the functions dispatched to, which must all have distinct names.
     263Though name-overloading removes a major use-case for @_Generic@ expressions, \CFA does implement @_Generic@ for backwards-compatibility purposes. \TODO{actually implement that}
    263264
    264265% http://fanf.livejournal.com/144696.html
     
    19841985
    19851986In C, @0@ has the special property that it is the only ``false'' value; by the standard, any value which compares equal to @0@ is false, while any value that compares unequal to @0@ is true.
    1986 As such, an expression @x@ in any boolean context (such as the condition of an @if@ or @while@ statement, or the arguments to an @&&@, @||@, or ternary operator) can be rewritten as @x != 0@ without changing its semantics.
     1987As such, an expression @x@ in any boolean context (such as the condition of an @if@ or @while@ statement, or the arguments to @&&@, @||@, or @?:@) can be rewritten as @x != 0@ without changing its semantics.
    19871988The operator overloading feature of \CFA provides a natural means to implement this truth value comparison for arbitrary types, but the C type system is not precise enough to distinguish an equality comparison with @0@ from an equality comparison with an arbitrary integer or pointer.
    1988 To provide this precision, \CFA introduces a new type @zero_t@ as type type of literal @0@ (somewhat analagous to @nullptr_t@ and @nullptr@ in \CCeleven); @zero_t@ can only take the value @0@, but has implicit conversions to the integer and pointer types so that standard C code involving @0@ continues to work properly.
     1989To provide this precision, \CFA introduces a new type @zero_t@ as type type of literal @0@ (somewhat analagous to @nullptr_t@ and @nullptr@ in \CCeleven); @zero_t@ can only take the value @0@, but has implicit conversions to the integer and pointer types so that C code involving @0@ continues to work properly.
    19891990With this addition, the \CFA compiler rewrites @if (x)@ and similar expressions to @if ((x) != 0)@ or the appropriate analogue, and any type @T@ can be made ``truthy'' by defining an operator overload @int ?!=?(T, zero_t)@.
    19901991\CC makes types truthy by adding a conversion to @bool@; prior to the addition of explicit cast operators in \CCeleven this approach had the pitfall of making truthy types transitively convertable to any numeric type; our design for \CFA avoids this issue.
     
    19931994The addition of @one_t@ allows generic algorithms to handle the unit value uniformly for types where that is meaningful.
    19941995\TODO{Make this sentence true} In particular, polymorphic functions in the \CFA prelude define @++x@ and @x++@ in terms of @x += 1@, allowing users to idiomatically define all forms of increment for a type @T@ by defining the single function @T & ?+=(T &, one_t)@; analogous overloads for the decrement operators are present as well.
    1995 
    19961996
    19971997\subsection{Integral Suffixes}
  • src/prelude/builtins.c

    r2a8427c6 r8f13c98  
    2323void exit( int status, const char fmt[], ... ) __attribute__ (( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
    2424void abort ( const char fmt[], ... ) __attribute__ (( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ ));
     25
     26// increment/decrement unification
     27
     28static inline forall( dtype T | { T& ?+=?( T&, one_t ); } )
     29T& ++? ( T& x ) { return x += 1; }
     30
     31static inline forall( dtype T | sized(T) | { void ?{}( T&, T ); void ^?{}( T& ); T& ?+=?( T&, one_t ); } )
     32T& ?++ ( T& x ) { T tmp = x; x += 1; return tmp; }
     33
     34static inline forall( dtype T | { T& ?-=?( T&, one_t ); } )
     35T& --? ( T& x ) { return x -= 1; }
     36
     37static inline forall( dtype T | sized(T) | { void ?{}( T&, T ); void ^?{}( T& ); T& ?-=?( T&, one_t ); } )
     38T& ?-- ( T& x ) { T tmp = x; x -= 1; return tmp; }
    2539
    2640// exponentiation operator implementation
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