Changeset 9f10d1f2 for doc/proposals/concurrency/text/cforall.tex
- Timestamp:
- Nov 23, 2017, 1:31:43 PM (7 years ago)
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- ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc
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- 07c1e595
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doc/proposals/concurrency/text/cforall.tex
r07c1e595 r9f10d1f2 7 7 The following is a quick introduction to the \CFA language, specifically tailored to the features needed to support concurrency. 8 8 9 \CFA is a extension of ISO-C and therefore supports all of the same paradigms as C. It is a non-object oriented system language, meaning most of the major abstractions have either no runtime overhead or can be opt-out easily. Like C, the basics of \CFA revolve around structures and routines, which are thin abstractions over machine code. The vast majority of the code produced by the \CFA translator respects memory-layouts and calling-conventions laid out by C. Interestingly, while \CFA is not an object-oriented language, lacking the concept of a receiver (e.g., this), it does have some notion of objects\footnote{C defines the term objects as : ``region of data storage in the execution environment, the contents of which can represent10 values'' \cite[3.15]{C11}}, most importantly construction and destruction of objects. Most of the following code examples can be found on the \CFA website\cite{www-cfa}9 \CFA is an extension of ISO-C and therefore supports all of the same paradigms as C. It is a non-object-oriented system-language, meaning most of the major abstractions have either no runtime overhead or can be opt-out easily. Like C, the basics of \CFA revolve around structures and routines, which are thin abstractions over machine code. The vast majority of the code produced by the \CFA translator respects memory-layouts and calling-conventions laid out by C. Interestingly, while \CFA is not an object-oriented language, lacking the concept of a receiver (e.g., {\tt this}), it does have some notion of objects\footnote{C defines the term objects as : ``region of data storage in the execution environment, the contents of which can represent 10 values''~\cite[3.15]{C11}}, most importantly construction and destruction of objects. Most of the following code examples can be found on the \CFA website~\cite{www-cfa} 11 11 12 12 \section{References} … … 21 21 *p3 = ...; //change p2 22 22 int y, z, & ar[3] = {x, y, z}; //initialize array of references 23 typeof( ar[1]) p; //is int, i.e., the type of referenced object24 typeof(&ar[1]) q; //is int &, i.e., the type of reference25 sizeof( ar[1]) == sizeof(int); //is true, i.e., the size of referenced object26 sizeof(&ar[1]) == sizeof(int *); //is true, i.e., the size of a reference23 typeof( ar[1]) p; //is int, referenced object type 24 typeof(&ar[1]) q; //is int &, reference type 25 sizeof( ar[1]) == sizeof(int); //is true, referenced object size 26 sizeof(&ar[1]) == sizeof(int *); //is true, reference size 27 27 \end{cfacode} 28 The important take away from this code example is that references offer a handle to an object, much like pointers, but which is automatically dereferenced for convenience.28 The important take away from this code example is that a reference offers a handle to an object, much like a pointer, but which is automatically dereferenced for convenience. 29 29 30 30 \section{Overloading} 31 31 32 Another important feature of \CFA is function overloading as in Java and \CC, where routines with the same name are selected based on the number and type of the arguments. As well, \CFA uses the return type as part of the selection criteria, as in Ada \cite{Ada}. For routines with multiple parameters and returns, the selection is complex.32 Another important feature of \CFA is function overloading as in Java and \CC, where routines with the same name are selected based on the number and type of the arguments. As well, \CFA uses the return type as part of the selection criteria, as in Ada~\cite{Ada}. For routines with multiple parameters and returns, the selection is complex. 33 33 \begin{cfacode} 34 34 //selection based on type and number of parameters … … 99 99 delete(s); //deallocation, call destructor 100 100 \end{cfacode} 101 Note that like \CC, \CFA introduces \code{new} and \code{delete}, which behave like \code{malloc} and \code{free} in addition to constructing and destructing objects, after calling \code{malloc} and before calling \code{free} respectively.101 Note that like \CC, \CFA introduces \code{new} and \code{delete}, which behave like \code{malloc} and \code{free} in addition to constructing and destructing objects, after calling \code{malloc} and before calling \code{free}, respectively. 102 102 103 103 \section{Parametric Polymorphism} 104 Routines in \CFA can also be reused for multiple types. This capability is done using the \code{forall} clause which gives \CFA its name. \code{forall} clauses allow separately compiled routines to support generic usage over multiple types. For example, the following sum function works for any type that supports construction from 0 and addition :104 Routines in \CFA can also be reused for multiple types. This capability is done using the \code{forall} clause, which gives \CFA its name. \code{forall} clauses allow separately compiled routines to support generic usage over multiple types. For example, the following sum function works for any type that supports construction from 0 and addition : 105 105 \begin{cfacode} 106 106 //constraint type, 0 and + … … 135 135 struct S { int i, j; }; 136 136 int mem(S & this) with (this) //with clause 137 i = 1; //this->i138 j = 2; //this->j137 i = 1; //this->i 138 j = 2; //this->j 139 139 } 140 140 int foo() { 141 141 struct S1 { ... } s1; 142 142 struct S2 { ... } s2; 143 with (s1) //with statement143 with (s1) //with statement 144 144 { 145 //access fields of s1 146 //without qualification 145 //access fields of s1 without qualification 147 146 with (s2) //nesting 148 147 { 149 //access fields of s1 and s2 150 //without qualification 148 //access fields of s1 and s2 without qualification 151 149 } 152 150 } 153 with (s1, s2) //scopes open in parallel151 with (s1, s2) //scopes open in parallel 154 152 { 155 //access fields of s1 and s2 156 //without qualification 153 //access fields of s1 and s2 without qualification 157 154 } 158 155 } 159 156 \end{cfacode} 160 157 158 \section{otype/dtype} 159 161 160 For more information on \CFA see \cite{cforall-ug,rob-thesis,www-cfa}.
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