1 | %% |
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2 | %% This is file `sample-manuscript.tex', |
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3 | %% generated with the docstrip utility. |
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4 | %% |
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5 | %% The original source files were: |
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6 | %% |
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7 | %% samples.dtx (with options: `manuscript') |
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8 | %% |
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9 | %% IMPORTANT NOTICE: |
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10 | %% |
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11 | %% For the copyright see the source file. |
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12 | %% |
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13 | %% Any modified versions of this file must be renamed |
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14 | %% with new filenames distinct from sample-manuscript.tex. |
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15 | %% |
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16 | %% For distribution of the original source see the terms |
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17 | %% for copying and modification in the file samples.dtx. |
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18 | %% |
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19 | %% This generated file may be distributed as long as the |
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20 | %% original source files, as listed above, are part of the |
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21 | %% same distribution. (The sources need not necessarily be |
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22 | %% in the same archive or directory.) |
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23 | %% |
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24 | %% Commands for TeXCount |
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25 | %TC:macro \cite [option:text,text] |
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26 | %TC:macro \citep [option:text,text] |
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27 | %TC:macro \citet [option:text,text] |
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28 | %TC:envir table 0 1 |
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29 | %TC:envir table* 0 1 |
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30 | %TC:envir tabular [ignore] word |
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31 | %TC:envir displaymath 0 word |
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32 | %TC:envir math 0 word |
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33 | %TC:envir comment 0 0 |
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34 | %% |
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35 | %% |
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36 | %% The first command in your LaTeX source must be the \documentclass command. |
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37 | \documentclass[manuscript,screen,review]{acmart} |
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38 | \usepackage{xcolor} |
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39 | \usepackage{listings} |
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40 | \usepackage[ligature, inference]{semantic} |
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41 | \usepackage{array} |
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42 | |
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43 | \definecolor{mGreen}{rgb}{0,0.6,0} |
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44 | \definecolor{mGray}{rgb}{0.5,0.5,0.5} |
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45 | \definecolor{mPurple}{rgb}{0.58,0,0.82} |
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46 | \definecolor{backgroundColour}{rgb}{0.95,0.95,0.92} |
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47 | |
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48 | \lstdefinestyle{CStyle}{ |
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49 | backgroundcolor=\color{backgroundColour}, |
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50 | commentstyle=\color{mGreen}, |
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51 | keywordstyle=\color{magenta}, |
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52 | numberstyle=\tiny\color{mGray}, |
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53 | stringstyle=\color{mPurple}, |
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54 | basicstyle=\footnotesize, |
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55 | breakatwhitespace=false, |
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56 | breaklines=true, |
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57 | captionpos=b, |
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58 | keepspaces=true, |
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59 | numbers=left, |
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60 | numbersep=5pt, |
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61 | showspaces=false, |
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62 | showstringspaces=false, |
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63 | showtabs=false, |
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64 | tabsize=2, |
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65 | language=C |
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66 | } |
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67 | |
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68 | %% |
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69 | %% \BibTeX command to typeset BibTeX logo in the docs |
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70 | \AtBeginDocument{% |
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71 | \providecommand\BibTeX{{% |
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72 | \normalfont B\kern-0.5em{\scshape i\kern-0.25em b}\kern-0.8em\TeX}}} |
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73 | |
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74 | |
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75 | %% |
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76 | %% end of the preamble, start of the body of the document source. |
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77 | \begin{document} |
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78 | |
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79 | %% |
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80 | %% The "title" command has an optional parameter, |
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81 | %% allowing the author to define a "short title" to be used in page headers. |
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82 | \title{Enumeration in Cforall} |
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83 | |
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84 | %% |
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85 | %% The "author" command and its associated commands are used to define |
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86 | %% the authors and their affiliations. |
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87 | %% Of note is the shared affiliation of the first two authors, and the |
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88 | %% "authornote" and "authornotemark" commands |
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89 | %% used to denote shared contribution to the research. |
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90 | \author{Jiada Liang} |
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91 | |
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92 | |
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93 | %% |
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94 | %% The abstract is a short summary of the work to be presented in the |
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95 | %% article. |
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96 | \begin{abstract} |
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97 | An enumeration, or enum in short, is a type that defines a list of named constant values in C. C uses integral type as the underlying representation of enum. Cforall extends C enum to allow more types, including custom types, to be used as enumeration inner representation. |
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98 | \end{abstract} |
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99 | |
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100 | %% |
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101 | %% The code below is generated by the tool at http://dl.acm.org/ccs.cfm. |
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102 | %% Please copy and paste the code instead of the example below. |
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103 | %% |
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104 | |
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105 | |
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106 | %% |
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107 | %% This command processes the author and affiliation and title |
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108 | %% information and builds the first part of the formatted document. |
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109 | \maketitle |
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110 | |
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111 | \section{C-Style Enum} |
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112 | \begin{lstlisting}[style=CStyle, label{lst:weekday}] |
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113 | enum Weekday { Monday, Tuesday, Wednesday, Thursday=10, Friday, Saturday, Sunday }; |
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114 | \end{lstlisting} |
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115 | Cforall supports the C-Style enumeration (C-enum for short). It has the same syntax as C and resembles the same language semantics. In code~\ref{lst:weekday} example, the syntax defines an enum class $Weekday$ with enumerators $Monday$, $Tuesday$, $Wednesday$, $Thursday$, $Friday$, $Saturday$ and $Sunday$ in order. The successor of $Tuesday$ is $Monday$ and the predecessor of $Tuesday$ is $Wednesday$. Enumerators have an integral type, either being explicitly initialized by an initializer or being assigned a value by the compiler. For example, $Thursday$ has been assigned with value $10$. If not explicitly initialized, the first value of an enum, $Monday$ in the $Weekday$ example, has the integer value 0. Other uninitialized enum value has a value that is equal to their successor $+ 1$. The enum value $Tuesday$, $Wednesday$, $Friday$, $Saturday$, and $Sunday$ have value 1, 2, 11, 12, and 13 respectively. |
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116 | |
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117 | \begin{lstlisting}[label{lst:enum_scope}, style=CStyle] |
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118 | { |
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119 | { |
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120 | enum RGB {R, G, B}; |
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121 | int i = R // i == 0 |
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122 | } |
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123 | int j = G; // ERROR! G is not declared in this scope |
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124 | } |
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125 | \end{lstlisting} |
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126 | C-enums are unscoped: enumerators declared inside of an enum are visible in the enclosing scope of the enum class. |
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127 | |
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128 | \section{Cforall-Style Enum} |
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129 | \begin{lstlisting}[style=CStyle, label{lst:color}] |
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130 | enum Color(char *) { Red="R", Green="G", Blue="B" }; |
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131 | \end{lstlisting} |
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132 | A Cforall enumeration is parameterized by a type declared. Cforall allows any oType in the enum declaration, and values assigned to enumerators must be in the declared type. |
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133 | |
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134 | \section{Enumerable Type Traits} |
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135 | A trait is a collection of constraints in Cforall, which can be used to describe types. Cforall standard library defines traits to categorize types that are related enumeration features. |
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136 | \subsection{Enumerable} |
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137 | A type is enumerable if it can map an integer to a value. |
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138 | \begin{lstlisting}[style=CStyle] |
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139 | forall(T) |
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140 | trait Enumerable { |
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141 | T value( *class_name* , int ); |
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142 | }; |
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143 | \end{lstlisting} |
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144 | The parameter class name stands for the name of an enumeration class, Weekday, for example. |
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145 | |
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146 | \subsection{AutoInitializable} |
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147 | \begin{lstlisting}[style=CStyle] |
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148 | forall(T) |
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149 | trait AutoInitializable { |
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150 | void ?()( T & t, zero_t ); |
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151 | void ?()( T & t, one_t ); |
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152 | S& ?+=?( T & t, one_t ); |
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153 | void ?{}( T &, T ); |
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154 | T ?{}( T &, T ); |
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155 | }; |
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156 | \end{lstlisting} |
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157 | |
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158 | \subsection{AutoInitializable} |
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159 | \begin{lstlisting}[style=CStyle] |
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160 | forall(T) |
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161 | trait AutoInitializable { |
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162 | void ?()( T & t, zero_t ); |
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163 | void ?()( T & t, one_t ); |
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164 | S& ?+=?( T & t, one_t ); |
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165 | void ?{}( T &, T ); |
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166 | T ?{}( T &, T ); |
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167 | }; |
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168 | \end{lstlisting} |
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169 | A type is AutoInitializable if it has defined a zero\_t constructor, a one\_t constructor, an addition assignment operator, a copy constructor, and a copy assignment operator. |
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170 | |
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171 | \subsection{Enumerable Type} |
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172 | \begin{lstlisting}[style=CStyle] |
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173 | forall(T) |
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174 | trait enumerable { |
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175 | void ?()( T & t, zero_t ); |
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176 | void ?()( T & t, one_t ); |
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177 | S& ?+=?( T & t, one_t ); |
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178 | void ?{}( T &, T ); |
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179 | T ?{}( T &, T ); |
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180 | }; |
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181 | \end{lstlisting} |
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182 | |
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183 | |
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184 | |
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185 | |
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186 | |
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187 | (Should change the definition of enumerable to something else. Maybe auto-constructible. If a type is not auto-constructible, all enumeration must be explicitly initialized) |
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188 | \begin{lstlisting}[caption={An example enumerable type}, label{lst:sample_enumerable}, style=CStyle] |
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189 | struct Type { int i; }; |
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190 | void ?()( Type & t, zero_t ) { t.i = 0; }; |
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191 | void ?()( Type & t, one_t ) { t.i = 1; }; |
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192 | int ?!=?( Type t, zero_t ) { return t.i != 0; }; |
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193 | S& ?+=?( Type & t, one_t ) { t.i += 1; return t; }; |
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194 | void ?()( Type & t, Type rhs ) { t.i = rhs.i; }; |
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195 | Type ?()( Type & t, Type rhs ) { t.i = rhs.i; return t; }; |
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196 | \end{lstlisting} |
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197 | |
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198 | A Cforall-enum is a C-enum parameterized by an enumerable type. For example, $enum(int)$ turns a C-enum into a Cforall-enum. |
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199 | \begin{lstlisting}[caption={An example Cforall enum}, label{lst:sample_cforall_enum}, style=CStyle] |
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200 | enum Color(Type) { Red, Green, Blue }; |
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201 | |
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202 | > Type Color.values[] = { 0, values[0]++, values[1]++ }; |
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203 | > enum Color.Label { Red_Label, Green_Label, Blue_Label }; |
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204 | \end{lstlisting} |
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205 | Declaring a Cforall-enum, the compiler defines a C-enum names every element in the Cforall-enum, and an array that stores Cforall enumeration values. |
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206 | |
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207 | \subsection{Cforall Enumerations Behaviour} |
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208 | An instance of Cforall-enum (denoted as $<enum\_instance>$) has a label, the defined enum name. The label can be retrieved by calling the function $label()$ on a $<enum\_instance>$. The $value()$ function on the other hand returns the value used to initialize the Cforall-enum. |
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209 | |
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210 | Cforall-enum supports a qualified expression. The syntax of the qualified expression for Cforall-enum is $$<enum\_type\_name>.<enum\_instance\_name>$$. In the $Color$ example, $Color$ is a $<enum\_type\_name>$ and $Red$, $Green$, $Blue$ are $<enum\_instance\_name>$. |
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211 | |
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212 | \begin{lstlisting}[caption={An example Cforall enum}, label{lst:sample_cforall_enum_usage}, style=CStyle] |
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213 | enum Color red = Color.Red; |
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214 | > enum Color.Label red = = Color.Label.Red_Label; |
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215 | Type instance = Color.Red; |
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216 | > Type instance = Color.values[ Color.Label.Red_Label ]; |
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217 | \end{lstlisting} |
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218 | |
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219 | The expression $Color.Red$ is overloaded to represent both $value(Color.Red)$ and $label(Color.Red)$. The expression returns the $label(Color.Red)$ by default but returns $value()$ whenever the $value()$ is a closer candidate in the context. [more explanation] In \ref{lst:sample_cforall_enum_usage}, when assigned to an enum variable, $Color.Red$ returns the label. This is to reduce the memory to store a Cforall-enum variable. In an assignment expression when the left-hand-side expects a $Type$, the resolution finds $value(Color.Red)$ is a better candidate than $label(Color.Red)$, and returns the value instead. |
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220 | |
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221 | \subsection{Enum Type Functions} |
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222 | \begin{lstlisting}[caption={Enum Type Functions}, label{lst:cforall_enum_functions}, style=CStyle] |
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223 | enum Color(string) { // assume String has been defined as an enumerable type |
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224 | R = "Red", G = "Green", B = "Blue" |
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225 | }; |
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226 | values( Color ); |
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227 | > [ String("Red"), String("Green"), String("Blue") ]; |
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228 | label_strings( Color ); |
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229 | > [ "R", "G", "B" ]; |
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230 | enum Color green = Color.G; |
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231 | |
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232 | label_string( Color, green ); |
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233 | > "G" |
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234 | label( Color, green ); |
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235 | > 1 |
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236 | value( Color, green ) ; |
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237 | > "Green" |
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238 | value( Color, "G" ); |
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239 | > "Green" |
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240 | label( Color, "G" ); |
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241 | > 1 |
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242 | value( Color, "DNE" ); |
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243 | > (null) |
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244 | value( Color, 1 ); // "1" is the label "G" |
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245 | > "Green" |
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246 | \end{lstlisting} |
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247 | Names of labels are distinct in an enum declaration. Cforall therefore allows indexing an enum value with its string representation of a label. |
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248 | |
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249 | \subsection{Iteration and Range} |
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250 | A Cforall enum is iterable and supports range function. |
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251 | \begin{lstlisting}[caption={Range Functions}, label{lst:range_functions}, style=CStyle] |
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252 | struct string; |
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253 | enum(string) Weekday( |
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254 | Monday = "M", Tuesday = "Tu", ... |
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255 | }; |
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256 | for ( i; Weekday ) { sout | i; } |
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257 | >> M Tu W Th F Sat Sun |
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258 | for ( Monday ~= Tuesday ) |
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259 | >> M Tu |
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260 | \end{lstlisting} |
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261 | |
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262 | \section{Implementation} |
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263 | |
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264 | \subsection{Companion Object} |
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265 | The intuition to create a companion object is that functions that support enumeration features need static information of an enumeration class. For example, values() returns an array of values defined for the enumeration. $label( Color, "G" )$ needs information about enum names defined for the enum class $Color$. Theoretically, enum-type functions can be defined as functions that take $TypeName$ expression as the first parameter. An alternative approach is to define that "companion object". |
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266 | |
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267 | \begin{lstlisting}[caption={Enum Type Functions}, label{lst:cforall_enum_functions}, style=CStyle] |
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268 | struct string; |
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269 | enum Color( string ) { |
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270 | R = "Red", G = "Green", B = "Blue" |
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271 | }; |
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272 | |
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273 | forall( T | enumerable(T) ) { |
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274 | struct Companion { |
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275 | T* values; |
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276 | char** labels; |
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277 | }; |
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278 | } |
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279 | >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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280 | enum Color.Label; |
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281 | Companion( string ) Color = { |
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282 | .values = [ "Red", "Green", "Blue" ], |
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283 | .labels = [ "R", "G", "B" ] |
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284 | }; |
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285 | >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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286 | forall( T | enumerable(T) ) |
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287 | T value( Companion companion, int index ) { return companion.values[ index ]; } |
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288 | T value( Companion, enum Color.Label ); |
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289 | char* label( Companion companion, int index ) { return companion.values[ index ]; } |
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290 | char* label( Companion, enum Color.Label ); |
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291 | |
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292 | \end{lstlisting} |
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293 | |
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294 | |
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295 | \subsection{Companion Trait} |
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296 | Users can define the companion object themselves. A companion object should define an array of any type called values and an array of strings representing a label. Defining a companion object effectively creates a new enumerable type. |
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297 | |
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298 | \subsection{Companion Mapping} |
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299 | |
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300 | |
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301 | |
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302 | \begin{lstlisting}[caption={Enum Type Functions}, label{lst:cforall_enum_functions}, style=CStyle] |
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303 | |
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304 | \end{lstlisting} |
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305 | %% |
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306 | %% If your work has an appendix, this is the place to put it. |
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307 | \appendix |
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308 | |
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309 | |
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310 | \end{document} |
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311 | \endinput |
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312 | %% |
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313 | %% End of file `sample-manuscript.tex'. |
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