Changeset 956299b

Timestamp:

Feb 8, 2024, 10:48:41 AM (9 months ago)

Author:

Peter A. Buhr <pabuhr@…>

Branches:

master

Children:

14755e5, 714e206

Parents:

211def2

Message:

copy enum proposal to enum thesis

Location:

doc/theses/jiada_liang_MMath

Files:

• CFAenum.tex (added)
• background.tex (modified) (1 diff)
• content1.tex (deleted)
• content2.tex (deleted)
• implementation.tex (added)
• intro.tex (modified) (1 diff)
• relatedwork.tex (added)
• uw-ethesis-frontpgs.tex (modified) (1 diff)
• uw-ethesis.tex (modified) (1 diff)

doc/theses/jiada_liang_MMath/background.tex

@@ -1 +1 @@
 \chapter{Background}
+
+
+\section{C-Style Enum}
+
+The C-Style enumeration has the following syntax and semantics.
+\begin{cfa}
+enum Weekday { Monday, Tuesday, Wednesday, Thursday@ = 10@, Friday, Saturday, Sunday };
+\end{cfa}
+Enumerators without an explicitly designated constant value are \Newterm{auto-initialized} by the compiler: from left to right, starting at zero or the next explicitly initialized constant, incrementing by @1@.
+For example, @Monday@ to @Wednesday@ are implicitly assigned with constants @0@--@2@, @Thursday@ is explicitly set to constant @10@, and @Friday@ to @Sunday@ are implicitly assigned with constants @11@--@13@.
+Initialization may occur in any order.
+\begin{cfa}
+enum Weekday { Thursday@ = 10@, Friday, Saturday, Sunday, Monday@ = 0@, Tuesday, Wednesday };
+\end{cfa}
+Note, the comma in the enumerator list can be a terminator or a separator, allowing the list to end with a dangling comma.
+\begin{cfa}
+enum Weekday {
+        Thursday = 10, Friday, Saturday, Sunday,
+        Monday = 0, Tuesday, Wednesday@,@ // terminating comma
+};
+\end{cfa}
+This feature allow enumerator lines to be interchanged without moving a comma.\footnote{
+A terminating comma appears in other C syntax, e.g., the initializer list.}
+Finally, C enumerators are \Newterm{unscoped}, i.e., enumerators declared inside of an @enum@ are visible (projected) into the enclosing scope of the @enum@ type.
+
+In theory, a C enumeration \emph{variable} is an implementation-defined integral type large enough to hold all enumerated values.
+In practice, since integral constants are used, which have type @int@ (unless qualified with a size suffix), C uses @int@ as the underlying type for enumeration variables.
+Finally, there is an implicit bidirectional conversion between an enumeration and integral types.
+\begin{cfa}
+{
+        enum Weekday { /* as above */ };        $\C{// enumerators implicitly projected into local scope}$
+        Weekday weekday = Monday;                       $\C{// weekday == 0}$
+        weekday = Friday;                                       $\C{// weekday == 11}$
+        int i = Sunday;                                         $\C{// implicit conversion to int, i == 13}$
+        weekday = 10000;                                        $\C{// UNDEFINED! implicit conversion to Weekday}$
+}
+int j = Wednesday;                                              $\C{// ERROR! Wednesday is not declared in this scope}$
+\end{cfa}
+The implicit conversion from @int@ to an enumeration type is an unnecessary source of error.
+
+It is common for C programmers to ``believe'' there are 3 equivalent forms of constant enumeration.
+\begin{cfa}
+#define Monday 0
+static const int Monday = 0;
+enum { Monday };
+\end{cfa}
+For @#define@, the programmer has to play compiler and explicitly manage the enumeration values;
+furthermore, these are independent constants outside of any language type mechanism.
+The same explicit management is true for @const@ declarations, and the @const@ variable cannot appear in constant-expression locations, like @case@ labels, array dimensions,\footnote{
+C allows variable-length array-declarations (VLA), so this case does work, but it fails in \CC, which does not support VLAs, unless it is \lstinline{g++}.} and immediate operands of assembler instructions.
+Only the @enum@ form is managed by the compiler, is part of the language type-system, and works in all C constant-expression locations.

doc/theses/jiada_liang_MMath/intro.tex

@@ -1 +1 @@
 \chapter{Introduction}
 
-Testing glossy abbreviations \gls{foo} and \gls{bar}, and glossy definitions \gls{git} and \gls{gulp}.
+Naming values is a common practice in mathematics and engineering, e.g., $\pi$, $\tau$ (2$\pi$), $\phi$ (golden ratio), MHz (1E6), etc.
+Naming is also commonly used to represent many other numerical phenomenon, such as days of the week, months of a year, floors of a building (basement), specific times (noon, New Years).
+Many programming languages capture this important software-engineering capability through a mechanism called an \Newterm{enumeration}.
+An enumeration is similar to other programming-language types by providing a set of constrained values, but adds the ability to name \emph{all} the values in its set.
+Note, all enumeration names must be unique but different names can represent the same value (eight note, quaver), which are synonyms.
 
-And use the glossy abbreviations \gls{foo} and \gls{bar}, and definitions \gls{git} and \gls{gulp} again.
+Specifically, an enumerated type restricts its values to a fixed set of named constants.
+While all types are restricted to a fixed set of values because of the underlying von Neumann architecture, and hence, to a corresponding set of constants, e.g., @3@, @3.5@, @3.5+2.1i@, @'c'@, @"abc"@, etc., these values are not named, other than the programming-language supplied constant names.
+
+Fundamentally, all enumeration systems have an \Newterm{enumeration} type with an associated set of \Newterm{enumerator} names.
+An enumeration has three universal attributes, \Newterm{position}, \Newterm{label}, and \Newterm{value}, as shown by this representative enumeration, where position and value can be different.
+\begin{cquote}
+\small\sf\setlength{\tabcolsep}{3pt}
+\begin{tabular}{rccccccccccc}
+\it\color{red}enumeration & \multicolumn{7}{c}{\it\color{red}enumerators}       \\
+$\downarrow$\hspace*{25pt} & \multicolumn{7}{c}{$\downarrow$}                           \\
+@enum@ Weekday \{                               & Monday,       & Tuesday,      & Wednesday,    & Thursday,& Friday,    & Saturday,     & Sunday \}; \\
+\it\color{red}position                  & 0                     & 1                     & 2                             & 3                             & 4                     & 5                     & 6                     \\
+\it\color{red}label                             & Monday        & Tuesday       & Wednesday             & Thursday              & Friday        & Saturday      & Sunday        \\
+\it\color{red}value                             & 0                     & 1                     & 2                             & 3                             & 4                     & 5             & 6
+\end{tabular}
+\end{cquote}
+Here, the \Newterm{enumeration} @Weekday@ defines the ordered \Newterm{enumerator}s @Monday@, @Tuesday@, @Wednesday@, @Thursday@, @Friday@, @Saturday@ and @Sunday@.
+By convention, the successor of @Tuesday@ is @Monday@ and the predecessor of @Tuesday@ is @Wednesday@, independent of the associated enumerator constant values.
+Because an enumerator is a constant, it cannot appear in a mutable context, e.g. @Mon = Sun@ is meaningless, and an enumerator has no address, it is an \Newterm{rvalue}\footnote{
+The term rvalue defines an expression that can only appear on the right-hand side of an assignment.}.

doc/theses/jiada_liang_MMath/uw-ethesis-frontpgs.tex

@@ -131 +131 @@
 \begin{center}\textbf{Abstract}\end{center}
 
-Enumerated type ...
+An enumeration is a type defining an ordered set of named constant values, where a name abstracts a value, e.g., @PI@ versus @3.145159@.
+C restrict an enumeration type to the integral type @signed int@, which \CC support , meaning enumeration names bind to integer constants.
+\CFA extends C enumerations to allow all basic and custom types for the enumeration type, like other modern programming languages.
+Furthermore, \CFA adds other useful features for enumerations to support better software-engineering practices and simplify program development.
 
 \cleardoublepage

doc/theses/jiada_liang_MMath/uw-ethesis.tex

@@ -211 +211 @@
 \input{intro}
 \input{background}
-\input{content1}
-\input{content2}
+\input{CFAenum}
+\input{implementation}
+\input{relatedwork}
 \input{performance}
 \input{conclusion}