Cleanups

[xonotic/gmqcc.git] / doc / specification.tex

diff --git a/doc/specification.tex b/doc/specification.tex
index 2687946f1da77fe0e1572fe2d042e95f86f0b3f7..74190fc4aa766cd838bcebe51797a1cd6670f07d 100644 (file)
--- a/doc/specification.tex
+++ b/doc/specification.tex
@@ -363,17 +363,17 @@ types, as follows:
 
 \begin{itemize}
        \item An array type describes a contiguously allocated nonempty set of objects with a 
-             particular object type, called the element type. Array types are characterized 
-             by their element type and by the number of elements in the array.  An array type
-             is said to be derived     from its element type, and if its element is type T, the 
-             array type is sometimes called "array of T".  The construction of an array type
-                 from an element type is called "array type derivation".
+          particular object type, called the element type. Array types are characterized 
+          by their element type and by the number of elements in the array.  An array type
+          is said to be derived        from its element type, and if its element is type T, the 
+          array type is sometimes called "array of T".  The construction of an array type
+          from an element type is called "array type derivation".
        \item A function type describes a function with a specified return type. A function
-                 type is characterized by its return type and the number and types of its
-                 parameters. A function type is said to be derived from its return type, and if 
-                 its return type is T, the function type is sometimes called "function returning
-                  T". The construction of a function type from a return type is called "function
-                  type derivation".
+          type is characterized by its return type and the number and types of its
+          parameters. A function type is said to be derived from its return type, and if 
+          its return type is T, the function type is sometimes called "function returning
+          T". The construction of a function type from a return type is called "function
+          type derivation".
 \end{itemize}
 
 Arithmetic types are collectively called scalar types. Arrays and vectors are 
@@ -707,6 +707,52 @@ those of the unparenthesized expression.  It is an lvalue, a function designator
 void expression if the unparenthesized expression is, respectively, an lvalue, a 
 function designator, or a void expression.
 
+%% ->-> Constant expressions %%
+\subsubsection{Constant expressions}
+\paragraph*{Syntax}
+\begin{lstlisting}[language=bnf]
+constant-expression ::= conditional-expression
+\end{lstlisting}
+\paragraph*{Description}
+A constant expression can be evaluated during translation rather than runtime, and
+accordingly may be used in any place that a constant may be.
+\paragraph*{Constraints}
+\begin{itemize}
+       \item Constant expressions shall not contain assignment, increment, decrement,
+                 function-call, or comma operators, except when contained within a subexpression
+                 that is not evaluated.
+       \item Each constant expression shall evaluate to a constant that is in range of
+                 representable values for its type.
+\end{itemize}
+\paragraph*{Semantics}
+An expression that evaluates to a constant is required in several contexts. If a floating
+point expression is evaluated in the translation environment, the arithmetic precision range
+shall be as great is if the expression were being evaluated in the execution environment.
+\linebreak
+
+An integer constant expression shall have integer type and shall only have operands that 
+are integer constants, enumeration constants, character constants, and floating constants
+that are the immediate operand of casts. Cast operators in an integer constant expression 
+shall only convert arithmetic types to integer types.
+\linebreak
+
+More latitude is permitted for constant expressions in initializers. Such a constant expression
+shall be, or evaluate to an arithmetic constant expression.
+\linebreak
+
+An arithmetic constant expression shall have arithmetic type and shall only have operands that
+are integer constants, floating constants, enumeration constants, and character constants. Cast
+operators in an arithmetic constant expression shall only convert arithmetic types to arithmetic
+types.
+\linebreak
+
+An implementation may accept other forms of constant expressions.
+\linebreak
+
+The semantic rules for the evaluation of a constant expression are the same as for nonconstant
+expressions.
+
+
 \bibliographystyle{abbrv}
 \bibliography{main}