Skip to content

Adding a sentence about the semantics of >> in JavaScript compiled code #1448

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Feb 15, 2021
Merged

Adding a sentence about the semantics of >> in JavaScript compiled code #1448

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
d61e9a7
Adding a sentence about the semantics of >> in JavaScript compiled code
eernstg Feb 10, 2021
b2a3b56
Review response, now using symbols rather than names for operations, …
eernstg Feb 12, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
61 changes: 35 additions & 26 deletions specification/dartLangSpec.tex
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -423,7 +423,7 @@ \section{Notation}
\alt <oneOrMoreThings>+
\alt <anOptionalThing>?
\alt (<some> <grouped> <things>)
\alt \gtilde{}<notAThing>
\alt \gtilde<notAThing>
\alt `aTerminal'
\alt <A\_LEXICAL\_THING>
\end{grammar}
Expand Down Expand Up @@ -2383,7 +2383,7 @@ \subsubsection{Operators}
\lit{-},
\lit{+},
\lit{/},
\lit{\gtilde{}/},
\lit{\gtilde/},
\lit{*},
\lit{\%},
\lit{|},
Expand All @@ -2394,7 +2394,7 @@ \subsubsection{Operators}
\lit{\gtgt},
\lit{[]=},
\lit{[]},
\lit{\gtilde{}}.
\lit{\gtilde}.

\LMHash{}%
It is a compile-time error if the arity of the user-declared operator
Expand All @@ -2407,7 +2407,7 @@ \subsubsection{Operators}
\lit{==},
\lit{-},
\lit{+},
\lit{\gtilde{}/},
\lit{\gtilde/},
\lit{/},
\lit{*},
\lit{\%},
Expand Down Expand Up @@ -6579,7 +6579,7 @@ \subsection{Constants}
\end{enumerate}

\item
An expression of the form \code{\gtilde{}$e_1$} is
An expression of the form \code{\gtilde$e_1$} is
a potentially constant expression
if $e_1$ is a potentially constant expression.
It is further a constant expression if $e_1$ is
Expand All @@ -6596,14 +6596,14 @@ \subsection{Constants}
\lit{\&}, \lit{|}, respectively \lit{\^}
denotes an instance operator invocation.

\item An expression of one of the forms \code{$e_1$\,\gtilde{}/\,$e_2$},
\item An expression of one of the forms \code{$e_1$\,\gtilde/\,$e_2$},
\code{$e_1$\,\gtgt\,$e_2$}, \code{$e_1$\,\gtgtgt\,$e_2$},
or \code{$e_1$\,\ltlt\,$e_2$} is potentially constant
if $e_1$ and $e_2$ are both potentially constant expressions.
It is further constant if both $e_1$ and $e_2$ are constant expressions that
both evaluate to an instance of \code{int},
such that the operator symbol
\lit{\gtilde{}/}, \lit{\gtgt}, \lit{\gtgtgt}, respectively \lit{\ltlt}
\lit{\gtilde/}, \lit{\gtgt}, \lit{\gtgtgt}, respectively \lit{\ltlt}
denotes an instance operator invocation.

\item An expression of the form \code{$e_1$\,+\,$e_2$} is
Expand Down Expand Up @@ -6772,8 +6772,8 @@ \subsubsection{Further Remarks on Constants and Potential Constants}
}

\begin{dartCode}
\CONST{} x = 1 \gtilde{}/ 0;
\FINAL{} y = 1 \gtilde{}/ 0;
\CONST{} x = 1 \gtilde/ 0;
\FINAL{} y = 1 \gtilde/ 0;
\\
\CLASS{} K \{
m1() \{
Expand Down Expand Up @@ -7157,12 +7157,12 @@ \subsection{Strings}
(<SINGLE\_LINE\_STRING\_DQ\_MID\_MID> <expression>)* \gnewline{}
<SINGLE\_LINE\_STRING\_DQ\_MID\_END>

<RAW\_SINGLE\_LINE\_STRING> ::= `r' `\sq' (\gtilde{}(`\sq' | `\\r' | `\\n'))* `\sq'
\alt `r' `"' (\gtilde{}(`"' | `\\r' | `\\n'))* `"'
<RAW\_SINGLE\_LINE\_STRING> ::= `r' `\sq' (\gtilde(`\sq' | `\\r' | `\\n'))* `\sq'
\alt `r' `"' (\gtilde(`"' | `\\r' | `\\n'))* `"'

<STRING\_CONTENT\_COMMON> ::= \gtilde{}(`\\' | `\sq' | `"' | `$' | `\\r' | `\\n')
<STRING\_CONTENT\_COMMON> ::= \gtilde(`\\' | `\sq' | `"' | `$' | `\\r' | `\\n')
\alt <ESCAPE\_SEQUENCE>
\alt `\\' \gtilde{}(`n' | `r' | `b' | `t' | `v' | `x' | `u' | `\\r' | `\\n')
\alt `\\' \gtilde(`n' | `r' | `b' | `t' | `v' | `x' | `u' | `\\r' | `\\n')
\alt <SIMPLE\_STRING\_INTERPOLATION>

<STRING\_CONTENT\_SQ> ::= <STRING\_CONTENT\_COMMON> | `"'
Expand Down Expand Up @@ -12119,8 +12119,8 @@ \subsubsection{Ordinary Member Closurization}
is defined to be equivalent
(\commentary{except for equality, as noted below}) to:
\begin{itemize}
%\item $(a) \{\RETURN{}$ $u$ $op$ $a;$\} if $f$ is named $op$ and $op$ is one of \code{<, >, <=, >=, ==, -, +, /, \gtilde{}/, *, \%, $|$, \^{}, \&, $<<$, $>>$} (this precludes closurization of unary -).
%\item $() \{\RETURN{}$ \gtilde{} $u;$\} if $f$ is named \gtilde{}.
%\item $(a) \{\RETURN{}$ $u$ $op$ $a;$\} if $f$ is named $op$ and $op$ is one of \code{<, >, <=, >=, ==, -, +, /, \gtilde/, *, \%, $|$, \^{}, \&, $<<$, $>>$} (this precludes closurization of unary -).
%\item $() \{\RETURN{}$ \gtilde{} $u;$\} if $f$ is named \gtilde.
%\item $(a) \{\RETURN{}$ $u[a];$\} if $f$ is named \code{[]}.
%\item $(a, b) \{\RETURN{}$ $u[a] = b;$\} if $f$ is named \code{[]=}.
\item
Expand Down Expand Up @@ -12258,8 +12258,8 @@ \subsubsection{Super Closurization}

\LMHash{}%
\begin{itemize}
%\item $(a) \{\RETURN{}$ \SUPER{} $op$ $a;$\} if $f$ is named $op$ and $op$ is one of \code{<, >, <=, >=, ==, -, +, /, \gtilde{}/, *, \%, $|$, \^{}, \&, $<<$, $>>$}.
%\item $() \{\RETURN{}$ \gtilde{}\SUPER;\} if $f$ is named \gtilde{}.
%\item $(a) \{\RETURN{}$ \SUPER{} $op$ $a;$\} if $f$ is named $op$ and $op$ is one of \code{<, >, <=, >=, ==, -, +, /, \gtilde/, *, \%, $|$, \^{}, \&, $<<$, $>>$}.
%\item $() \{\RETURN{}$ \gtilde\SUPER;\} if $f$ is named \gtilde.
%\item $(a) \{\RETURN{}$ $\SUPER[a];$\} if $f$ is named \code{[]}.
%\item $(a, b) \{\RETURN{}$ $\SUPER[a] = b;$\} if $f$ is named \code{[]=}.
\item
Expand Down Expand Up @@ -16190,7 +16190,7 @@ \section{Libraries and Scripts}
<scriptTag>? <libraryName>? <importOrExport>* <partDirective>*
\gnewline{} (<metadata> <topLevelDeclaration>)* <EOF>

<scriptTag> ::= `#!' (\gtilde{}<NEWLINE>)* <NEWLINE>
<scriptTag> ::= `#!' (\gtilde<NEWLINE>)* <NEWLINE>

<libraryName> ::= <metadata> \LIBRARY{} <dottedIdentifierList> `;'

Expand Down Expand Up @@ -19230,7 +19230,7 @@ \subsubsection{Comments}
are sections of program text that are used for documentation.

\begin{grammar}
<SINGLE\_LINE\_COMMENT> ::= `//' \gtilde{}(<NEWLINE>)* (<NEWLINE>)?
<SINGLE\_LINE\_COMMENT> ::= `//' \gtilde(<NEWLINE>)* (<NEWLINE>)?

<MULTI\_LINE\_COMMENT> ::= \gnewline{}
`/*' (<MULTI\_LINE\_COMMENT> | \gtilde{} `*/')* `*/'
Expand Down Expand Up @@ -19278,9 +19278,9 @@ \subsection{Operator Precedence}
Unary postfix & \code{$e$.}, \code{$e$?.}, \code{$e$++}, \code{$e$-{}-}, \code{$e1$[$e2$]},
\code{$e$()} & None & 16 \\
\hline
Unary prefix & \code{-$e$}, \code{!$e$}, \code{\gtilde{}$e$}, \code{++$e$}, \code{-{}-$e$}, \code{\AWAIT{} $e$} & None & 15\\
Unary prefix & \code{-$e$}, \code{!$e$}, \code{\gtilde$e$}, \code{++$e$}, \code{-{}-$e$}, \code{\AWAIT{} $e$} & None & 15\\
\hline
Multiplicative & \code{*}, \code{/}, \code{\gtilde{}/}, \code{\%} & Left & 14\\
Multiplicative & \code{*}, \code{/}, \code{\gtilde/}, \code{\%} & Left & 14\\
\hline
Additive & \code{+}, \code{-} & Left & 13\\
\hline
Expand Down Expand Up @@ -19499,11 +19499,20 @@ \section*{Appendix: Integer Implementations}
common subclass implementing both \code{int} and \code{double}.
Fractional numbers only implement \code{double}.
\item[$\bullet$]
Bitwise operations on integers (and, or, xor, negation, and shifts)
all truncate the operands to 32-bit two's complement integers,
perform 32-bit operations on those,
and the resulting 32 bits are interpreted as a 32-bit unsigned integer
(for example, \code{-1 <{}< 1} evaluates to 4294967294).
Bitwise operations on integers (\lit{\&}, \lit{|}, \lit{\^},
\lit{\gtilde}, \lit{\ltlt}, and \lit{\gtgt}) all truncate the
operands to 32-bit two's complement integers, perform 32-bit
operations on those, and the resulting 32 bits are interpreted as a
32-bit unsigned integer. For example, \code{-1\,\ltlt\,1} evaluates
to 4294967294 (also known as \code{(-2).toUnsigned(32)}. The right
shift operator, \lit{\gtgt}, performs a signed right shift on the
32 bits when the original number is negative, and an unsigned right
shift when the original number is non-negative. For example:
\code{0x80000002\,\gtgt\,1\ ==\ 0x40000001}, but
\code{-0x7FFFFFFD\,\gtgt\,1\ ==\ 0xC0000001}
(where we note that both \code{0x80000002} and \code{-0x7FFFFFFD}
yield the 32-bit two's complement representation \code{0x80000002},
but have different values for the IEEE 754 sign bit).
\item[$\bullet$]
The \code{identical} method cannot distinguish the values $0.0$ and
$-0.0$, and it cannot recognize any \Index{NaN} value as identical
Expand Down