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Specify behavior of e?.v++ and e?.v--

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BUG=
R=hausner@google.com

Review URL: https://codereview.chromium.org//1181733003.
This commit is contained in:
Gilad Bracha 2015-06-11 15:01:06 -07:00
parent 585402d77f
commit 58708e3ad1
2 changed files with 20 additions and 11 deletions
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2
docs/language/Makefile
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@ -39,4 +39,4 @@ cleanish:
clean: cleanish
rm -f *.dvi *.pdf $(HASH) $(LIST)

29
docs/language/dartLangSpec.tex
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@ -5012,47 +5012,56 @@ Postfix expressions invoke the postfix operators on objects.
A {\em postfix expression} is either a primary expression, a function, method or getter invocation, or an invocation of a postfix operator on an expression $e$.
\LMHash{}
A postfix expression of the form \code{$v$++}, where $v$ is an identifier, is equivalent to \code{()\{var r = $v$; $v$ = r + 1; return r\}()}.
A postfix expression of the form \code{$v$++}, where $v$ is an identifier, is equivalent to \code{()\{\VAR{} r = $v$; $v$ = r + 1; \RETURN{} r\}()}.
\rationale{The above ensures that if $v$ is a field, the getter gets called exactly once. Likewise in the cases below.
}
%what about e?.x++
\LMHash{}
A postfix expression of the form \code{$C.v$ ++} is equivalent to
\code{()\{var r = $C.v$; $C.v$ = r + 1; return r\}()}.
\code{()\{\VAR{} r = $C.v$; $C.v$ = r + 1; \RETURN{} r\}()}.
\LMHash{}
A postfix expression of the form \code{$e_1.v$++} is equivalent to
\code{(x)\{var r = x.v; x.v = r + 1; \RETURN{} r\}($e_1$)}.
\code{(x)\{\VAR{} r = x.v; x.v = r + 1; \RETURN{} r\}($e_1$)}.
\LMHash{}
A postfix expression of the form \code{$e_1[e_2]$++}, is equivalent to
\code{(a, i)\{var r = a[i]; a[i] = r + 1; return r\}($e_1$, $e_2$)}.
\code{(a, i)\{\VAR{} r = a[i]; a[i] = r + 1; \RETURN{} r\}($e_1$, $e_2$)}.
\LMHash{}
A postfix expression of the form \code{$v$-{}-}, where $v$ is an identifier, is equivalent to
\code{()\{var r = $v$; $v$ = r - 1; return r\}()}.
\code{()\{\VAR{} r = $v$; $v$ = r - 1; \RETURN{} r\}()}.
\LMHash{}
A postfix expression of the form \code{$C.v$-{}-} is equivalent to
\code{()\{var r = $C.v$; $C.v$ = r - 1; return r\}()}.
\code{()\{\VAR{} r = $C.v$; $C.v$ = r - 1; \RETURN{} r\}()}.
\LMHash{}
A postfix expression of the form \code{$e_1.v$-{}-} is equivalent to
\code{(x)\{var r = x.v; x.v = r - 1; \RETURN{} r\}($e_1$)}.
\code{(x)\{\VAR{} r = x.v; x.v = r - 1; \RETURN{} r\}($e_1$)}.
\LMHash{}
A postfix expression of the form \code{$e_1[e_2]$-{}-}, is equivalent to
\code{(a, i)\{var r = a[i]; a[i] = r - 1; return r\}($e_1$, $e_2$)}.
\code{(a, i)\{\VAR{} r = a[i]; a[i] = r - 1; \RETURN{} r\}($e_1$, $e_2$)}.
\LMHash{}
A postfix expression of the form \code{$e_1?.v$++} is equivalent to
\code{((x) =$>$ x == \NULL? \NULL : x.v++)($e_1$)}.
\LMHash{}
A postfix expression of the form \code{$e_1?.v$-{}-} is equivalent to
\code{((x) =$>$ x == \NULL? \NULL : x.v-{}-)($e_1$)}.
\subsection{ Assignable Expressions}
\LMLabel{assignableExpressions}