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Merged
merged 6 commits into from
Nov 21, 2016
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Define 'continue' and 'break' statements. #35

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5e69efc
Define 'continue' and 'break' statements.
mikewest Nov 18, 2016
a5a397e
fixup to make things more generic.
mikewest Nov 18, 2016
1cd451e
Tweaks
domenic Nov 18, 2016
b71819f
Add Mike West to the acks
domenic Nov 18, 2016
59bf36c
fixup typo
mikewest Nov 19, 2016
cd3bf39
fixups
annevk Nov 21, 2016
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Expand Up @@ -107,12 +107,59 @@ leading spaces" or "return false") are to be interpreted with the meaning of the
manner, so long as the end result is equivalent. (In particular, the algorithms are intended to be
easy to follow, and not intended to be performant.)

<h4 id=algorithm-control-flow>Control flow</h4>

<p>The control flow of algorithms is such that a requirement to "return" or "throw" terminates the
algorithm the statement was in. "Return" will hand the given value, if any, to its caller. "Throw"
will make the caller automatically rethrow the given value, if any, and thereby terminate the
caller's algorithm. Using prose the caller has the ability to "catch" the exception and perform
another action.

<p>An iteration's flow can be controlled via requirements to
<dfn export for=iteration>continue</dfn> or <dfn export for=iteration>break</dfn>.
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@domenic if we export these, why not export return and throw? Is the plan to do that later once we figure things out with IDL?

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Yes, we should wait there.

<a for=iteration>Continue</a> will skip over any remaining steps in an iteration, proceeding to the
next item. If no further items remain, the iteration will stop. <a for=iteration>Break</a> will skip
over any remaining steps in an iteration, and skip over any remaining items as well, stopping the
iteration.

<div class=example id=example-break-continue>
<p>Let |example| be the <a>list</a> « 1, 2, 3, 4 ». The following prose would perform |operation|
upon 1, then 2, then 3, then 4:

<ol>
<li>
<p><a for=list>For each</a> |item| in |example|:
<ol>
<li>Perform |operation| on |item|.
</ol>
</li>
</ol>

<p>The following prose would perform |operation| upon 1, then 2, then 4. 3 would be skipped.

<ol>
<li>
<p><a for=list>For each</a> |item| in |example|:
<ol>
<li>If |item| is 3, then <a for=iteration>continue</a>.
<li>Perform |operation| on |item|.
</ol>
</li>
</ol>

<p>The following prose would perform |operation| upon 1, then 2. 3 and 4 would be skipped.

<ol>
<li>
<p><a for=list>For each</a> |item| in |example|:
<ol>
<li>If |item| is 3, then <a for=iteration>break</a>.
<li>Perform |operation| on |item|.
</ol>
</li>
</ol>
</div>


<h3 id=terminology>Terminology</h3>

Expand Down Expand Up @@ -426,6 +473,7 @@ for each pair of converted key/original value. [[!WEBIDL]]

<p>Many thanks to
Michael™ Smith,
Mike West,
Philip Jägenstedt,
and Simon Pieters
for being awesome!
Expand Down