Add cycle detection and determinism to context processing.
--- a/spec/latest/json-ld-api/index.html Tue Oct 30 15:14:18 2012 -0400
+++ b/spec/latest/json-ld-api/index.html Tue Oct 30 16:48:17 2012 -0400
@@ -1287,12 +1287,17 @@
with the lexical form of an <tref>absolute IRI</tref>, or <tref>null</tref>. Add the vocabulary mapping to the <tref>local context</tref>.</li>
<li id="object-context">Otherwise, for each property in <em>context</em> perform the following steps:
<ol class="algorithm">
- <li>If the property's value is a simple <tref>string</tref>, determine the IRI mapping value by
+ <li>If the <em>property</em> has finished processing, continue to the next <em>property</em>. If
+ the <em>property</em> is still processing, return an error because a cyclical dependency has been
+ detected. Otherwise, mark the <em>property</em> as processing.</li>
+ <li>If the <em>property</em> has the form of a <tref>compact IRI</tref> and the resulting prefix is in
+ <em>context</em>, then process the prefix starting at step 2.4.3.1. Otherwise, continue.</li>
+ <li>If the <em>property</em>'s <em>value</em> is a simple <tref>string</tref>, determine the IRI mapping value by
performing <a href="#iri-expansion">IRI Expansion</a> on the associated value. If the result of the IRI
- mapping is an <tref>absolute IRI</tref>, merge the property into the <tref>local context</tref>
- <tref>term mapping</tref>, unless the property is a JSON-LD <tref>keyword</tref>, in which
+ mapping is an <tref>absolute IRI</tref>, merge the <em>property</em> into the <tref>local context</tref>
+ <tref>term mapping</tref>, unless the <em>property</em> is a JSON-LD <tref>keyword</tref>, in which
case return an error.</li>
- <li>Otherwise, if the property's value is <tref>null</tref> remove mapping, coercion,
+ <li>Otherwise, if the <em>property</em>'s <em>value</em> is <tref>null</tref> remove mapping, coercion,
container and language information associated with property from the
<tref>local context</tref>.</li>
<li>Otherwise, the <em>property</em>'s <em>value</em> MUST be a <tref>JSON object</tref>.
@@ -1309,7 +1314,7 @@
by performing <a href="#iri-expansion">IRI Expansion</a> on the associated value.
If the result of the IRI mapping is an <tref>absolute IRI</tref>, merge the
<em>property</em> into the <tref>local context</tref> <tref>term mapping</tref>.</li>
- <li>If the <em>property</em> has the form of of a <tref>compact IRI</tref> or <tref>absolute IRI</tref>,
+ <li>If the <em>property</em> has the form of a <tref>compact IRI</tref> or <tref>absolute IRI</tref>,
the <em>value</em> MAY have a <code>@id</code> property with a string value which MUST have the
form of a <tref>term</tref>, <tref>compact IRI</tref>, or absolute <tref>IRI</tref>.
Determine the IRI mapping by performing <a href="#iri-expansion">IRI Expansion</a> on the associated
@@ -1329,9 +1334,8 @@
<em>property</em>.</li>
</ol>
</li>
- <li>Merge the <tref>local context</tref> into the <tref>active context</tref>.</li>
- <li>Repeat <a href="#object-context">Step 2.4.2</a> until no entries are added to the <tref>local
- context</tref>.</li>
+ <li>Mark the <em>property</em> as finished processing and merge the <tref>local context</tref> into
+ the <tref>active context</tref>.</li>
</ol>
</li>
</ol>
@@ -1340,12 +1344,6 @@
</li>
</ol>
- <p class="note">It can be difficult to distinguish between a <tref>compact IRI</tref> and an <tref>absolute IRI</tref>,
- as a <tref>compact IRI</tref> may seem to be a valid IRI <em>scheme</em>. When performing repeated IRI expansion,
- a term used as a prefix may not have a valid mapping due to dependencies in resolving term definitions. By
- continuing <a href="#object-context">Step 2.3.2</a> until no changes are made, mappings to IRIs created
- using an undefined term prefix will eventually expand to an <tref>absolute IRI</tref>s.</p>
-
</section>
<section>