Clarify compact IRIs and add two test cases

This addresses #224.

spec/latest/json-ld-syntax/index.html

@@ -861,24 +861,18 @@ <h2>Default Vocabulary</h2>
   <h2>Compact IRIs</h2>
 
   <p>A <tdef>compact IRI</tdef> is a way of expressing an <tref>IRI</tref>
-    using a <em>prefix</em> and <em>suffix</em> separated by a colon (<code>:</code>) which is
-    similar to the <cite><a href="http://www.w3.org/TR/rdfa-core/#s_curies">CURIE Syntax</a></cite>
-    in [[RDFA-CORE]]. The <tdef>prefix</tdef> is a <tref>term</tref> taken from the
+    using a <em>prefix</em> and <em>suffix</em> separated by a colon (<code>:</code>).
+    The <tdef>prefix</tdef> is a <tref>term</tref> taken from the
     <tref>active context</tref> and is a short string identifying a
-    particular <tref>IRI</tref> in a JSON-LD document.
-    For example, the prefix <code>foaf</code> may be used as a short
-    hand for the Friend-of-a-Friend vocabulary, which is identified using
-    the IRI <code>http://xmlns.com/foaf/0.1/</code>. A developer may append
+    particular <tref>IRI</tref> in a JSON-LD document. For example, the
+    prefix <code>foaf</code> may be used as a short hand for the
+    Friend-of-a-Friend vocabulary, which is identified using the <tref>IRI</tref>
+    <code>http://xmlns.com/foaf/0.1/</code>. A developer may append
     any of the FOAF vocabulary terms to the end of the prefix to specify a short-hand
     version of the <tref>absolute IRI</tref> for the vocabulary term. For example,
-    <code>foaf:name</code> would be expanded out to the IRI
+    <code>foaf:name</code> would be expanded to the IRI
     <code>http://xmlns.com/foaf/0.1/name</code>.</p>
 
-  <p><tref title="prefix">Prefixes</tref> are expanded when the form of the value
-    is a <tref>compact IRI</tref> represented as a <code>prefix:suffix</code>
-    combination, and the prefix matches a <tref>term</tref> defined within the
-    <tref>active context</tref>:</p>
-
   <pre class="example" data-transform="updateExample"
        title="Prefix expansion">
   <!--
@@ -888,70 +882,52 @@ <h2>Compact IRIs</h2>
       "****foaf****": "****http://xmlns.com/foaf/0.1/****"
   ...
     },
+    "@type": "****foaf:Person****"
     "****foaf:name****": "Dave Longley",
   ...
   }
   -->
   </pre>
 
-  <p><code>foaf:name</code> above will automatically expand out to the IRI
-    <code>http://xmlns.com/foaf/0.1/name</code>.</p>
+  <p>In the example above, <code>foaf:name</code> expands to the <tref>IRI</tref>
+    <code>http://xmlns.com/foaf/0.1/name</code> and <code>foaf:Person</code> expands
+    to <code>http://xmlns.com/foaf/0.1/Person</code>.</p>
 
-  <p>Terms are interpreted as <tref title="compact iri">compact IRIs</tref> if they contain at least one
-    colon and the first colon is not followed by two slashes (<code>//</code>, as in
-    <code>http://example.com</code>). To generate the full <tref>IRI</tref>,
-    the value is first split into a <em>prefix</em> and <em>suffix</em> at the first
-    occurrence of a colon (<code>:</code>). If the <tref>active context</tref>
-    contains a term mapping for <em>prefix</em>, an IRI is generated by
-    prepending the mapped <em>prefix</em> to the (possibly empty) <em>suffix</em>
-    using textual concatenation.  If no prefix mapping is defined, the value is interpreted
-    as an <tref>absolute IRI</tref>. If the prefix is an underscore
-    (<code>_</code>), the IRI remains unchanged.</p>
-  <p>Consider the following example:</p>
+  <p><tref title="prefix">Prefixes</tref> are expanded when the form of the value
+    is a <tref>compact IRI</tref> represented as a <code>prefix:suffix</code>
+    combination, the <em>prefix</em> matches a <tref>term</tref> defined within the
+    <tref>active context</tref>, and the <em>suffix</em> does not begin with two
+    slashes&nbsp;(<code>//</code>). The <tref>compact IRI</tref> is expanded by
+    concatenating the <tref>IRI</tref> mapped to the <em>prefix</em> to the (possibly empty)
+    <em>suffix</em>. If the <em>prefix</em> is not defined in the <tref>active context</tref>,
+    or the suffix begins with two slashes (such as in <code>http://example.com</code>),
+    the value is interpreted as <tref>absolute IRI</tref> instead. If the prefix is an
+    underscore (<code>_</code>), the value is interpreted as <tref>blank node identifier</tref>
+    instead.</p>
+
+
+  <p>It's also possible to use compact IRIs within the context as shown in the
+    following example:</p>
 
   <pre class="example" data-transform="updateExample"
-     title="Compact IRIs">
+     title="Using vocabularies">
   <!--
   {
     "@context":
     {
-      ****"dc": "http://purl.org/dc/elements/1.1/",****
-      ****"ex": "http://example.org/vocab#"****
+      "xsd": "http://www.w3.org/2001/XMLSchema#",
+      ****"foaf": "http://xmlns.com/foaf/0.1/"****,
+      ****"foaf:homepage"****: { "@type": "@id" },
+      "picture": { "@id": ****"foaf:depiction"****, "@type": "@id" }
     },
-    "@id": "http://example.org/library/the-republic",
-    "@type": ****"ex:Book"****,
-    ****"dc:creator"****: "Plato",
-    ****"dc:title"****: "The Republic"
+    "@id": "http://me.markus-lanthaler.com/",
+    "@type": "foaf:Person",
+    "foaf:name": "Markus Lanthaler",
+    "foaf:homepage": "http://www.markus-lanthaler.com/",
+    "picture": "http://twitter.com/account/profile_image/markuslanthaler"
   }
   -->
   </pre>
-
-  <p>In this example, two different vocabularies are referred to using prefixes.
-    Those prefixes are then used as type and property values using the compact
-    IRI <code>prefix:suffix</code> notation.</p>
-
-  <p>It's also possible to use compact IRIs within the context as shown in the
-    following example:</p>
-
-  <pre class="example" data-transform="updateExample"
-     title="Using vocabularies">
-<!--
-{
-  "@context":
-  {
-    "xsd": "http://www.w3.org/2001/XMLSchema#",
-    ****"foaf": "http://xmlns.com/foaf/0.1/"****,
-    ****"foaf:homepage"****: { "@type": "@id" },
-    "picture": { "@id": ****"foaf:depiction"****, "@type": "@id" }
-  },
-  "@id": "http://me.markus-lanthaler.com/",
-  "@type": "foaf:Person",
-  "foaf:name": "Markus Lanthaler",
-  "foaf:homepage": "http://www.markus-lanthaler.com/",
-  "picture": "http://twitter.com/account/profile_image/markuslanthaler"
-}
--->
-  </pre>
 </section>
 
 <section>

test-suite/tests/expand-0067-in.jsonld

@@ -0,0 +1,8 @@
+{
+  "@context": {
+    "http": "http://example.com/this-prefix-would-overwrite-all-http-iris"
+  },
+  "@id": "http://example.org/node1",
+  "@type": "http://example.org/type",
+  "http://example.org/property": "all these IRIs remain unchanged because they are interpreted as absolute IRIs"
+}

test-suite/tests/expand-0067-out.jsonld

@@ -0,0 +1,9 @@
+[
+  {
+    "@id": "http://example.org/node1",
+    "@type": ["http://example.org/type"],
+    "http://example.org/property": [
+      { "@value": "all these IRIs remain unchanged because they are interpreted as absolute IRIs" }
+    ]
+  }
+]

test-suite/tests/expand-0068-in.jsonld

@@ -0,0 +1,8 @@
+{
+  "@context": {
+    "_": "http://example.com/this-prefix-would-overwrite-all-blank-node-identifiers"
+  },
+  "@id": "_:node1",
+  "@type": "_:type",
+  "_:property": "all these IRIs remain unchanged because they are interpreted as blank node identifiers"
+}

test-suite/tests/expand-0068-out.jsonld

@@ -0,0 +1,9 @@
+[
+  {
+    "@id": "_:b0",
+    "@type": ["_:b1"],
+    "_:b2": [
+      { "@value": "all these IRIs remain unchanged because they are interpreted as blank node identifiers" }
+    ]
+  }
+]

test-suite/tests/expand-manifest.jsonld

@@ -338,6 +338,16 @@
       "name": "Use @vocab to expand keys in reverse-maps",
       "input": "expand-0066-in.jsonld",
       "expect": "expand-0066-out.jsonld"
+    }, {
+      "@type": ["test:TestCase", "jld:ExpandTest"],
+      "name": "prefix:suffix values are not interpreted as compact IRIs if suffix begins with two slashes",
+      "input": "expand-0067-in.jsonld",
+      "expect": "expand-0067-out.jsonld"
+    }, {
+      "@type": ["test:TestCase", "jld:ExpandTest"],
+      "name": "prefix:suffix values are not interpreted as compact IRIs if prefix is an underscore",
+      "input": "expand-0068-in.jsonld",
+      "expect": "expand-0068-out.jsonld"
     }
   ]
 }