Fix problem compacting a type map with three types.

Author: gkellogg

README.md

@@ -334,7 +334,7 @@ Note, the API method signatures differed in versions before 1.0, in that they al
 
 ## Dependencies
 * [Ruby](http://ruby-lang.org/) (>= 2.2.2)
-* [RDF.rb](http://rubygems.org/gems/rdf) (>= 2.0)
+* [RDF.rb](http://rubygems.org/gems/rdf) (>= 2.2)
 * [JSON](https://rubygems.org/gems/json) (>= 1.5)
 
 ## Installation

json-ld.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |gem|
 
   gem.required_ruby_version = '>= 2.2.2'
   gem.requirements          = []
-  gem.add_runtime_dependency     'rdf',             '~> 2.1'
+  gem.add_runtime_dependency     'rdf',             '~> 2.2'
   gem.add_runtime_dependency     'multi_json',      '~> 1.12'
   gem.add_development_dependency 'linkeddata',      '~> 2.0'
   gem.add_development_dependency 'jsonlint',        '~> 0.2' unless RUBY_ENGINE == "jruby"
@@ -37,7 +37,7 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "rest-client",     '~> 1.8'
   gem.add_development_dependency "rest-client-components", '~> 1.4'
   gem.add_development_dependency 'rdf-isomorphic',  '~> 2.0'
-  gem.add_development_dependency 'rdf-spec',        '~> 2.0'
+  gem.add_development_dependency 'rdf-spec',        '~> 2.2'
   gem.add_development_dependency 'rdf-trig',        '~> 2.0'
   gem.add_development_dependency 'rdf-turtle',      '~> 2.0'
   gem.add_development_dependency 'rdf-vocab',       '~> 2.0'

lib/json/ld/compact.rb

@@ -163,11 +163,11 @@ def compact(element, property: nil)
                 value?(expanded_item) ? expanded_item['@value'] : compacted_item
               when '@type'
                 type_prop = context.compact_iri('@type', vocab: true, quiet: true)
-                map_key, types = Array(compacted_item[type_prop])
-                if Array(types).empty?
-                  compacted_item.delete(type_prop)
-                else
-                  compacted_item[type_prop] = types
+                map_key, *types = Array(compacted_item[type_prop])
+                case types.length
+                when 0 then compacted_item.delete(type_prop)
+                when 1 then compacted_item[type_prop] = types.first
+                else        compacted_item[type_prop] = types
                 end
                 compacted_item
               end

spec/compact_spec.rb

@@ -582,6 +582,34 @@
             }
           })
         },
+        "Indexes to object already having multiple @type values" => {
+          input: %([{
+            "http://example/typemap": [
+              {
+                "@type": ["_:bar", "_:foo", "_:baz"],
+                "http://example/label": [{"@value": "Object with @type _:bar"}]
+              },
+              {
+                "@type": ["http://example.org/foo", "http://example.org/bar", "http://example.org/baz"],
+                "http://example/label": [{"@value": "Object with @type <foo>"}]
+              }
+            ]
+          }]),
+          context: %({
+            "@vocab": "http://example/",
+            "typemap": {"@container": "@type"}
+          }),
+          output: %({
+            "@context": {
+              "@vocab": "http://example/",
+              "typemap": {"@container": "@type"}
+            },
+            "typemap": {
+              "http://example.org/foo": {"@type": ["http://example.org/bar", "http://example.org/baz"], "label": "Object with @type <foo>"},
+              "_:bar": {"@type": ["_:foo", "_:baz"], "label": "Object with @type _:bar"}
+            }
+          })
+        },
       }.each_pair do |title, params|
         it(title) {run_compact(params)}
       end