Added support for creating a Jsgf object from a string

lib/pocketsphinx/grammar/jsgf.rb

@@ -3,13 +3,24 @@ module Grammar
     class Jsgf
       attr_reader :raw
 
-      def initialize(path = nil, &block)
-        if path.nil? && !block_given?
+      # A convenience method for creating a new {Jsgf} from a string
+      # @param jsgf_string  [String]  the JSGF string to use
+      def self.from_string(jsgf_string)
+        self.new(nil, jsgf_string)
+      end
+
+      # @param path [String]  the path to the file to be loaded
+      # @param jsgf [String]  a string to be parsed as a JSGF grammar (set path to nil)
+      def initialize(path = nil, jsgf = nil, &block)
+        if path.nil? && jsgf.nil? && !block_given?
           raise "Either a path or block is required to create a JSGF grammar"
         end
 
         if block_given?
           @raw = grammar_from_block(&block)
+        elsif jsgf
+          @raw = jsgf
+          check_grammar
         else
           @raw = grammar_from_file(path)
           check_grammar
@@ -30,7 +41,7 @@ def grammar_from_block(&block)
 
       def check_grammar
         # Simple header check for now
-        raise 'Invalid JSGF grammar' unless raw.lines.first.strip == "#JSGF V1.0;"
+        raise 'Invalid JSGF grammar' unless raw.lines.first && raw.lines.first.strip == "#JSGF V1.0;"
       end
     end
   end

spec/grammar_spec.rb

@@ -35,6 +35,19 @@
     end
   end
 
+  context "building a grammar from a string" do
+    it "stores the string" do
+      grammar = Pocketsphinx::Grammar::Jsgf.from_string("#JSGF V1.0;\ngrammar turtle;\npublic <turtle> = go forward ten meters;")
+      expect(grammar.raw.lines.count).to eq(3)
+    end
+
+    context "the grammar string is invalid" do
+      it "raises an exception" do
+        expect { Pocketsphinx::Grammar::Jsgf.from_string("") }.to raise_exception "Invalid JSGF grammar"
+      end
+    end
+  end
+
   private
 
   def grammar(name)