From 429e214477b46eb0a73f971d8f325be3aeb3d196 Mon Sep 17 00:00:00 2001
From: Michael Burrows <asplake@Unknown-00-1f-5b-b8-2d-ff.home>
Date: Fri, 10 Apr 2009 11:58:49 +0100
Subject: [PATCH] Fix URI template operators 'prefix', 'suffix' and 'list' to
 return the empty string for undefined variables.

As per draft 3 of the URI template spec, made the the 'prefix', 'suffix' and 'list' to return the empty string for undefined variables.
Previously, 'prefix' and 'suffix' returned the arg regardless and 'list' raised an exception.

Added tests.  Ideally the next draft of the spec would include examples equivalent to these.
---
 lib/addressable/uri.rb       |  7 ++++---
 spec/addressable/uri_spec.rb | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/lib/addressable/uri.rb b/lib/addressable/uri.rb
index 4b7f5604..927c1ddd 100644
--- a/lib/addressable/uri.rb
+++ b/lib/addressable/uri.rb
@@ -461,7 +461,7 @@ def self.expand_prefix_operator(argument, variables, mapping)
       value = mapping[variables.first]
       if value.kind_of?(Array)
         (value.map { |list_value| argument + list_value }).join("")
-      else
+      elsif value
         argument + value.to_s
       end
     end
@@ -483,7 +483,7 @@ def self.expand_suffix_operator(argument, variables, mapping)
       value = mapping[variables.first]
       if value.kind_of?(Array)
         (value.map { |list_value| list_value + argument }).join("")
-      else
+      elsif value
         value.to_s + argument
       end
     end
@@ -526,7 +526,8 @@ def self.expand_list_operator(argument, variables, mapping)
         raise InvalidTemplateOperatorError,
           "Template operator 'list' takes exactly one variable."
       end
-      mapping[variables.first].join(argument)
+      values = mapping[variables.first]
+      values.join(argument) if values
     end
     class <<self; private :expand_list_operator; end
 
diff --git a/spec/addressable/uri_spec.rb b/spec/addressable/uri_spec.rb
index c44929b5..5164dbcc 100644
--- a/spec/addressable/uri_spec.rb
+++ b/spec/addressable/uri_spec.rb
@@ -3697,6 +3697,36 @@ def self.transform(name, value)
   end
 end
 
+describe Addressable::URI, "when given an empty mapping" do
+  before do
+    @mapping = {}
+  end
+
+  it "should result in 'http://example.com/search/'" +
+      " when used to expand 'http://example.com/search/{-list|+|query}'" do
+    Addressable::URI.expand_template(
+      "http://example.com/search/{-list|+|query}",
+      @mapping).to_str.should ==
+        "http://example.com/search/"
+  end
+
+  it "should result in 'http://example.com'" +
+      " when used to expand 'http://example.com{-prefix|/|foo}'" do
+    Addressable::URI.expand_template(
+      "http://example.com{-prefix|/|foo}",
+      @mapping).to_str.should ==
+        "http://example.com"
+  end
+
+  it "should result in 'http://example.com'" +
+      " when used to expand 'http://example.com{-suffix|/|foo}'" do
+    Addressable::URI.expand_template(
+      "http://example.com{-suffix|/|foo}",
+      @mapping).to_str.should ==
+        "http://example.com"
+  end
+end
+
 class SuperString
   def initialize(string)
     @string = string.to_s