Handle invalid templates

lib/uri_template.rb

@@ -1,13 +1,17 @@
-require "uri_template/version"
-require "uri_template/parser"
-require "uri_template/transformer"
+__dir__ = File.dirname(__FILE__)
+require __dir__ + "/uri_template/version"
+require __dir__ + "/uri_template/parser"
+require __dir__ + "/uri_template/transformer"
 
 class URITemplate
+  class ParseError < StandardError; end
 
   def initialize(uri_template)
     @uri_template = uri_template
     tree = Parser.new.parse(@uri_template)
     @template = Transform.new.apply(tree)
+    rescue Parslet::ParseFailed => ex
+      raise ParseError, "invalid template: #{uri_template}"
   end
 
   def expand(params)

lib/uri_template/parser.rb

@@ -1,54 +1,58 @@
-class UriTemplate::Parser < Parslet::Parser
+require 'parslet'
 
-  rule(:uri_template) do
-    uri_element.repeat(1)
-  end
+class URITemplate
+  class Parser < Parslet::Parser
 
-  rule(:uri_element) do
-    expansion | uri_part
-  end
+    rule(:uri_template) do
+      uri_element.repeat(1)
+    end
 
-  rule(:expansion) do
-    str('{') >> operator.maybe.as(:operator) >> (var_list | var) >> str('}')
-  end
+    rule(:uri_element) do
+      expansion | uri_part
+    end
 
-  rule(:operator) do
-    str('?')
-  end
+    rule(:expansion) do
+      str('{') >> operator.maybe.as(:operator) >> (var_list | var) >> str('}')
+    end
 
-  rule(:var_list) do
-    (var >> ( str(",") >> var ).repeat(1)).as(:list)
-  end
+    rule(:operator) do
+      str('?')
+    end
 
-  rule(:var) do
-    match('[a-zA-Z0-9]').repeat(1).as(:var)
-  end
+    rule(:var_list) do
+      (var >> ( str(",") >> var ).repeat(1)).as(:list)
+    end
 
-  rule(:uri_part) do
-    (unreserved | reserved | pct_encoded).repeat(1).as(:string)
-  end
+    rule(:var) do
+      match('[a-zA-Z0-9]').repeat(1).as(:var)
+    end
 
-  rule(:unreserved) do
-    alphanumeric | match("[-._~]")
-  end
+    rule(:uri_part) do
+      (unreserved | reserved | pct_encoded).repeat(1).as(:string)
+    end
 
-  rule(:alphanumeric) do
-    match('[A-Za-z0-9]')
-  end
+    rule(:unreserved) do
+      alphanumeric | match("[-._~]")
+    end
 
-  rule(:reserved) do
-    match("[:/?#\\[\\]@!$&'()*+,;=]")
-  end
+    rule(:alphanumeric) do
+      match('[A-Za-z0-9]')
+    end
 
-  rule(:pct_encoded) do
-    str('%') >> hex >> hex
-  end
+    rule(:reserved) do
+      match("[:/?#\\[\\]@!$&'()*+,;=]")
+    end
 
-  rule(:hex) do
-    match('[a-fA-F0-9]')
-  end
+    rule(:pct_encoded) do
+      str('%') >> hex >> hex
+    end
+
+    rule(:hex) do
+      match('[a-fA-F0-9]')
+    end
 
-  root(:uri_template)
+    root(:uri_template)
 
+  end
 end
 

lib/uri_template/transformer.rb

@@ -1,8 +1,12 @@
-class UriTemplate::Transformer < Parslet::Transformer
+require 'parslet'
 
-  rule(:string => simple(:st)) { st.to_s }
+class URITemplate
+  class Transformer < Parslet::Transform
 
-  rule(:var    => simple(:var)) { var.to_s }
+    rule(:string => simple(:st)) { st.to_s }
 
+    rule(:var    => simple(:var)) { var.to_s }
+
+  end
 end
 

spec/errors_spec.rb

@@ -0,0 +1,36 @@
+require 'rspec'
+require File.expand_path(File.dirname(__FILE__) + "/../lib/uri_template")
+
+describe URITemplate do
+
+  describe "with good uris" do
+
+    good = [
+      "http://example.com/",
+      "http://example.com/{foo}",
+      "http://example.com/search{?q}",
+      "http://example.com/search{?q,list}"
+    ]
+
+    good.each do |tmpl|
+      it "should parse #{tmpl.inspect}" do
+        lambda { URITemplate.new(tmpl) }.should_not raise_error(URITemplate::ParseError)
+      end
+    end
+  end
+
+  describe "with invaldi uris" do
+
+    bad = [
+      "http://example.com/{",
+      "http://example.com/{^foo}"
+    ]
+
+    bad.each do |tmpl|
+      it "should not parse #{tmpl.inspect}" do
+        lambda { URITemplate.new(tmpl) }.should raise_error(URITemplate::ParseError)
+      end
+    end
+  end
+end
+

uri_template.gemspec

@@ -17,4 +17,5 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency "parslet"
 
+  gem.add_development_dependency "rspec"
 end