Change URI#to_s to handle default ports for more schemes than http/https

spec/std/uri_spec.cr

@@ -100,10 +100,53 @@ describe "URI" do
     end
     it { URI.new("http", "www.example.com", user: "@al:ce", password: "s/cr3t").to_s.should eq("http://%40al%3Ace:s%2Fcr3t@www.example.com") }
     it { URI.new("http", "www.example.com", fragment: "top").to_s.should eq("http://www.example.com#top") }
-    it { URI.new("http", "www.example.com", 1234).to_s.should eq("http://www.example.com:1234") }
     it { URI.new("http", "www.example.com", 80, "/hello").to_s.should eq("http://www.example.com/hello") }
     it { URI.new("http", "www.example.com", 80, "/hello", "a=1").to_s.should eq("http://www.example.com/hello?a=1") }
     it { URI.new("mailto", opaque: "foo@example.com").to_s.should eq("mailto:foo@example.com") }
+
+    it "removes default port" do
+      URI.new("http", "www.example.com", 80).to_s.should eq("http://www.example.com")
+      URI.new("https", "www.example.com", 443).to_s.should eq("https://www.example.com")
+      URI.new("ftp", "www.example.com", 21).to_s.should eq("ftp://www.example.com")
+      URI.new("sftp", "www.example.com", 22).to_s.should eq("sftp://www.example.com")
+      URI.new("ldap", "www.example.com", 389).to_s.should eq("ldap://www.example.com")
+      URI.new("ldaps", "www.example.com", 636).to_s.should eq("ldaps://www.example.com")
+    end
+
+    it "preserves non-default port" do
+      URI.new("http", "www.example.com", 1234).to_s.should eq("http://www.example.com:1234")
+      URI.new("https", "www.example.com", 1234).to_s.should eq("https://www.example.com:1234")
+      URI.new("ftp", "www.example.com", 1234).to_s.should eq("ftp://www.example.com:1234")
+      URI.new("sftp", "www.example.com", 1234).to_s.should eq("sftp://www.example.com:1234")
+      URI.new("ldap", "www.example.com", 1234).to_s.should eq("ldap://www.example.com:1234")
+      URI.new("ldaps", "www.example.com", 1234).to_s.should eq("ldaps://www.example.com:1234")
+    end
+
+    it "preserves port for unknown scheme" do
+      URI.new("xyz", "www.example.com").to_s.should eq("xyz://www.example.com")
+      URI.new("xyz", "www.example.com", 1234).to_s.should eq("xyz://www.example.com:1234")
+    end
+  end
+
+  describe ".default_port" do
+    it "returns default port for well known schemes" do
+      URI.default_port("http").should eq(80)
+      URI.default_port("https").should eq(443)
+    end
+
+    it "returns nil for unknown schemes" do
+      URI.default_port("xyz").should eq(nil)
+    end
+
+    it "registers port for scheme" do
+      URI.set_default_port("ponzi", 9999)
+      URI.default_port("ponzi").should eq(9999)
+    end
+
+    it "unregisters port for scheme" do
+      URI.set_default_port("ftp", nil)
+      URI.default_port("ftp").should eq(nil)
+    end
   end
 
   describe ".unescape" do

src/uri.cr

@@ -149,7 +149,7 @@ class URI
     if host
       io << host
     end
-    if port && !((scheme == "http" && port == 80) || (scheme == "https" && port == 443))
+    unless port.nil? || default_port?
       io << ':'
       io << port
     end
@@ -426,4 +426,52 @@ class URI
       URI.escape(password, io)
     end
   end
+
+  # A map of schemes and their respective default ports, seeded
+  # with some well-known schemes.
+  @@default_ports = {
+    "ftp"    => 21,
+    "ftps"   => 990,
+    "gopher" => 70,
+    "http"   => 80,
+    "https"  => 443,
+    "ldap"   => 389,
+    "ldaps"  => 636,
+    "nntp"   => 119,
+    "scp"    => 22,
+    "sftp"   => 22,
+    "ssh"    => 22,
+    "telnet" => 23,
+  }
+
+  # Returns the default port for the given scheme if known, otherwise
+  # returns nil.
+  #
+  # ```
+  # URI.default_port "http" # => 80
+  # ```
+  def self.default_port(scheme : String) : Int32?
+    @@default_ports[scheme.downcase]?
+  end
+
+  # Registers the default port for the given scheme.
+  #
+  # If port is nil, the existing default port for the scheme, if any,
+  # will be unregistered.
+  #
+  # ```
+  # URI.set_default_port "ponzi" = 9999
+  # ```
+  def self.set_default_port(scheme : String, port : Int32?)
+    if port
+      @@default_ports[scheme.downcase] = port
+    else
+      @@default_ports.delete scheme.downcase
+    end
+  end
+
+  # Returns true if this URI's port is the default port for its scheme.
+  private def default_port?
+    port == @@default_ports[scheme]?
+  end
 end