From 98ea6d94abde5795e3b321b9b39b39843cab3ba0 Mon Sep 17 00:00:00 2001
From: Nando Vieira <me@fnando.com>
Date: Fri, 2 Oct 2020 10:58:29 -0700
Subject: [PATCH] Delay parsing AcceptLanguage until
 `Browser::Base#accept_language` is first called (#499)

Co-authored-by: Keiji Yoshimi <walf443@gmail.com>
---
 CHANGELOG.md         |  7 ++++++-
 lib/browser/base.rb  | 14 +++++++++-----
 test/browser_test.rb |  2 +-
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b6c09269..00c03859 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+- Delay parsing `Accept-Language` until `Browser::Base#accept_language` is
+  called for the first time.
+
 ## 5.0.0
 
 - Rename `Browser::Platform#other?` to `Browser::Platform#unknown?`.
@@ -18,7 +23,7 @@
 - Fix QQ detection.
 - Fix Alipay detection.
 - Add Sougou Browser detection.
-- User agent has a size limit of 512 bytes. This can be customized through 
+- User agent has a size limit of 512 bytes. This can be customized through
   `Browser.user_agent_size_limit`.
 - Accept-Language has a size limit of 256 bytes. This can be customized through
   `Browser.accept_language_size_limit`.
diff --git a/lib/browser/base.rb b/lib/browser/base.rb
index 4ddd07f4..11aba7e6 100644
--- a/lib/browser/base.rb
+++ b/lib/browser/base.rb
@@ -6,15 +6,11 @@ class Base
 
     attr_reader :ua
 
-    # Return an array with all preferred languages that this browser accepts.
-    attr_reader :accept_language
-
     def initialize(ua, accept_language: nil)
       validate_size(:user_agent, ua.to_s)
-      validate_size(:accept_language, accept_language.to_s)
 
       @ua = ua
-      @accept_language = AcceptLanguage.parse(accept_language)
+      @accept_language_raw = accept_language.to_s
     end
 
     # Return a meta info about this browser.
@@ -22,6 +18,14 @@ def meta
       Meta.get(self)
     end
 
+    # Return an array with all preferred languages that this browser accepts.
+    def accept_language
+      @accept_language ||= begin
+        validate_size(:accept_language, @accept_language_raw)
+        AcceptLanguage.parse(@accept_language_raw)
+      end
+    end
+
     alias_method :to_a, :meta
 
     # Return meta representation as string.
diff --git a/test/browser_test.rb b/test/browser_test.rb
index 8795e96c..25726c5b 100644
--- a/test/browser_test.rb
+++ b/test/browser_test.rb
@@ -169,7 +169,7 @@ class BrowserTest < Minitest::Test
               "is 257 bytes"
 
     assert_raises(Browser::Error, message) do
-      Browser.new("Chrome", accept_language: "a" * 257)
+      Browser.new("Chrome", accept_language: "a" * 257).accept_language
     end
   end
 end