From ee2deb5a51e416d607cce45ddd10d4e19c050771 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 25 Oct 2010 04:13:12 -0400
Subject: [PATCH] Handle all numeric entities by converting them to UTF-8
 rather than hard-coding each conversion.

---
 src/Twitter/Xml.hs | 47 ++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/src/Twitter/Xml.hs b/src/Twitter/Xml.hs
index 1b1ea48..e284a0d 100644
--- a/src/Twitter/Xml.hs
+++ b/src/Twitter/Xml.hs
@@ -2,8 +2,9 @@
 module Twitter.Xml
 where
 
+import Data.Char (chr)
 import Test.HUnit
-import Text.Regex (mkRegex, subRegex)
+import Text.Regex (matchRegex, mkRegex, subRegex)
 import Text.XML.HaXml
 
 -- |Returns the 'CharData' contained within the given 'Content', or
@@ -51,6 +52,22 @@ status_user = keep /> (tag "user")
 user_screen_name :: CFilter
 user_screen_name = keep /> (tag "screen_name") /> txt
 
+-- |A wrapper around the 'read' function which returns either Nothing
+-- or (Just <the thing that could be read>).
+maybe_read :: (Read a) => String -> Maybe a
+maybe_read str =
+    case (reads str) of
+      [] -> Nothing
+      ((y,_):_) -> Just y
+
+-- |Takes a unicode codepoint in decimal and returns it as a
+-- one-character string.
+entity_from_codepoint :: String -> String
+entity_from_codepoint codepoint =
+    case (maybe_read codepoint) of
+      Nothing  -> ""
+      Just num -> [(chr num)]
+
 
 -- |A list of tuples whose first entry is a regular expression
 -- matching XML entities, and whose second entry is the ASCII
@@ -60,16 +77,34 @@ xml_entities = [("[lr]dquo", "\""),
                 ("quot",     "\""),
                 ("[mn]dash", "-"),
                 ("nbsp",     " "),
-                ("#8217",    "'"),
                 ("amp",      "&"),
                 ("lt",       "<"),
                 ("gt",       ">"),
-                ("#8230",    "..."),
-                ("hellip",   "...")]
+                ("hellip",   "…")]
 
 -- |Replace all of the XML entities in target.
 replace_entities :: String -> String
-replace_entities target = unescape_recursive xml_entities target
+replace_entities target =
+    unescape_numeric (unescape_recursive xml_entities target)
+
+-- |Recursively unescape all numeric entities in the given String.
+unescape_numeric :: String -> String
+unescape_numeric target =
+    case match of
+      Nothing -> target
+      Just subexprs ->
+          case subexprs of
+            []   -> target
+            s1:_ ->
+                let this_entity_regex = mkRegex ("&#" ++ s1 ++ ";") in
+                let replacement = entity_from_codepoint s1 in
+                let new_target = subRegex this_entity_regex target replacement in
+                unescape_numeric new_target
+    where
+      from = "&#([0-9]+);"
+      match = matchRegex (mkRegex from) target
+
+
 
 -- |The recursive function which does the real work for
 -- 'replace_entities'.
@@ -93,4 +128,4 @@ test_replace_entities =
     TestCase $ assertEqual "All entities are replaced correctly." expected_text actual_text
     where
       actual_text = (replace_entities "&quot;The moon is gay&#8230;&hellip;&quot; said &lt;insert the current president of the United States of America&gt;. &ldquo;It&#8217;s OK&mdash;&ndash;he&#8217;s not a real doctor.&rdquo;")
-      expected_text = "\"The moon is gay......\" said <insert the current president of the United States of America>. \"It's OK--he's not a real doctor.\""
+      expected_text = "\"The moon is gay……\" said <insert the current president of the United States of America>. \"It’s OK--he’s not a real doctor.\""
-- 
2.43.2