Haisheng/tweak parser comment line (#1505)

* Tweak the comment line parsing rule

- In order to support `-- |` being an empty line

* run through stylish-haskell

* Update changelog

* Update changelog - update PR number

persistent/ChangeLog.md

@@ -4,6 +4,8 @@
 
 * [#1496](https://github.com/yesodweb/persistent/pull/1496)
     * Fixes name shadowing error at the generated `keyFromRecordM` function.
+* [#1505](https://github.com/yesodweb/persistent/pull/1505)
+    * Fixes the comment line parsing rule so that accommodates paragraph breaks.
 
 ## 2.14.5.0
 

persistent/Database/Persist/Quasi/Internal.hs

@@ -53,8 +53,8 @@ module Database.Persist.Quasi.Internal
 import Prelude hiding (lines)
 
 import Control.Applicative (Alternative((<|>)))
-import Data.Char (isDigit, isLower, isSpace, isUpper, toLower)
 import Control.Monad
+import Data.Char (isDigit, isLower, isSpace, isUpper, toLower)
 import Data.List (find, foldl')
 import Data.List.NonEmpty (NonEmpty(..))
 import qualified Data.List.NonEmpty as NEL
@@ -238,7 +238,7 @@ parseIndentationAmount txt =
 tokenize :: Text -> [Token]
 tokenize t
     | T.null t = []
-    | Just txt <- T.stripPrefix "-- | " t = [DocComment txt]
+    | Just txt <- T.stripPrefix "-- |" t = [DocComment (T.stripStart txt)]
     | "--" `T.isPrefixOf` t = [] -- Comment until the end of the line.
     | "#" `T.isPrefixOf` t = [] -- Also comment to the end of the line, needed for a CPP bug (#110)
     | T.head t == '"' = quotes (T.tail t) id

persistent/test/Database/Persist/QuasiSpec.hs

@@ -236,6 +236,13 @@ spec = describe "Quasi" $ do
                             [ DocComment "this is a comment"
                             ]
                         )
+            it "recognizes empty line" $ do
+                parseLine "-- |" `shouldBe`
+                    Just
+                        ( Line 0
+                            [ DocComment ""
+                            ]
+                        )
 
             it "works if comment is indented" $ do
                 parseLine "  -- | comment" `shouldBe`