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typeclassed String to StringLike #82

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typeclassed String to StringLike #82

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dd95b70
removed strings
BebeSparkelSparkel May 2, 2019
ee0b370
fixed .travis/stack*.yaml
BebeSparkelSparkel May 2, 2019
f2a69db
added ExtendedDefaultRules to benchmarks
BebeSparkelSparkel May 2, 2019
a91324b
exposed select
BebeSparkelSparkel May 3, 2019
800c6a9
Merge branch 'expose_select'
BebeSparkelSparkel May 3, 2019
4cad1b3
removed export of `select`
BebeSparkelSparkel May 11, 2019
dfa2fd3
Uses stackage tagsoup
BebeSparkelSparkel May 11, 2019
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3 changes: 3 additions & 0 deletions .gitignore
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Expand Up @@ -10,3 +10,6 @@ cabal-dev
.stack-work/
cabal.sandbox.config
cabal.config
*.swp
*.swo
*.DS_Store
1 change: 1 addition & 0 deletions .travis/stack-lts-2.yaml
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Expand Up @@ -8,4 +8,5 @@ extra-deps:
- http-client-0.4.30
- http-client-tls-0.2.4
- pointedlist-0.6.1
- tagsoup-0.14.8@sha256:56b2023d2e9fdbff093719ce9af5285d2436b234c6c684d6a69f14595a8348ae
resolver: lts-2.0
1 change: 1 addition & 0 deletions .travis/stack-lts-6.yaml
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Expand Up @@ -6,4 +6,5 @@ packages:
extra-deps:
- fail-4.9.0.0
- http-client-0.4.30
- tagsoup-0.14.8@sha256:56b2023d2e9fdbff093719ce9af5285d2436b234c6c684d6a69f14595a8348ae
resolver: lts-6.0
1 change: 1 addition & 0 deletions .travis/stack-lts-7.yaml
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Expand Up @@ -5,4 +5,5 @@ packages:
- ../examples/
extra-deps:
- fail-4.9.0.0
- tagsoup-0.14.8@sha256:56b2023d2e9fdbff093719ce9af5285d2436b234c6c684d6a69f14595a8348ae
resolver: lts-7.4
5 changes: 4 additions & 1 deletion examples/complex-predicates/Main.hs
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@@ -1,10 +1,13 @@
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ExtendedDefaultRules #-}

import Text.HTML.Scalpel
import Control.Applicative
import Control.Monad
import Data.List (isInfixOf)

default (String)


exampleHtml :: String
exampleHtml = "<html>\
Expand Down Expand Up @@ -37,7 +40,7 @@ catComment :: Scraper String String
catComment =
-- 1. First narrow the current context to the div containing the comment's
-- textual content.
chroot ("div" @: [hasClass "comment", hasClass "text"]) $ do
chroot (("div" :: TagName String) @: [hasClass "comment", hasClass "text"]) $ do
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I think this is why I chose to mix String and StringLike. It seems a lot less convenient to have to explicitly type each tag name as a TagName String.

Is there a specific benefit that using StringLike enables?

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What if we have a String or Text specific file that just declares the type

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Hrmmm, there's already Text.HTML.Scalpel and Text.HTML.Scalpel.Core. I'd rather not create more re-exports of the API if its not necessary.

Other than API consistency is there a benefit to having StringLike, Text, and String versions of the API? I'm not super familiar with the implementation of OverloadedStrings, but I think the conversion happens at run time. If that's the case I don't think there would be a performance difference since internally, the library is already converting to Text for comparing nodes.

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I am using libs that use Text and it's inconvenient to convert to strings and from strings.

What if we have a classed based file Text.HTML.Scalpel.StringLike and then just apply String to all the functions in Text.HTML.Scalpel?

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@fimad fimad May 15, 2019 •
edited
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Gotcha, I was not really expecting people to be passing dynamic values as attributes. I think having a single Text.HTML.Scalpel.StringLike is a bit more palatable, let's go with that.

-- 2. Any can be used to access the root tag of the current context.
contents <- text anySelector
-- 3. Skip comment divs that do not contain "cat".
Expand Down
13 changes: 8 additions & 5 deletions examples/example-from-documentation/Main.hs
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@@ -1,8 +1,11 @@
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ExtendedDefaultRules #-}

import Text.HTML.Scalpel
import Control.Applicative

default (String)


exampleHtml :: String
exampleHtml = "<html>\
Expand Down Expand Up @@ -35,19 +38,19 @@ main :: IO ()
main = print $ scrapeStringLike exampleHtml comments
where
comments :: Scraper String [Comment]
comments = chroots ("div" @: [hasClass "container"]) comment
comments = chroots (("div" :: TagName String) @: [hasClass "container"]) comment

comment :: Scraper String Comment
comment = textComment <|> imageComment

textComment :: Scraper String Comment
textComment = do
author <- text $ "span" @: [hasClass "author"]
commentText <- text $ "div" @: [hasClass "text"]
author <- text $ ("span" :: TagName String) @: [hasClass "author"]
commentText <- text $ ("div" :: TagName String) @: [hasClass "text"]
return $ TextComment author commentText

imageComment :: Scraper String Comment
imageComment = do
author <- text $ "span" @: [hasClass "author"]
imageURL <- attr "src" $ "img" @: [hasClass "image"]
author <- text $ ("span" :: TagName String) @: [hasClass "author"]
imageURL <- attr "src" $ ("img" :: TagName String) @: [hasClass "image"]
return $ ImageComment author imageURL
1 change: 1 addition & 0 deletions examples/html-to-markdown/Main.hs
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Expand Up @@ -2,6 +2,7 @@
-- the rough markdown equivalent using serial scrapers.

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes #-}
import Control.Applicative
import System.Environment
import Text.HTML.Scalpel
Expand Down
3 changes: 3 additions & 0 deletions scalpel-core/benchmarks/Main.hs
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@@ -1,4 +1,5 @@
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ExtendedDefaultRules #-}

import Text.HTML.Scalpel.Core

Expand All @@ -9,6 +10,8 @@ import Data.Foldable (foldr')
import qualified Data.Text as T
import qualified Text.HTML.TagSoup as TagSoup

default (String, Int)


main :: IO ()
main = do
Expand Down
2 changes: 1 addition & 1 deletion scalpel-core/scalpel-core.cabal
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Expand Up @@ -50,7 +50,7 @@ library
, pointedlist
, regex-base
, regex-tdfa
, tagsoup >= 0.12.2
, tagsoup >= 0.14.8
, text
, vector
default-extensions:
Expand Down
4 changes: 4 additions & 0 deletions scalpel-core/src/Text/HTML/Scalpel/Core.hs
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Expand Up @@ -61,10 +61,14 @@ module Text.HTML.Scalpel.Core (
, seekBack
, untilNext
, untilBack

-- * Select
, select
) where

import Text.HTML.Scalpel.Internal.Scrape
import Text.HTML.Scalpel.Internal.Scrape.StringLike
import Text.HTML.Scalpel.Internal.Select.Combinators
import Text.HTML.Scalpel.Internal.Select
import Text.HTML.Scalpel.Internal.Select.Types
import Text.HTML.Scalpel.Internal.Serial
45 changes: 23 additions & 22 deletions scalpel-core/src/Text/HTML/Scalpel/Internal/Scrape.hs
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Expand Up @@ -22,6 +22,7 @@ import Text.HTML.Scalpel.Internal.Select.Types
import Control.Applicative
import Control.Monad
import Data.Maybe
import Text.StringLike (StringLike, castString)
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Nice! I never really liked that StringLike was a part of the TagSoup package.

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I think StringLike is an abomination as well


import qualified Control.Monad.Fail as Fail
import qualified Data.Vector as Vector
Expand Down Expand Up @@ -67,7 +68,7 @@ instance Fail.MonadFail (Scraper str) where

-- | The 'scrape' function executes a 'Scraper' on a list of
-- 'TagSoup.Tag's and produces an optional value.
scrape :: (TagSoup.StringLike str)
scrape :: (StringLike str)
=> Scraper str a -> [TagSoup.Tag str] -> Maybe a
scrape s = scrapeTagSpec s . tagsToSpec . TagSoup.canonicalizeTags

Expand All @@ -77,7 +78,7 @@ scrape s = scrapeTagSpec s . tagsToSpec . TagSoup.canonicalizeTags
--
-- This function will match only the first set of tags matching the selector, to
-- match every set of tags, use 'chroots'.
chroot :: (TagSoup.StringLike str)
chroot :: (StringLike str)
=> Selector -> Scraper str a -> Scraper str a
chroot selector inner = do
maybeResult <- listToMaybe <$> chroots selector inner
Expand All @@ -91,30 +92,30 @@ chroot selector inner = do
--
-- > s = "<div><div>A</div></div>"
-- > scrapeStringLike s (chroots "div" (pure 0)) == Just [0, 0]
chroots :: (TagSoup.StringLike str)
chroots :: (StringLike str)
=> Selector -> Scraper str a -> Scraper str [a]
chroots selector (MkScraper inner) = MkScraper
$ return . mapMaybe inner . select selector

-- | The 'matches' function takes a selector and returns `()` if the selector
-- matches any node in the DOM.
matches :: (TagSoup.StringLike str) => Selector -> Scraper str ()
matches :: (StringLike str) => Selector -> Scraper str ()
matches s = MkScraper $ withHead (pure ()) . select s

-- | The 'text' function takes a selector and returns the inner text from the
-- set of tags described by the given selector.
--
-- This function will match only the first set of tags matching the selector, to
-- match every set of tags, use 'texts'.
text :: (TagSoup.StringLike str) => Selector -> Scraper str str
text :: (StringLike str) => Selector -> Scraper str str
text s = MkScraper $ withHead tagsToText . select s

-- | The 'texts' function takes a selector and returns the inner text from every
-- set of tags (possibly nested) matching the given selector.
--
-- > s = "<div>Hello <div>World</div></div>"
-- > scrapeStringLike s (texts "div") == Just ["Hello World", "World"]
texts :: (TagSoup.StringLike str)
texts :: (StringLike str)
=> Selector -> Scraper str [str]
texts s = MkScraper $ withAll tagsToText . select s

Expand All @@ -123,15 +124,15 @@ texts s = MkScraper $ withAll tagsToText . select s
--
-- This function will match only the first set of tags matching the selector, to
-- match every set of tags, use 'htmls'.
html :: (TagSoup.StringLike str) => Selector -> Scraper str str
html :: (StringLike str) => Selector -> Scraper str str
html s = MkScraper $ withHead tagsToHTML . select s

-- | The 'htmls' function takes a selector and returns the html string from
-- every set of tags (possibly nested) matching the given selector.
--
-- > s = "<div><div>A</div></div>"
-- > scrapeStringLike s (htmls "div") == Just ["<div><div>A</div></div>", "<div>A</div>"]
htmls :: (TagSoup.StringLike str)
htmls :: (StringLike str)
=> Selector -> Scraper str [str]
htmls s = MkScraper $ withAll tagsToHTML . select s

Expand All @@ -141,7 +142,7 @@ htmls s = MkScraper $ withAll tagsToHTML . select s
--
-- This function will match only the first set of tags matching the selector, to
-- match every set of tags, use 'innerHTMLs'.
innerHTML :: (TagSoup.StringLike str)
innerHTML :: (StringLike str)
=> Selector -> Scraper str str
innerHTML s = MkScraper $ withHead tagsToInnerHTML . select s

Expand All @@ -150,7 +151,7 @@ innerHTML s = MkScraper $ withHead tagsToInnerHTML . select s
--
-- > s = "<div><div>A</div></div>"
-- > scrapeStringLike s (innerHTMLs "div") == Just ["<div>A</div>", "A"]
innerHTMLs :: (TagSoup.StringLike str)
innerHTMLs :: (StringLike str)
=> Selector -> Scraper str [str]
innerHTMLs s = MkScraper $ withAll tagsToInnerHTML . select s

Expand All @@ -160,22 +161,22 @@ innerHTMLs s = MkScraper $ withAll tagsToInnerHTML . select s
--
-- This function will match only the opening tag matching the selector, to match
-- every tag, use 'attrs'.
attr :: (Show str, TagSoup.StringLike str)
=> String -> Selector -> Scraper str str
attr :: (Show str, StringLike str)
=> str -> Selector -> Scraper str str
attr name s = MkScraper
$ join . withHead (tagsToAttr $ TagSoup.castString name) . select s
$ join . withHead (tagsToAttr $ castString name) . select s

-- | The 'attrs' function takes an attribute name and a selector and returns the
-- value of the attribute of the given name for every opening tag
-- (possibly nested) that matches the given selector.
--
-- > s = "<div id=\"out\"><div id=\"in\"></div></div>"
-- > scrapeStringLike s (attrs "id" "div") == Just ["out", "in"]
attrs :: (Show str, TagSoup.StringLike str)
=> String -> Selector -> Scraper str [str]
attrs :: (Show str, StringLike str)
=> str -> Selector -> Scraper str [str]
attrs name s = MkScraper
$ fmap catMaybes . withAll (tagsToAttr nameStr) . select s
where nameStr = TagSoup.castString name
where nameStr = castString name

-- | The 'position' function is intended to be used within the do-block of a
-- `chroots` call. Within the do-block position will return the index of the
Expand Down Expand Up @@ -211,7 +212,7 @@ attrs name s = MkScraper
-- , (2, "Third paragraph.")
-- ]
-- @
position :: (TagSoup.StringLike str) => Scraper str Int
position :: (StringLike str) => Scraper str Int
position = MkScraper $ Just . tagsToPosition

withHead :: (a -> b) -> [a] -> Maybe b
Expand All @@ -221,27 +222,27 @@ withHead f (x:_) = Just $ f x
withAll :: (a -> b) -> [a] -> Maybe [b]
withAll f xs = Just $ map f xs

foldSpec :: TagSoup.StringLike str
foldSpec :: StringLike str
=> (TagSoup.Tag str -> str -> str) -> TagSpec str -> str
foldSpec f = Vector.foldr' (f . infoTag) TagSoup.empty . (\(a, _, _) -> a)


tagsToText :: TagSoup.StringLike str => TagSpec str -> str
tagsToText :: StringLike str => TagSpec str -> str
tagsToText = foldSpec f
where
f (TagSoup.TagText str) s = str `TagSoup.append` s
f _ s = s

tagsToHTML :: TagSoup.StringLike str => TagSpec str -> str
tagsToHTML :: StringLike str => TagSpec str -> str
tagsToHTML = foldSpec (\tag s -> TagSoup.renderTags [tag] `TagSoup.append` s)

tagsToInnerHTML :: TagSoup.StringLike str => TagSpec str -> str
tagsToInnerHTML :: StringLike str => TagSpec str -> str
tagsToInnerHTML (tags, tree, ctx)
| len < 2 = TagSoup.empty
| otherwise = tagsToHTML (Vector.slice 1 (len - 2) tags, tree, ctx)
where len = Vector.length tags

tagsToAttr :: (Show str, TagSoup.StringLike str)
tagsToAttr :: (Show str, StringLike str)
=> str -> TagSpec str -> Maybe str
tagsToAttr attr (tags, _, _) = do
guard $ 0 < Vector.length tags
Expand Down
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