Questions to which this is the answer #3

jamesdbrock · 2019-08-18T02:11:58Z

jamesdbrock · 2019-08-21T03:56:14Z

Megaparsec parsers are aware
of line numbers, and the Parsereplace.streamEdit function allows you to
edit pattern matches in a stream. Here is a solution
using Parsereplace.streamEdit.

import Parsereplace
import Text.Megaparsec
import Text.Megaparsec.Char

let a = "\n\n\nShape(Rectangle 3 5)"

:{
let pattern :: Parsec Void String (Int,String)
pattern = do
string "Shape("
lineNumber <- unPos <$> sourceLine <$> getSourcePos
parenInner <- many $ noneOf ")"
string ")"
return (lineNumber, parenInner)
:}

:{
let editor (lineNumber, parenInner) =
"TrackedShape(" ++
show lineNumber ++
" "John" (" ++
parenInner ++
"))"
:}

streamEdit pattern editor a

"\n\n\nTrackedShape(4 \"John\" (Rectangle 3 5))"

jamesdbrock · 2019-08-21T19:21:51Z

Ⓐ https://stackoverflow.com/questions/5230700/best-way-for-substring-replace-in-haskell

jamesdbrock · 2019-08-21T19:23:37Z

https://mail.haskell.org/pipermail/haskell-cafe/2010-May/077943.html

jamesdbrock · 2019-08-24T10:14:43Z

Ⓐ https://stackoverflow.com/questions/29549435/parsec-how-to-find-matches-within-a-string

jamesdbrock · 2019-08-27T14:27:00Z

Ⓐ https://stackoverflow.com/questions/29546940/parsec-ignore-everything-except-one-fragment

You can use Replace.Megaparsec.findall to find the substrings in a document which match a parser.

import Replace.Megaparsec
import Text.Megaparsec

let parseSelect :: Parsec Void String String
    parseSelect = do
        chunk "<select"
        manyTill anySingle $ chunk "</select>"

let input = "<html>\n   random content with lots of tags...\n   <select id=something title=\"whatever\"><option value=1 selected>1. First<option value=2>2. Second</select>\n   more random content...\n</html>"

>>> parseTest (findAll parseSelect) input
[Left "<html>\n   random content with lots of tags...\n   "
,Right "<select id=something title=\"whatever\"><option value=1 selected>1. First<option value=2>2. Second</select>"
,Left "\n   more random content...\n</html>"
]

jamesdbrock · 2019-08-28T23:11:00Z

Ⓐ https://stackoverflow.com/questions/57667534/how-can-i-use-a-parser-in-haskell-to-find-the-locations-of-some-substrings-in-a

-- We can do this with the [`findAllCap`](https://hackage.haskell.org/package/replace-megaparsec/docs/Replace-Megaparsec.html#v:findAllCap) combinator from [replace-megaparsec](https://hackage.haskell.org/package/replace-megaparsec/).

-- Requires packages `megaparsec, replace-megaparsec, containers`

import Replace.Megaparsec
import Text.Megaparsec
import Text.Megaparsec.Char
import Data.Maybe
import Data.Either
import Data.Map.Strict as Map

:{
let colorWords :: Parsec Void String (String, [Int])
    colorWords = do
            i <- getOffset
            c <- choice
                [ try $ string' "blue" >>
                        anySingle >>
                        string' "green" >>
                        pure "blue green"
                , try $ string' "blue" >> pure "blue"
                , try $ string' "green" >> pure "green"
                ]
            return (c,[i])
:}

input = "First there was blue\nand then there was Green,\nand then blue\ngreen all of a sudden, and not to mention blue-green"

Map.toList $ fromListWith mappend $ rights $ fromJust $ parseMaybe (sepCap colorWords) input

-- [("blue",[16]),("blue green",[103,56]),("green",[40])]