roc/examples/csv/main.roc

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app "main"
packages { pf: "platform/main.roc" }
imports [Parser.Core.{Parser}, Parser.Str.{RawStr}, Parser.CSV.{CSV}]
provides [main] to pf
# Until issue https://github.com/rtfeldman/roc/issues/3438 is fixed,
# use the simple 'hello world' platform for testing
# with hard-coded input.
main = fullTest csvParser "10,20\n\"An escaped field!\"\"\n,,,\",30\n"
# main = partialTest fieldParser "\"An escaped field with some \"\"<- double quotes\""
# main = fullTest fieldContentsParser "My very cool,\"\"\r\n string"
# main = partialTest betweenParser "\"this is a test\"\" to see\""
# main = partialTest manyParser "this is a very long string\"\""
partialTest = \parser, input ->
when Parser.Str.parseStrPartial parser input is
Ok result ->
# val = result.val |> Str.joinWith("\r\n")
val = result.val
leftover = result.input
"Parse success: \(val) (leftover string: \(leftover))\n"
Err (ParsingFailure problem) ->
"Parse failure: \(problem)\n"
fullTest = \parser, input ->
when Parser.Str.parseStr parser input is
Ok result ->
# val = result |> Str.joinWith(", ")
val = result |> Str.joinWith("\r\n")
# val = result
"Parse success: \(val)\n"
Err (ParsingFailure problem) ->
"Parse failure: \(problem)\n"
Err (ParsingIncomplete leftover) ->
"Parse failure: Expected to reach end of input, but the following was still left: `\(leftover)`\n"
betweenParser : Parser RawStr Str
betweenParser =
Parser.Core.between manyParser (Parser.Str.codepoint 34) (Parser.Str.codepoint 34)
manyParser : Parser RawStr Str
manyParser =
Parser.Str.string "\"\"" |> Parser.Core.map(\_ -> 34) # Escaped double quote
|> Parser.Core.alt (Parser.Str.codepoint 44) # Comma
|> Parser.Core.alt (Parser.Str.codepoint 13) # CR
|> Parser.Core.alt (Parser.Str.codepoint 10) # LF
|> Parser.Core.alt (Parser.Str.codepointSatisfies (\x -> (x >= 32 && x <= 33) || (x >= 35 && x <= 43) || (x >= 45 && x <= 126))) # Any printable char except " (34) and , (44)
|> Parser.Core.many
|> Parser.Core.map (\field -> field |> Str.fromUtf8 |> Result.withDefault "Should not happen")
fieldContentsParser : Parser RawStr Str
fieldContentsParser =
Parser.CSV.escapedContents
|> Parser.Core.map (\field -> field |> Str.fromUtf8 |> Result.withDefault "Should not happen")
fieldParser : Parser RawStr Str
fieldParser =
Parser.CSV.escapedField
|> Parser.Core.map (\field -> field |> Str.fromUtf8 |> Result.withDefault "Should not happen")
csvParser : Parser RawStr (List Str)
csvParser =
Parser.CSV.file
|> Parser.Core.map \records ->
records
|> List.map (\record ->
record
|> List.map (\field ->
field
|> Str.fromUtf8
|> Result.withDefault "Unexpected problem while turning a List U8 back into a Str")
|> Str.joinWith ", ")