Iceshrimp.NET/Iceshrimp.Parsing/Mfm.fs

646 lines
23 KiB
FSharp

namespace Iceshrimp.Parsing
open System
open System.Collections.Generic
open System.Diagnostics
open System.Runtime.InteropServices
open FParsec
module MfmNodeTypes =
[<AbstractClass>]
type MfmNode() =
member val Children: MfmNode list = [] with get, set
[<AbstractClass>]
type MfmInlineNode(c: MfmInlineNode list) =
inherit MfmNode()
do base.Children <- c |> List.map (fun x -> x :> MfmNode)
[<AbstractClass>]
type MfmBlockNode(c: MfmInlineNode list) =
inherit MfmNode()
do base.Children <- c |> List.map (fun x -> x :> MfmNode)
type InlineNodeType =
| Symbol
| HtmlTag
type MfmTextNode(v: string) =
inherit MfmInlineNode([])
member val Text = v
type MfmTimeoutTextNode(v: string) =
inherit MfmTextNode(v)
type MfmItalicNode(c, t) =
inherit MfmInlineNode(c)
member val Type: InlineNodeType = t
type MfmBoldNode(c, t) =
inherit MfmInlineNode(c)
member val Type: InlineNodeType = t
type MfmStrikeNode(c, t) =
inherit MfmInlineNode(c)
member val Type: InlineNodeType = t
type MfmInlineCodeNode(v: string) =
inherit MfmInlineNode([])
member val Code = v
type MfmPlainNode(v: string) =
inherit MfmInlineNode([ MfmTextNode(v) ])
type MfmSmallNode(c) =
inherit MfmInlineNode(c)
type MfmQuoteNode(c, followedByQuote, followedByEof) =
inherit MfmBlockNode(c)
member val FollowedByQuote = followedByQuote
member val FollowedByEof = followedByEof
type MfmSearchNode(content: string, query: string) =
inherit MfmBlockNode([])
member val Content = content
member val Query = query
type MfmCodeBlockNode(code, lang: string option) =
inherit MfmBlockNode([])
member val Code = code
member val Language = lang
type MfmMathBlockNode(f) =
inherit MfmBlockNode([])
member val Formula = f
type MfmCenterNode(c) =
inherit MfmBlockNode(c)
type MfmEmojiCodeNode(n) =
inherit MfmInlineNode([])
member val Name = n
type MfmMathInlineNode(f) =
inherit MfmInlineNode([])
member val Formula = f
type MfmMentionNode(acct, user, host: string option) =
inherit MfmInlineNode([])
member val Acct = acct
member val Username = user
member val Host = host
type MfmHashtagNode(h) =
inherit MfmInlineNode([])
member val Hashtag = h
type MfmUrlNode(url, brackets) =
inherit MfmInlineNode([])
member val Url = url
member val Brackets = brackets
type MfmLinkNode(url, text, silent) =
inherit MfmInlineNode([ MfmTextNode(text) ])
member val Url = url
member val Silent = silent
type MfmFnNode(name, args: IDictionary<string, string option> option, children) =
inherit MfmInlineNode(children)
member val Name = name
member val Args = args
type internal MfmCharNode(v: char) =
inherit MfmInlineNode([])
member val Char = v
type internal UserState =
{ ParenthesisStack: char list
LastLine: int64
Depth: int
TimeoutAt: int64 }
member this.TimeoutReached = Stopwatch.GetTimestamp() > this.TimeoutAt
static member Timeout =
match RuntimeInformation.OSArchitecture with
| Architecture.Wasm -> Stopwatch.Frequency * 2L // 2000ms
| _ -> Stopwatch.Frequency / 2L // 500ms
static member Default =
fun () ->
{ ParenthesisStack = []
LastLine = 0
Depth = 0
TimeoutAt = Stopwatch.GetTimestamp() + UserState.Timeout }
open MfmNodeTypes
module private MfmParser =
// Override - prevents O(n!) complexity for recursive grammars where endp applies immediately
let many1Till p endp = notFollowedBy endp >>. many1Till p endp
let skipMany1Till p endp =
notFollowedBy endp >>. skipMany1Till p endp
// Abstractions
let str s = pstring s
let seqAttempt s = s |> Seq.map attempt
let isWhitespace c = Char.IsWhiteSpace c
let isNotWhitespace c = Char.IsWhiteSpace c = false
let isAsciiLetterOrNumber c = Char.IsAsciiLetter c || Char.IsDigit c
let isLetterOrNumber c = Char.IsLetterOrDigit c
let isNewline c = '\n'.Equals(c)
let isNotNewline c = not (isNewline c)
let followedByChar c = nextCharSatisfies <| fun ch -> c = ch
let (|CharNode|MfmNode|) (x: MfmNode) =
if x :? MfmCharNode then
CharNode(x :?> MfmCharNode)
else
MfmNode x
let folder (current, result) node =
match (node: MfmNode), (current: char list) with
| CharNode node, _ -> node.Char :: current, result
| MfmNode node, [] -> current, node :: result
| MfmNode node, _ -> [], node :: (MfmTextNode(current |> List.toArray |> String) :: result)
let aggregateText nodes =
nodes
|> List.rev
|> List.fold folder ([], [])
|> function
| [], result -> result
| current, result -> MfmTextNode(current |> List.toArray |> String) :: result
let aggregateTextInline nodes =
nodes |> aggregateText |> List.map (fun x -> x :?> MfmInlineNode)
let domainComponent =
many1Chars (
satisfy isAsciiLetterOrNumber
<|> pchar '_'
<|> attempt (
previousCharSatisfies isAsciiLetterOrNumber >>. pchar '-'
.>> lookAhead (satisfy isAsciiLetterOrNumber)
)
<|> attempt (
(previousCharSatisfies '-'.Equals <|> previousCharSatisfies isAsciiLetterOrNumber)
>>. pchar '-'
.>> lookAhead (satisfy '-'.Equals <|> satisfy isAsciiLetterOrNumber)
)
)
let domain =
domainComponent .>>. (many <| attempt (skipChar '.' >>. domainComponent))
|>> fun (a, b) -> String.concat "." <| Seq.append [ a ] b
let acct (user: string, host: string option) =
match host with
| None -> user
| Some v -> user + "@" + v
let fnArg =
many1Chars asciiLetter
.>>. opt (
pchar '='
>>. manyCharsTill anyChar (nextCharSatisfies <| fun p -> p = ',' || isWhitespace p)
)
let fnDict (input: (string * string option) list option) : IDictionary<string, string option> option =
match input with
| None -> None
| Some items -> items |> dict |> Some
let pushLine: Parser<unit, UserState> =
fun stream ->
stream.UserState <-
{ stream.UserState with
LastLine = stream.Line }
Reply(())
let assertLine: Parser<unit, UserState> =
let error = messageError "Line changed"
fun stream ->
match stream.UserState.LastLine = stream.Line with
| true -> Reply(())
| false -> Reply(Error, error)
let assertParen = userStateSatisfies <| fun u -> u.ParenthesisStack.Length > 0
let assertNoParen = userStateSatisfies <| fun u -> u.ParenthesisStack.Length = 0
let pushParen =
updateUserState
<| fun u ->
{ u with
ParenthesisStack = '(' :: u.ParenthesisStack }
let popParen =
assertParen
>>. updateUserState (fun u ->
{ u with
ParenthesisStack = List.tail u.ParenthesisStack })
let clearParen = updateUserState <| fun u -> { u with ParenthesisStack = [] }
let (|GreaterEqualThan|_|) k value = if value >= k then Some() else None
let restOfLineContains (s: string) : Parser<unit, UserState> =
let error = messageError "No match found"
fun (stream: CharStream<_>) ->
let pos = stream.Position
let rest = stream.ReadRestOfLine false
do stream.Seek pos.Index
match rest with
| c when c.Contains(s) -> Reply(())
| _ -> Reply(Error, error)
let restOfLineContainsChar (c: char) : Parser<unit, UserState> =
let error = messageError "No match found"
let func ch = ch <> c && isNotNewline ch
fun (stream: CharStream<_>) ->
let pos = stream.Position
let _ = stream.SkipCharsOrNewlinesWhile(func)
let ch = stream.Read()
do stream.Seek pos.Index
match ch with
| m when m = c -> Reply(())
| _ -> Reply(Error, error)
let restOfSegmentContains (s: string, segment: char -> bool) : Parser<unit, UserState> =
let error = messageError "No match found"
fun (stream: CharStream<_>) ->
let pos = stream.Position
let rest = stream.ReadCharsOrNewlinesWhile(segment, false)
do stream.Seek pos.Index
match rest with
| c when c.Contains s -> Reply(())
| _ -> Reply(Error, error)
let restOfStreamContains (s: string) : Parser<unit, UserState> =
restOfSegmentContains (s, (fun _ -> true))
let streamMatches (s: string) : Parser<unit, UserState> =
fun stream ->
match stream.Match s with
| true -> Reply(())
| false -> Reply(Error, NoErrorMessages)
let streamMatchesOrEof (s: string) : Parser<unit, UserState> =
fun stream ->
match (stream.Match s, stream.IsEndOfStream) with
| false, false -> Reply(Error, NoErrorMessages)
| _ -> Reply(())
let anyCharExceptNewline: Parser<char, UserState> =
let error = messageError "anyCharExceptNewline"
fun stream ->
let c = stream.ReadCharOrNewline()
if c <> EOS && isNotNewline c then
Reply(c)
else
Reply(Error, error)
let createParameterizedParserRef () =
let dummyParser _ =
fun _ -> failwith "a parser created with createParameterizedParserRef was not initialized"
let r = ref dummyParser
(fun endp -> (fun stream -> r.Value endp stream)), r
// References
let manyInlineNodesTill, manyInlineNodesTillRef = createParameterizedParserRef ()
let many1InlineNodesTill, many1InlineNodesTillRef = createParameterizedParserRef ()
let seqFlatten items =
seq {
for item in items do
yield! item
}
// Patterns
let italicPatternAsterisk = notFollowedByString "**" >>. skipChar '*'
let italicPatternUnderscore = notFollowedByString "__" >>. skipChar '_'
let codePattern = notFollowedByString "```" >>. skipChar '`'
// Matchers
let hashtagMatcher = letter <|> digit <|> anyOf "-_"
let hashtagSatisfier = attempt hashtagMatcher
// Node parsers
let italicAsteriskNode =
previousCharSatisfiesNot isNotWhitespace
>>. italicPatternAsterisk
>>. restOfLineContainsChar '*' // TODO: this doesn't cover the case where a bold node ends before the italic one
>>. pushLine // Remove when above TODO is resolved
>>. manyInlineNodesTill italicPatternAsterisk
.>> assertLine // Remove when above TODO is resolved
|>> fun c -> MfmItalicNode(aggregateTextInline c, Symbol) :> MfmNode
let italicUnderscoreNode =
previousCharSatisfiesNot isNotWhitespace
>>. italicPatternUnderscore
>>. restOfLineContainsChar '_' // TODO: this doesn't cover the case where a bold node ends before the italic one
>>. pushLine // Remove when above TODO is resolved
>>. manyInlineNodesTill italicPatternUnderscore
.>> assertLine // Remove when above TODO is resolved
|>> fun c -> MfmItalicNode(aggregateTextInline c, Symbol) :> MfmNode
let italicTagNode =
skipString "<i>"
>>. restOfStreamContains "</i>"
>>. manyInlineNodesTill (skipString "</i>")
|>> fun c -> MfmItalicNode(aggregateTextInline c, HtmlTag) :> MfmNode
let boldAsteriskNode =
previousCharSatisfiesNot isNotWhitespace
>>. skipString "**"
>>. restOfLineContains "**"
>>. manyInlineNodesTill (skipString "**")
|>> fun c -> MfmBoldNode(aggregateTextInline c, Symbol) :> MfmNode
let boldUnderscoreNode =
previousCharSatisfiesNot isNotWhitespace
>>. skipString "__"
>>. restOfLineContains "__"
>>. manyInlineNodesTill (skipString "__")
|>> fun c -> MfmBoldNode(aggregateTextInline c, Symbol) :> MfmNode
let boldTagNode =
skipString "<b>"
>>. restOfStreamContains "</b>"
>>. manyInlineNodesTill (skipString "</b>")
|>> fun c -> MfmBoldNode(aggregateTextInline c, HtmlTag) :> MfmNode
let strikeNode =
skipString "~~"
>>. restOfLineContains "~~"
>>. manyInlineNodesTill (skipString "~~")
|>> fun c -> MfmStrikeNode(aggregateTextInline c, Symbol) :> MfmNode
let strikeTagNode =
skipString "<s>"
>>. restOfStreamContains "</s>"
>>. manyInlineNodesTill (skipString "</s>")
|>> fun c -> MfmStrikeNode(aggregateTextInline c, HtmlTag) :> MfmNode
let codeNode =
codePattern
>>. restOfLineContainsChar '`' // TODO: this doesn't cover the case where a code block node ends before the inline one
>>. pushLine // Remove when above TODO is resolved
>>. manyCharsTill anyChar codePattern
.>> assertLine // Remove when above TODO is resolved
|>> fun v -> MfmInlineCodeNode(v) :> MfmNode
let codeBlockNode =
opt skipNewline
>>. opt skipNewline
>>. followedByString "```"
>>. restOfStreamContains "```"
>>. previousCharSatisfiesNot isNotNewline
>>. skipString "```"
>>. opt (many1CharsTill asciiLetter (lookAhead newline))
.>>. (skipNewline
>>. manyCharsTill anyChar (attempt (skipNewline >>. skipString "```")))
.>> (skipNewline <|> eof)
.>> opt skipNewline
|>> fun (lang: string option, code: string) -> MfmCodeBlockNode(code, lang) :> MfmNode
let mathNode =
skipString "\("
>>. restOfLineContains "\)"
>>. manyCharsTill anyChar (skipString "\)")
|>> fun f -> MfmMathInlineNode(f) :> MfmNode
let mathBlockNode =
previousCharSatisfiesNot isNotWhitespace
>>. skipString "\["
>>. restOfStreamContains "\]"
>>. many1CharsTill anyChar (skipString "\]")
|>> fun f -> MfmMathBlockNode(f) :> MfmNode
let emojiCodeNode =
skipChar ':'
>>. restOfLineContains ":"
>>. manyCharsTill (satisfy isAsciiLetter <|> satisfy isDigit <|> anyOf "+-_") (skipChar ':')
|>> fun e -> MfmEmojiCodeNode(e) :> MfmNode
let fnNode =
skipString "$["
>>. restOfStreamContains "]"
>>. many1Chars (asciiLower <|> digit)
.>>. opt (skipChar '.' >>. sepBy1 fnArg (skipChar ','))
.>> skipChar ' '
.>>. many1InlineNodesTill (skipChar ']')
|>> fun ((n, o), c) -> MfmFnNode(n, fnDict o, aggregateTextInline c) :> MfmNode
let plainNode =
skipString "<plain>"
>>. restOfStreamContains "</plain>"
>>. manyCharsTill anyChar (skipString "</plain>")
|>> fun v -> MfmPlainNode(v) :> MfmNode
let smallNode =
skipString "<small>"
>>. restOfStreamContains "</small>"
>>. manyInlineNodesTill (skipString "</small>")
|>> fun c -> MfmSmallNode(aggregateTextInline c) :> MfmNode
let centerNode =
skipString "<center>"
>>. restOfStreamContains "</center>"
>>. manyInlineNodesTill (skipString "</center>")
|>> fun c -> MfmCenterNode(aggregateTextInline c) :> MfmNode
let mentionNode =
(previousCharSatisfiesNot isNotWhitespace
<|> previousCharSatisfies (isAnyOf <| "()"))
>>. skipString "@"
>>. many1Chars (
satisfy isLetterOrNumber
<|> pchar '_'
<|> attempt (anyOf ".-" .>> nextCharSatisfies isLetterOrNumber)
)
.>>. opt (skipChar '@' >>. domain)
.>> (lookAhead
<| choice
[ eof
skipNoneOf ":"
skipChar ':' .>> nextCharSatisfiesNot isAsciiLetterOrNumber ])
|>> fun (user: string, host: string option) -> MfmMentionNode(acct (user, host), user, host) :> MfmNode
let hashtagNode =
previousCharSatisfiesNot isNotWhitespace
>>. skipChar '#'
>>. many1CharsTill hashtagMatcher (notFollowedBy hashtagSatisfier)
|>> fun h -> MfmHashtagNode(h) :> MfmNode
let urlNode =
lookAhead (skipString "https://" <|> skipString "http://")
>>. manyCharsTill
((pchar '(' .>> pushParen) <|> (pchar ')' .>> popParen) <|> anyChar)
(nextCharSatisfies isWhitespace
<|> (assertNoParen >>. followedByChar ')')
<|> eof)
.>> clearParen
>>= fun uri ->
match Uri.TryCreate(uri, UriKind.Absolute) with
| true, NonNullQuick finalUri ->
match finalUri.Scheme with
| "http" -> preturn (MfmUrlNode(uri, false) :> MfmNode)
| "https" -> preturn (MfmUrlNode(uri, false) :> MfmNode)
| _ -> fail "invalid scheme"
| _ -> fail "invalid url"
let urlNodeBrackets =
skipChar '<'
>>. lookAhead (skipString "https://" <|> skipString "http://")
>>. restOfLineContains ">" // This intentionally breaks compatibility with mfm-js, as there's no reason to allow newlines in urls
>>. manyCharsTill anyChar (skipChar '>')
>>= fun uri ->
match Uri.TryCreate(uri, UriKind.Absolute) with
| true, NonNullQuick finalUri ->
match finalUri.Scheme with
| "http" -> preturn (MfmUrlNode(uri, true) :> MfmNode)
| "https" -> preturn (MfmUrlNode(uri, true) :> MfmNode)
| _ -> fail "invalid scheme"
| _ -> fail "invalid url"
let linkNode =
(opt (pchar '?'))
.>>. (pchar '[' >>. restOfLineContains "]" >>. manyCharsTill anyChar (pchar ']'))
.>>. (pchar '('
>>. restOfLineContains ")"
>>. lookAhead (skipString "https://" <|> skipString "http://")
>>. manyCharsTill
((pchar '(' .>> pushParen) <|> (pchar ')' .>> popParen) <|> anyCharExceptNewline)
(assertNoParen >>. skipChar ')'))
.>> clearParen
>>= fun ((silent, text), uri) ->
match Uri.TryCreate(uri, UriKind.Absolute) with
| true, NonNullQuick finalUri ->
match finalUri.Scheme with
| "http" -> preturn (MfmLinkNode(uri, text, silent.IsSome) :> MfmNode)
| "https" -> preturn (MfmLinkNode(uri, text, silent.IsSome) :> MfmNode)
| _ -> fail "invalid scheme"
| _ -> fail "invalid url"
let quoteNode =
previousCharSatisfiesNot isNotNewline
>>. many1 (
pchar '>'
>>. (opt <| pchar ' ')
>>. (many1InlineNodesTill (skipNewline <|> eof))
)
.>> (opt <| attempt (skipNewline >>. (notFollowedBy <| pchar '>')))
.>>. (opt <| attempt (skipNewline >>. (followedBy <| pchar '>')) .>>. opt eof)
|>> fun (q, (followedByQuote, followedByEof)) ->
MfmQuoteNode(
List.collect (fun e -> e @ [ (MfmCharNode('\n') :> MfmInlineNode) ]) q
|> fun q -> List.take (q.Length - 1) q
|> aggregateTextInline,
followedByQuote.IsSome,
followedByEof.IsSome
)
:> MfmNode
let charNode = anyChar |>> fun v -> MfmCharNode(v) :> MfmNode
// Custom parser for higher throughput
type ParseMode =
| Full
| Inline
| Simple
let parseNode (m: ParseMode) =
let inlineTagNodes =
[ plainNode
smallNode
italicTagNode
boldTagNode
strikeTagNode
urlNodeBrackets ]
let failIfTimeout: Parser<unit, UserState> =
let error = messageError "Timeout exceeded"
fun (stream: CharStream<_>) ->
match stream.UserState.TimeoutReached with
| true -> Reply(FatalError, error)
| _ -> Reply(())
let prefixedNode (m: ParseMode) : Parser<MfmNode, UserState> =
fun (stream: CharStream<_>) ->
match stream.UserState.Depth with
| GreaterEqualThan 20 -> stream |> charNode
| _ ->
match (stream.Peek(), m) with
// Block nodes, ordered by expected frequency
| '`', Full -> codeBlockNode <|> codeNode
| '\n', Full when stream.Match("\n```") -> codeBlockNode
| '\n', Full when stream.Match("\n\n```") -> codeBlockNode
| '>', Full -> quoteNode
| '<', Full when stream.Match "<center>" -> centerNode
| '\\', Full when stream.Match "\\[" -> mathBlockNode
// Inline nodes, ordered by expected frequency
| '*', (Full | Inline) -> italicAsteriskNode <|> boldAsteriskNode
| '_', (Full | Inline) -> italicUnderscoreNode <|> boldUnderscoreNode
| '@', (Full | Inline) -> mentionNode
| '#', (Full | Inline) -> hashtagNode
| '`', Inline -> codeNode
| 'h', (Full | Inline) when stream.Match "http" -> urlNode
| ':', (Full | Inline | Simple) -> emojiCodeNode
| '~', (Full | Inline) when stream.Match "~~" -> strikeNode
| '[', (Full | Inline) -> linkNode
| '<', (Full | Inline) -> choice inlineTagNodes
| '<', Simple when stream.Match "<plain>" -> plainNode
| '\\', (Full | Inline) when stream.Match "\\(" -> mathNode
| '$', (Full | Inline) when stream.Match "$[" -> fnNode
| '?', (Full | Inline) when stream.Match "?[" -> linkNode
// Fallback to char node
| _ -> charNode
<| stream
failIfTimeout >>. (attempt <| prefixedNode m <|> charNode)
// Parser abstractions
let node = parseNode Full
let simple = parseNode Simple
let inlinep = parseNode Inline |>> fun v -> v :?> MfmInlineNode
// Populate references
let pushDepth = updateUserState (fun u -> { u with Depth = (u.Depth + 1) })
let popDepth = updateUserState (fun u -> { u with Depth = (u.Depth - 1) })
do manyInlineNodesTillRef.Value <- fun endp -> pushDepth >>. manyTill inlinep endp .>> popDepth
do many1InlineNodesTillRef.Value <- fun endp -> pushDepth >>. many1Till inlinep endp .>> popDepth
// Final parse command
let parse = spaces >>. manyTill node eof .>> spaces
let parseSimple = spaces >>. manyTill simple eof .>> spaces
open MfmParser
module Mfm =
let internal runParser p str =
let state = UserState.Default()
let result = runParserOnString p state "" str
match (result, state.TimeoutReached) with
| Success(result, _, _), _ -> aggregateText result
| Failure _, true -> [ MfmTimeoutTextNode(str) ]
| Failure(s, _, _), false -> failwith $"Failed to parse MFM: {s}"
let parse str = runParser parse str
let parseSimple str = runParser parseSimple str