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![用意したデータ構造に変換
// この発表ではFParsecというライブラリを使います
let jnull = pstring "null" >>% JNull
let jtrue = pstring "true" >>% (JBool true)
let jfalse = pstring "false" >>% (JBool false)
let jnumber = pfloat |>> JNumber
let str = manyChars (noneOf """) |> between (pchar '"') (pchar '"')
let jstring = str |>> JString
let jvalue, jvalueRef = createParserForwardedToRef ()
let jlist =
sepBy jvalue (pchar ',')
|> between (pchar '[') (pchar ']') |>> JList
let jobject =
let jprop = str .>> pchar ':' .>>. jvalue
sepBy jprop (pchar ',')
|> between (pchar '{') (pchar '}')
|>> (Map.ofList >> JObject)
jvalueRef :=
choice [ jobject; jlist; jstring; jnumber; jtrue; jfalse; jnull ]
let json : Parser<Json, unit> = jvalue .>> eof](https://image.slidesharecdn.com/ngk2017b-171202141245/75/PC-21-2048.jpg)
![JSONパーサー(改良版)
let ws = spaces
let jnull = pstring "null" .>> ws >>% JNull
let jtrue = pstring "true" .>> ws >>% (JBool true)
let jfalse = pstring "false" .>> ws >>% (JBool false)
let jnumber = pfloat .>> ws |>> JNumber
let str = manyChars (noneOf """) |> between (pchar '"') (pchar '"') .>> ws
let jstring = str |>> JString
let jvalue, jvalueRef = createParserForwardedToRef ()
let jlist =
sepBy jvalue (pchar ',' .>> ws)
|> between (pchar '[' .>> ws) (pchar ']' .>> ws) |>> JList
let jobject =
let jprop = str .>> pchar ':' .>> ws .>>. jvalue
sepBy jprop (pchar ',' .>> ws)
|> between (pchar '{' .>> ws) (pchar '}' .>> ws)
|>> (Map.ofList >> JObject)
jvalueRef :=
choice [ jobject; jlist; jstring; jnumber; jtrue; jfalse; jnull ]
let json : Parser<Json, unit> = ws >>. jvalue .>> eof](https://image.slidesharecdn.com/ngk2017b-171202141245/75/PC-27-2048.jpg)
![こう?
let integer = regex "([1-9][0-9]*|0)" |>> Int
let real = regex @"([1-9][0-9]*|0).[0-9]*" |>> Real
let number = integer <|> real](https://image.slidesharecdn.com/ngk2017b-171202141245/75/PC-32-2048.jpg)
![これでOK
let integer = regex "([1-9][0-9]*|0)" |>> Int
let real = regex @"([1-9][0-9]*|0).[0-9]*" |>> Real
// attemptでrealが失敗したら、realが消費した文字を入力に戻す
let number = attempt real <|> integer](https://image.slidesharecdn.com/ngk2017b-171202141245/75/PC-37-2048.jpg)
![パーサー
let integer = pint32 .>> ws |>> Integer
let expr, exprRef = createParserForwardedToRef ()
let add =
tuple2 (expr .>> pchar '+' .>> ws) integer |>> Add
let sub =
tuple2 (expr .>> pchar '-' .>> ws) integer |>> Sub
exprRef := choice [attempt add; attempt sub; integer]](https://image.slidesharecdn.com/ngk2017b-171202141245/75/PC-40-2048.jpg)
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PCさえあればいい。
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- 20. データ構造 type Json = |JNull | JBool of bool | JNumber of float | JString of string | JList of Json list | JObject of Map<string, Json>
- 21. 用意したデータ構造に変換 // この発表ではFParsecというライブラリを使います let jnull= pstring "null" >>% JNull let jtrue = pstring "true" >>% (JBool true) let jfalse = pstring "false" >>% (JBool false) let jnumber = pfloat |>> JNumber let str = manyChars (noneOf """) |> between (pchar '"') (pchar '"') let jstring = str |>> JString let jvalue, jvalueRef = createParserForwardedToRef () let jlist = sepBy jvalue (pchar ',') |> between (pchar '[') (pchar ']') |>> JList let jobject = let jprop = str .>> pchar ':' .>>. jvalue sepBy jprop (pchar ',') |> between (pchar '{') (pchar '}') |>> (Map.ofList >> JObject) jvalueRef := choice [ jobject; jlist; jstring; jnumber; jtrue; jfalse; jnull ] let json : Parser<Json, unit> = jvalue .>> eof
- 22. おしまい let parse str= match run json str with | Success (res, _, _) -> res | Failure (msg, _, _) -> failwithf "oops!: %s" msg
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- 27. JSONパーサー(改良版) let ws =spaces let jnull = pstring "null" .>> ws >>% JNull let jtrue = pstring "true" .>> ws >>% (JBool true) let jfalse = pstring "false" .>> ws >>% (JBool false) let jnumber = pfloat .>> ws |>> JNumber let str = manyChars (noneOf """) |> between (pchar '"') (pchar '"') .>> ws let jstring = str |>> JString let jvalue, jvalueRef = createParserForwardedToRef () let jlist = sepBy jvalue (pchar ',' .>> ws) |> between (pchar '[' .>> ws) (pchar ']' .>> ws) |>> JList let jobject = let jprop = str .>> pchar ':' .>> ws .>>. jvalue sepBy jprop (pchar ',' .>> ws) |> between (pchar '{' .>> ws) (pchar '}' .>> ws) |>> (Map.ofList >> JObject) jvalueRef := choice [ jobject; jlist; jstring; jnumber; jtrue; jfalse; jnull ] let json : Parser<Json, unit> = ws >>. jvalue .>> eof
- 28. 文字列のエスケープ対応 // 文字列パーサー再掲 let str= // エスケープシーケンスに対応していない manyChars (noneOf """) |> between (pchar '"') (pchar '"') .>> ws
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- 30. こんな感じで let str = letnonEscaped = noneOf """ |> many1Chars let escaped = pchar '"' >>. anyOf @"""/bfnrt" |>> function | 'b' -> "b" | 'f' -> "f" | 'n' -> "n" | 'r' -> "r" | 't' -> "t" | c -> string c let elem = nonEscaped <|> escaped // four hex digitsなやつは省略 manyStrings elem |> between (pchar '"') (pchar '"') .>> ws
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- 32. こう? let integer =regex "([1-9][0-9]*|0)" |>> Int let real = regex @"([1-9][0-9]*|0).[0-9]*" |>> Real let number = integer <|> real
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- 34. 順番の変更 ・numberの定義を修正 ・integer <|> realから ・real <|> integer に これで大丈夫?
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- 37. これでOK let integer =regex "([1-9][0-9]*|0)" |>> Int let real = regex @"([1-9][0-9]*|0).[0-9]*" |>> Real // attemptでrealが失敗したら、realが消費した文字を入力に戻す let number = attempt real <|> integer
- 38. これをそのまま書いてみましょう 左再帰の文法 ・数値と加算と減算のみの数式をパースしたい ・加算も減算も、左の項に加算や減算を許す ・10 - 2- 4は((10-2) - 4) ・(10 - (2-4))ではない
- 39. データ構造 // Add/SubでExpr自体を使っている(再帰構造) type Expr= | Integer of int | Add of Expr * Expr // 加算を表す | Sub of Expr * Expr // 減算を表す
- 40. パーサー let integer =pint32 .>> ws |>> Integer let expr, exprRef = createParserForwardedToRef () let add = tuple2 (expr .>> pchar '+' .>> ws) integer |>> Add let sub = tuple2 (expr .>> pchar '-' .>> ws) integer |>> Sub exprRef := choice [attempt add; attempt sub; integer]
- 41. これに10 - 2- 4を食わせると・・・
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- 44. 左再帰の繰り返しへの変換 // 元のコードの意味(左再帰) // expr::= expr op integer // | integer // から、下記(繰り返し)に変換 // expr ::= integer (op integer)* let expr = integer .>>. (many (op .>>. integer)) |>> fun (x, xs) -> List.fold (fun x (f, y) -> f x y) x xs and op = anyOf "+-" .>> ws |>> (function | '+' -> fun a b -> Add(a, b) | '-' -> fun a b -> Sub(a, b) | other -> invalidOp ("invalid char: " + string other))
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- 46. chainl1を使いましょう // expr ::=integer (op integer)* let expr = chainl1 integer op and op = anyOf "+-" .>> ws |>> (function | '+' -> fun a b -> Add(a, b) | '-' -> fun a b -> Sub(a, b) | other -> invalidOp ("invalid char: " + string other))
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