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Merged
cartermp merged 4 commits into from
Mar 3, 2021
Merged

Tail recursive parse #1225

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6358bb3
Add test for parsing deep arrays
eugbaranov Jun 18, 2019
91cae9d
Rewrite parseArray in CPS (closes #1180)
eugbaranov Jun 18, 2019
f5553ce
Add test for parsing deep objects
eugbaranov Jun 18, 2019
2ed8ec8
Rewrite parseObject in CPS
eugbaranov Jun 18, 2019
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88 changes: 54 additions & 34 deletions src/Json/JsonValue.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -167,18 +167,18 @@ type private JsonParser(jsonText:string) =
if not cond then throw()

// Recursive descent parser for JSON that uses global mutable index
let rec parseValue() =
let rec parseValue cont =
skipWhitespace()
ensure(i < s.Length)
match s.[i] with
| '"' -> JsonValue.String(parseString())
| '-' -> parseNum()
| c when Char.IsDigit(c) -> parseNum()
| '{' -> parseObject()
| '[' -> parseArray()
| 't' -> parseLiteral("true", JsonValue.Boolean true)
| 'f' -> parseLiteral("false", JsonValue.Boolean false)
| 'n' -> parseLiteral("null", JsonValue.Null)
| '"' -> JsonValue.String(parseString()) |> cont
| '-' -> parseNum() |> cont
| c when Char.IsDigit(c) -> parseNum() |> cont
| '{' -> parseObject cont
| '[' -> parseArray cont
| 't' -> parseLiteral("true", JsonValue.Boolean true) |> cont
| 'f' -> parseLiteral("false", JsonValue.Boolean false) |> cont
| 'n' -> parseLiteral("null", JsonValue.Null) |> cont
| _ -> throw()

and parseString() =
Expand Down Expand Up @@ -243,47 +243,67 @@ type private JsonParser(jsonText:string) =
| Some x -> JsonValue.Float x
| _ -> throw()

and parsePair() =
and parsePair cont =
let key = parseString()
skipWhitespace()
ensure(i < s.Length && s.[i] = ':')
i <- i + 1
skipWhitespace()
key, parseValue()
parseValue (fun v -> (key, v) |> cont)

and parseObject() =
and parseObject cont =
ensure(i < s.Length && s.[i] = '{')
i <- i + 1
skipWhitespace()
let pairs = ResizeArray<_>()
let parseObjectEnd() =
ensure(i < s.Length && s.[i] = '}')
i <- i + 1
pairs.ToArray() |> JsonValue.Record |> cont
if i < s.Length && s.[i] = '"' then
pairs.Add(parsePair())
skipWhitespace()
while i < s.Length && s.[i] = ',' do
i <- i + 1
skipWhitespace()
pairs.Add(parsePair())
parsePair (fun p ->
pairs.Add(p)
skipWhitespace()
ensure(i < s.Length && s.[i] = '}')
i <- i + 1
JsonValue.Record(pairs.ToArray())

and parseArray() =
let rec parsePairItem() =
if i < s.Length && s.[i] = ',' then
i <- i + 1
skipWhitespace()
parsePair (fun p ->
pairs.Add(p)
skipWhitespace()
parsePairItem())
else
parseObjectEnd()
parsePairItem())
else
parseObjectEnd()

and parseArray cont =
ensure(i < s.Length && s.[i] = '[')
i <- i + 1
skipWhitespace()
let vals = ResizeArray<_>()
let parseArrayEnd() =
ensure(i < s.Length && s.[i] = ']')
i <- i + 1
vals.ToArray() |> JsonValue.Array |> cont
if i < s.Length && s.[i] <> ']' then
vals.Add(parseValue())
skipWhitespace()
while i < s.Length && s.[i] = ',' do
i <- i + 1
parseValue (fun v ->
vals.Add(v)
skipWhitespace()
vals.Add(parseValue())
skipWhitespace()
ensure(i < s.Length && s.[i] = ']')
i <- i + 1
JsonValue.Array(vals.ToArray())
let rec parseArrayItem() =
if i < s.Length && s.[i] = ',' then
i <- i + 1
skipWhitespace()
parseValue (fun v ->
vals.Add(v)
skipWhitespace()
parseArrayItem())
else
parseArrayEnd()
parseArrayItem())
else
parseArrayEnd()

and parseLiteral(expected, r) =
ensure(i+expected.Length <= s.Length)
Expand All @@ -294,7 +314,7 @@ type private JsonParser(jsonText:string) =

// Start by parsing the top-level value
member x.Parse() =
let value = parseValue()
let value = parseValue id
skipWhitespace()
if i <> s.Length then
throw()
Expand All @@ -303,7 +323,7 @@ type private JsonParser(jsonText:string) =
member x.ParseMultiple() =
seq {
while i <> s.Length do
yield parseValue()
yield parseValue id
skipWhitespace()
}

Expand Down
12 changes: 12 additions & 0 deletions tests/FSharp.Data.Tests/JsonValue.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,18 @@ let ``Can parse document with datetime offset from iso date format``() =
let j = JsonValue.Parse "{\"anniversary\": \"2009-05-19 14:39:22+0600\"}"
j?anniversary.AsDateTimeOffset() |> should equal <| DateTimeOffset(2009, 05, 19, 14, 39, 22, TimeSpan.FromHours 6.)

[<Test; Explicit>]
let ``Can parse deep arrays``() =
String.replicate 50000 "[" + String.replicate 50000 "]"
|> FSharp.Data.JsonValue.Parse
|> ignore

[<Test; Explicit>]
let ``Can parse deep objects``() =
(String.replicate 50000 "{\"a\":") + "\"\"" + (String.replicate 50000 "}")
|> FSharp.Data.JsonValue.Parse
|> ignore

// TODO: Due to limitations in the current ISO 8601 datetime parsing these fail, and should be made to pass
//[<Test>]
//let ``Cant Yet parse document with basic iso date``() =
Expand Down