Module json

This module implements a simple high performance JSON parser. JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write (unlike XML). It is easy for machines to parse and generate. JSON is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition - December 1999.

Types

TJsonEventKind* = enum 
  jsonError,                  ## an error ocurred during parsing
  jsonEof,                    ## end of file reached
  jsonString,                 ## a string literal
  jsonInt,                    ## an integer literal
  jsonFloat,                  ## a float literal
  jsonTrue,                   ## the value ``true``
  jsonFalse,                  ## the value ``false``
  jsonNull,                   ## the value ``null``
  jsonObjectStart,            ## start of an object: the ``{`` token
  jsonObjectEnd,              ## end of an object: the ``}`` token
  jsonArrayStart,             ## start of an array: the ``[`` token
  jsonArrayEnd                ## start of an array: the ``]`` token
enumeration of all events that may occur when parsing
TJsonError* = enum 
  errNone,                    ## no error
  errInvalidToken,            ## invalid token
  errStringExpected,          ## string expected
  errColonExpected,           ## ``:`` expected
  errCommaExpected,           ## ``,`` expected
  errBracketRiExpected,       ## ``]`` expected
  errCurlyRiExpected,         ## ``}`` expected
  errQuoteExpected,           ## ``"`` or ``'`` expected
  errEOC_Expected,            ## ``*/`` expected
  errEofExpected,             ## EOF expected
  errExprExpected             ## expr expected
enumeration that lists all errors that can occur
TJsonParser* = object of TBaseLexer
  a: string
  tok: TTokKind
  kind: TJsonEventKind
  err: TJsonError
  state: seq[TParserState]
  filename: string
the parser object.
TJsonNodeKind* = enum 
  JNull, JBool, JInt, JFloat, JString, JObject, JArray
possible JSON node types
PJsonNode* = ref TJsonNode
JSON node
TJsonNode* {.final, pure, acyclic.} = object 
  case kind*: TJsonNodeKind
  of JString: 
      str*: string

  of JInt: 
      num*: biggestInt

  of JFloat: 
      fnum*: float

  of JBool: 
      bval*: bool

  of JNull: 
      nil

  of JObject: 
      fields*: seq[tuple[key: string, val: PJsonNode]]

  of JArray: 
      elems*: seq[PJsonNode]

  
EJsonParsingError* = object of EInvalidValue
is raised for a JSON error

Procs

proc open*(my: var TJsonParser; input: PStream; filename: string)
initializes the parser with an input stream. Filename is only used for nice error messages.
proc close*(my: var TJsonParser) {.inline.}
closes the parser my and its associated input stream.
proc str*(my: TJsonParser): string {.inline.}
returns the character data for the events: jsonInt, jsonFloat, jsonString
proc getInt*(my: TJsonParser): biggestInt {.inline.}
returns the number for the event: jsonInt
proc getFloat*(my: TJsonParser): float {.inline.}
returns the number for the event: jsonFloat
proc kind*(my: TJsonParser): TJsonEventKind {.inline.}
returns the current event type for the JSON parser
proc getColumn*(my: TJsonParser): int {.inline.}
get the current column the parser has arrived at.
proc getLine*(my: TJsonParser): int {.inline.}
get the current line the parser has arrived at.
proc getFilename*(my: TJsonParser): string {.inline.}
get the filename of the file that the parser processes.
proc errorMsg*(my: TJsonParser): string
returns a helpful error message for the event jsonError
proc errorMsgExpected*(my: TJsonParser; e: string): string
returns an error message "e expected" in the same format as the other error messages
proc next*(my: var TJsonParser)
retrieves the first/next event. This controls the parser.
proc raiseParseErr*(p: TJsonParser; msg: string) {.noinline, noreturn.}
raises an EJsonParsingError exception.
proc newJString*(s: String): PJsonNode
Creates a new JString PJsonNode.
proc newJInt*(n: biggestInt): PJsonNode
Creates a new JInt PJsonNode.
proc newJFloat*(n: Float): PJsonNode
Creates a new JFloat PJsonNode.
proc newJBool*(b: Bool): PJsonNode
Creates a new JBool PJsonNode.
proc newJNull*(): PJsonNode
Creates a new JNull PJsonNode.
proc newJObject*(): PJsonNode
Creates a new JObject PJsonNode
proc newJArray*(): PJsonNode
Creates a new JArray PJsonNode
proc `%`*(s: string): PJsonNode
Generic constructor for JSON data. Creates a new JString PJsonNode.
proc `%`*(n: biggestInt): PJsonNode
Generic constructor for JSON data. Creates a new JInt PJsonNode.
proc `%`*(n: float): PJsonNode
Generic constructor for JSON data. Creates a new JFloat PJsonNode.
proc `%`*(b: bool): PJsonNode
Generic constructor for JSON data. Creates a new JBool PJsonNode.
proc `%`*(keyVals: openArray[tuple[key: string, val: PJsonNode]]): PJsonNode
Generic constructor for JSON data. Creates a new JObject PJsonNode
proc `%`*(elements: openArray[PJSonNode]): PJsonNode
Generic constructor for JSON data. Creates a new JArray PJsonNode
proc len*(n: PJsonNode): int
If n is a JArray, it returns the number of elements. If n is a JObject, it returns the number of pairs. Else it returns 0.
proc `[]`*(node: PJsonNode; name: String): PJsonNode
Gets a field from a JObject.
proc `[]`*(node: PJsonNode; index: Int): PJsonNode
Gets the node at index in an Array.
proc existsKey*(node: PJsonNode; key: String): Bool
Checks if key exists in node.
proc add*(father, child: PJsonNode)
Adds child to a JArray node father.
proc add*(obj: PJsonNode; key: string; val: PJsonNode)
Adds (key, val) pair to the JObject node obj. For speed reasons no check for duplicate keys is performed! But []= performs the check.
proc `[] =`*(obj: PJsonNode; key: String; val: PJsonNode)
Sets a field from a JObject. Performs a check for duplicate keys.
proc delete*(obj: PJsonNode; key: string)
Deletes obj[key] preserving the order of the other (key, value)-pairs.
proc copy*(p: PJsonNode): PJsonNode
Performs a deep copy of a.
proc escapeJson*(s: string): string
Converts a string s to its JSON representation.
proc pretty*(node: PJsonNode; indent = 2): String
Converts node to its JSON Representation, with indentation and on multiple lines.
proc `$`*(node: PJsonNode): String
Converts node to its JSON Representation on one line.
proc parseJson*(s: PStream; filename: string): PJsonNode
Parses from a stream s into a PJsonNode. filename is only needed for nice error messages.
proc parseJson*(buffer: string): PJsonNode
Parses JSON from buffer.
proc parseFile*(filename: string): PJsonNode
Parses file into a PJsonNode.

Iterators

iterator items*(node: PJsonNode): PJSonNode
Iterator for the items of node. node has to be a JArray.
iterator pairs*(node: PJsonNode): tuple[key: string, val: PJsonNode]
Iterator for the child elements of node. node has to be a JObject.
Generated: 2012-09-23 21:47:54 UTC