#
#
# Nim's Runtime Library
# (c) Copyright 2015 Andreas Rumpf, Dominik Picheta
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements a simple high performance `JSON`:idx:
## 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.
##
## Usage example:
##
## .. code-block:: nim
## let
## small_json = """{"test": 1.3, "key2": true}"""
## jobj = parseJson(small_json)
## assert (jobj.kind == JObject)
## echo($jobj["test"].fnum)
## echo($jobj["key2"].bval)
##
## Results in:
##
## .. code-block:: nim
##
## 1.3000000000000000e+00
## true
##
## This module can also be used to comfortably create JSON using the `%*`
## operator:
##
## .. code-block:: nim
##
## var hisName = "John"
## let herAge = 31
## var j = %*
## [
## {
## "name": hisName,
## "age": 30
## },
## {
## "name": "Susan",
## "age": herAge
## }
## ]
import
hashes, strutils, lexbase, streams, unicode, macros
type
JsonEventKind* = enum ## enumeration of all events that may occur when parsing
jsonError, ## an error occurred 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
TTokKind = enum # must be synchronized with TJsonEventKind!
tkError,
tkEof,
tkString,
tkInt,
tkFloat,
tkTrue,
tkFalse,
tkNull,
tkCurlyLe,
tkCurlyRi,
tkBracketLe,
tkBracketRi,
tkColon,
tkComma
JsonError* = enum ## enumeration that lists all errors that can occur
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
ParserState = enum
stateEof, stateStart, stateObject, stateArray, stateExpectArrayComma,
stateExpectObjectComma, stateExpectColon, stateExpectValue
JsonParser* = object of BaseLexer ## the parser object.
a: string
tok: TTokKind
kind: JsonEventKind
err: JsonError
state: seq[ParserState]
filename: string
{.deprecated: [TJsonEventKind: JsonEventKind, TJsonError: JsonError,
TJsonParser: JsonParser].}
const
errorMessages: array [JsonError, string] = [
"no error",
"invalid token",
"string expected",
"':' expected",
"',' expected",
"']' expected",
"'}' expected",
"'\"' or \"'\" expected",
"'*/' expected",
"EOF expected",
"expression expected"
]
tokToStr: array [TTokKind, string] = [
"invalid token",
"EOF",
"string literal",
"int literal",
"float literal",
"true",
"false",
"null",
"{", "}", "[", "]", ":", ","
]
proc open*(my: var JsonParser, input: Stream, filename: string) =
## initializes the parser with an input stream. `Filename` is only used
## for nice error messages.
lexbase.open(my, input)
my.filename = filename
my.state = @[stateStart]
my.kind = jsonError
my.a = ""
proc close*(my: var JsonParser) {.inline.} =
## closes the parser `my` and its associated input stream.
lexbase.close(my)
proc str*(my: JsonParser): string {.inline.} =
## returns the character data for the events: ``jsonInt``, ``jsonFloat``,
## ``jsonString``
assert(my.kind in {jsonInt, jsonFloat, jsonString})
return my.a
proc getInt*(my: JsonParser): BiggestInt {.inline.} =
## returns the number for the event: ``jsonInt``
assert(my.kind == jsonInt)
return parseBiggestInt(my.a)
proc getFloat*(my: JsonParser): float {.inline.} =
## returns the number for the event: ``jsonFloat``
assert(my.kind == jsonFloat)
return parseFloat(my.a)
proc kind*(my: JsonParser): JsonEventKind {.inline.} =
## returns the current event type for the JSON parser
return my.kind
proc getColumn*(my: JsonParser): int {.inline.} =
## get the current column the parser has arrived at.
result = getColNumber(my, my.bufpos)
proc getLine*(my: JsonParser): int {.inline.} =
## get the current line the parser has arrived at.
result = my.lineNumber
proc getFilename*(my: JsonParser): string {.inline.} =
## get the filename of the file that the parser processes.
result = my.filename
proc errorMsg*(my: JsonParser): string =
## returns a helpful error message for the event ``jsonError``
assert(my.kind == jsonError)
result = "$1($2, $3) Error: $4" % [
my.filename, $getLine(my), $getColumn(my), errorMessages[my.err]]
proc errorMsgExpected*(my: JsonParser, e: string): string =
## returns an error message "`e` expected" in the same format as the
## other error messages
result = "$1($2, $3) Error: $4" % [
my.filename, $getLine(my), $getColumn(my), e & " expected"]
proc handleHexChar(c: char, x: var int): bool =
result = true # Success
case c
of '0'..'9': x = (x shl 4) or (ord(c) - ord('0'))
of 'a'..'f': x = (x shl 4) or (ord(c) - ord('a') + 10)
of 'A'..'F': x = (x shl 4) or (ord(c) - ord('A') + 10)
else: result = false # error
proc parseString(my: var JsonParser): TTokKind =
result = tkString
var pos = my.bufpos + 1
var buf = my.buf
while true:
case buf[pos]
of '\0':
my.err = errQuoteExpected
result = tkError
break
of '"':
inc(pos)
break
of '\\':
case buf[pos+1]
of '\\', '"', '\'', '/':
add(my.a, buf[pos+1])
inc(pos, 2)
of 'b':
add(my.a, '\b')
inc(pos, 2)
of 'f':
add(my.a, '\f')
inc(pos, 2)
of 'n':
add(my.a, '\L')
inc(pos, 2)
of 'r':
add(my.a, '\C')
inc(pos, 2)
of 't':
add(my.a, '\t')
inc(pos, 2)
of 'u':
inc(pos, 2)
var r: int
if handleHexChar(buf[pos], r): inc(pos)
if handleHexChar(buf[pos], r): inc(pos)
if handleHexChar(buf[pos], r): inc(pos)
if handleHexChar(buf[pos], r): inc(pos)
add(my.a, toUTF8(Rune(r)))
else:
# don't bother with the error
add(my.a, buf[pos])
inc(pos)
of '\c':
pos = lexbase.handleCR(my, pos)
buf = my.buf
add(my.a, '\c')
of '\L':
pos = lexbase.handleLF(my, pos)
buf = my.buf
add(my.a, '\L')
else:
add(my.a, buf[pos])
inc(pos)
my.bufpos = pos # store back
proc skip(my: var JsonParser) =
var pos = my.bufpos
var buf = my.buf
while true:
case buf[pos]
of '/':
if buf[pos+1] == '/':
# skip line comment:
inc(pos, 2)
while true:
case buf[pos]
of '\0':
break
of '\c':
pos = lexbase.handleCR(my, pos)
buf = my.buf
break
of '\L':
pos = lexbase.handleLF(my, pos)
buf = my.buf
break
else:
inc(pos)
elif buf[pos+1] == '*':
# skip long comment:
inc(pos, 2)
while true:
case buf[pos]
of '\0':
my.err = errEOC_Expected
break
of '\c':
pos = lexbase.handleCR(my, pos)
buf = my.buf
of '\L':
pos = lexbase.handleLF(my, pos)
buf = my.buf
of '*':
inc(pos)
if buf[pos] == '/':
inc(pos)
break
else:
inc(pos)
else:
break
of ' ', '\t':
inc(pos)
of '\c':
pos = lexbase.handleCR(my, pos)
buf = my.buf
of '\L':
pos = lexbase.handleLF(my, pos)
buf = my.buf
else:
break
my.bufpos = pos
proc parseNumber(my: var JsonParser) =
var pos = my.bufpos
var buf = my.buf
if buf[pos] == '-':
add(my.a, '-')
inc(pos)
if buf[pos] == '.':
add(my.a, "0.")
inc(pos)
else:
while buf[pos] in Digits:
add(my.a, buf[pos])
inc(pos)
if buf[pos] == '.':
add(my.a, '.')
inc(pos)
# digits after the dot:
while buf[pos] in Digits:
add(my.a, buf[pos])
inc(pos)
if buf[pos] in {'E', 'e'}:
add(my.a, buf[pos])
inc(pos)
if buf[pos] in {'+', '-'}:
add(my.a, buf[pos])
inc(pos)
while buf[pos] in Digits:
add(my.a, buf[pos])
inc(pos)
my.bufpos = pos
proc parseName(my: var JsonParser) =
var pos = my.bufpos
var buf = my.buf
if buf[pos] in IdentStartChars:
while buf[pos] in IdentChars:
add(my.a, buf[pos])
inc(pos)
my.bufpos = pos
proc getTok(my: var JsonParser): TTokKind =
setLen(my.a, 0)
skip(my) # skip whitespace, comments
case my.buf[my.bufpos]
of '-', '.', '0'..'9':
parseNumber(my)
if {'.', 'e', 'E'} in my.a:
result = tkFloat
else:
result = tkInt
of '"':
result = parseString(my)
of '[':
inc(my.bufpos)
result = tkBracketLe
of '{':
inc(my.bufpos)
result = tkCurlyLe
of ']':
inc(my.bufpos)
result = tkBracketRi
of '}':
inc(my.bufpos)
result = tkCurlyRi
of ',':
inc(my.bufpos)
result = tkComma
of ':':
inc(my.bufpos)
result = tkColon
of '\0':
result = tkEof
of 'a'..'z', 'A'..'Z', '_':
parseName(my)
case my.a
of "null": result = tkNull
of "true": result = tkTrue
of "false": result = tkFalse
else: result = tkError
else:
inc(my.bufpos)
result = tkError
my.tok = result
proc next*(my: var JsonParser) =
## retrieves the first/next event. This controls the parser.
var tk = getTok(my)
var i = my.state.len-1
# the following code is a state machine. If we had proper coroutines,
# the code could be much simpler.
case my.state[i]
of stateEof:
if tk == tkEof:
my.kind = jsonEof
else:
my.kind = jsonError
my.err = errEofExpected
of stateStart:
# tokens allowed?
case tk
of tkString, tkInt, tkFloat, tkTrue, tkFalse, tkNull:
my.state[i] = stateEof # expect EOF next!
my.kind = JsonEventKind(ord(tk))
of tkBracketLe:
my.state.add(stateArray) # we expect any
my.kind = jsonArrayStart
of tkCurlyLe:
my.state.add(stateObject)
my.kind = jsonObjectStart
of tkEof:
my.kind = jsonEof
else:
my.kind = jsonError
my.err = errEofExpected
of stateObject:
case tk
of tkString, tkInt, tkFloat, tkTrue, tkFalse, tkNull:
my.state.add(stateExpectColon)
my.kind = JsonEventKind(ord(tk))
of tkBracketLe:
my.state.add(stateExpectColon)
my.state.add(stateArray)
my.kind = jsonArrayStart
of tkCurlyLe:
my.state.add(stateExpectColon)
my.state.add(stateObject)
my.kind = jsonObjectStart
of tkCurlyRi:
my.kind = jsonObjectEnd
discard my.state.pop()
else:
my.kind = jsonError
my.err = errCurlyRiExpected
of stateArray:
case tk
of tkString, tkInt, tkFloat, tkTrue, tkFalse, tkNull:
my.state.add(stateExpectArrayComma) # expect value next!
my.kind = JsonEventKind(ord(tk))
of tkBracketLe:
my.state.add(stateExpectArrayComma)
my.state.add(stateArray)
my.kind = jsonArrayStart
of tkCurlyLe:
my.state.add(stateExpectArrayComma)
my.state.add(stateObject)
my.kind = jsonObjectStart
of tkBracketRi:
my.kind = jsonArrayEnd
discard my.state.pop()
else:
my.kind = jsonError
my.err = errBracketRiExpected
of stateExpectArrayComma:
case tk
of tkComma:
discard my.state.pop()
next(my)
of tkBracketRi:
my.kind = jsonArrayEnd
discard my.state.pop() # pop stateExpectArrayComma
discard my.state.pop() # pop stateArray
else:
my.kind = jsonError
my.err = errBracketRiExpected
of stateExpectObjectComma:
case tk
of tkComma:
discard my.state.pop()
next(my)
of tkCurlyRi:
my.kind = jsonObjectEnd
discard my.state.pop() # pop stateExpectObjectComma
discard my.state.pop() # pop stateObject
else:
my.kind = jsonError
my.err = errCurlyRiExpected
of stateExpectColon:
case tk
of tkColon:
my.state[i] = stateExpectValue
next(my)
else:
my.kind = jsonError
my.err = errColonExpected
of stateExpectValue:
case tk
of tkString, tkInt, tkFloat, tkTrue, tkFalse, tkNull:
my.state[i] = stateExpectObjectComma
my.kind = JsonEventKind(ord(tk))
of tkBracketLe:
my.state[i] = stateExpectObjectComma
my.state.add(stateArray)
my.kind = jsonArrayStart
of tkCurlyLe:
my.state[i] = stateExpectObjectComma
my.state.add(stateObject)
my.kind = jsonObjectStart
else:
my.kind = jsonError
my.err = errExprExpected
# ------------- higher level interface ---------------------------------------
type
JsonNodeKind* = enum ## possible JSON node types
JNull,
JBool,
JInt,
JFloat,
JString,
JObject,
JArray
JsonNode* = ref JsonNodeObj ## JSON node
JsonNodeObj* {.acyclic.} = object
case kind*: JsonNodeKind
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: JsonNode]]
of JArray:
elems*: seq[JsonNode]
JsonParsingError* = object of ValueError ## is raised for a JSON error
{.deprecated: [EJsonParsingError: JsonParsingError, TJsonNode: JsonNodeObj,
PJsonNode: JsonNode, TJsonNodeKind: JsonNodeKind].}
proc raiseParseErr*(p: JsonParser, msg: string) {.noinline, noreturn.} =
## raises an `EJsonParsingError` exception.
raise newException(JsonParsingError, errorMsgExpected(p, msg))
proc newJString*(s: string): JsonNode =
## Creates a new `JString JsonNode`.
new(result)
result.kind = JString
result.str = s
proc newJStringMove(s: string): JsonNode =
new(result)
result.kind = JString
shallowCopy(result.str, s)
proc newJInt*(n: BiggestInt): JsonNode =
## Creates a new `JInt JsonNode`.
new(result)
result.kind = JInt
result.num = n
proc newJFloat*(n: float): JsonNode =
## Creates a new `JFloat JsonNode`.
new(result)
result.kind = JFloat
result.fnum = n
proc newJBool*(b: bool): JsonNode =
## Creates a new `JBool JsonNode`.
new(result)
result.kind = JBool
result.bval = b
proc newJNull*(): JsonNode =
## Creates a new `JNull JsonNode`.
new(result)
proc newJObject*(): JsonNode =
## Creates a new `JObject JsonNode`
new(result)
result.kind = JObject
result.fields = @[]
proc newJArray*(): JsonNode =
## Creates a new `JArray JsonNode`
new(result)
result.kind = JArray
result.elems = @[]
proc getStr*(n: JsonNode, default: string = ""): string =
## Retrieves the string value of a `JString JsonNode`.
##
## Returns ``default`` if ``n`` is not a ``JString``.
if n.kind != JString: return default
else: return n.str
proc getNum*(n: JsonNode, default: BiggestInt = 0): BiggestInt =
## Retrieves the int value of a `JInt JsonNode`.
##
## Returns ``default`` if ``n`` is not a ``JInt``.
if n.kind != JInt: return default
else: return n.num
proc getFNum*(n: JsonNode, default: float = 0.0): float =
## Retrieves the float value of a `JFloat JsonNode`.
##
## Returns ``default`` if ``n`` is not a ``JFloat``.
if n.kind != JFloat: return default
else: return n.fnum
proc getBVal*(n: JsonNode, default: bool = false): bool =
## Retrieves the bool value of a `JBool JsonNode`.
##
## Returns ``default`` if ``n`` is not a ``JBool``.
if n.kind != JBool: return default
else: return n.bval
proc getFields*(n: JsonNode,
default: seq[tuple[key: string, val: JsonNode]] = @[]):
seq[tuple[key: string, val: JsonNode]] =
## Retrieves the key, value pairs of a `JObject JsonNode`.
##
## Returns ``default`` if ``n`` is not a ``JObject``.
if n.kind != JObject: return default
else: return n.fields
proc getElems*(n: JsonNode, default: seq[JsonNode] = @[]): seq[JsonNode] =
## Retrieves the int value of a `JArray JsonNode`.
##
## Returns ``default`` if ``n`` is not a ``JArray``.
if n.kind != JArray: return default
else: return n.elems
proc `%`*(s: string): JsonNode =
## Generic constructor for JSON data. Creates a new `JString JsonNode`.
new(result)
result.kind = JString
result.str = s
proc `%`*(n: BiggestInt): JsonNode =
## Generic constructor for JSON data. Creates a new `JInt JsonNode`.
new(result)
result.kind = JInt
result.num = n
proc `%`*(n: float): JsonNode =
## Generic constructor for JSON data. Creates a new `JFloat JsonNode`.
new(result)
result.kind = JFloat
result.fnum = n
proc `%`*(b: bool): JsonNode =
## Generic constructor for JSON data. Creates a new `JBool JsonNode`.
new(result)
result.kind = JBool
result.bval = b
proc `%`*(keyVals: openArray[tuple[key: string, val: JsonNode]]): JsonNode =
## Generic constructor for JSON data. Creates a new `JObject JsonNode`
new(result)
result.kind = JObject
newSeq(result.fields, keyVals.len)
for i, p in pairs(keyVals): result.fields[i] = p
proc `%`*(elements: openArray[JsonNode]): JsonNode =
## Generic constructor for JSON data. Creates a new `JArray JsonNode`
new(result)
result.kind = JArray
newSeq(result.elems, elements.len)
for i, p in pairs(elements): result.elems[i] = p
proc toJson(x: NimNode): NimNode {.compiletime.} =
case x.kind
of nnkBracket:
result = newNimNode(nnkBracket)
for i in 0 .. <x.len:
result.add(toJson(x[i]))
of nnkTableConstr:
result = newNimNode(nnkTableConstr)
for i in 0 .. <x.len:
assert x[i].kind == nnkExprColonExpr
result.add(newNimNode(nnkExprColonExpr).add(x[i][0]).add(toJson(x[i][1])))
else:
result = x
result = prefix(result, "%")
macro `%*`*(x: expr): expr =
## Convert an expression to a JsonNode directly, without having to specify
## `%` for every element.
result = toJson(x)
proc `==`* (a,b: JsonNode): bool =
## Check two nodes for equality
if a.isNil:
if b.isNil: return true
return false
elif b.isNil or a.kind != b.kind:
return false
else:
return case a.kind
of JString:
a.str == b.str
of JInt:
a.num == b.num
of JFloat:
a.fnum == b.fnum
of JBool:
a.bval == b.bval
of JNull:
true
of JArray:
a.elems == b.elems
of JObject:
a.fields == b.fields
proc hash* (n:JsonNode): THash =
## Compute the hash for a JSON node
case n.kind
of JArray:
result = hash(n.elems)
of JObject:
result = hash(n.fields)
of JInt:
result = hash(n.num)
of JFloat:
result = hash(n.fnum)
of JBool:
result = hash(n.bval.int)
of JString:
result = hash(n.str)
of JNull:
result = hash(0)
proc len*(n: JsonNode): 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.
case n.kind
of JArray: result = n.elems.len
of JObject: result = n.fields.len
else: discard
proc `[]`*(node: JsonNode, name: string): JsonNode {.inline.} =
## Gets a field from a `JObject`, which must not be nil.
## If the value at `name` does not exist, returns nil
assert(not isNil(node))
assert(node.kind == JObject)
for key, item in items(node.fields):
if key == name:
return item
return nil
proc `[]`*(node: JsonNode, index: int): JsonNode {.inline.} =
## Gets the node at `index` in an Array. Result is undefined if `index`
## is out of bounds
assert(not isNil(node))
assert(node.kind == JArray)
return node.elems[index]
proc hasKey*(node: JsonNode, key: string): bool =
## Checks if `key` exists in `node`.
assert(node.kind == JObject)
for k, item in items(node.fields):
if k == key: return true
proc existsKey*(node: JsonNode, key: string): bool {.deprecated.} = node.hasKey(key)
## Deprecated for `hasKey`
proc add*(father, child: JsonNode) =
## Adds `child` to a JArray node `father`.
assert father.kind == JArray
father.elems.add(child)
proc add*(obj: JsonNode, key: string, val: JsonNode) =
## Adds ``(key, val)`` pair to the JObject node `obj`. For speed
## reasons no check for duplicate keys is performed!
## But ``[]=`` performs the check.
assert obj.kind == JObject
obj.fields.add((key, val))
proc `[]=`*(obj: JsonNode, key: string, val: JsonNode) {.inline.} =
## Sets a field from a `JObject`. Performs a check for duplicate keys.
assert(obj.kind == JObject)
for i in 0..obj.fields.len-1:
if obj.fields[i].key == key:
obj.fields[i].val = val
return
obj.fields.add((key, val))
proc `{}`*(node: JsonNode, keys: varargs[string]): JsonNode =
## Traverses the node and gets the given value. If any of the
## keys do not exist, returns nil. Also returns nil if one of the
## intermediate data structures is not an object
result = node
for key in keys:
if isNil(result) or result.kind!=JObject:
return nil
result=result[key]
proc `{}=`*(node: JsonNode, keys: varargs[string], value: JsonNode) =
## Traverses the node and tries to set the value at the given location
## to `value` If any of the keys are missing, they are added
var node = node
for i in 0..(keys.len-2):
if isNil(node[keys[i]]):
node[keys[i]] = newJObject()
node = node[keys[i]]
node[keys[keys.len-1]] = value
proc delete*(obj: JsonNode, key: string) =
## Deletes ``obj[key]`` preserving the order of the other (key, value)-pairs.
assert(obj.kind == JObject)
for i in 0..obj.fields.len-1:
if obj.fields[i].key == key:
obj.fields.delete(i)
return
raise newException(IndexError, "key not in object")
proc copy*(p: JsonNode): JsonNode =
## Performs a deep copy of `a`.
case p.kind
of JString:
result = newJString(p.str)
of JInt:
result = newJInt(p.num)
of JFloat:
result = newJFloat(p.fnum)
of JBool:
result = newJBool(p.bval)
of JNull:
result = newJNull()
of JObject:
result = newJObject()
for key, field in items(p.fields):
result.fields.add((key, copy(field)))
of JArray:
result = newJArray()
for i in items(p.elems):
result.elems.add(copy(i))
# ------------- pretty printing ----------------------------------------------
proc indent(s: var string, i: int) =
s.add(spaces(i))
proc newIndent(curr, indent: int, ml: bool): int =
if ml: return curr + indent
else: return indent
proc nl(s: var string, ml: bool) =
if ml: s.add("\n")
proc escapeJson*(s: string): string =
## Converts a string `s` to its JSON representation.
result = newStringOfCap(s.len + s.len shr 3)
result.add("\"")
for x in runes(s):
var r = int(x)
if r >= 32 and r <= 127:
var c = chr(r)
case c
of '"': result.add("\\\"")
of '\\': result.add("\\\\")
else: result.add(c)
else:
result.add("\\u")
result.add(toHex(r, 4))
result.add("\"")
proc toPretty(result: var string, node: JsonNode, indent = 2, ml = true,
lstArr = false, currIndent = 0) =
case node.kind
of JObject:
if currIndent != 0 and not lstArr: result.nl(ml)
result.indent(currIndent) # Indentation
if node.fields.len > 0:
result.add("{")
result.nl(ml) # New line
for i in 0..len(node.fields)-1:
if i > 0:
result.add(", ")
result.nl(ml) # New Line
# Need to indent more than {
result.indent(newIndent(currIndent, indent, ml))
result.add(escapeJson(node.fields[i].key))
result.add(": ")
toPretty(result, node.fields[i].val, indent, ml, false,
newIndent(currIndent, indent, ml))
result.nl(ml)
result.indent(currIndent) # indent the same as {
result.add("}")
else:
result.add("{}")
of JString:
if lstArr: result.indent(currIndent)
result.add(escapeJson(node.str))
of JInt:
if lstArr: result.indent(currIndent)
result.add($node.num)
of JFloat:
if lstArr: result.indent(currIndent)
result.add($node.fnum)
of JBool:
if lstArr: result.indent(currIndent)
result.add($node.bval)
of JArray:
if lstArr: result.indent(currIndent)
if len(node.elems) != 0:
result.add("[")
result.nl(ml)
for i in 0..len(node.elems)-1:
if i > 0:
result.add(", ")
result.nl(ml) # New Line
toPretty(result, node.elems[i], indent, ml,
true, newIndent(currIndent, indent, ml))
result.nl(ml)
result.indent(currIndent)
result.add("]")
else: result.add("[]")
of JNull:
if lstArr: result.indent(currIndent)
result.add("null")
proc pretty*(node: JsonNode, indent = 2): string =
## Converts `node` to its JSON Representation, with indentation and
## on multiple lines.
result = ""
toPretty(result, node, indent)
proc toUgly*(result: var string, node: JsonNode) =
## Converts `node` to its JSON Representation, without
## regard for human readability. Meant to improve ``$`` string
## conversion performance.
##
## This provides higher efficiency than the ``toPretty`` procedure as it
## does **not** attempt to format the resulting JSON to make it human readable.
var comma = false
case node.kind:
of JArray:
result.add "["
for child in node.elems:
if comma: result.add ","
else: comma = true
result.toUgly child
result.add "]"
of JObject:
result.add "{"
for key, value in items(node.fields):
if comma: result.add ","
else: comma = true
result.add key.escapeJson()
result.add ":"
result.toUgly value
result.add "}"
of JString:
result.add node.str.escapeJson()
of JInt:
result.add($node.num)
of JFloat:
result.add($node.fnum)
of JBool:
result.add(if node.bval: "true" else: "false")
of JNull:
result.add "null"
proc `$`*(node: JsonNode): string =
## Converts `node` to its JSON Representation on one line.
result = newStringOfCap(node.len shl 1)
toUgly(result, node)
iterator items*(node: JsonNode): JsonNode =
## Iterator for the items of `node`. `node` has to be a JArray.
assert node.kind == JArray
for i in items(node.elems):
yield i
iterator mitems*(node: var JsonNode): var JsonNode =
## Iterator for the items of `node`. `node` has to be a JArray. Items can be
## modified.
assert node.kind == JArray
for i in mitems(node.elems):
yield i
iterator pairs*(node: JsonNode): tuple[key: string, val: JsonNode] =
## Iterator for the child elements of `node`. `node` has to be a JObject.
assert node.kind == JObject
for key, val in items(node.fields):
yield (key, val)
iterator mpairs*(node: var JsonNode): var tuple[key: string, val: JsonNode] =
## Iterator for the child elements of `node`. `node` has to be a JObject.
## Items can be modified
assert node.kind == JObject
for keyVal in mitems(node.fields):
yield keyVal
proc eat(p: var JsonParser, tok: TTokKind) =
if p.tok == tok: discard getTok(p)
else: raiseParseErr(p, tokToStr[tok])
proc parseJson(p: var JsonParser): JsonNode =
## Parses JSON from a JSON Parser `p`.
case p.tok
of tkString:
# we capture 'p.a' here, so we need to give it a fresh buffer afterwards:
result = newJStringMove(p.a)
p.a = ""
discard getTok(p)
of tkInt:
result = newJInt(parseBiggestInt(p.a))
discard getTok(p)
of tkFloat:
result = newJFloat(parseFloat(p.a))
discard getTok(p)
of tkTrue:
result = newJBool(true)
discard getTok(p)
of tkFalse:
result = newJBool(false)
discard getTok(p)
of tkNull:
result = newJNull()
discard getTok(p)
of tkCurlyLe:
result = newJObject()
discard getTok(p)
while p.tok != tkCurlyRi:
if p.tok != tkString:
raiseParseErr(p, "string literal as key expected")
var key = p.a
discard getTok(p)
eat(p, tkColon)
var val = parseJson(p)
result[key] = val
if p.tok != tkComma: break
discard getTok(p)
eat(p, tkCurlyRi)
of tkBracketLe:
result = newJArray()
discard getTok(p)
while p.tok != tkBracketRi:
result.add(parseJson(p))
if p.tok != tkComma: break
discard getTok(p)
eat(p, tkBracketRi)
of tkError, tkCurlyRi, tkBracketRi, tkColon, tkComma, tkEof:
raiseParseErr(p, "{")
when not defined(js):
proc parseJson*(s: Stream, filename: string): JsonNode =
## Parses from a stream `s` into a `JsonNode`. `filename` is only needed
## for nice error messages.
var p: JsonParser
p.open(s, filename)
discard getTok(p) # read first token
result = p.parseJson()
p.close()
proc parseJson*(buffer: string): JsonNode =
## Parses JSON from `buffer`.
result = parseJson(newStringStream(buffer), "input")
proc parseFile*(filename: string): JsonNode =
## Parses `file` into a `JsonNode`.
var stream = newFileStream(filename, fmRead)
if stream == nil:
raise newException(IOError, "cannot read from file: " & filename)
result = parseJson(stream, filename)
else:
from math import `mod`
type
TJSObject = object
proc parseNativeJson(x: cstring): TJSObject {.importc: "JSON.parse".}
proc getVarType(x): JsonNodeKind =
result = JNull
proc getProtoName(y): cstring
{.importc: "Object.prototype.toString.call".}
case $getProtoName(x) # TODO: Implicit returns fail here.
of "[object Array]": return JArray
of "[object Object]": return JObject
of "[object Number]":
if cast[float](x) mod 1.0 == 0:
return JInt
else:
return JFloat
of "[object Boolean]": return JBool
of "[object Null]": return JNull
of "[object String]": return JString
else: assert false
proc len(x: TJSObject): int =
assert x.getVarType == JArray
asm """
return `x`.length;
"""
proc `[]`(x: TJSObject, y: string): TJSObject =
assert x.getVarType == JObject
asm """
return `x`[`y`];
"""
proc `[]`(x: TJSObject, y: int): TJSObject =
assert x.getVarType == JArray
asm """
return `x`[`y`];
"""
proc convertObject(x: TJSObject): JsonNode =
case getVarType(x)
of JArray:
result = newJArray()
for i in 0 .. <x.len:
result.add(x[i].convertObject())
of JObject:
result = newJObject()
asm """for (property in `x`) {
if (`x`.hasOwnProperty(property)) {
"""
var nimProperty: cstring
var nimValue: TJSObject
asm "`nimProperty` = property; `nimValue` = `x`[property];"
result[$nimProperty] = nimValue.convertObject()
asm "}}"
of JInt:
result = newJInt(cast[int](x))
of JFloat:
result = newJFloat(cast[float](x))
of JString:
result = newJString($cast[cstring](x))
of JBool:
result = newJBool(cast[bool](x))
of JNull:
result = newJNull()
proc parseJson*(buffer: string): JsonNode =
return parseNativeJson(buffer).convertObject()
when false:
import os
var s = newFileStream(paramStr(1), fmRead)
if s == nil: quit("cannot open the file" & paramStr(1))
var x: JsonParser
open(x, s, paramStr(1))
while true:
next(x)
case x.kind
of jsonError:
Echo(x.errorMsg())
break
of jsonEof: break
of jsonString, jsonInt, jsonFloat: echo(x.str)
of jsonTrue: echo("!TRUE")
of jsonFalse: echo("!FALSE")
of jsonNull: echo("!NULL")
of jsonObjectStart: echo("{")
of jsonObjectEnd: echo("}")
of jsonArrayStart: echo("[")
of jsonArrayEnd: echo("]")
close(x)
# { "json": 5 }
# To get that we shall use, obj["json"]
when isMainModule:
var parsed = parseFile("tests/testdata/jsontest.json")
var parsed2 = parseFile("tests/testdata/jsontest2.json")
try:
discard parsed["key2"][12123]
assert(false)
except IndexError: assert(true)
let testJson = parseJson"""{ "a": [1, 2, 3, 4], "b": "asd" }"""
# nil passthrough
assert(testJson{"doesnt_exist"}{"anything"}.isNil)
testJson{["c", "d"]} = %true
assert(testJson["c"]["d"].bval)
# test `$`
let stringified = $testJson
let parsedAgain = parseJson(stringified)
assert(parsedAgain["b"].str == "asd")
# Bounds checking
try:
let a = testJson["a"][9]
assert(false, "EInvalidIndex not thrown")
except IndexError:
discard
try:
let a = testJson["a"][-1]
assert(false, "EInvalidIndex not thrown")
except IndexError:
discard
try:
assert(testJson["a"][0].num == 1, "Index doesn't correspond to its value")
except:
assert(false, "EInvalidIndex thrown for valid index")
assert(testJson{"b"}.str=="asd", "Couldn't fetch a singly nested key with {}")
assert(isNil(testJson{"nonexistent"}), "Non-existent keys should return nil")
assert(parsed2{"repository", "description"}.str=="IRC Library for Haskell", "Couldn't fetch via multiply nested key using {}")
assert(isNil(testJson{"a", "b"}), "Indexing through a list should return nil")
assert(isNil(testJson{"a", "b"}), "Indexing through a list should return nil")
assert(testJson{"a"}==parseJson"[1, 2, 3, 4]", "Didn't return a non-JObject when there was one to be found")
assert(isNil(parseJson("[1, 2, 3]"){"foo"}), "Indexing directly into a list should return nil")
# Generator:
var j = %* [{"name": "John", "age": 30}, {"name": "Susan", "age": 31}]
assert j == %[%{"name": %"John", "age": %30}, %{"name": %"Susan", "age": %31}]
var j2 = %*
[
{
"name": "John",
"age": 30
},
{
"name": "Susan",
"age": 31
}
]
assert j2 == %[%{"name": %"John", "age": %30}, %{"name": %"Susan", "age": %31}]
var name = "John"
let herAge = 30
const hisAge = 31
var j3 = %*
[ { "name": "John"
, "age": herAge
}
, { "name": "Susan"
, "age": hisAge
}
]
assert j3 == %[%{"name": %"John", "age": %30}, %{"name": %"Susan", "age": %31}]