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‎jsmn.nim

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# Copyright 2016 Huy Doan
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#
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# This file is a Nim fork of Jsmn: https://github.com/zserge/jsmn
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# Copyright (c) 2010 Serge A. Zaitsev
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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## This module is a fork of `Jsmn <http://zserge.com/jsmn.html>`_ - a world fastest JSON parser/tokenizer - in pure Nim
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##
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## It also supports ``PARENT LINKS`` and ``STRICTMODE``, you can enable them via command line switch
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##
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## Installation
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## ============
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##.. code-block::
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## nimble install jsmn
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##
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## Usage
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## =====
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##.. code-block:: nim
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## import jsmn
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##
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## const
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## json = """{
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## "user": "johndoe",
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## "admin": false,
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## "uid": 1000,
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## "groups": ["users", "wheel", "audio", "video"]}"""
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##
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## var
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## tokens: array[32, JsmnToken] # expect not more than 32 tokens
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##
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## let r = parseJson(json, tokens)
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## if r < 0:
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## echo "Failed to parse JSON: ", r
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##
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## for i in 1..r:
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## var token = addr tokens[i]
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## echo "Kind: ", token.kind
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## echo "Value: ", json[token.start..<token.stop]
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type
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JsmnKind* = enum ## JSON type identifier
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JSMN_UNDEFINED, ## Undefined
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JSMN_OBJECT, ## Object, tuple
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JSMN_ARRAY, ## Array, seq
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JSMN_STRING, ## String
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JSMN_PRIMITIVE ## Other primitive: number, boolean (true/false) or null
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JsmnToken* = object
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## JSON token description.
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kind*: JsmnKind
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start*: int ## start position in JSON data string
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stop*: int ## end position in JSON data string
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size*: int
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when defined(JSMN_PARENT_LINKS):
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parent*: int
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JsmnParser = tuple[pos: int, toknext: int, toksuper: int]
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const
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JSMN_ERROR_NOMEM* = -1 ## not enough tokens, JSON string is too large
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JSMN_ERROR_INVAL* = -2 ## bad token, JSON string is corrupted
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JSMN_ERROR_PART* = -3 ## JSON string is too short, expecting more JSON data
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proc initToken(parser: var JsmnParser, tokens: var openarray[JsmnToken]): ptr JsmnToken =
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## Allocates a fresh unused token from the token pull.
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if parser.toknext >= tokens.len - 1:
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return
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inc(parser.toknext)
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result = addr tokens[parser.toknext]
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result.start = -1
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result.stop = - 1
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result.size = 0
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when defined(JSMN_PARENT_LINKS):
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result.parent = - 1
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proc fillToken(token: ptr JsmnToken, kind: JsmnKind, start, stop: int) =
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## Fills token type and boundaries.
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token.kind = kind
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token.start = start
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token.stop = stop
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token.size = 0
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when defined(JSMN_STRICT):
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# In strict mode primitive must be followed by "," or "}" or "]"
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const PRIMITIVE_DELIMITERS = ['\x09', '\x0D', '\x0A', ' ', ',', ']', '}']
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else:
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const PRIMITIVE_DELIMITERS = [':', '\x09', '\x0D', '\x0A', ' ', ',', ']', '}']
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proc parsePrimitive(parser: var JsmnParser, json: string, len: int, tokens: var openarray[JsmnToken]): int =
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## Fills next available token with JSON primitive.
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var start = parser.pos
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while parser.pos < len and json[parser.pos] != '\0':
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case json[parser.pos]
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of PRIMITIVE_DELIMITERS:
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if tokens.len <= 0:
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dec(parser.pos)
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return 0
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var token = initToken(parser, tokens)
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if token == nil:
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parser.pos = start
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return JSMN_ERROR_NOMEM
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fillToken(token, JSMN_PRIMITIVE, start, parser.pos)
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when defined(JSMN_PARENT_LINKS):
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token.parent = parser.toksuper
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dec(parser.pos)
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return 0
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else:
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discard
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if json[parser.pos].ord < 32 or json[parser.pos].ord >= 127:
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parser.pos = start
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return JSMN_ERROR_INVAL
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inc(parser.pos)
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when defined(JSMN_STRICT):
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# In strict mode primitive must be followed by a comma/object/array
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parser.pos = start
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return JSMN_ERROR_PART
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proc parseString(parser: var JsmnParser, json: string, tokens: var openarray[JsmnToken]): int =
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## Fills next token with JSON string.
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var start = parser.pos
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inc(parser.pos)
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# Skip starting quote
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while parser.pos < json.len and json[parser.pos] != '\0':
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let c = json[parser.pos]
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# Quote: end of string
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if c == '\"':
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if tokens.len <= 0:
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return 0
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var token = initToken(parser, tokens)
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if token == nil:
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parser.pos = start
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return JSMN_ERROR_NOMEM
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fillToken(token, JSMN_STRING, start + 1, parser.pos)
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when defined(JSMN_PARENT_LINKS):
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token.parent = parser.toksuper
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return 0
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if c == '\x08' and parser.pos + 1 < json.len:
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inc(parser.pos)
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case json[parser.pos] # Allowed escaped symbols
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of '\"', '/', '\x08', 'b', 'f', 'r', 'n', 't':
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discard
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of 'u':
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inc(parser.pos)
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var i = 0
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while i < 4 and parser.pos < json.len and json[parser.pos] != '\0':
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# If it isn't a hex character we have an error
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if not ((json[parser.pos].ord >= 48 and json[parser.pos].ord <= 57) or
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(json[parser.pos].ord >= 65 and json[parser.pos].ord <= 70) or
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(json[parser.pos].ord >= 97 and json[parser.pos].ord <= 102)): # A-F
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# 0-9
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# a-f
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parser.pos = start
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return JSMN_ERROR_INVAL
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inc(parser.pos)
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inc(i)
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dec(parser.pos)
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else:
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parser.pos = start
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return JSMN_ERROR_INVAL
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inc(parser.pos)
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parser.pos = start
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return JSMN_ERROR_PART
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proc parse(parser: var JsmnParser, json: string, tokens: var openarray[JsmnToken]): int =
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## Parse JSON string and fill tokens.
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var token: ptr JsmnToken
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var count = parser.toknext
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while parser.pos < json.len and json[parser.pos] != '\0':
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var kind: JsmnKind
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var c = json[parser.pos]
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case c
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of '{', '[':
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inc(count)
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if tokens.len <= 0:
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break
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token = initToken(parser, tokens)
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if token == nil: return JSMN_ERROR_NOMEM
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if parser.toksuper != - 1:
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inc(tokens[parser.toksuper].size)
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when defined(JSMN_PARENT_LINKS):
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token.parent = parser.toksuper
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token.kind = (if c == '{': JSMN_OBJECT else: JSMN_ARRAY)
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token.start = parser.pos
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parser.toksuper = parser.toknext - 1
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of '}', ']':
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if tokens.len <= 0: break
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kind = (if c == '}': JSMN_OBJECT else: JSMN_ARRAY)
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when defined(JSMN_PARENT_LINKS):
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if parser.toknext < 1:
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return JSMN_ERROR_INVAL
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token = addr(tokens[parser.toknext - 1])
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while true:
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if token.start != - 1 and token.stop == - 1:
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if token.kind != kind:
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return JSMN_ERROR_INVAL
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token.stop = parser.pos + 1
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parser.toksuper = token.parent
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break
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if token.parent == - 1:
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break
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token = addr(tokens[token.parent])
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else:
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var i = parser.toknext - 1
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while i >= 0:
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token = addr tokens[i]
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if token.start != - 1 and token.stop == - 1:
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if token.kind != kind:
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return JSMN_ERROR_INVAL
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parser.toksuper = - 1
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token.stop = parser.pos + 1
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break
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dec(i)
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# Error if unmatched closing bracket
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if i == - 1: return JSMN_ERROR_INVAL
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while i >= 0:
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token = addr tokens[i]
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if token.start != - 1 and token.stop == - 1:
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parser.toksuper = i
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break
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dec(i)
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of '\"':
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let r = parseString(parser, json, tokens)
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if r < 0: return r
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inc(count)
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if parser.toksuper != - 1 and tokens.len <= 0:
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inc(tokens[parser.toksuper].size)
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of '\t', '\r', '\x0A', ' ':
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discard
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of ':':
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parser.toksuper = parser.toknext - 1
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of ',':
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if tokens.len <= 0 and parser.toksuper != - 1 and
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tokens[parser.toksuper].kind != JSMN_ARRAY and
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tokens[parser.toksuper].kind != JSMN_OBJECT:
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when defined(JSMN_PARENT_LINKS):
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parser.toksuper = tokens[parser.toksuper].parent
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else:
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var i = parser.toknext - 1
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while i >= 0:
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if tokens[i].kind == JSMN_ARRAY or
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tokens[i].kind == JSMN_OBJECT:
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if tokens[i].start != - 1 and tokens[i].stop == - 1:
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parser.toksuper = i
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break
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dec(i)
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else:
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when defined(JSMN_STRICT):
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# In strict mode primitives are: numbers and booleans
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case c
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of '-', '0', '1', '2', '3', '4', '5', '6', '7', '8','9', 't', 'f', 'n':
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# And they must not be keys of the object
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if tokens.len <= 0 and parser.toksuper != - 1:
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var t: ptr JsmnToken = addr(tokens[parser.toksuper])
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if t.kind == JSMN_OBJECT or (t.kind == JSMN_STRING and t.size != 0):
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return JSMN_ERROR_INVAL
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let r = parsePrimitive(parser, json, json.len, tokens)
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if r < 0: return r
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inc(count)
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if parser.toksuper != - 1 and tokens.len <= 0:
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inc(tokens[parser.toksuper].size)
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else:
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return JSMN_ERROR_INVAL
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else:
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let r = parsePrimitive(parser, json, json.len, tokens)
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if r < 0: return r
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inc(count)
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if parser.toksuper != - 1 and tokens.len <= 0:
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inc(tokens[parser.toksuper].size)
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inc(parser.pos)
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if tokens.len <= 0:
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var i = parser.toknext - 1
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while i >= 0:
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# Unmatched opened object or array
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if tokens[i].start != - 1 and tokens[i].stop == - 1:
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return JSMN_ERROR_PART
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dec(i)
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return count
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proc parseJson*(json: string, tokens: var openarray[JsmnToken]): int =
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## Parse a JSON data string into and array of tokens, each describing a single JSON object.
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var parser: JsmnParser = (0, 0, -1)
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parser.parse(json, tokens)
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when isMainModule:
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const
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json = "{\"user\": \"johndoe\", \"admin\": false, \"uid\": 1000, \"groups\": [\"users\", \"wheel\", \"audio\", \"video\"]}"
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var
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tokens: array[10, JsmnToken]
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let r = parseJson(json, tokens)
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if r < 0:
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echo "Failed to parse JSON: ", r
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for i in 1..r:
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var token = addr tokens[i]
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echo "Kind: ", token.kind
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echo "Value: ", json[token.start..<token.stop]

‎jsmn.nimble

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# Package
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version = "0.1.0"
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author = "Huy Doan"
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description = "Jsmn - a world fastest JSON parser - in pure Nim"
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license = "MIT"
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# Dependencies
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requires "nim >= 0.13.1"
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