JSON+ de/serializer in pure lua
This folder defines an LSON spec and an example public domain pure-lua implementation of LSON/JSON encoder and decoder.

Lua Library

lson is a pure-lua JSON+ de/serialization library. The main functions are the encoding functions json() and lson() and the decode() function (which decodes either encoder's output).
See also the types #lson.Json, #lson.Lson and #lson.Decoder and their documentation to have more control of the usage, including pretty printing and a decoding iterator.

LSON spec

LSON is a strict superset of JSON: all valid JSON is valid LSON but not vice versa. The difference is:

• LSON ignores commas (it treats them as whitespace). List and map entries can be separated by any whitespace (including commas). This makes it easier for a human to write and vcs to diff.
• LSON adds binary syntax for bytes |any binary data|. The data within
• |...| is arbitrary bytes except the following will be converted: \\ -> \   \| -> |    \n -> newline Other "escapes" are preserved, i.e. \d -> \d. This makes encoding binary data in LSON MUCH more compact (and possible) than JSON.

Mod lson

Types: Json Lson De
Functions

• fn json(v, pretty) -> string
  Encode lua value to JSON string
• fn lson(v, pretty) -> string
  Encode lua value to LSON string
• fn decode(s, podder, pset) -> obj
• fn bytes(f, s)
• fn deNull(de) -> de.null
• fn deTrue(de) -> true
• fn deFalse(de) -> false
• fn deNumber(de)
• fn deString(de)
• fn deBytes(de)
• fn deArray(de)
• fn deObject(de)

Record Json

Json Encoder (via fmt.Fmt) This works identically to metaty.Fmt except it overrides how tables are formatted to use JSON instead of printing them. Fields:

• .styleenable styling. If true, set to=Styler
• .toif set calls write
• .keyEnd =","
• .keySet =":"
• .indexEnd =","
• .tableStart ="{"
• .tableEnd ="}"
• .listEnd ="]"
• .indent ="  "
• .maxIndent =20
• .numfmt ="%q"
• .strfmt ="%q"
• .table =function() instance
• .string =function() instance
• .null =ds.nonevalue to use for null
• .listStart ="["
• .listEnd ="]"

Methods

• fn toPretty(f)
• fn pretty(E, t)
• fn:level(add) -> int: current level
  Add to the indent level and get the new value call with add=nil to just get the current level
• fn:write(...)
  Same as file:write.
• fn:flush()
• fn:close()
• fn styled(f, style, text, ...)
  Call to:styled(...) if it is enabled, else simply f:write(text, ...). This allows for configurable styling of output, both for objects as well as command-line utilities/etc.
• fn tableKey(f, v, podder, pod)
• fn nil(f)
  format a nil value.
• fn boolean(f, b)
  format a boolean value.
• fn number(f, n)
  format a number value.
• fn string(enc, s)
• fn thread(f, th)
  format a thread value.
• fn userdata(f, ud)
  format a userdata value.
• fn function(f, fn)
  format a function value.
• fn items(f, t, hasKeys, listEnd)
  format items in table "list"
• fn keyvals(f, t, keys)
  format key/vals in table "map".
• fn list(f, t)
  Format only the list-elements of a table.
• fn rawtable(f, t)
• fn table(f, t)
• fn format(f, fmt, ...) -> varargsUsed
  like string.format but use Fmt for %q. Doesn't return the string, instead writes to Fmt
• fn concat(f, sep, ...) -> f
  fmt ... separated by sep
• fn tabulated(f, ...) -> f:concat('\t', ...)
  fmt ... separated by tabs
• fn lined(f, ...) -> f:concat('\n', ...)
  fmt ... separated by newlines
• fn tostring

Record Lson

Similar to JSON but no commas and strings are encoded as |bytes| Fields:

• .styleenable styling. If true, set to=Styler
• .toif set calls write
• .keyEnd =" "
• .keySet =":"
• .indexEnd =" "
• .tableStart ="{"
• .tableEnd ="}"
• .listEnd ="]"
• .indent ="  "
• .maxIndent =20
• .numfmt ="%q"
• .strfmt ="%q"
• .table =function() instance
• .string =lson.bytes
• .null =ds.nonevalue to use for null
• .listStart ="["
• .listEnd ="]"

Methods

• fn toPretty(f)
• fn pretty(E, t)
• fn:level(add) -> int: current level
  Add to the indent level and get the new value call with add=nil to just get the current level
• fn:write(...)
  Same as file:write.
• fn:flush()
• fn:close()
• fn styled(f, style, text, ...)
  Call to:styled(...) if it is enabled, else simply f:write(text, ...). This allows for configurable styling of output, both for objects as well as command-line utilities/etc.
• fn tableKey(f, v, podder, pod)
• fn nil(f)
  format a nil value.
• fn boolean(f, b)
  format a boolean value.
• fn number(f, n)
  format a number value.
• fn string(f, s)
• fn thread(f, th)
  format a thread value.
• fn userdata(f, ud)
  format a userdata value.
• fn function(f, fn)
  format a function value.
• fn items(f, t, hasKeys, listEnd)
  format items in table "list"
• fn keyvals(f, t, keys)
  format key/vals in table "map".
• fn list(f, t)
  Format only the list-elements of a table.
• fn rawtable(f, t)
• fn table(f, t)
• fn format(f, fmt, ...) -> varargsUsed
  like string.format but use Fmt for %q. Doesn't return the string, instead writes to Fmt
• fn concat(f, sep, ...) -> f
  fmt ... separated by sep
• fn tabulated(f, ...) -> f:concat('\t', ...)
  fmt ... separated by tabs
• fn lined(f, ...) -> f:concat('\n', ...)
  fmt ... separated by newlines
• fn tostring

Record De

De(string or lines) -> value-iter for val in De'["my", "lson"' do ... end