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Add pretty printing #18

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Add pretty printing #18

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54 changes: 42 additions & 12 deletions json.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -46,19 +46,33 @@ for k, v in pairs(escape_char_map) do
end


local function make_indent(state)
return string.rep(" ", state.currentIndentLevel * state.opts.indent)
end


local function escape_char(c)
return escape_char_map[c] or string.format("\\u%04x", c:byte())
end


local function encode_nil(val)
local function encode_nil()
return "null"
end


local function encode_table(val, stack)
local function encode_table(val, state)
local res = {}
stack = stack or {}
local stack = state.stack
local pretty = state.opts.indent > 0

local close_indent = make_indent(state)
local comma = pretty and ",\n" or ","
local colon = pretty and ": " or ":"
local open_brace = pretty and "{\n" or "{"
local close_brace = pretty and ("\n" .. close_indent .. "}") or "}"
local open_bracket = pretty and "[\n" or "["
local close_bracket = pretty and ("\n" .. close_indent .. "]") or "]"

-- Circular reference?
if stack[val] then error("circular reference") end
Expand All @@ -78,22 +92,26 @@ local function encode_table(val, stack)
error("invalid table: sparse array")
end
-- Encode
for i, v in ipairs(val) do
table.insert(res, encode(v, stack))
for _, v in ipairs(val) do
state.currentIndentLevel = state.currentIndentLevel + 1
table.insert(res, make_indent(state) .. encode(v, state))
state.currentIndentLevel = state.currentIndentLevel - 1
end
stack[val] = nil
return "[" .. table.concat(res, ",") .. "]"
return open_bracket .. table.concat(res, comma) .. close_bracket

else
-- Treat as an object
for k, v in pairs(val) do
if type(k) ~= "string" then
error("invalid table: mixed or invalid key types")
end
table.insert(res, encode(k, stack) .. ":" .. encode(v, stack))
state.currentIndentLevel = state.currentIndentLevel + 1
table.insert(res, make_indent(state) .. encode(k, state) .. colon .. encode(v, state))
state.currentIndentLevel = state.currentIndentLevel - 1
end
stack[val] = nil
return "{" .. table.concat(res, ",") .. "}"
return open_brace .. table.concat(res, comma) .. close_brace
end
end

Expand Down Expand Up @@ -121,18 +139,30 @@ local type_func_map = {
}


encode = function(val, stack)
encode = function(val, state)
local t = type(val)
local f = type_func_map[t]
if f then
return f(val, stack)
return f(val, state)
end
error("unexpected type '" .. t .. "'")
end


function json.encode(val)
return ( encode(val) )
local function add_default_opts(opts)
opts = opts or {}
opts.indent = opts.indent or 0
return opts
end


function json.encode(val, opts)
local state = {
opts = add_default_opts(opts),
currentIndentLevel = 0,
stack = {}
}
return encode(val, state)
end


Expand Down