pretty/pretty.lua

-- Ensure loading library, if it exists, no matter where pretty.lua was loaded from.

-- Load the library component
local format_number, format_function, analyze_structure, get_table_info, TABLE_TYPE
do
    local thispath = ... and select('1', ...):match('.+%.') or ''

    -- Load number and function formatting
    format_number      =  select(2, pcall(require, thispath..'number'))
    format_function    =  select(2, pcall(require, thispath..'function'))

    -- Load other stuff
    local was_loaded
    was_loaded, analyze_structure  =  pcall(require, thispath..'analyze_structure')
    analyze_structure, get_table_info  =  analyze_structure[1], analyze_structure[2]
    assert(was_loaded, '[pretty]: Could not load vital library: analyze_structure')
    was_loaded, TABLE_TYPE         =  pcall(require, thispath..'table_type')
    assert(was_loaded, '[pretty]: Could not load vital library: table_type')
end
--

local ERROR_UNKNOWN_TYPE = [[
[pretty]: Attempting to format unsupported value of type "%s".
    A native formatting of the value is: %s

We are attempting to cover all Lua features, so please report this bug, so we can improve.
]]

local SINGLE_LINE_TABLE_TYPES = {
    [TABLE_TYPE.SEQUENCE]   = true,
    [TABLE_TYPE.PURE_MAP]   = true,
    [TABLE_TYPE.STRING_MAP] = true,
}

local SINGLE_LINE_SEQ_MAX_ELEMENTS    = 10
local SINGLE_LINE_MAP_MAX_ELEMENTS    = 5
local NR_CHARS_IN_LONG_STRING         = 40
local MAX_WIDTH_FOR_SINGLE_LINE_TABLE = 38

local KEY_TYPE_SORT_ORDER = {
    ['number']   = 0,
    ['string']   = 1,
    ['boolean']  = 2,
    ['table']    = 3,
    ['userdata'] = 4,
    ['thread']   = 5,
    ['function'] = 6,
}

local VALUE_TYPE_SORT_ORDER = {
    ['nil']      = 0,
    ['boolean']  = 1,
    ['number']   = 2,
    ['string']   = 3,
    ['table']    = 4,
    ['userdata'] = 5,
    ['thread']   = 6,
    ['function'] = 7,
}

local RESERVED_LUA_WORDS = {
    ['and']      = true,
    ['break']    = true,
    ['do']       = true,
    ['else']     = true,
    ['elseif']   = true,
    ['end']      = true,
    ['false']    = true,
    ['for']      = true,
    ['function'] = true,
    ['if']       = true,
    ['in']       = true,
    ['local']    = true,
    ['nil']      = true,
    ['not']      = true,
    ['or']       = true,
    ['repeat']   = true,
    ['return']   = true,
    ['then']     = true,
    ['true']     = true,
    ['until']    = true,
    ['while']    = true,
}

local CHAR_TO_STR_REPR = {}

do
    for i = 00, 031 do  CHAR_TO_STR_REPR[i] = '\\0'..(i < 10 and '0' or '')..i  end
    for i = 32, 255 do  CHAR_TO_STR_REPR[i] = string.char(i)  end
    CHAR_TO_STR_REPR[7]   = '\\a'
    CHAR_TO_STR_REPR[8]   = '\\b'
    CHAR_TO_STR_REPR[9]   = '\t'
    CHAR_TO_STR_REPR[10]  = '\n'
    CHAR_TO_STR_REPR[11]  = '\\v'
    CHAR_TO_STR_REPR[12]  = '\\f'
    CHAR_TO_STR_REPR[13]  = '\\r'
    CHAR_TO_STR_REPR[92]  = '\\\\'
    CHAR_TO_STR_REPR[127] = '\\127'
end

--------------------------------------------------------------------------------
-- Util

local function padnum(d)
    local dec, n = string.match(d, "(%.?)0*(.+)")
    return #dec > 0 and ("%.12f"):format(d) or ("%s%03d%s"):format(dec, #n, n)
end

local function alphanum_compare_strings (a, b)
    return tostring(a):gsub("%.?%d+", padnum)..("%3d"):format(#b)
         < tostring(b):gsub("%.?%d+", padnum)..("%3d"):format(#a)
end

local function smallest_secure_longform_string_level (str)
    -- Determines the level a longform string needs to use, to avoid "code"
    -- injection. For example, if we want to use longform on the string
    -- 'Hello ]] World', we cannot use level-0 as this would result in
    -- '[[Hello ]] World]]', which could be an issue in certain applications.

    local levels = { [1] = 1 }
    str:gsub('%]=*%]', function (m) levels[m:len()] = true end)
    return #levels - 1
end

local function compare_key_value_pairs (a, b)
    -- Get types
    local type_key_a,   type_key_b   = type(a[1]), type(b[1])
    local type_value_a, type_value_b = type(a[2]), type(b[2])

    -- Tons of compare
    if (1 == (type_key_a == 'number' and 1 or 0) + (type_key_b == 'number' and 1 or 0)) then
        return type_key_a == 'number'
    elseif (type_key_a == 'number' and type_key_b == 'number') then
        return a[1] < b[1]
    elseif (type_value_a ~= type_value_b) then
        return VALUE_TYPE_SORT_ORDER[type_value_a] < VALUE_TYPE_SORT_ORDER[type_value_b]
    elseif (type_key_a == 'string' and type_key_b == 'string') then
        return alphanum_compare_strings(a[1], b[1])
    elseif (type_key_a ~= type_key_b) then
        return KEY_TYPE_SORT_ORDER[type_value_a] < KEY_TYPE_SORT_ORDER[type_value_b]
    end
end

local function get_key_value_pairs_in_proper_order (t)
    -- Generates a sequence of key value pairs, in proper order.
    -- Proper order is:
    -- 1. All integer keys are first, in order
    -- 2. Then by value type, as defined in  VALUE_TYPE_SORT_ORDER in the top.
    -- 3. Then by key type.
    -- 3.1. String in alphanumeric order
    -- 3.2. Other wierdness.

    local key_value_pairs = {}

    for key, value in pairs(t) do
        key_value_pairs[#key_value_pairs+1] = { key, value }
    end

    table.sort(key_value_pairs, compare_key_value_pairs)

    return key_value_pairs
end

local function fill_holes_in_key_value_pairs (key_value_pairs)
    -- NOTE: Assumes that all keys are numbers
    for i = 2, #key_value_pairs do
        for j = key_value_pairs[i-1][1] + 1, key_value_pairs[i][1] - 1 do
            key_value_pairs[#key_value_pairs+1] = { j, nil }
        end
    end
    table.sort(key_value_pairs, compare_key_value_pairs)
end

local function is_identifier(str)
    -- An identier is defined in the lua reference guide

    return str:match('^[_%a][_%w]*$') and not RESERVED_LUA_WORDS[str]
end

local function contains_only_nice_string_keys (t)
    -- A "nice" string is here defined is one following the rules of lua
    -- identifiers.

    for k, _ in pairs(t) do
        if type(k) ~= 'string' or not is_identifier(k) then
            return false
        end
    end
    return true
end

local function contains_only_nice_number_indexes (t)
    -- A "nice" index is here defined as one which would be visited when using
    -- ipairs: An integer larger than 1 and less than #t

    local max_index  =  #t
    for k, v in pairs(t) do
        if type(k) ~= 'number' or k < 1 or max_index < k or k ~= math.floor(k) then
            return false
        end
    end

    return true
end

local function escape_string (str)
    local l = {}
    for i = 1, #str do
        l[#l+1] = CHAR_TO_STR_REPR[str:byte(i)]
    end
    return table.concat(l, '')
end

local function width_of_strings_in_l (l, start_i, end_i)
    local  width = 0
    for i = start_i or 1, (end_i or #l) do
        width = width + ((type(l[i]) ~= 'string') and 1 or #l[i])
    end
    return width
end

local function ignore_alignment_info (l, start_i, stop_i)
    for i = start_i or 1, stop_i or #l do
        if type(l[i]) == 'table' then
            l[i] = ''
        end
    end
end

local function fix_alignment (l, start_i, stop_i)
    local start_i, stop_i = start_i or 1, stop_i or #l

    -- Find maximums
    local max  =  {}
    for i = start_i, stop_i do
        if type(l[i]) == 'table' then
            max[ l[i][2] ]  =  math.max( l[i][1], max[ l[i][2] ] or 0 )
        end
    end

    -- Insert the proper whitespace
    for i = start_i, stop_i do
        if type(l[i]) == 'table' then
            l[i] = string.rep(' ', max[ l[i][2] ] - l[i][1])
        end
    end
end

local function replace_seperator_info (l, replace_with, indent_char, depth, start_i, stop_i)
    for i = start_i or 1, stop_i or #l do
        if type(l[i]) ~= 'table' then
            -- Do nothing
        elseif l[i][1] == 'seperator' then
            l[i] = replace_with .. indent_char:rep(depth)
        elseif l[i][1] == 'indent' then
            l[i], depth = '', depth + 1
        elseif l[i][1] == 'unindent' then
            l[i], depth = '', depth - 1
        end
    end
end

--------------------------------------------------------------------------------
-- Identifyer stuff

local function is_empty_table (value)
    if type(value) ~= 'table' then
        error(('[pretty/internal]: Only tables allowed in function pretty.is_empty_table, but was given %s (%s)'):format(value, type(value)), 2)
    end
    return next(value) == nil
end

local function get_table_type (value)
    -- Determines table type:
    -- * Sequence:  All keys are integer in the range 1..#value
    -- * Pure Map:  #value == 0
    -- * Mixed:     Any other

    if is_empty_table(value) then  return TABLE_TYPE.EMPTY  end

    local is_sequence      =  contains_only_nice_number_indexes(value)
    local only_string_keys =  contains_only_nice_string_keys(value)
    local is_pure_map      =  (#value == 0)

    -- Return type
    if     is_sequence      then  return TABLE_TYPE.SEQUENCE
    elseif only_string_keys then  return TABLE_TYPE.STRING_MAP
    elseif is_pure_map      then  return TABLE_TYPE.PURE_MAP
    else                          return TABLE_TYPE.MIXED
    end
end

--------------------------------------------------------------------------------
-- Formatting stuff

local format_table, format_value

-- Ways to format keys

local function format_key_and_value_string_map (l, key, value, options, depth)
    l[#l+1] = key
    l[#l+1] = { #key, 'key' }
    l[#l+1] = ' = '
    return format_value(value, options, depth, l)
end

local function format_key_and_value_arbitr_map (l, key, value, options, depth)
    local index_before_key = #l+1
    l[#l+1] = '['
    format_value(key, options, 'max', l)     -- TODO: Outphase the usage of the "max" depth thingy.
    l[#l+1] = ']'
    l[#l+1] = { width_of_strings_in_l(l, index_before_key), 'key' }
    l[#l+1] = ' = '
    return format_value(value, options, depth, l)
end

local function format_key_and_value_sequence (l, key, value, options, depth)
    return format_value(value, options, depth, l)
end

local TABLE_TYPE_TO_PAIR_FORMAT = {
    [TABLE_TYPE.EMPTY]      = format_key_and_value_sequence,
    [TABLE_TYPE.SEQUENCE]   = format_key_and_value_sequence,
    [TABLE_TYPE.SET]        = format_key_and_value_arbitr_map,
    [TABLE_TYPE.MIXED]      = format_key_and_value_arbitr_map,
    [TABLE_TYPE.STRING_MAP] = format_key_and_value_string_map,
    [TABLE_TYPE.PURE_MAP]   = format_key_and_value_arbitr_map,
}

-- Formatting tables

local function format_map (t, options, depth, l)
    -- NOTE: Assumes that the input table was pre-checked with `is_single_line_table()`

    local table_info       = l.info[t] or get_table_info(t)
    local key_value_pairs  = get_key_value_pairs_in_proper_order(t)
    if table_info.type == TABLE_TYPE.SEQUENCE and l.info[t].has_holes then
        fill_holes_in_key_value_pairs(key_value_pairs)
    end
    local pair_format_func = TABLE_TYPE_TO_PAIR_FORMAT[table_info.type]

    local start_of_table_i = #l + 1
    l[#l+1] = '{'
    l[#l+1] = {'indent'}
    l[#l+1] = {'seperator'}

    for _, pair in ipairs(key_value_pairs) do
        pair_format_func(l, pair[1], pair[2], options, depth + 1)
        l[#l+1] = ','
        l[#l+1] = {'seperator'}
    end

    if l[#l][1] == 'seperator' then  l[#l-1], l[#l] = nil, nil  end
    l[#l+1] = {'unindent'}
    l[#l+1] = {'seperator'}
    l[#l+1] = '}'

    local table_width  =  width_of_strings_in_l(l, start_of_table_i)

    if table_width <= MAX_WIDTH_FOR_SINGLE_LINE_TABLE then
        -- Is short table: Ignore the "width of key"-shit
        replace_seperator_info(l, ' ', '', 0, start_of_table_i)
        ignore_alignment_info(l, start_of_table_i)
    else
        -- Is long table: Fix whitespace alignment
        replace_seperator_info(l, '\n', options.indent, depth, start_of_table_i)
        fix_alignment(l, start_of_table_i)
    end
end

function format_table (t, options, depth, l)
    local info = l.info[t] or {}
    --local table_type = get_table_type(t)

    if options.recursion == 'marked' and info.marker then
        l[#l+1], l[#l+2], l[#l+3] = '<', info.marker, '>'
    end

    -- Empty or exteeding max-depth?
    if info.type == TABLE_TYPE.EMPTY then  l[#l+1] = '{}'; return
    elseif depth ~= 'max' and depth >= options.max_depth or l.visited[t] then  l[#l+1] = '{...}'; return
    end

    l.visited[t] = true

    if depth == 'max' then  l[#l+1] = '{...}'; return  end

    -- Normal table
    format_map(t, options, depth, l)
end

local function format_string (str, options, depth, l)
    -- TODO: Add option for escaping unicode characters.

    local is_long_string         =  (str:len() >= NR_CHARS_IN_LONG_STRING)
    local newline_or_tab_index   =  str:find('[\n\t]')
    local single_quote_index     =  str:find('\'')
    local double_quote_index     =  str:find('\"')

    -- ...
    local chance_of_longform     =  is_long_string and ((newline_or_tab_index or math.huge) <= NR_CHARS_IN_LONG_STRING) or double_quote_index and single_quote_index
    local cut_string_index       =  options.cut_strings and (is_long_string or chance_of_longform)
                                                        and math.min(NR_CHARS_IN_LONG_STRING - 3, newline_or_tab_index or 1/0, double_quote_index or 1/0, single_quote_index or 1/0)

    local longform   = chance_of_longform and ((not cut_string_index) or cut_string_index < math.min(newline_or_tab_index or 1/0, double_quote_index or 1/0, single_quote_index or 1/0))

    local escape_newline_and_tab  =  not longform and newline_or_tab_index

    -- Determine string delimiters
    local left, right
    if longform then
        local level = smallest_secure_longform_string_level(str)
        left, right = '['..string.rep('=', level)..'[', ']'..string.rep('=', level)..']'
        if newline_or_tab_index then  str = '\n' .. str  end
    elseif not single_quote_index then
        left, right = '\'', '\''
    else
        left, right = '\"', '\"'
    end

    -- Cut string
    if cut_string_index then        str = str:sub(1, cut_string_index)  end
    str = escape_string(str)
    -- Escape newline and tab
    if escape_newline_and_tab then  str = str:gsub('\n', '\\n'):gsub('\t', '\\t')  end

    l[#l+1] = left
    l[#l+1] = str
    l[#l+1] = right
end

if not format_number then
    -- Very simple number formatting, if number.lua is not available.
    format_number = function (value, _, _, l)
        l[#l+1]  =  tostring(value)
    end
end

local function format_coroutine (value, options, depth, l)
    l[#l+1] = coroutine.status(value)
    l[#l+1] = ' coroutine: '
    l[#l+1] = tostring(value):sub(9)
end

local function format_primitive (value, options, depth, l)
    l[#l+1] = tostring(value)
end

if not format_function then
    -- Very simple function formatting, if function.lua is not available.
    format_function = function (value, _, _, l)
        l[#l+1]  =  'function (...) --[['..tostring(value):sub(11)..']] end'
    end
end

local TYPE_TO_FORMAT_FUNC = {
    ['nil']      =  format_primitive,
    ['boolean']  =  format_primitive,
    ['number']   =  format_number,
    ['string']   =  format_string,
    ['thread']   =  format_coroutine,
    ['table']    =  format_table,

    -- TODO
    ['function'] =  format_function,
    ['userdata'] =  format_primitive,
    ['cdata']    =  format_primitive,  -- Luajit exclusive ?
}

function format_value (value, _, depth, l)
    local formatting = TYPE_TO_FORMAT_FUNC[type(value)]
    if formatting then
        formatting(value, l.options, depth, l, format_value)
    else
        error(ERROR_UNKNOWN_TYPE:format(type(value), tostring(value)), 2)
    end
end

--------------------------------------------------------------------------------

local KNOWN_OPTIONS = {
    _all_function_info  = 'boolean',
    cut_strings         = 'boolean',
    include_closure     = 'boolean',
    indent              = 'string',
    math_shorthand      = 'boolean',
    max_depth           = 'number',
    more_function_info  = 'boolean',
    recursion           = 'string',
    short_builtins      = 'boolean',
}

local function ensure_that_all_options_are_known (options)
    for option_name, option_value in pairs(options) do
        if not KNOWN_OPTIONS[option_name] then
            error(('[pretty]: Unknown option: %s. Was given value %s (%s)'):format(option_name, option_value, type(option_value)), 2)
        elseif type(option_value) ~= KNOWN_OPTIONS[option_name] then
            error(('[pretty]: Bad value given to option %s: %s (%s). Expected value of type %s'):format(option_name, option_value, type(option_value), KNOWN_OPTIONS[option_name]), 2)
        end
    end
end

local function pretty_format (value, options)
    local l = { visited = { next_mark = 1 } }
    l.options = options or {}
    l.options.max_depth = l.options.max_depth or math.huge
    l.options.indent    = l.options.indent    or '\t'
    ensure_that_all_options_are_known(l.options)
    l.info = (type(value) == 'table') and analyze_structure(value) or {}
    format_value(value, nil, 0, l)

    -- If any alignment info still exists, ignore it
    ignore_alignment_info(l)

    return table.concat(l, '')
end

return pretty_format