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pretty/pretty.lua

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-- pretty.pretty
-- Main module of the `pretty` library.
-- TODO: Maybe move table formatting into its own file?
--[=[ Thoughts on displaying tables in an intuitive way.
Lua's table data-structure is likely to be the most concise data structure ever
invented. (If not, please send me a link!) Lists, maps, objects, classes,
proxies, etc. This obviously brings about it some difficulty when attempting to
represent these tables. What do we want to highlight, and what do we choose to
avoid?
One notable issue is whether to show every key that a table answers (to lift
some Smalltalk terms) to, or to just display those it contains. That is, do we
think about `__index` in the table's metatable and what it returns, or do we
ignore `__index`? For cases where `__index` is a function, we cannot say
anything about the keys that the table answers to. If `__index` is a table, we
have a better idea, but it would be cluttered to display both types of keys side
by side.
1. Native representation: Lua's native representation includes the type and
address of the table. It allows for distinguishing between unique tables,
but won't tell us anything about the contents.
2. Omission: By representing tables as the pseudo-parsable `{...}`, it's
clear we are talking about a table. We disregard the ability to
distinguish between tables.
2A. If the table is empty, we could represent it as `{}`. But what if the table
has a metatable with `__index` defined? We could continue to represent it as
`{}`, but `{...}` would be more "honest".
3. Single-line: TODO
4. Multi-line: TODO
5. Columns: For some highly-regular structures, like lists of short strings,
giving each string it's own line would be too long, but formatting them as a
single-line list would be too cluttered. Thus we can take inspiration from
the classic `ls` unix tool, and place the output into columns, to help guide
the eyes.
6. Tabular: Other structures are formatted like actual tables of data, e.g. a
sequence of tuples, like one would see in an SQL database. For these
structures it's an obvious choice to align them based on the keys.
7. Pseudo-Tabular: Some structures are almost tabular, e.g. they are sequences
of tuples, but some of the tuples differ in their structure. For these
structures it's still useful to tabulate the keys that all tuples share. To
do this we should sort the key order descending by the number of tuples with
the key.
But what do we do about the the outlier keys? We can either justify the
entire table, and give specific spots for the outlier keys, thereby
significantly increasing the size of the table, or we can leave the table
unjustified, abandoning it's eye-guiding attributes.
8. Special cases: (Array-tree, Table-Tree, Linked-List, Predictive Sequences) TODO
--]=]
--------------------------------------------------------------------------------
-- Import files
local import
do
local thispath = ... and select('1', ...):match('.+%.') or ''
import = function (name, ignore_failure) return require(thispath..name) end
end
--------------------------------------------------------------------------------
-- Constants
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 TERMINAL_WIDTH = 80
local MAX_WIDTH_FOR_SINGLE_LINE_TABLE = 38
if io and io.popen then
local f = io.popen "tput cols"
local term_width = f:read '*n'
f:close()
if term_width then
TERMINAL_WIDTH = term_width
--MAX_WIDTH_FOR_SINGLE_LINE_TABLE = term_width * (2 / 3)
end
end
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 COLUMN_SEPERATION = 1
--------------------------------------------------------------------------------
-- Key-value-pair Util
local function padnum(minus, dec, zeroes, n)
return dec == '.' and ("%.12f"):format(dec..zeroes..n) or ("%s%03d%s"):format(minus == '' and ':' or minus, #n, n)
end
local function alphanum_compare_strings (a, b)
-- Compares two strings alphanumerically.
assert(type(a) == 'string')
assert(type(b) == 'string')
local a_padded = a:gsub("(%-?)(%.?)(0*)(%d+)", padnum)..("\0%3d"):format(#b)
local b_padded = b:gsub("(%-?)(%.?)(0*)(%d+)", padnum)..("\0%3d"):format(#a)
-- Correction for sorting of negative numbers:
if a_padded:sub(1,1) == '-' and b_padded:sub(1,1) == '-' then
a_padded, b_padded = b_padded, a_padded
end
--
local A_padded, B_padded = a_padded:upper(), b_padded:upper()
if A_padded == B_padded then return a_padded < b_padded end
return A_padded < B_padded
end
local function compare_key_value_pair (a, b)
-- Function for comparing two key-value pairs, given as `{ key, value }`.
-- Pretty complex due to our high standards for sorting.
assert(type(a) == 'table')
assert(type(b) == 'table')
-- 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.
-- Error checking
assert(type(t) == 'table')
-- Find Key-Value Pairs
local kv_pairs = {}
for key, value in pairs(t) do kv_pairs[#kv_pairs+1] = { key, value } end
-- Sort them into the correct order
table.sort(kv_pairs, compare_key_value_pair)
-- Return them
return kv_pairs
end
local function fill_holes_in_key_value_pairs (kv_pairs)
-- Fills holes in key-value pairs for a sequences with `nil` values. All
-- keys must be numbers, and key-value pairs must be sorted already.
-- Holes can sometimes appear in otherwise nicely structured sequences. We
-- want to avoid displaying a sequence as `{[1] = 1, [3] = 3}` when
-- `{1, nil, 3}` would work nicely.
-- Error checking
assert(type(kv_pairs) == 'table')
-- Add hole filling value
assert(type(kv_pairs[1][1]) == 'number')
for i = 2, #kv_pairs do
assert(type(kv_pairs[i][1]) == 'number')
for j = kv_pairs[i-1][1] + 1, kv_pairs[i][1] - 1 do
kv_pairs[#kv_pairs+1] = { j, nil }
end
end
-- Sort key-value pairs, to place above pairs into their correct locations.
table.sort(kv_pairs, compare_key_value_pair)
end
--------------------------------------------------------------------------------
-- Formatting Util
local length_of_utf8_string = import 'common' . utf8_string_length
local width_of_strings_in_l = import 'common' . width_of_strings_in_l
local function ignore_alignment_info (l, start_i, stop_i)
-- Argument fixing and Error Checking
assert(type(l) == 'table')
local start_i, stop_i = start_i or 1, stop_i or #l
assert(type(start_i) == 'number')
assert(type(stop_i) == 'number')
-- Do stuff
for i = start_i, stop_i do
if type(l[i]) == 'table' and l[i][1] == 'align' then
l[i] = ''
end
end
end
local function insert_alignment_estimations (l, start_i, stop_i)
-- Argument fixing and Error Checking
assert(type(l) == 'table')
local start_i, stop_i = start_i or 1, stop_i or #l
assert(type(start_i) == 'number')
assert(type(stop_i) == 'number')
-- Find maximums
local max = {}
for i = start_i, stop_i do
if type(l[i]) == 'table' and l[i][1] == 'align' then
max[ l[i][2] ] = math.max( l[i][3], max[ l[i][2] ] or 0 )
end
end
-- Insert the proper whitespace
for i = start_i, stop_i do
if type(l[i]) == 'table' and l[i][1] == 'align' then
l[i].est_width = max[ l[i][2] ] - l[i][3]
end
end
end
local function fix_alignment (l, start_i, stop_i)
-- Argument fixing and Error Checking
assert(type(l) == 'table')
local start_i, stop_i = start_i or 1, stop_i or #l
assert(type(start_i) == 'number')
assert(type(stop_i) == 'number')
-- Find whitespace to insert
insert_alignment_estimations(l, start_i, stop_i)
-- Insert whitespace
for i = start_i, stop_i do
if type(l[i]) == 'table' and l[i][1] == 'align' then
l[i] = string.rep(' ', l[i].est_width)
end
end
end
local function attempt_to_align_into_columns (l, start_i, stop_i, nr_items_pr_row)
assert(type(l) == 'table')
assert(type(start_i) == 'number')
assert(type(stop_i) == 'number')
assert(type(nr_items_pr_row) == 'number')
local column = {}
---
local start_of_item_i, item_nr = nil, 0
for i = start_i, stop_i do
if type(l[i]) == 'table' and (l[i][1] == 'indent' or l[i][1] == 'seperator' or l[i][1] == 'unindent') then
if start_of_item_i then
local width_of_item = width_of_strings_in_l(l, start_of_item_i, i-1)
local column_i = (item_nr-1)%nr_items_pr_row+1
column[column_i] = math.max(column[column_i] or 0, width_of_item)
end
start_of_item_i, item_nr = i + 1, item_nr + 1
end
end
---
local width = nr_items_pr_row * 2 - 1 -- FIXME: Magic numbers: 2 = #', ', 1 = #' '
for i = 1, #column do width = width + column[i] end
--
return width, column
end
local function align_into_columns (l, start_i, stop_i)
-- Argument fixing and Error Checking
assert(type(l) == 'table')
local start_i, stop_i = start_i or 1, stop_i or #l
assert(type(start_i) == 'number')
assert(type(stop_i) == 'number')
insert_alignment_estimations(l, start_i, stop_i)
-- Find columns
local columns = nil
for nr_items_pr_row = 10, 1, -1 do -- TODO: Do this more intelligently.
local column_width
column_width, columns = attempt_to_align_into_columns(l, start_i, stop_i, nr_items_pr_row)
if column_width <= l.options.max_width_for_single_line_table then break end
end
-- Change alignment of columns
local start_of_item_i, item_nr = nil, 0
for i = start_i, stop_i do
if type(l[i]) == 'table' and l[i][1] == 'align' then
local column_i = (item_nr-1)%#columns+1
l[i][2] = l[i][2] .. '_column_'..column_i
elseif (l[i][1] == 'indent' or l[i][1] == 'seperator' or l[i][1] == 'unindent') then
start_of_item_i, item_nr = i + 1, item_nr + 1
end
end
-- Fix newly changed alignment
fix_alignment(l, start_i, stop_i)
-- Quick-exit on only a single column
if #columns == 1 then return end
-- Fit into columns.
local start_of_item_i, item_nr = nil, 0
for i = start_i, stop_i do
if type(l[i]) ~= 'table' then
-- Do nothing
elseif (l[i][1] == 'indent' or l[i][1] == 'seperator' or l[i][1] == 'unindent') then
if start_of_item_i and l[i][1] == 'seperator' then
local column_i = (item_nr-1)%#columns+1
if column_i ~= #columns then
local width_of_item = width_of_strings_in_l(l, start_of_item_i, i-1)
l[i] = l[i][2] .. (' '):rep(COLUMN_SEPERATION+columns[column_i]-width_of_item)
end
end
start_of_item_i, item_nr = i + 1, item_nr + 1
end
end
end
local function align_into_tabular_style (l, start_i, stop_i)
-- Adds alignment after separators, to create nicely aligned tabular-format.
-- Argument fixing and Error Checking
local start_i, stop_i = start_i or 1, stop_i or #l
assert(type(l) == 'table')
assert(type(start_i) == 'number')
assert(type(stop_i) == 'number')
assert(type(l[start_i]) == 'table' and l[start_i][1] == 'indent')
assert(type(l[stop_i]) == 'table' and l[stop_i][1] == 'unindent')
-- Calculate where to insert new alignment.
local indent, key_nr, index_of_last_meta, insert_later = 0, 0, 1, {}
for i = start_i + 1, stop_i - 1 do
if type(l[i]) ~= 'table' then
-- Do nothing
elseif l[i][1] == 'indent' then
indent = indent + 1
if indent == 1 then key_nr = 1 end
index_of_last_meta = i
elseif l[i][1] == 'unindent' then
insert_later[#insert_later+1] = {'align', 'end_subtable_'..key_nr, width_of_strings_in_l(l, index_of_last_meta+1, i), i}
index_of_last_meta, key_nr = i, key_nr + 1
indent = indent - 1
elseif l[i][1] == 'seperator' and indent ~= 0 then
insert_later[#insert_later+1] = {'align', 'key_'..key_nr, width_of_strings_in_l(l, index_of_last_meta+1, i), i+1}
index_of_last_meta, key_nr = i, key_nr + 1
end
end
-- Insert new alignment.
for i = #insert_later, 1, -1 do
local dat = insert_later[i]
table.insert(l, dat[#dat], dat)
dat[#dat] = nil
end
-- Fix that alignemnt
return fix_alignment(l, start_i)
end
local function fix_seperator_info (l, indent_char)
-- Error Checking
assert(type(l) == 'table')
assert(type(indent_char) == 'string')
-- Do stuff
local display, inline_depth = 0, nil
for i = 1, #l do
if type(l[i]) ~= 'table' then
-- Do nothing
elseif l[i][1] == 'seperator' then
assert(l[i][2] == nil or type(l[i][2]) == 'string')
l[i] = (l[i][2] or '') .. (inline_depth and ' ' or ('\n' .. indent_char:rep(display)))
elseif l[i][1] == 'indent' then
display, inline_depth = display + 1, inline_depth or l[i][3] == 'inline' and display + 1 or nil
l[i] = l[i][2] .. (inline_depth and ' ' or ('\n' .. indent_char:rep(display)))
elseif l[i][1] == 'unindent' then
l[i] = (inline_depth and ' ' or ('\n' .. indent_char:rep(display-1))) .. l[i][2]
display, inline_depth = display - 1, (display ~= inline_depth) and inline_depth or nil
end
end
end
--------------------------------------------------------------------------------
local analyze_structure = import 'analyze_structure'
local TABLE_TYPE = import 'common' . TABLE_TYPE
local DISPLAY = import 'common' . DISPLAY
--------------------------------------------------------------------------------
-- Key-value pair formatting.
local function format_key_and_value_string_map (key, value, display, l, format_value)
l[#l+1] = key
l[#l+1] = { 'align', 'key', length_of_utf8_string(key) }
l[#l+1] = ' = '
return format_value(value, display, l)
end
local function format_key_and_value_arbitr_map (key, value, display, l, format_value)
local index_before_key = #l+1
l[#l+1] = '['
format_value(key, DISPLAY.HIDE, l)
l[#l+1] = ']'
l[#l+1] = { 'align', 'key', width_of_strings_in_l(l, index_before_key) }
l[#l+1] = ' = '
return format_value(value, display, l)
end
local function format_key_and_value_sequence (key, value, display, l, format_value)
return format_value(value, display, 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,
}
-------------------------------------------------------------------------------
-- Table formatting
local function format_table (t, display, l, format_value)
-- Error Checking
assert(type(t) == 'table')
assert(type(display) == 'number' and type(l) == 'table')
-- Find table info
if not l.info[t] then analyze_structure(t, display, l.info) end
local table_info = l.info[t]
assert(table_info)
-- If empty or not a lot of space, give a small represetation: `{...}`
if table_info.type == TABLE_TYPE.EMPTY or display <= DISPLAY.SMALL then
l '{'
if l.options._table_addr_comment then l[#l+1] = ' --[[' .. table_info.address .. ']] ' end
if table_info.type ~= TABLE_TYPE.EMPTY then l[#l+1] = '...' end
return l '}'
end
-- Get key-value pairs, and possibly fill holes.
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
-- Find pair formatting function
local pair_format_func = TABLE_TYPE_TO_PAIR_FORMAT[table_info.type]
local start_of_table_i = #l + 1
assert(pair_format_func)
-- Begin formatting table.
local next_display = display - 1
if (l.info[t].value_types.nr_types >= 2) then next_display = DISPLAY.SMALL end
l[#l+1] = {'indent', '{'}
if l.options._table_addr_comment then l[#l+1], l[#l+2] = '--[['..table_info.address..']]', {'seperator'} end
for _, pair in ipairs(key_value_pairs) do
pair_format_func(pair[1], pair[2], next_display, l, format_value)
l[#l+1] = {'seperator', ','}
end
if l[#l][1] == 'seperator' then l[#l] = nil end
l[#l+1] = {'unindent', '}'}
-- Decide for short or long table formatting.
local table_width = width_of_strings_in_l(l, start_of_table_i)
if table_width <= l.options.max_width_for_single_line_table then
-- Is short table: Ignore "width of key".
l[start_of_table_i][3] = 'inline'
ignore_alignment_info(l, start_of_table_i)
elseif table_info.is_leaf_node then
-- Is leaf node: Can format into columns.
-- Only if long or sequence.
-- NOTE: Currently we only allow leaf-nodes to format into columns, due
-- to issues with table alignment.
align_into_columns(l, start_of_table_i)
elseif table_info.is_tabular then
align_into_tabular_style(l, start_of_table_i, #l)
else
-- Is long table: Fix whitespace alignment
fix_alignment(l, start_of_table_i)
end
end
-------------------------------------------------------------------------------
-- Coroutine formatting
local function format_coroutine (value, _, l)
-- Formats a coroutine. Unfortunantly we cannot gather a lot of information
-- about coroutines.
-- Error check
assert(type(value) == 'thread')
assert(type(l) == 'table')
-- Do stuff
l[#l+1] = coroutine.status(value)
l[#l+1] = ' coroutine: '
l[#l+1] = tostring(value):sub(9)
end
-------------------------------------------------------------------------------
-- Primitive formatting
local function format_primitive (value, _, l)
-- Error check
assert(type(l) == 'table')
-- Do stuff
l[#l+1] = tostring(value)
end
local TYPE_TO_FORMAT_FUNC = {
['nil'] = format_primitive,
['boolean'] = format_primitive,
['number'] = import 'number',
['string'] = import 'pstring',
['thread'] = format_coroutine,
['table'] = format_table,
['function'] = import 'function',
-- TODO
['userdata'] = format_primitive,
['cdata'] = import 'cdata', -- Luajit exclusive ?
}
local function format_value (value, display, l)
assert(type(display) == 'number' and type(l) == 'table')
local formatting = TYPE_TO_FORMAT_FUNC[type(value)]
if formatting then
formatting(value, display, l, format_value)
else
error(ERROR_UNKNOWN_TYPE:format(type(value), tostring(value)), 2)
end
end
--------------------------------------------------------------------------------
-- StringBuilder
local StringBuilder = {}
StringBuilder.__index = StringBuilder
StringBuilder.__call = function (l, s) l[#l+1] = s end
setmetatable(StringBuilder, {
__call = function() return setmetatable({}, StringBuilder) end
})
--------------------------------------------------------------------------------
local DEBUG_OPTION_USED = { }
local KNOWN_OPTIONS = {
_table_addr_comment = { type = 'boolean', default = false, debug = 'debug' }, -- TODO: Maybe automatically display table address when display = 0?
indent = { type = 'string', default = ' ' },
max_output_width = { type = 'number', default = TERMINAL_WIDTH }
}
local function ensure_that_all_options_are_known (input_options)
-- Goes through all the given options, throws error if one is unknown, gives
-- warning if debug or experimental. Creates a clone of the given table, to
-- avoid defaults leaking.
-- Error check that options were table
assert(type(input_options) == 'table')
-- Error check options
for option_name, option_value in pairs(input_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].type 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].type), 2)
elseif KNOWN_OPTIONS[option_name].accepted and not KNOWN_OPTIONS[option_name].accepted[option_value] then
error(('[pretty]: Bad value given to option %s: %s (%s).'):format(option_name, option_value, type(option_value)), 2)
elseif KNOWN_OPTIONS[option_name].debug and not DEBUG_OPTION_USED[option_name] then
DEBUG_OPTION_USED[option_name] = true
print(('[pretty]: Using %s option "%s".\n Please note that this option may change at any time. It is not stable,\n not tested, and may indeed break or be removed without warning.'):format(KNOWN_OPTIONS[option_name].debug, option_name))
end
end
-- Create output options
local output_options = {}
-- Assign default values
for option_name, option_info in pairs(KNOWN_OPTIONS) do
if input_options[option_name] ~= nil then
output_options[option_name] = input_options[option_name]
else
output_options[option_name] = option_info.default
end
end
-- Calculate derived settings
output_options.max_width_for_single_line_table = MAX_WIDTH_FOR_SINGLE_LINE_TABLE -- TODO: Make dynamic
-- Returns input_options
return output_options
end
local function length_of_longest_line_in_text (text)
assert(type(text) == 'string')
local longest_line_len = text:match '([^\n]*)$' : len()
for line in text:gmatch '(.-)\n' do
longest_line_len = math.max(longest_line_len, line:len())
end
return longest_line_len
end
local function internal_warning (fmt, ...)
io.stderr:write('[pretty/internal]: '..string.format(fmt, ...))
end
local function assert_pretty_result (repr, options)
assert(type(repr) == 'string')
assert(type(options) == 'table')
-- Determine length of longest line in output
local max_width = length_of_longest_line_in_text(repr)
if max_width > options.max_output_width then
internal_warning('Internal assertion failed. Width of output was %i, but should be less than %i.', max_width, options.max_output_width)
end
end
local function pretty_format (value, options)
-- Error checking
local options = ensure_that_all_options_are_known(options or {})
-- Setup StringBuilder
local l = StringBuilder()
l.options = options
l.info = analyze_structure(value, 3)
-- Format value.
format_value(value, DISPLAY.EXPAND, l)
-- If any alignment info still exists, ignore it
fix_seperator_info(l, l.options.indent)
ignore_alignment_info(l)
-- Concat and perform last assertions.
local repr = table.concat(l, '')
assert_pretty_result(repr, options)
-- Return
return repr
end
return pretty_format
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