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pretty/function.lua

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--[=[ The function formatting module for pretty.
How is one supposed to pretty print functions? Well, there are many different
formats, and no "best" one, only "best for the purpose". Lets first look at how
you could display the most raw data about a function.
1. The default Lua format: "function: 0x41f71c60"
This is the default, and by far the easiest. Also, very uninformative. We
only get a unique id for the function.
2. Include the arguments: "function (t, str) ... end"
This is slightly more advanced, as it requires using the debug library to
discover the names of the arguments. In addition it adds a pseudo-correct
formatting for the function. Now we know the arguments, and if they possess
descriptive names, we can learn a lot about the function.
3. Include some documentation: "function (x) --[[math.cosh: Returns the hyperbolic cosine of x.]] ... end"
We retain the arguments and pseudo-correct formatting from above, and add
documentation taken from elsewhere (for example the Lua Reference Manual, or
LuaJIT webpage), as comments. This is great for explorative programming, as
we can read about the language from within the language.
4. Short names: "math.min"
Rather than giving an overly descriptive overview of some inbuilt, we assume
that we can find it by its standard name. With this one we gain complete
native representation, assuming the standard enviroment, of course. It won't
work at all with custom functions.
5. Include source code: "function (a, b) return (a + b)/2 end"
Now we find the source code somehow, and use it as the representation. This
is powerful because we can directly inspect the code. It won't work with
builtins, closured functions, or when fucking around with the source files.
6. Include closures: "(function () local i = 5; return function () i = i + 1; return i end end)()"
In cases where a function has a closure, we can use debug.getinfo to get
the names and values of the upvalues. We can then represent the closure, by
creating the closure itself. Iterators like the example above works nicely,
but more complex chains of closures break down. For example:
local val_a = 1
local func_a = function () val_a = val_a + 1; return val_a end
local val_a = val_a
local func_c = function () return func_a() + val_a end
Here we have two functions, both with their own upvalue, both named "val_a",
yet those names refer to two different "slots". Successive calls to
`func_c` should produce the list: 2, 3, 4, 5, 6, 7, ...
To break through this barrier, we need to parse the Lua AST, and that is
beyond this project.
--]=]
-- Import
local LIBRARY
do
local thispath = ... and select('1', ...):match('.+%.') or ''
local was_loaded, library = pcall(require, thispath..'library')
LIBRARY = was_loaded and library or {}
end
-- Constants
--------------------------------------------------------------------------------
-- Util
local function get_function_info (f)
-- NOTE: Works best in LuaJIT or Lua 5.2+
-- Regarding get-info:
-- * No need to includ 'f'. Function is already known
-- * No need to include 'L' (active lines) option. Ignored
-- * No need to include 'n' (name and namewhat). Won't work.
assert(type(f) == 'function')
local info = debug.getinfo(f, 'Su')
info.params = {}
info.ups = {}
info.env = debug.getfenv and debug.getfenv(f)
info.builtin = (info.source == '=[C]')
for i = 1, info.nparams or 0 do info.params[i] = debug.getlocal(f, i) end
if info.isvararg or not info.nparams then info.params[#info.params+1] = '...' end
-- Get upvalues
for i = 1, info.nups do
local k, v = debug.getupvalue(f, i)
if k == '_ENV' and not debug.getfenv then
info.env = v
else
info.ups[k] = v
end
end
if info.source:sub(1,1) == '=' then info.defined_how = 'C'
elseif info.source:sub(1,1) == '@' then info.defined_how = 'file'
elseif info.source:find'^%w+.lua$' then info.defined_how = 'file' -- Hotfix for Love2d boot.lua issue.
else info.defined_how = 'string'
end
if info.builtin and LIBRARY[f] then
info.name = LIBRARY[f].name
info.params[1] = LIBRARY[f].para
info.doc = LIBRARY[f].docs
end
return info
end
local function get_line_index (str, line_nr)
assert(type(str) == 'string')
assert(type(line_nr) == 'number')
local index = 0
for _ = 2, line_nr do
index = str:find('\n', index, true)
if not index then return #str end
index = index + 1
end
return index
end
local function get_function_paramlist_and_body (str, start_line, end_line)
-- Will attempt to find a string which refer to a function starting on
-- line `start_line` and ending on line `end_line`.
assert(type(str) == 'string')
assert(type(start_line) == 'number')
assert(type(end_line) == 'number')
local start_line_index = get_line_index(str, start_line)
local end_line_index = get_line_index(str, end_line + 1)
local function_params, function_body = str:sub(start_line_index, end_line_index):match('function%s*[a-zA-Z0-9_.]*%s*(%([a-zA-Z0-9_,. \t]*%))[ \t]*(.-)[ \t]*end')
--print(function_params, function_body)
assert(type(function_params) == 'string' and type(function_body) == 'string')
return function_params, function_body
end
local function get_full_function_str (...)
local function_params, function_body = get_function_paramlist_and_body(...)
return 'function '..function_params..' '..function_body..' end'
end
local function get_function_str_from_file (filename, start_line, end_line)
assert(type(filename) == 'string')
assert(type(start_line) == 'number')
assert(type(end_line) == 'number')
local file = io.open(filename, 'r')
local str = file:read('*all')
file:close()
return get_full_function_str(str, start_line, end_line)
end
local function width_of_strings_in_l (l, start_i, end_i)
-- FIXME: Copy of the one in pretty.lua
local width = 0
for i = start_i or 1, (end_i or #l) do
width = width + #l[i]
end
return width
end
local function add_indent_to_string (str, indent)
assert(type(str) == 'string')
assert(type(indent) == 'string')
local l = {}
for line in string.gmatch(str, '\n', true) do
l[#l+1] = indent
l[#l+1] = line
end
return table.concat(l, '\n')
end
--------------------------------------------------------------------------------
local function format_function_with_closure (value, depth, l, format_value)
assert(type(value) == 'function')
assert(type(depth) == 'number' and type(l) == 'table' and type(format_value) == 'function')
local info = get_function_info(value)
local function_str = nil
if (info.defined_how == 'string') then
function_str = get_full_function_str(info.source, info.linedefined, info.lastlinedefined)
else
function_str = get_function_str_from_file(info.short_src, info.linedefined, info.lastlinedefined)
end
if info.nups > 0 then l[#l+1] = '(function () ' end
-- Upvalues
for k, v in pairs(info.ups) do
l[#l+1] = 'local '
l[#l+1] = tostring(k)
l[#l+1] = ' = '
format_value(v, depth + 1, l)
l[#l+1] = '; '
end
-- Return function
if info.nups > 0 then l[#l+1] = 'return ' end
l[#l+1] = function_str
--
if info.nups > 0 then l[#l+1] = ' end)()' end
end
return function (value, depth, l, format_value)
assert(type(value) == 'function')
assert(type(depth) == 'number' and type(l) == 'table' and type(format_value) == 'function')
local info = get_function_info(value)
if l.options.include_closure and not info.builtin then
return format_function_with_closure(value, depth, l, format_value)
end
local function_params, function_body = nil, '...'
if info.defined_how == 'string' and l.options.embed_loaded_funcs then
-- Function was defined as a string.
function_params, function_body = get_function_paramlist_and_body(info.source, info.linedefined, info.lastlinedefined)
end
if info.builtin and l.options.short_builtins then
return l(info.name);
end
-- Include function modifier, and alignment info.
l[#l+1] = info.builtin and 'builtin ' or ''
l[#l+1] = { 'align', 'func_mod', #l[#l]}
-- Build rest of function signature
l[#l+1] = 'function '
local top_before = #l
if function_params then
l[#l+1] = function_params
else
l[#l+1] = '('
for _, param in ipairs(info.params) do l[#l+1], l[#l+2] = param, ', ' end
if l[#l] == ', ' then l[#l] = nil end
l[#l+1] = ')'
end
l[#l+1] = { 'align', 'func_def', width_of_strings_in_l(l, top_before) }
-- Cleanup and finish
if not l.options.more_function_info or depth ~= 0 then
l[#l+1] = (function_body:sub(1,1) == '\n') and '' or ' '
l[#l+1] = function_body
l[#l+1] = { 'align', 'func_end', #function_body }
l[#l+1] = (function_body:sub(-1) == '\n' or function_body == '') and '' or ' '
return l 'end'
end
-- More info! --
local indent = '\n' .. l.options.indent
-- Name
if info.name then
l[#l+1] = indent
l[#l+1] = '-- '
l[#l+1] = info.name
end
-- Doc
if info.doc then
for doc_line in info.doc:gmatch('[^\n]+') do
l[#l+1] = indent
l[#l+1] = '-- '
l[#l+1] = doc_line
end
end
-- source
if not info.builtin then
l[#l+1] = indent
l[#l+1] = ('-- source_file: \'%s\' '):format(info.short_src)
if info.linedefined == info.lastlinedefined then
l[#l+1] = ('[Line: %i]'):format(info.linedefined)
else
l[#l+1] = ('[Lines: %i - %i]'):format(info.linedefined, info.lastlinedefined)
end
end
-- upvalues
if info.nups > 0 and not info.builtin then
l[#l+1] = indent
l[#l+1] = '-- up_values: '
format_value(info.ups, depth + 1, l)
end
if l.options._all_function_info then
-- NOTE: This is for testing/debugging/experimentation purposes, and is
-- not designed to be pretty.
l[#l+1] = indent
l[#l+1] = '--[[ Function Body:\n\t'
l[#l+1] = add_indent_to_string(get_function_str_from_file(info.short_src, info.linedefined, info.lastlinedefined), l.options.indent)
l[#l+1] = indent
l[#l+1] = '--]]'
l[#l+1] = indent
l[#l+1] = '--[[\n\tNative repr:'
l[#l+1] = tostring(value)
l[#l+1] = indent
format_value(info, depth + 1, l)
l[#l+1] = indent
l[#l+1] = '--]]'
end
l[#l+1] = '\n'
l[#l+1] = indent
l[#l+1] = '...\nend'
end
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