266 lines
7.8 KiB
Lua
266 lines
7.8 KiB
Lua
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-- pretty.analyze_structure
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-- The datastructure analyzing module for pretty.
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--------------------------------------------------------------------------------
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local TABLE_TYPE
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do
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local thispath, was_loaded = ... and select('1', ...):match('.+%.') or ''
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was_loaded, TABLE_TYPE = pcall(require, thispath..'table_type')
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assert(was_loaded, '[pretty]: Could not load vital library: table_type')
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end
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local RESERVED_LUA_WORDS = {
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['and'] = true,
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['break'] = true,
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['do'] = true,
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['else'] = true,
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['elseif'] = true,
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['end'] = true,
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['false'] = true,
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['for'] = true,
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['function'] = true,
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['if'] = true,
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['in'] = true,
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['local'] = true,
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['nil'] = true,
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['not'] = true,
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['or'] = true,
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['repeat'] = true,
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['return'] = true,
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['then'] = true,
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['true'] = true,
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['until'] = true,
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['while'] = true,
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['goto'] = true,
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}
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local SIMPLE_VALUE_TYPES = {
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['nil'] = true,
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['boolean'] = true,
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['number'] = true,
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}
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local SHORT_STRING_MAX_LEN = 7
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local MINIMUM_NUMBER_OF_SET_ELEMENTS = 2
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--------------------------------------------------------------------------------
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local function is_identifier(str)
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-- An identier is defined in the lua reference guide
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return str:match('^[_%a][_%w]*$') and not RESERVED_LUA_WORDS[str]
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end
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local function get_key_types (t)
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local types = { nr_types = -1 }
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for key, _ in pairs(t) do
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types[type(key)] = true
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end
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--
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for type_name, _ in pairs(types) do
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types.nr_types = types.nr_types + 1
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end
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return types
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end
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local function get_value_types (t)
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local types = { nr_types = -1 }
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for _, value in pairs(t) do
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types[type(value)] = true
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end
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--
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for type_name, _ in pairs(types) do
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types.nr_types = types.nr_types + 1
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end
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return types
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end
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local function largest_number_index (t)
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-- Returns the largest number index in t.
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local max_index = 0
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for k,v in pairs(t) do
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if type(k) == 'number' then
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max_index = math.max(max_index, k)
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end
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end
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return max_index
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end
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local function nr_elements_in_table (t)
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local k, count = nil, -1
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repeat
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k, count = next(t, k), count + 1
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until k == nil
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return count
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end
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local function nr_elements_in_seq (t)
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assert(type(t) == 'table')
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if getmetatable(t) and getmetatable(t).__index then
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return 0, false -- FIXME: Temporary stopgap for when __index throws an
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-- error. I think we need to clone the numbers part of the table, to
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-- fix this.
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end
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local i, last_elem_i, nr_elems, has_holes = 0, 0, 0, false
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while i <= last_elem_i + 2 do
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i = i + 1
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if t[i] ~= nil then
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last_elem_i, nr_elems = i, nr_elems + 1
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else
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has_holes = true
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end
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end
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return nr_elems, has_holes
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end
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--------------------------------------------------------------------------------
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local function contains_only_nice_string_keys (t)
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-- Predicate: Does t contain only string keys which could be used as
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-- identifiers, eg.
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for k, _ in pairs(t) do
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if type(k) ~= 'string' or not is_identifier(k) then
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return false
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end
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end
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return true
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end
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local function is_set (t)
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-- Predicate: Does t contain only boolean values.
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local value_types = get_value_types(t)
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return value_types.boolean and value_types.nr_types == 1
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end
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local function is_tabular (t)
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-- Predicate: Does t contain sub-tables with identical substructure.
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-- Quick return if table is empty, or not conctaining only values of type table.
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local value_types = get_value_types(t)
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if not value_types.table or value_types.nr_types ~= 1 then
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return false
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end
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-- Determine keys of first child.
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local children_keys = {}
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for key, _ in pairs(t[next(t)]) do
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children_keys[key] = true
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end
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-- Make sure every other child has exact same sub-structure.
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for _, child in pairs(t) do
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for key, _ in pairs(children_keys) do
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if not child[key] then return false end
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end
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for key, _ in pairs(child) do
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if not children_keys[key] then return false end
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end
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end
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return children_keys
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end
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local function has_uniform_structure (t)
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-- TODO: This can probably be more relaxed. Maybe combine string, number and boolean?
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assert(type(t) == 'table')
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-- Find the key and value types.
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local first_key = next(t)
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if first_key == nil then return true end
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local key_type, value_type = type(first_key), type(t[first_key])
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-- Ensure every other key value pair is the same.
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for key, value in pairs(t) do
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if type(key) ~= key_type or type(value) ~= value_type then
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return false
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end
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end
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return true
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end
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--------------------------------------------------------------------------------
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local function get_table_info (t)
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local key_types = get_key_types(t)
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local info = {}
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info.address = tostring(t):sub(8)
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info.nr_elems = nr_elements_in_table(t)
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info.seq_elems, info.has_holes = nr_elements_in_seq(t)
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info.map_elems = info.nr_elems - info.seq_elems
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info.has_seq = info.seq_elems > 0
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info.has_map = info.map_elems > 0
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info.is_set = is_set(t) and info.nr_elems >= MINIMUM_NUMBER_OF_SET_ELEMENTS
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info.is_tabular = is_tabular(t)
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info.is_uniform = has_uniform_structure(t)
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-- Determine type of table
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if not info.has_seq and not info.has_map then info.type = TABLE_TYPE.EMPTY
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elseif info.has_seq and not info.has_map then info.type = TABLE_TYPE.SEQUENCE
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elseif info.is_set then info.type = TABLE_TYPE.SET
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elseif info.has_seq then info.type = TABLE_TYPE.MIXED
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elseif contains_only_nice_string_keys(t) then info.type = TABLE_TYPE.STRING_MAP
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else info.type = TABLE_TYPE.PURE_MAP
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end
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return info
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end
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--------------------------------------------------------------------------------
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local function analyze_structure (root, max_depth, info)
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-- Argument fixing
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local info = info or {}
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local max_depth = max_depth or math.huge
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-- Quick return
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if type(root) ~= 'table' then return info end
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-- Error checking
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assert(type(root) == 'table')
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if type(max_depth) ~= 'number' then error(('[pretty/internal]: Bad argument #2, expected number, got %s (%s)'):format(max_depth, type(max_depth)), 2) end
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info.root = info.root or root
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local visited, next_mark, depth = {}, 1, { [root] = 0 }
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local queue = { root, bottom = 1, top = 2 }
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while queue.bottom < queue.top do
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queue.bottom = queue.bottom + 1
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local node = queue[queue.bottom-1]
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-- Who've been visited? Bookkeeping
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visited[node], info[node] = (visited[node] or 0) + 1, info[node] or get_table_info(node)
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if visited[node] == 2 then
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info[node].marker, next_mark = next_mark, next_mark + 1
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end
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-- Get table info & visit children.
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if visited[node] < 2 and depth[node] < max_depth then
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for k, v in pairs(node) do
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if type(k) == 'table' then queue[queue.top], queue.top, depth[k] = k, queue.top + 1, math.min(depth[k] or math.huge, depth[node] + 1) end
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if type(v) == 'table' then queue[queue.top], queue.top, depth[v] = v, queue.top + 1, math.min(depth[v] or math.huge, depth[node] + 1) end
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end
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end
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end
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-- Use depth collected
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for node in pairs(depth) do
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info[node].depth = depth[node]
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info[node].address = info[node].address .. ': ' .. info[node].depth
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end
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assert(type(info) == 'table')
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return info
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end
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--------------------------------------------------------------------------------
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return analyze_structure
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