/usr/share/lua/5.1/luacheck/linearize.lua is in lua-check 0.21.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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local utils = require "luacheck.utils"
local pseudo_labels = utils.array_to_set({"do", "else", "break", "end", "return"})
-- Who needs classes anyway.
local function new_line(node, parent, value)
return {
accessed_upvalues = {}, -- Maps variables to arrays of accessing items.
mutated_upvalues = {}, -- Maps variables to arrays of mutating items.
set_upvalues = {}, -- Maps variables to arays of setting items.
lines = {},
node = node,
parent = parent,
value = value,
items = utils.Stack()
}
end
local function new_scope(line)
return {
vars = {},
labels = {},
gotos = {},
line = line
}
end
local function new_var(line, node, type_)
return {
name = node[1],
location = node.location,
type = type_,
self = node.implicit,
line = line,
scope_start = line.items.size + 1,
values = {}
}
end
local function new_value(var_node, value_node, item, is_init)
local value = {
var = var_node.var,
location = var_node.location,
type = is_init and var_node.var.type or "var",
initial = is_init,
node = value_node,
using_lines = {},
empty = is_init and not value_node and (var_node.var.type == "var"),
item = item
}
if value_node and value_node.tag == "Function" then
value.type = "func"
value_node.value = value
end
return value
end
local function new_label(line, name, location, end_column)
return {
name = name,
location = location,
end_column = end_column,
index = line.items.size + 1
}
end
local function new_goto(name, jump, location)
return {
name = name,
jump = jump,
location = location
}
end
local function new_jump_item(is_conditional)
return {
tag = is_conditional and "Cjump" or "Jump"
}
end
local function new_eval_item(expr)
return {
tag = "Eval",
expr = expr,
location = expr.location,
token = expr.first_token,
accesses = {},
used_values = {},
lines = {}
}
end
local function new_noop_item(node, loop_end)
return {
tag = "Noop",
location = node.location,
token = node.first_token,
loop_end = loop_end
}
end
local function new_local_item(lhs, rhs, location, token)
return {
tag = "Local",
lhs = lhs,
rhs = rhs,
location = location,
token = token,
accesses = rhs and {},
used_values = rhs and {},
lines = rhs and {}
}
end
local function new_set_item(lhs, rhs, location, token)
return {
tag = "Set",
lhs = lhs,
rhs = rhs,
location = location,
token = token,
accesses = {},
mutations = {},
used_values = {},
lines = {}
}
end
local function is_unpacking(node)
return node.tag == "Dots" or node.tag == "Call" or node.tag == "Invoke"
end
local LinState = utils.class()
function LinState:__init(chstate)
self.chstate = chstate
self.lines = utils.Stack()
self.scopes = utils.Stack()
end
function LinState:enter_scope()
self.scopes:push(new_scope(self.lines.top))
end
function LinState:leave_scope()
local left_scope = self.scopes:pop()
local prev_scope = self.scopes.top
for _, goto_ in ipairs(left_scope.gotos) do
local label = left_scope.labels[goto_.name]
if label then
goto_.jump.to = label.index
label.used = true
else
if not prev_scope or prev_scope.line ~= self.lines.top then
if goto_.name == "break" then
parser.syntax_error(
goto_.location, goto_.location.column + 4, "'break' is not inside a loop")
else
parser.syntax_error(
goto_.location, goto_.location.column + 3, ("no visible label '%s'"):format(goto_.name))
end
end
table.insert(prev_scope.gotos, goto_)
end
end
for name, label in pairs(left_scope.labels) do
if not label.used and not pseudo_labels[name] then
self.chstate:warn_unused_label(label)
end
end
for _, var in pairs(left_scope.vars) do
var.scope_end = self.lines.top.items.size
end
end
function LinState:register_var(node, type_)
local var = new_var(self.lines.top, node, type_)
local prev_var = self:resolve_var(var.name)
if prev_var then
local same_scope = self.scopes.top.vars[var.name]
self.chstate:warn_redefined(var, prev_var, same_scope)
if same_scope then
prev_var.scope_end = self.lines.top.items.size
end
end
self.scopes.top.vars[var.name] = var
node.var = var
return var
end
function LinState:register_vars(nodes, type_)
for _, node in ipairs(nodes) do
self:register_var(node, type_)
end
end
function LinState:resolve_var(name)
for _, scope in utils.ripairs(self.scopes) do
local var = scope.vars[name]
if var then
return var
end
end
end
function LinState:check_var(node)
if not node.var then
node.var = self:resolve_var(node[1])
end
return node.var
end
function LinState:register_label(name, location, end_column)
if self.scopes.top.labels[name] then
assert(not pseudo_labels[name])
parser.syntax_error(location, end_column, ("label '%s' already defined on line %d"):format(
name, self.scopes.top.labels[name].location.line))
end
self.scopes.top.labels[name] = new_label(self.lines.top, name, location, end_column)
end
-- `node` is assignment node (`Local or `Set).
function LinState:check_balance(node)
if node[2] then
if #node[1] < #node[2] then
self.chstate:warn_unbalanced(node.equals_location, true)
elseif (#node[1] > #node[2]) and node.tag ~= "Local" and not is_unpacking(node[2][#node[2]]) then
self.chstate:warn_unbalanced(node.equals_location)
end
end
end
function LinState:check_empty_block(block)
if #block == 0 then
self.chstate:warn_empty_block(block.location, block.tag == "Do")
end
end
function LinState:emit(item)
self.lines.top.items:push(item)
end
function LinState:emit_goto(name, is_conditional, location)
local jump = new_jump_item(is_conditional)
self:emit(jump)
table.insert(self.scopes.top.gotos, new_goto(name, jump, location))
end
local tag_to_boolean = {
Nil = false, False = false,
True = true, Number = true, String = true, Table = true, Function = true
}
-- Emits goto that jumps to ::name:: if bool(cond_node) == false.
function LinState:emit_cond_goto(name, cond_node)
local cond_bool = tag_to_boolean[cond_node.tag]
if cond_bool ~= true then
self:emit_goto(name, cond_bool ~= false)
end
end
function LinState:emit_noop(node, loop_end)
self:emit(new_noop_item(node, loop_end))
end
function LinState:emit_stmt(stmt)
self["emit_stmt_" .. stmt.tag](self, stmt)
end
function LinState:emit_stmts(stmts)
for _, stmt in ipairs(stmts) do
self:emit_stmt(stmt)
end
end
function LinState:emit_block(block)
self:enter_scope()
self:emit_stmts(block)
self:leave_scope()
end
function LinState:emit_stmt_Do(node)
self:check_empty_block(node)
self:emit_noop(node)
self:emit_block(node)
end
function LinState:emit_stmt_While(node)
self:emit_noop(node)
self:enter_scope()
self:register_label("do")
self:emit_expr(node[1])
self:emit_cond_goto("break", node[1])
self:emit_block(node[2])
self:emit_noop(node, true)
self:emit_goto("do")
self:register_label("break")
self:leave_scope()
end
function LinState:emit_stmt_Repeat(node)
self:emit_noop(node)
self:enter_scope()
self:register_label("do")
self:enter_scope()
self:emit_stmts(node[1])
self:emit_expr(node[2])
self:leave_scope()
self:emit_cond_goto("do", node[2])
self:register_label("break")
self:leave_scope()
end
function LinState:emit_stmt_Fornum(node)
self:emit_noop(node)
self:emit_expr(node[2])
self:emit_expr(node[3])
if node[5] then
self:emit_expr(node[4])
end
self:enter_scope()
self:register_label("do")
self:emit_goto("break", true)
self:enter_scope()
self:emit(new_local_item({node[1]}))
self:register_var(node[1], "loopi")
self:emit_stmts(node[5] or node[4])
self:leave_scope()
self:emit_noop(node, true)
self:emit_goto("do")
self:register_label("break")
self:leave_scope()
end
function LinState:emit_stmt_Forin(node)
self:emit_noop(node)
self:emit_exprs(node[2])
self:enter_scope()
self:register_label("do")
self:emit_goto("break", true)
self:enter_scope()
self:emit(new_local_item(node[1]))
self:register_vars(node[1], "loop")
self:emit_stmts(node[3])
self:leave_scope()
self:emit_noop(node, true)
self:emit_goto("do")
self:register_label("break")
self:leave_scope()
end
function LinState:emit_stmt_If(node)
self:emit_noop(node)
self:enter_scope()
for i = 1, #node - 1, 2 do
self:enter_scope()
self:emit_expr(node[i])
self:emit_cond_goto("else", node[i])
self:check_empty_block(node[i + 1])
self:emit_block(node[i + 1])
self:emit_goto("end")
self:register_label("else")
self:leave_scope()
end
if #node % 2 == 1 then
self:check_empty_block(node[#node])
self:emit_block(node[#node])
end
self:register_label("end")
self:leave_scope()
end
function LinState:emit_stmt_Label(node)
self:register_label(node[1], node.location, node.end_column)
end
function LinState:emit_stmt_Goto(node)
self:emit_noop(node)
self:emit_goto(node[1], false, node.location)
end
function LinState:emit_stmt_Break(node)
self:emit_goto("break", false, node.location)
end
function LinState:emit_stmt_Return(node)
self:emit_noop(node)
self:emit_exprs(node)
self:emit_goto("return")
end
function LinState:emit_expr(node)
local item = new_eval_item(node)
self:scan_expr(item, node)
self:emit(item)
end
function LinState:emit_exprs(exprs)
for _, expr in ipairs(exprs) do
self:emit_expr(expr)
end
end
LinState.emit_stmt_Call = LinState.emit_expr
LinState.emit_stmt_Invoke = LinState.emit_expr
function LinState:emit_stmt_Local(node)
self:check_balance(node)
local item = new_local_item(node[1], node[2], node.location, node.first_token)
self:emit(item)
if node[2] then
self:scan_exprs(item, node[2])
end
self:register_vars(node[1], "var")
end
function LinState:emit_stmt_Localrec(node)
local item = new_local_item({node[1]}, {node[2]}, node.location, node.first_token)
self:register_var(node[1], "var")
self:emit(item)
self:scan_expr(item, node[2])
end
function LinState:emit_stmt_Set(node)
self:check_balance(node)
local item = new_set_item(node[1], node[2], node.location, node.first_token)
self:scan_exprs(item, node[2])
for _, expr in ipairs(node[1]) do
if expr.tag == "Id" then
local var = self:check_var(expr)
if var then
self:register_upvalue_action(item, var, "set_upvalues")
end
else
assert(expr.tag == "Index")
self:scan_lhs_index(item, expr)
end
end
self:emit(item)
end
function LinState:scan_expr(item, node)
local scanner = self["scan_expr_" .. node.tag]
if scanner then
scanner(self, item, node)
end
end
function LinState:scan_exprs(item, nodes)
for _, node in ipairs(nodes) do
self:scan_expr(item, node)
end
end
function LinState:register_upvalue_action(item, var, key)
for _, line in utils.ripairs(self.lines) do
if line == var.line then
break
end
if not line[key][var] then
line[key][var] = {}
end
table.insert(line[key][var], item)
end
end
function LinState:mark_access(item, node)
node.var.accessed = true
if not item.accesses[node.var] then
item.accesses[node.var] = {}
end
table.insert(item.accesses[node.var], node)
self:register_upvalue_action(item, node.var, "accessed_upvalues")
end
function LinState:mark_mutation(item, node)
node.var.mutated = true
if not item.mutations[node.var] then
item.mutations[node.var] = {}
end
table.insert(item.mutations[node.var], node)
self:register_upvalue_action(item, node.var, "mutated_upvalues")
end
function LinState:scan_expr_Id(item, node)
if self:check_var(node) then
self:mark_access(item, node)
end
end
function LinState:scan_expr_Dots(item, node)
local dots = self:check_var(node)
if not dots or dots.line ~= self.lines.top then
parser.syntax_error(node.location, node.location.column + 2, "cannot use '...' outside a vararg function")
end
self:mark_access(item, node)
end
function LinState:scan_lhs_index(item, node)
if node[1].tag == "Id" then
if self:check_var(node[1]) then
self:mark_mutation(item, node[1])
end
elseif node[1].tag == "Index" then
self:scan_lhs_index(item, node[1])
else
self:scan_expr(item, node[1])
end
self:scan_expr(item, node[2])
end
LinState.scan_expr_Index = LinState.scan_exprs
LinState.scan_expr_Call = LinState.scan_exprs
LinState.scan_expr_Invoke = LinState.scan_exprs
LinState.scan_expr_Paren = LinState.scan_exprs
local function node_to_lua_value(node)
if node.tag == "True" then
return true, "true"
elseif node.tag == "False" then
return false, "false"
elseif node.tag == "String" then
return node[1], node[1]
elseif node.tag == "Number" then
local str = node[1]
if str:find("[iIuUlL]") then
-- Ignore LuaJIT cdata literals.
return
end
-- On Lua 5.3 convert to float to get same results as on Lua 5.1 and 5.2.
if _VERSION == "Lua 5.3" and not str:find("[%.eEpP]") then
str = str .. ".0"
end
local number = tonumber(str)
if number and number == number and number < 1/0 and number > -1/0 then
return number, node[1]
end
end
end
function LinState:scan_expr_Table(item, node)
local array_index = 1.0
local key_to_node = {}
for _, pair in ipairs(node) do
local key, field
if pair.tag == "Pair" then
key, field = node_to_lua_value(pair[1])
self:scan_exprs(item, pair)
else
key = array_index
field = tostring(math.floor(key))
array_index = array_index + 1.0
self:scan_expr(item, pair)
end
if field then
if key_to_node[key] then
self.chstate:warn_unused_field_value(key_to_node[key], pair)
end
key_to_node[key] = pair
pair.field = field
pair.is_index = pair.tag ~= "Pair" or nil
end
end
end
function LinState:scan_expr_Op(item, node)
self:scan_expr(item, node[2])
if node[3] then
self:scan_expr(item, node[3])
end
end
-- Puts tables {var = value{} into field `set_variables` of items in line which set values.
-- Registers set values in field `values` of variables.
function LinState:register_set_variables()
local line = self.lines.top
for _, item in ipairs(line.items) do
if item.tag == "Local" or item.tag == "Set" then
item.set_variables = {}
local is_init = item.tag == "Local"
local unpacking_item -- Rightmost item of rhs which may unpack into several lhs items.
if item.rhs then
local last_rhs_item = item.rhs[#item.rhs]
if is_unpacking(last_rhs_item) then
unpacking_item = last_rhs_item
end
end
local secondaries -- Array of values unpacked from rightmost rhs item.
if unpacking_item and (#item.lhs > #item.rhs) then
secondaries = {}
end
for i, node in ipairs(item.lhs) do
local value
if node.var then
value = new_value(node, item.rhs and item.rhs[i] or unpacking_item, item, is_init)
item.set_variables[node.var] = value
table.insert(node.var.values, value)
end
if secondaries and (i >= #item.rhs) then
if value then
value.secondaries = secondaries
table.insert(secondaries, value)
else
-- If one of secondary values is assigned to a global or index,
-- it is considered used.
secondaries.used = true
end
end
end
end
end
end
function LinState:build_line(node)
self.lines:push(new_line(node, self.lines.top))
self:enter_scope()
self:emit(new_local_item(node[1]))
self:enter_scope()
self:register_vars(node[1], "arg")
self:emit_stmts(node[2])
self:leave_scope()
self:register_label("return")
self:leave_scope()
self:register_set_variables()
local line = self.lines:pop()
for _, prev_line in ipairs(self.lines) do
table.insert(prev_line.lines, line)
end
return line
end
function LinState:scan_expr_Function(item, node)
local line = self:build_line(node)
table.insert(item.lines, line)
for _, nested_line in ipairs(line.lines) do
table.insert(item.lines, nested_line)
end
end
-- Builds linear representation of AST and returns it.
-- Emits warnings: global, redefined/shadowed, unused field, unused label, unbalanced assignment, empty block.
local function linearize(chstate, ast)
local linstate = LinState(chstate)
local line = linstate:build_line({{{tag = "Dots", "..."}}, ast})
assert(linstate.lines.size == 0)
assert(linstate.scopes.size == 0)
return line
end
return linearize
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