/usr/share/lua/5.1/luacheck/parser.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 parser = {}
local function new_state(src)
return {
lexer = lexer.new_state(src),
code_lines = {}, -- Set of line numbers containing code.
line_endings = {}, -- Maps line numbers to "comment", "string", or nil based on whether
-- the line ending is within a token.
comments = {}, -- Array of {comment = string, location = location}.
hanging_semicolons = {} -- Array of locations of semicolons not following a statement.
}
end
local function location(state)
return {
line = state.line,
column = state.column,
offset = state.offset
}
end
parser.SyntaxError = utils.class()
function parser.SyntaxError:__init(loc, end_column, msg)
self.line = loc.line
self.column = loc.column
self.end_column = end_column
self.msg = msg
end
function parser.syntax_error(loc, end_column, msg)
error(parser.SyntaxError(loc, end_column, msg), 0)
end
local function token_body_or_line(state)
return state.lexer.src:sub(state.offset, state.lexer.offset - 1):match("^[^\r\n]*")
end
local function mark_line_endings(state, first_line, last_line, token_type)
for line = first_line, last_line - 1 do
state.line_endings[line] = token_type
end
end
local function skip_token(state)
while true do
local err_end_column
state.token, state.token_value, state.line,
state.column, state.offset, err_end_column = lexer.next_token(state.lexer)
if not state.token then
parser.syntax_error(state, err_end_column, state.token_value)
elseif state.token == "comment" then
state.comments[#state.comments+1] = {
contents = state.token_value,
location = location(state),
end_column = state.column + #token_body_or_line(state) - 1
}
mark_line_endings(state, state.line, state.lexer.line, "comment")
else
if state.token ~= "eof" then
mark_line_endings(state, state.line, state.lexer.line, "string")
state.code_lines[state.line] = true
state.code_lines[state.lexer.line] = true
end
break
end
end
end
local function init_ast_node(node, loc, tag)
node.location = loc
node.tag = tag
return node
end
local function new_ast_node(state, tag)
return init_ast_node({}, location(state), tag)
end
local token_names = {
eof = "<eof>",
name = "identifier",
["do"] = "'do'",
["end"] = "'end'",
["then"] = "'then'",
["in"] = "'in'",
["until"] = "'until'",
["::"] = "'::'"
}
local function token_name(token)
return token_names[token] or lexer.quote(token)
end
local function parse_error(state, msg)
local token_repr, end_column
if state.token == "eof" then
token_repr = "<eof>"
end_column = state.column
else
token_repr = token_body_or_line(state)
end_column = state.column + #token_repr - 1
token_repr = lexer.quote(token_repr)
end
parser.syntax_error(state, end_column, msg .. " near " .. token_repr)
end
local function check_token(state, token)
if state.token ~= token then
parse_error(state, "expected " .. token_name(token))
end
end
local function check_and_skip_token(state, token)
check_token(state, token)
skip_token(state)
end
local function test_and_skip_token(state, token)
if state.token == token then
skip_token(state)
return true
end
end
local function check_closing_token(state, opening_token, closing_token, opening_line)
if state.token ~= closing_token then
local err = "expected " .. token_name(closing_token)
if opening_line ~= state.line then
err = err .. " (to close " .. token_name(opening_token) .. " on line " .. tostring(opening_line) .. ")"
end
parse_error(state, err)
end
skip_token(state)
end
local function check_name(state)
check_token(state, "name")
return state.token_value
end
-- If needed, wraps last expression in expressions in "Paren" node.
local function opt_add_parens(expressions, is_inside_parentheses)
if is_inside_parentheses then
local last = expressions[#expressions]
if last and last.tag == "Call" or last.tag == "Invoke" or last.tag == "Dots" then
expressions[#expressions] = init_ast_node({last}, last.location, "Paren")
end
end
end
local parse_block, parse_expression
local function parse_expression_list(state)
local list = {}
local is_inside_parentheses
repeat
list[#list+1], is_inside_parentheses = parse_expression(state)
until not test_and_skip_token(state, ",")
opt_add_parens(list, is_inside_parentheses)
return list
end
local function parse_id(state, tag)
local ast_node = new_ast_node(state, tag or "Id")
ast_node[1] = check_name(state)
skip_token(state) -- Skip name.
return ast_node
end
local function atom(tag)
return function(state)
local ast_node = new_ast_node(state, tag)
ast_node[1] = state.token_value
skip_token(state)
return ast_node
end
end
local simple_expressions = {}
simple_expressions.number = atom("Number")
simple_expressions.string = atom("String")
simple_expressions["nil"] = atom("Nil")
simple_expressions["true"] = atom("True")
simple_expressions["false"] = atom("False")
simple_expressions["..."] = atom("Dots")
simple_expressions["{"] = function(state)
local ast_node = new_ast_node(state, "Table")
local start_line = state.line
skip_token(state)
local is_inside_parentheses = false
repeat
if state.token == "}" then
break
else
local lhs, rhs
local item_location = location(state)
local first_key_token
if state.token == "name" then
local name = state.token_value
skip_token(state) -- Skip name.
if test_and_skip_token(state, "=") then
-- `name` = `expr`.
first_key_token = name
lhs = init_ast_node({name}, item_location, "String")
rhs, is_inside_parentheses = parse_expression(state)
else
-- `name` is beginning of an expression in array part.
-- Backtrack lexer to before name.
state.lexer.line = item_location.line
state.lexer.line_offset = item_location.offset-item_location.column+1
state.lexer.offset = item_location.offset
skip_token(state) -- Load name again.
rhs, is_inside_parentheses = parse_expression(state, nil, true)
end
elseif state.token == "[" then
-- [ `expr` ] = `expr`.
item_location = location(state)
first_key_token = "["
skip_token(state)
lhs = parse_expression(state)
check_closing_token(state, "[", "]", item_location.line)
check_and_skip_token(state, "=")
rhs = parse_expression(state)
else
-- Expression in array part.
rhs, is_inside_parentheses = parse_expression(state, nil, true)
end
if lhs then
-- Pair.
ast_node[#ast_node+1] = init_ast_node({lhs, rhs, first_token = first_key_token}, item_location, "Pair")
else
-- Array part item.
ast_node[#ast_node+1] = rhs
end
end
until not (test_and_skip_token(state, ",") or test_and_skip_token(state, ";"))
check_closing_token(state, "{", "}", start_line)
opt_add_parens(ast_node, is_inside_parentheses)
return ast_node
end
-- Parses argument list and the statements.
local function parse_function(state, func_location)
local paren_line = state.line
check_and_skip_token(state, "(")
local args = {}
if state.token ~= ")" then -- Are there arguments?
repeat
if state.token == "name" then
args[#args+1] = parse_id(state)
elseif state.token == "..." then
args[#args+1] = simple_expressions["..."](state)
break
else
parse_error(state, "expected argument")
end
until not test_and_skip_token(state, ",")
end
check_closing_token(state, "(", ")", paren_line)
local body = parse_block(state)
local end_location = location(state)
check_closing_token(state, "function", "end", func_location.line)
return init_ast_node({args, body, end_location = end_location}, func_location, "Function")
end
simple_expressions["function"] = function(state)
local function_location = location(state)
skip_token(state) -- Skip "function".
return parse_function(state, function_location)
end
local calls = {}
calls["("] = function(state)
local paren_line = state.line
skip_token(state) -- Skip "(".
local args = (state.token == ")") and {} or parse_expression_list(state)
check_closing_token(state, "(", ")", paren_line)
return args
end
calls["{"] = function(state)
return {simple_expressions[state.token](state)}
end
calls.string = calls["{"]
local suffixes = {}
suffixes["."] = function(state, lhs)
skip_token(state) -- Skip ".".
local rhs = parse_id(state, "String")
return init_ast_node({lhs, rhs}, lhs.location, "Index")
end
suffixes["["] = function(state, lhs)
local bracket_line = state.line
skip_token(state) -- Skip "[".
local rhs = parse_expression(state)
check_closing_token(state, "[", "]", bracket_line)
return init_ast_node({lhs, rhs}, lhs.location, "Index")
end
suffixes[":"] = function(state, lhs)
skip_token(state) -- Skip ":".
local method_name = parse_id(state, "String")
local args = (calls[state.token] or parse_error)(state, "expected method arguments")
table.insert(args, 1, lhs)
table.insert(args, 2, method_name)
return init_ast_node(args, lhs.location, "Invoke")
end
suffixes["("] = function(state, lhs)
local args = calls[state.token](state)
table.insert(args, 1, lhs)
return init_ast_node(args, lhs.location, "Call")
end
suffixes["{"] = suffixes["("]
suffixes.string = suffixes["("]
-- Additionally returns whether the expression is inside parens and the first non-paren token.
local function parse_simple_expression(state, kind, no_literals)
local expression, first_token
local in_parens = false
if state.token == "(" then
in_parens = true
local paren_line = state.line
skip_token(state)
local _
expression, _, first_token = parse_expression(state)
check_closing_token(state, "(", ")", paren_line)
elseif state.token == "name" then
expression = parse_id(state)
first_token = expression[1]
else
local literal_handler = simple_expressions[state.token]
if not literal_handler or no_literals then
parse_error(state, "expected " .. (kind or "expression"))
end
first_token = token_body_or_line(state)
return literal_handler(state), false, first_token
end
while true do
local suffix_handler = suffixes[state.token]
if suffix_handler then
in_parens = false
expression = suffix_handler(state, expression)
else
return expression, in_parens, first_token
end
end
end
local unary_operators = {
["not"] = "not",
["-"] = "unm", -- Not mentioned in Metalua documentation.
["~"] = "bnot",
["#"] = "len"
}
local unary_priority = 12
local binary_operators = {
["+"] = "add", ["-"] = "sub",
["*"] = "mul", ["%"] = "mod",
["^"] = "pow",
["/"] = "div", ["//"] = "idiv",
["&"] = "band", ["|"] = "bor", ["~"] = "bxor",
["<<"] = "shl", [">>"] = "shr",
[".."] = "concat",
["~="] = "ne", ["=="] = "eq",
["<"] = "lt", ["<="] = "le",
[">"] = "gt", [">="] = "ge",
["and"] = "and", ["or"] = "or"
}
local left_priorities = {
add = 10, sub = 10,
mul = 11, mod = 11,
pow = 14,
div = 11, idiv = 11,
band = 6, bor = 4, bxor = 5,
shl = 7, shr = 7,
concat = 9,
ne = 3, eq = 3,
lt = 3, le = 3,
gt = 3, ge = 3,
["and"] = 2, ["or"] = 1
}
local right_priorities = {
add = 10, sub = 10,
mul = 11, mod = 11,
pow = 13,
div = 11, idiv = 11,
band = 6, bor = 4, bxor = 5,
shl = 7, shr = 7,
concat = 8,
ne = 3, eq = 3,
lt = 3, le = 3,
gt = 3, ge = 3,
["and"] = 2, ["or"] = 1
}
-- Additionally returns whether subexpression is inside parentheses, and its first non-paren token.
local function parse_subexpression(state, limit, kind)
local expression
local first_token
local in_parens = false
local unary_operator = unary_operators[state.token]
if unary_operator then
first_token = state.token
local unary_location = location(state)
skip_token(state) -- Skip operator.
local unary_operand = parse_subexpression(state, unary_priority)
expression = init_ast_node({unary_operator, unary_operand}, unary_location, "Op")
else
expression, in_parens, first_token = parse_simple_expression(state, kind)
end
-- Expand while operators have priorities higher than `limit`.
while true do
local binary_operator = binary_operators[state.token]
if not binary_operator or left_priorities[binary_operator] <= limit then
break
end
in_parens = false
skip_token(state) -- Skip operator.
-- Read subexpression with higher priority.
local subexpression = parse_subexpression(state, right_priorities[binary_operator])
expression = init_ast_node({binary_operator, expression, subexpression}, expression.location, "Op")
end
return expression, in_parens, first_token
end
-- Additionally returns whether expression is inside parentheses and the first non-paren token.
function parse_expression(state, kind, save_first_token)
local expression, in_parens, first_token = parse_subexpression(state, 0, kind)
expression.first_token = save_first_token and first_token
return expression, in_parens, first_token
end
local statements = {}
statements["if"] = function(state, loc)
local start_line, start_token
local next_line, next_token = loc.line, "if"
local ast_node = init_ast_node({}, loc, "If")
repeat
ast_node[#ast_node+1] = parse_expression(state, "condition", true)
local branch_location = location(state)
check_and_skip_token(state, "then")
ast_node[#ast_node+1] = parse_block(state, branch_location)
start_line, start_token = next_line, next_token
next_line, next_token = state.line, state.token
until not test_and_skip_token(state, "elseif")
if state.token == "else" then
start_line, start_token = next_line, next_token
local branch_location = location(state)
skip_token(state)
ast_node[#ast_node+1] = parse_block(state, branch_location)
end
check_closing_token(state, start_token, "end", start_line)
return ast_node
end
statements["while"] = function(state, loc)
local condition = parse_expression(state, "condition")
check_and_skip_token(state, "do")
local block = parse_block(state)
check_closing_token(state, "while", "end", loc.line)
return init_ast_node({condition, block}, loc, "While")
end
statements["do"] = function(state, loc)
local ast_node = init_ast_node(parse_block(state), loc, "Do")
check_closing_token(state, "do", "end", loc.line)
return ast_node
end
statements["for"] = function(state, loc)
local ast_node = init_ast_node({}, loc) -- Will set ast_node.tag later.
local first_var = parse_id(state)
if state.token == "=" then
-- Numeric "for" loop.
ast_node.tag = "Fornum"
skip_token(state)
ast_node[1] = first_var
ast_node[2] = parse_expression(state)
check_and_skip_token(state, ",")
ast_node[3] = parse_expression(state)
if test_and_skip_token(state, ",") then
ast_node[4] = parse_expression(state)
end
check_and_skip_token(state, "do")
ast_node[#ast_node+1] = parse_block(state)
elseif state.token == "," or state.token == "in" then
-- Generic "for" loop.
ast_node.tag = "Forin"
local iter_vars = {first_var}
while test_and_skip_token(state, ",") do
iter_vars[#iter_vars+1] = parse_id(state)
end
ast_node[1] = iter_vars
check_and_skip_token(state, "in")
ast_node[2] = parse_expression_list(state)
check_and_skip_token(state, "do")
ast_node[3] = parse_block(state)
else
parse_error(state, "expected '=', ',' or 'in'")
end
check_closing_token(state, "for", "end", loc.line)
return ast_node
end
statements["repeat"] = function(state, loc)
local block = parse_block(state)
check_closing_token(state, "repeat", "until", loc.line)
local condition = parse_expression(state, "condition", true)
return init_ast_node({block, condition}, loc, "Repeat")
end
statements["function"] = function(state, loc)
local lhs_location = location(state)
local lhs = parse_id(state)
local self_location
while (not self_location) and (state.token == "." or state.token == ":") do
self_location = state.token == ":" and location(state)
skip_token(state) -- Skip "." or ":".
lhs = init_ast_node({lhs, parse_id(state, "String")}, lhs_location, "Index")
end
local function_node = parse_function(state, loc)
if self_location then
-- Insert implicit "self" argument.
local self_arg = init_ast_node({"self", implicit = true}, self_location, "Id")
table.insert(function_node[1], 1, self_arg)
end
return init_ast_node({{lhs}, {function_node}}, loc, "Set")
end
statements["local"] = function(state, loc)
if state.token == "function" then
-- Localrec
local function_location = location(state)
skip_token(state) -- Skip "function".
local var = parse_id(state)
local function_node = parse_function(state, function_location)
-- Metalua would return {{var}, {function}} for some reason.
return init_ast_node({var, function_node}, loc, "Localrec")
end
local lhs = {}
local rhs
repeat
lhs[#lhs+1] = parse_id(state)
until not test_and_skip_token(state, ",")
local equals_location = location(state)
if test_and_skip_token(state, "=") then
rhs = parse_expression_list(state)
end
-- According to Metalua spec, {lhs} should be returned if there is no rhs.
-- Metalua does not follow the spec itself and returns {lhs, {}}.
return init_ast_node({lhs, rhs, equals_location = rhs and equals_location}, loc, "Local")
end
statements["::"] = function(state, loc)
local end_column = loc.column + 1
local name = check_name(state)
if state.line == loc.line then
-- Label name on the same line as opening `::`, pull token end to name end.
end_column = state.column + #state.token_value - 1
end
skip_token(state) -- Skip label name.
if state.line == loc.line then
-- Whole label is on one line, pull token end to closing `::` end.
end_column = state.column + 1
end
check_and_skip_token(state, "::")
return init_ast_node({name, end_column = end_column}, loc, "Label")
end
local closing_tokens = utils.array_to_set({
"end", "eof", "else", "elseif", "until"})
statements["return"] = function(state, loc)
if closing_tokens[state.token] or state.token == ";" then
-- No return values.
return init_ast_node({}, loc, "Return")
else
return init_ast_node(parse_expression_list(state), loc, "Return")
end
end
statements["break"] = function(_, loc)
return init_ast_node({}, loc, "Break")
end
statements["goto"] = function(state, loc)
local name = check_name(state)
skip_token(state) -- Skip label name.
return init_ast_node({name}, loc, "Goto")
end
local function parse_expression_statement(state, loc)
local lhs
repeat
local first_loc = lhs and location(state) or loc
local expected = lhs and "identifier or field" or "statement"
local primary_expression, in_parens = parse_simple_expression(state, expected, true)
if in_parens then
-- (expr) is invalid.
parser.syntax_error(first_loc, first_loc.column, "expected " .. expected .. " near '('")
end
if primary_expression.tag == "Call" or primary_expression.tag == "Invoke" then
if lhs then
-- This is an assingment, and a call is not a valid lvalue.
parse_error(state, "expected call or indexing")
else
-- It is a call.
primary_expression.location = loc
return primary_expression
end
end
-- This is an assignment.
lhs = lhs or {}
lhs[#lhs+1] = primary_expression
until not test_and_skip_token(state, ",")
local equals_location = location(state)
check_and_skip_token(state, "=")
local rhs = parse_expression_list(state)
return init_ast_node({lhs, rhs, equals_location = equals_location}, loc, "Set")
end
local function parse_statement(state)
local loc = location(state)
local statement_parser = statements[state.token]
if statement_parser then
skip_token(state)
return statement_parser(state, loc)
else
return parse_expression_statement(state, loc)
end
end
function parse_block(state, loc)
local block = {location = loc}
local after_statement = false
while not closing_tokens[state.token] do
local first_token = state.token
if first_token == ";" then
if not after_statement then
table.insert(state.hanging_semicolons, location(state))
end
skip_token(state)
-- Do not allow several semicolons in a row, even if the first one is valid.
after_statement = false
else
first_token = state.token_value or first_token
local statement = parse_statement(state)
after_statement = true
statement.first_token = first_token
block[#block+1] = statement
if first_token == "return" then
-- "return" must be the last statement.
-- However, one ";" after it is allowed.
test_and_skip_token(state, ";")
if not closing_tokens[state.token] then
parse_error(state, "expected end of block")
end
end
end
end
return block
end
-- Parses source string.
-- Returns AST (in almost MetaLua format), array of comments - tables {comment = string, location = location},
-- set of line numbers containing code, map of types of tokens wrapping line endings (nil, "string", or "comment"),
-- and array of locations of empty statements (semicolons).
-- On error throws {line = line, column = column, end_column = end_column, msg = msg} - an instance
-- of parser.SyntaxError.
function parser.parse(src)
local state = new_state(src)
skip_token(state)
local ast = parse_block(state)
check_token(state, "eof")
return ast, state.comments, state.code_lines, state.line_endings, state.hanging_semicolons
end
return parser
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