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Added actual parser, that allows parsing more complex expressions

This commit is contained in:
Jon Michael Aanes 2018-03-14 12:21:51 +01:00
parent fe9ab028ce
commit f8447cdd39
3 changed files with 442 additions and 77 deletions

163
Parser.lua Normal file
View File

@ -0,0 +1,163 @@
require 'errors' 'shunt' . enable_strict_globals ()
---- Algorithm
local DEFAULT_ASSOC = 'left'
local DEFAULT_ARITY = 2
local function greater_than (a, b)
assert(type(a) == 'number', a)
assert(type(b) == 'number', b)
return a > b
end
local function greater_than_or_equal (a, b)
assert(type(a) == 'number', a)
assert(type(b) == 'number', b)
return a >= b
end
local function shunting_yard (tokens, lang, num_arity_to_token)
-- Implementation of the shunting yard algorithm, for transforming
-- infix notation math to postfix notation math.
--
-- Features extension for variadic first-class functions, which
-- results in slightly complicated output.
-- Whenever a function is called, the output will be formatted
-- like: <function-identifier> <arguments...> <num-args>
-- <call-operator>
--
-- For example: f(1, 2, 3)
-- Output: "f" 1 2 3 3 $
--
-- The exact behavior can be customized.
--
assert(type(tokens) == 'table' and #tokens > 0)
assert(type(lang) == 'function')
local pop_i = 1
local stack, output, call_stack = {}, {}, {}
local prev_info = nil
for _, val in ipairs(tokens) do
local t_info = lang(val, prev_info)
assert(type(t_info) == 'table' and t_info.val ~= nil)
if t_info.type == 'imm' then
output[#output+1] = t_info
-- Binary operators
elseif t_info.type == 'op' then
-- Determine associativity
t_info.associativity = t_info.associativity or DEFAULT_ASSOC
t_info.arity = t_info.arity or DEFAULT_ARITY
assert(type(t_info.precedence) == 'number')
assert(t_info.associativity == 'left' or t_info.associativity == 'right')
assert(t_info.arity == 1 or t_info.arity == 2)
local test = t_info.associativity == 'left' and greater_than_or_equal or greater_than
-- Pop operations with higher precedence from the stack
if t_info.arity == 1 and t_info.associativity == 'right' then
-- Do not pop operations from the stack
elseif t_info.arity == 2 then
while #stack > 0 and stack[#stack].type == 'op' and test(stack[#stack].precedence, t_info.precedence) do
output[#output+1], stack[#stack] = stack[#stack], nil
end
else
assert(false)
end
-- Add this operation to the stack
stack[#stack+1] = t_info
-- Enclosures
elseif t_info.type == 'bracket' then
-- Determine opening and closing brackets
assert(t_info.open ~= nil and t_info.close ~= nil and t_info.open ~= t_info.close)
-- Are we opening or closing?
if t_info.val == t_info.open then
while #stack > 0 and stack[#stack].type == 'op' and stack[#stack].precedence >= t_info.precedence do
output[#output+1], stack[#stack] = stack[#stack], nil
end
if t_info.on_end_call_op and prev_info and prev_info.type ~= 'op' then
call_stack[#call_stack+1] = { arity = 1, bracket = t_info }
stack[#stack+1] = t_info.on_end_call_op
end
stack[#stack+1] = t_info
elseif t_info.val == t_info.close then
-- If closing, pop from stack into output
while #stack > 0 and stack[#stack].val ~= t_info.open do
output[#output+1], stack[#stack] = stack[#stack], nil
end
-- Remove remaining bracket.
-- Brackets are not needed in postfix notation.
assert(#stack > 0 and stack[#stack].val == t_info.open)
stack[#stack] = nil
-- If top of stack is a function, we should pop it
if #stack > 0 and stack[#stack].call_op then
assert(#call_stack > 0)
if prev_info.type == 'bracket' and prev_info.open == prev_info.val and t_info.open == prev_info.val then
-- No arguments for this function
call_stack[#call_stack].arity = 0
end
-- Pop from stacks and construct output
output[#output+1], call_stack[#call_stack] = num_arity_to_token(call_stack[#call_stack].arity), nil
output[#output+1], stack[#stack] = stack[#stack], nil
end
else
assert(false, require'pretty'(t_info))
end
elseif t_info.type == 'arg-sep' then
-- Ensure that we are in a call
assert(#call_stack > 0 and call_stack[#call_stack].bracket.open == t_info.open)
-- Pop from stack
while #stack > 0 and stack[#stack].val ~= t_info.open do
output[#output+1], stack[#stack] = stack[#stack], nil
end
-- Ensure open is on the stack
assert(#stack > 0 and stack[#stack].val == t_info.open)
-- Increment arity in call-stack
call_stack[#call_stack].arity = call_stack[#call_stack].arity + 1
else
assert(false, 'Unknown type: '..tostring(t_info.type))
end
prev_info = t_info
end
-- Pop remaining from stack onto output
while #stack > 0 do
output[#output+1], stack[#stack] = stack[#stack], nil
end
-- Find value for all tokens on the stack
for i = 1, #output do
assert(output[i].val and output[i].type ~= 'bracket', require'pretty'(output[i]))
output[i] = output[i].val
end
-- Post asserts
--assert(type(output) == 'table' and #output <= #tokens)
assert(#stack == 0)
--
return output
end
return shunting_yard

View File

@ -26,27 +26,6 @@ local CONSTANT_VALUE_TOKEN = {
NIL = function() return nil end
}
local VALUE_TOKEN = { IDENTIFIER = true }
for k in pairs(CONSTANT_VALUE_TOKEN) do VALUE_TOKEN[k] = true end
local COMPARE_BINOP = {
EQ = true,
NEQ = true,
LEQ = true,
GEQ = true,
LE = true,
GT = true,
}
local function get_value_token (token)
if CONSTANT_VALUE_TOKEN[token.token]then
return { exp = token.token, value = CONSTANT_VALUE_TOKEN[token.token](token.text) }
elseif token.token == 'IDENTIFIER' then
return { exp = 'LVALUE', token.text }
end
assert(false)
end
local function get_variable (var_name, info)
--
assert(type(var_name) == 'string')
@ -71,25 +50,209 @@ local function get_variable (var_name, info)
return env, 'global'
end
--[[
local function get_value_from_lvalue (lvalue, info)
assert(type(lvalue) == 'table')
assert(type(info) == 'table')
-- Base value
local value, var_scope, in_func = get_variable(lvalue[1], info)
ilocal value, var_scope, in_func = get_variable(lvalue[1], info)
-- Sub value
for i = 2, #lvalue do value = value[lvalue[i].value] end
--
return value, var_scope, in_func
end
--]]
--------------------------------------------------------------------------------
-- Parsing
local shunting_yard = require 'Parser'
local NO_PARSE_TOKENS = {
FUNCTION = true,
SEMICOLON = true,
BREAK = true,
DO = true,
ELSE = true,
ELSEIF = true,
END = true,
FOR = true,
IF = true,
IN = true,
LOCAL = true,
REPEAT = true,
RETURN = true,
THEN = true,
UNTIL = true,
WHILE = true,
ASSIGN = true,
-- TODO: These below should not be NO-PARSE-TOKENS:
VARARG = true,
LBRACE = true,
RBRACE = true,
}
local LUA_BINOP = {
['OR'] = { precedence = 1 },
['AND'] = { precedence = 2 },
['LE'] = { precedence = 3 },
['LEQ'] = { precedence = 3 },
['EQ'] = { precedence = 3 },
['NEQ'] = { precedence = 3 },
['GEQ'] = { precedence = 3 },
['GT'] = { precedence = 3 },
['CONCAT'] = { precedence = 4, associativity = 'right' },
['PLUS'] = { precedence = 5 },
['MINUS'] = { precedence = 5 },
['TIMES'] = { precedence = 6 },
['DIVIDE'] = { precedence = 6 },
['MODULO'] = { precedence = 6 },
['CARET'] = { precedence = 8, associativity = 'right' },
['DOT'] = { precedence = 10 },
['COLON'] = { precedence = 10 },
}
local LUA_PREOP = {
['MINUS'] = { precedence = 7, val = 'UMINUS' },
['NOT'] = { precedence = 7 },
['HASHTAG'] = { precedence = 7 },
}
for keyword, binop in pairs (LUA_BINOP) do
binop.type = 'op'
binop.arity = 2
binop.val = binop.val or keyword
binop.associativity = binop.associativity or 'left'
end
for keyword, unop in pairs (LUA_PREOP) do
unop.type = 'op'
unop.arity = 1
unop.val = unop.val or keyword
unop.associativity = 'right'
end
local LUA_OP_ARITY = {}
for _, op in pairs(LUA_BINOP) do LUA_OP_ARITY[op.val] = op.arity end
for _, op in pairs(LUA_PREOP) do LUA_OP_ARITY[op.val] = op.arity end
local function lua_expression_lang (token, prev_token_info)
local ttype = token.token
local binary_disallowed = prev_token_info == nil or prev_token_info.type == 'bracket' and prev_token_info.open == prev_token_info.val or prev_token_info.type == 'op'
if LUA_PREOP[ttype] and binary_disallowed then
-- TODO: Unary minus?
local op_info = LUA_PREOP[ttype]
return { type = 'op', arity = op_info.arity, associativity = op_info.associativity, precedence = op_info.precedence, val = token }
elseif LUA_BINOP[ttype] and not binary_disallowed then
local op_info = LUA_BINOP[ttype]
return { type = 'op', arity = op_info.arity, associativity = op_info.associativity, precedence = op_info.precedence, val = token }
elseif LUA_BINOP[ttype] or LUA_PREOP[ttype] then
error('Cannot use the operation '..ttype..' here')
elseif ttype == 'LBRACK' or ttype == 'RBRACK' then
return { type = 'bracket', val = ttype, open = 'LBRACK', close = 'RBRACK', precedence = 10, on_end_call_op = { type = 'op', val = '?', call_op = true } }
elseif ttype == 'LPAR' or ttype == 'RPAR' then
return { type = 'bracket', val = ttype, open = 'LPAR', close = 'RPAR', precedence = 9, on_end_call_op = { type = 'op', val = '$', call_op = true } }
elseif ttype == 'COMMA' then
return { type = 'arg-sep', val = 'COMMA', open = 'LPAR' }
elseif type (ttype) == 'number' or type (ttype) == 'string' then
return { type = 'imm', val = token }
end
end
local function NUM_ARITY (num)
assert(type(num) == 'number')
return { type = 'imm', val = num }
end
local function parse (tokens)
-- TODO: Make a more general parser
assert(type(tokens) == 'table')
--
for i = 2, #tokens do
if tokens[i].token == 'IDENTIFIER' and tokens[i-1].token == 'DOT' then
tokens[i].token = 'STRING'
tokens[i].text = '\''..tokens[i].text..'\''
end
end
-- Postfix the tokens
local postfix_tokens = shunting_yard(tokens, lua_expression_lang, NUM_ARITY)
assert(type(postfix_tokens) == 'table')
print(require'pretty'(postfix_tokens))
-- Create AST from postfix tokens
local ast_stack = {}
for _, token in ipairs(postfix_tokens) do
if type(token) == 'table' and LUA_OP_ARITY[token.token] then
-- Operation
local node = { exp = 'OP', binop = token.token }
local start_left, end_right = math.huge, -math.huge
--
for arg_index = LUA_OP_ARITY[token.token], 1, -1 do
local arg = table.remove(ast_stack)
assert(type(arg) == 'table')
start_left, end_right = math.min(start_left, arg.left), math.max(end_right, arg.right)
node[arg_index] = arg
end
--
node.left, node.right = start_left, end_right
ast_stack[#ast_stack+1] = node
elseif token == '$' then
-- Operation
local node = { exp = 'CALL' }
local start_left, end_right = math.huge, -math.huge
--
local num_args = table.remove(ast_stack)
assert(type(num_args) == 'number')
--
for arg_index = num_args + 1, 1, -1 do
local arg = table.remove(ast_stack)
assert(type(arg) == 'table')
start_left, end_right = math.min(start_left, arg.left), math.max(end_right, arg.right)
node[arg_index] = arg
end
--
node.left, node.right = start_left, end_right
ast_stack[#ast_stack+1] = node
elseif token == '?' then
-- Indexing
local node = { exp = 'OP', binop = 'DOT' }
local start_left, end_right = math.huge, -math.huge
--
local num_args = table.remove(ast_stack)
assert(type(num_args) == 'number' and num_args == 1)
--
for arg_index = num_args + 1, 1, -1 do
local arg = table.remove(ast_stack)
assert(type(arg) == 'table')
start_left, end_right = math.min(start_left, arg.left), math.max(end_right, arg.right)
node[arg_index] = arg
end
--
node.left, node.right = start_left, end_right
ast_stack[#ast_stack+1] = node
else
-- Immediate
ast_stack[#ast_stack+1] = token
end
end
assert(#ast_stack == 1)
return ast_stack[1]
--[[
if #tokens == 6 and tokens[1].text == 'type' and tokens[2].token == 'LPAR' and tokens[3].token == 'IDENTIFIER' and tokens[4].token == 'RPAR'and tokens[5].token == 'EQ'and tokens[6].token == 'STRING' then
return {
@ -121,6 +284,7 @@ local function parse (tokens)
else
io.stderr:write '[assert-gooder/internal]: Unknown AST structure!\n'
end
--]]
end
local function for_each_node_in_ast (ast, func)
@ -140,8 +304,14 @@ local function populate_ast_with_semantics (ast, info)
assert(type(ast) == 'table')
assert(type(info) == 'table')
return for_each_node_in_ast(ast, function(node)
if node.exp == 'LVALUE' then
node.value = get_value_from_lvalue(node, info)
if node.token == 'IDENTIFIER' then
-- TODO: Variable scope, and is it in a function?
node.value, node.scope, node.function_local = get_variable(node.text, info)
elseif CONSTANT_VALUE_TOKEN[node.token] then
node.value = CONSTANT_VALUE_TOKEN[node.token](node.text)
elseif node.exp == 'OP' and node.binop == 'DOT' then
assert(node[1].value and node[2].value)
node.value = node[1].value[ node[2].value ] --TODO
end
end)
end
@ -243,28 +413,41 @@ local function fmt_val (val)
end
end
local function fmt_lvalue (lvalue, var_scope)
assert(type(lvalue) == 'table' and lvalue.exp == 'LVALUE')
--
local base_var = tostring(lvalue[1])
if var_scope then
base_var = ('%s \'%s\''):format(var_scope, lvalue[1])
end
--
if #lvalue == 1 then return base_var
elseif #lvalue == 2 then return string.format('key %s in %s', fmt_val(lvalue[2].value), base_var)
else error 'Not implemented yet!'
local function fmt_lvalue (node, with_scope)
assert(type(node) == 'table')
if node.token == 'IDENTIFIER' then
local base = node.text
if with_scope then base = ('%s \'%s\''):format(node.scope, base) end
return base, node.function_local
elseif node.exp == 'OP' and node.binop == 'DOT' then
local base, function_local = fmt_lvalue(node[1], with_scope)
return ('key %s in %s'):format(fmt_val(node[2].value), base), function_local
end
error 'Not implemented yet!'
end
local function get_variable_and_prefix (lvalue, call_info)
assert(type(lvalue) == 'table' and lvalue.exp == 'LVALUE')
--[[
local function ast_to_formal_lvalue (ast)
if ast.token == 'IDENTIFIER' then
return { ast.text, exp = 'LVALUE' }
elseif ast.exp == 'OP' and ast.binop == 'DOT' then
local prev = ast_to_formal_lvalue(ast[1])
prev[#prev+1] = get_value_token(ast[2]).value
return prev
end
assert(false)
end
--]]
local function fmt_prefix (ast, call_info)
assert(type(ast) == 'table')
--
local value, var_scope, in_func = get_value_from_lvalue(lvalue, call_info)
--
local func_name = in_func and (' to '..get_function_name(call_info)) or ''
return value, ('bad %s%s'):format(fmt_lvalue(lvalue, var_scope), func_name)
local name, is_function_local = fmt_lvalue(ast, true)
local func_name = is_function_local and (' to '..get_function_name(call_info)) or ''
return ('bad %s%s'):format(name, func_name)
end
@ -373,43 +556,61 @@ local function determine_error_message (call_info, msg, condition)
assert(type(ast) == 'table')
populate_ast_with_semantics(ast, call_info)
local function is_l_value (ast)
print(ast.exp, ast.binop, ast.exp == 'OP' and ast.binop == 'DOT' )
if ast.exp == 'OP' and ast.binop == 'DOT' then
print 'Derp?'
return true
elseif ast.token == 'IDENTIFIER' then
return true
end
return false
end
-- Alternative more detailed formatting.
-- Identical to last message, but now with values of each involved
-- identifier.
do
local l = {}
for_each_node_in_ast(ast, function(node)
if node.exp == 'LVALUE' then
l[#l+1] = fmt_lvalue(node) ..' was ' .. fmt_val_with_type(node.value)
if is_l_value(node) then
local name = fmt_lvalue(node)
if not l[name] then
l[#l+1] = name..' was ' .. fmt_val_with_type(node.value)
l[name] = true
end
end
end)
msg[2] = #l > 0 and table.concat(l,', ') or nil
end
-- More specific types
local var_prefix = function(token) return get_variable_and_prefix(token, call_info) end
local var_prefix = function(token)
return get_variable_and_prefix(token, call_info)
end
if not ast then return nil
elseif ast.exp == 'COMPARE' and ast.binop == 'EQ' and ast[1].exp == 'CALL' and ast[1][1].exp == 'LVALUE' and ast[1][1][1] == 'type' then
local gotten_val, prefix = var_prefix(ast[1][2])
msg[1], msg[2] = prefix, ('%s expected, but got %s'):format(ast[2].value, fmt_val_with_type(gotten_val))
elseif ast.exp == 'OP' and ast.binop == 'EQ' and ast[1].exp == 'CALL' and ast[1][1].value == type then
local prefix = fmt_prefix(ast[1][2], call_info)
msg[1], msg[2] = prefix, ('%s expected, but got %s'):format(ast[2].value, fmt_val_with_type(ast[1][2].value))
elseif ast.exp == 'COMPARE' and ast.binop == 'EQ' then
local gotten_value, prefix = var_prefix(ast[1])
local expected_value = ast[2].value
elseif ast.exp == 'OP' and ast.binop == 'EQ' then
local prefix = fmt_prefix(ast[1], call_info)
local gotten_value, expected_value = ast[1].value, ast[2].value
local fmt_gotten = (type(expected_value) == type(gotten_value)) and fmt_val or fmt_val_with_type
msg[1], msg[2] = prefix, ('%s expected, but got %s'):format(fmt_val_with_type(expected_value), fmt_gotten(gotten_value))
elseif ast.exp == 'COMPARE' and ast.binop == 'NEQ' then
local gotten_val, prefix = var_prefix(ast[1])
local expected_value = ast[2].value
elseif ast.exp == 'OP' and ast.binop == 'NEQ' then
local prefix = fmt_prefix(ast[1], call_info)
local gotten_value, expected_value = ast[1].value, ast[2].value
msg[1], msg[2] = prefix, ('expected anything other than %s, but got %s'):format(fmt_val_with_type(expected_value), fmt_val(gotten_val))
elseif ast.exp == 'LVALUE' then
local gotten_val, prefix = var_prefix(ast)
local prefix = fmt_prefix(ast[1], call_info)
local gotten_value = ast[1].value
msg[1], msg[2] = prefix, ('truthy expected, but got %s'):format(fmt_val(gotten_val))
elseif CONSTANT_VALUE_TOKEN[ast.exp] then
elseif CONSTANT_VALUE_TOKEN[ast.token] then
local func_name = get_function_name(call_info)
msg[1] = ('this assert will always fail, as it\'s body is `%s`. assumingly this should be an unreachable part of %s'):format(body_text, func_name)

View File

@ -62,3 +62,4 @@ return Lexer {
{ '%-%-%[%[.-%]%]', Lexer.CONTINUE },
{ '%s+', Lexer.CONTINUE },
}