| 223 | 223 |
return t
|
| 224 | 224 |
end
|
| 225 | 225 |
|
| 226 | |
-- Strelnokoff = {Assignment}.
|
| 227 | |
-- Assignment = Variable [Index] "=" Expression0.
|
| 228 | |
-- Expression0 = Expression1 {"=" Expression1 | ">" Expression1}.
|
| 229 | |
-- Expression1 = Expression2 {"+" Expression2 | "-" Expression2}.
|
| 230 | |
-- Expression2 = Primitive {"*" Primitive | "/" Primitive}.
|
| 231 | |
-- Primitive = ["PRINT" | "INPUT"] ["CHAR"] Variable [Index]
|
| 232 | |
-- | IntegerLiteral | CharLiteral
|
| 233 | |
-- | "(" Expression0 ")".
|
| 234 | |
-- Index = "[" Expression0 {"," Expression0} "]".
|
| 235 | |
|
| 236 | 226 |
function Parser:program()
|
| 237 | 227 |
local assignments = {}
|
| 238 | 228 |
while self.scanner.toktype ~= "EOF" do
|
|
| 278 | 268 |
|
| 279 | 269 |
function Parser:expression2()
|
| 280 | 270 |
local expr, t, rhs
|
| 281 | |
expr = self:primitive()
|
|
271 |
expr = self:expression3()
|
| 282 | 272 |
assert(expr ~= nil)
|
| 283 | 273 |
while self.scanner.token == "*" or self.scanner.token == "/" do
|
| 284 | 274 |
t = self:consume_token()
|
| 285 | |
rhs = self:primitive()
|
|
275 |
rhs = self:expression3()
|
| 286 | 276 |
assert(rhs ~= nil)
|
| 287 | 277 |
expr = BinOp(t, expr, rhs)
|
| 288 | 278 |
end
|
| 289 | 279 |
return expr
|
| 290 | 280 |
end
|
| 291 | 281 |
|
| 292 | |
function Parser:primitive()
|
|
282 |
function Parser:expression3()
|
| 293 | 283 |
local action
|
| 294 | 284 |
local mode = "int"
|
| 295 | 285 |
|
| 296 | |
-- FIXME I feel like this should probably change to be an operator...
|
| 297 | 286 |
if self.scanner.token == "PRINT" then
|
| 298 | 287 |
action = "PRINT"
|
| 299 | 288 |
self.scanner:scan()
|
|
| 307 | 296 |
self.scanner:scan()
|
| 308 | 297 |
end
|
| 309 | 298 |
|
|
299 |
local expr = self:primitive()
|
|
300 |
|
|
301 |
if action == "PRINT" then
|
|
302 |
return Action("print", mode, expr)
|
|
303 |
else
|
|
304 |
-- FIXME what about "INPUT" ... ?
|
|
305 |
return expr
|
|
306 |
end
|
|
307 |
end
|
|
308 |
|
|
309 |
function Parser:primitive()
|
| 310 | 310 |
debug("parse", "primitive " .. self.scanner.toktype)
|
| 311 | 311 |
if self.scanner.toktype == "number" then
|
| 312 | 312 |
local val = tonumber(self.scanner.token)
|
| 313 | 313 |
local expr = Literal(val)
|
| 314 | 314 |
self.scanner:scan()
|
| 315 | |
if action == "PRINT" then
|
| 316 | |
return Action("print", mode, expr)
|
| 317 | |
else
|
| 318 | |
-- FIXME what about "INPUT" ... ?
|
| 319 | |
return expr
|
| 320 | |
end
|
|
315 |
return expr
|
| 321 | 316 |
elseif self.scanner.toktype == "char" then
|
| 322 | 317 |
local val = string.byte(self.scanner.token, 2)
|
| 323 | 318 |
local expr = Literal(val)
|
| 324 | |
-- FIXME just as above
|
| 325 | |
self.scanner:scan()
|
| 326 | |
if action == "PRINT" then
|
| 327 | |
return Action("print", mode, expr)
|
| 328 | |
else
|
| 329 | |
-- FIXME what about "INPUT" ... ?
|
| 330 | |
return expr
|
| 331 | |
end
|
|
319 |
self.scanner:scan()
|
|
320 |
return expr
|
| 332 | 321 |
elseif self.scanner.token == "(" then
|
| 333 | 322 |
self.scanner:scan()
|
| 334 | 323 |
local expr = self:expression0()
|
| 335 | 324 |
self.scanner:expect(")")
|
| 336 | |
-- FIXME just as above
|
| 337 | |
if action == "PRINT" then
|
| 338 | |
return Action("print", mode, expr)
|
| 339 | |
else
|
| 340 | |
-- FIXME what about "INPUT" ... ?
|
| 341 | |
return expr
|
| 342 | |
end
|
|
325 |
return expr
|
| 343 | 326 |
else
|
| 344 | 327 |
local name = self:expect_toktype("ident")
|
| 345 | 328 |
local varindex = "" -- problematic for AST helpers if nil so we use this
|
|
| 347 | 330 |
varindex = self:varindex()
|
| 348 | 331 |
end
|
| 349 | 332 |
debug("parse", "primitive varaccess " .. name .. "[]" .. tostring(varindex))
|
| 350 | |
local expr = VarAccess(name, varindex)
|
| 351 | |
if action == "PRINT" then
|
| 352 | |
expr = Action("print", mode, expr)
|
| 353 | |
end
|
| 354 | |
debug("parse", "primitive varaccess expr " .. render(expr))
|
| 355 | |
-- FIXME what about "INPUT" ... ?
|
| 356 | |
return expr
|
|
333 |
return VarAccess(name, varindex)
|
| 357 | 334 |
end
|
| 358 | 335 |
end
|
| 359 | 336 |
|