def to_if(tokens: tc.TokenSeq) -> tp.Union[stmt.IfStmt, stmt.ErrorStmt]:
paren = next(tu.token_find_index(tokens, {tt.RIGHT_PAREN}), len(tokens))
condition = ep.conditional(tokens[:paren + 1])
if condition.has_error():
return stmt.ErrorStmt()
else_index = next(tu.token_find_index(tokens, {tt.ELSE}), len(tokens))
then_stmt = to_meta_dec(tokens[paren + 1:else_index])
else_stmt = to_meta_dec(
tokens[else_index:]) if tokens[else_index:] else None
return stmt.IfStmt(condition, then_stmt, else_stmt)
def to_while(tokens: tc.TokenSeq) -> tp.Union[stmt.WhileStmt, stmt.ErrorStmt]:
right_paren = next(tu.token_find_index(tokens, {tt.RIGHT_PAREN}),
len(tokens))
condition = ep.conditional(tokens[:right_paren + 1])
if condition.has_error():
return stmt.ErrorStmt()
body = to_meta_dec(tokens[right_paren + 1:])
return stmt.WhileStmt(condition, body)
def call(tokens: tc.TokenSeq) -> ae.Expr:
last_paren = next(tu.token_find_index(tokens, {tt.LEFT_PAREN, tt.DOT}),
len(tokens))
if last_paren == 0:
return primary(tokens)
if tokens[last_paren - 1].type is tt.SUPER:
lox_function = primary(tokens[:last_paren + 2])
else:
lox_function = primary(tokens[:last_paren])
for paren_index in tu.token_find_index(tokens, {tt.RIGHT_PAREN, tt.DOT}):
if tokens[paren_index].type is tt.RIGHT_PAREN:
args = tuple(
function_call_args(
tokens[last_paren + CallIncrements[tokens[last_paren].
type]:paren_index], ))
lox_function = expr.Call(lox_function, tokens[paren_index], args)
elif tokens[paren_index - 1].type is not tt.SUPER:
lox_function = expr.Get(lox_function, tokens[paren_index + 1])
last_paren = paren_index
return lox_function
def assignment(tokens: tc.TokenSeq) -> ae.Expr:
equal_index = next(tu.token_find_index(tokens, {tt.EQUAL}), None)
if equal_index is None or not lu.is_lox_identifier(tokens[:equal_index]):
return logic_or(tokens)
var = call(tokens[:equal_index])
if not isinstance(var, (expr.Variable, expr.Get)):
error(tokens[equal_index].line, "Invalid assignment target.")
return expr.ErrorExpr()
value = equality(tokens[equal_index + 1:])
if isinstance(var, expr.Get):
return expr.Set(var, value)
return expr.Assign(var.name, value)
def to_var(
tokens: tp.Sequence[tc.Token]
) -> tp.Union[stmt.ErrorStmt, stmt.VarStmt]:
relevant_tokens = tu.token_find_index(tokens, {tt.IDENTIFIER, tt.EQUAL})
index = next(relevant_tokens, None)
name = tokens[index] if index is not None else tc.sentinel_token
if name.type is not tt.IDENTIFIER:
error(name.line, "Expect variable name.")
return stmt.ErrorStmt()
equal_index = next(relevant_tokens, None)
if equal_index is None and index != len(tokens) - 1:
error(name.line,
"Expect nothing between the variable name and the equals sign.")
return stmt.ErrorStmt()
initializer = (ep.expression(tokens[equal_index + 1:])
if equal_index is not None else None)
return stmt.VarStmt(name, initializer)