In Lua, only the last expression in an argument list preserves multiple
results and all earlier expressions yield exactly one value (their first).
For example:
```
f(a(), b(), c())
```
where
```
a -> (1,2)
b -> (3,4)
c -> (5,6)
```
becomes
```
f(1, 3, 5, 6)
```
which matches Lua behaviour (tested in version 5.4).
Changes:
* Function argument lists keep multiple results only from the last
argument.
* Fixes failing truthiness tests (`true and ret_one_two()`).
Sidenote: the `truthiness_test.lua` was not called at all because of
my obvious copy/paste typo (the `arithmetical_test.lua` was called twice
instead; now fixed too and both test suites pass ok).
This patch fixes the Lua arithmetic model at parser level only. Runtime
level fixtures are left for future work.
MOTIVATION
Space Lua treats all numbers as IEEE-754 doubles (JS semantics), so it
preserves negative zero. Lua uses integers and floats. The literal "-0"
in Lua is parsed as unary minus applied to the integer literal "0",
which yields the integer "0" (no sign). This difference flips the sign
of the divisor in "1/-0" and "-1/-0". Although it could be fixed without
touching the parser by changing only unary minus evaluation, this commit
goes a little further and provides integer vs float differenciating at
the parser level as well uses it to fix the unary minus evaluation.
Extensive tests are added to test this exact change works and the Space
Lua arithmetic model is aligned with Lua. Note that things like `-(expr)`
in general may still produce results inconsistent with Lua. This cannot
be fixed at parser level and must be fixed at runtime level which will
need far more complex change to the Space Lua interpreter code. Therefor
these cases we omitted from the tests.
Signed-off-by: Matouš Jan Fialka <mjf@mjf.cz>
The Lua 5.4 compatible `tonumber` implementation completely reworked
- custom char-by-char parser (no regexes)
- proper Lua space handling
- support for heximal integers and floats
- support for scientific float notation
- extended tests
- updated website docs
Signed-off-by: Matouš Jan Fialka <mjf@mjf.cz>
