This just makes these functions easier to understand all around.  In
the case of _token_list_append_list this is an actual bug fix, (where
append an empty list onto a non-empty list would previously scramble
the tail pointer of the original list).

That is, a function-like invocation foo(x) is valid as a
single-argument invocation even if 'x' is a macro that expands into a
value with a comma. Add a new COMMA_FINAL token type to handle this,
and add a test for this case, (which passes).

That is, the following case:

	#define foo(x) (x)
	#define bar
	bar(baz)

which now works with this (ugly) commit.

I definitely want to come up with something cleaner than this.

This adds three new pieces of state to the parser, (is_control_line,
newline_as_space, and paren_count), and a large amount of messy
code. I'd definitely like to see a cleaner solution for this.

With this fix, the "define-func-extra-newlines" now passes so we put
it back to test #26 where it was originally (lately it has been known
as test #55).

Also, we tweak test 25 slightly. Previously this test was ending a
file function-like macro name that was not actually a macro (not
followed by a left parenthesis). As is, this fix was making that test
fail because the text_line production expects to see a terminating
NEWLINE, but that NEWLINE is now getting turned into a SPACE here.

This seems unlikely to be a problem in the wild, (function macros
being used in a non-macro sense seems rare enough---but more than
likely they won't happen at the end of a file). Still, we document
this shortcoming in the README.

This is what I get for using a non-type-safe hash-table implementation.

To do this we have split the existing "HASH_IF expression" into two
productions:

First is HASH_IF pp_tokens which simply constructs a list of tokens.

Then, with that resulting token list, we first evaluate all DEFINED
operator tokens, then expand all macros, and finally start lexing from
the resulting token list. This brings us to the second production,
IF_EXPANDED expression

This final production works just like our previous "HASH_IF
expression", evaluating a constant integer expression.

The new test (54) added for this case now passes.

Which makes test 40 now pass.

Now that we no longer have nested for loops with 'i' and 'j' we can
use the 'node' that we already have.

All the code referencing these was removed some time ago.

With this fix, tests 37 - 39 now pass.

Always better to use proper grammar in our grammar.

As required by the C99 specification of the preprocessor.

With this fix, tests 33 through 36 now pass.

This doesn't change any functionality here, but will allow us to make
future changes that were not possible with direct printing.
Specifically, we need to expand macros within macro arguments before
performing argument substitution. And *that* expansion cannot result
in immediate printing.

With this fix, test 32 no longer recurses infinitely, but now passes.

This trailing whitespace was coming from macro definitions and from
macro arguments. We fix this with a little extra state in the
token_list. It now remembers the last non-space token added, so that
these can be trimmed off just before printing the list.

With this fix test 23 now passes. Tests 24 and 25 are also passing,
but they probbably would ahve before this fix---just that they weren't
being run earlier.

We're no longer using the expansion stack, so its functions can go
along with most of the body of glcpp_parser_lex that was using it.

We weren't including this left parenthesis in the argument's token
list so the nested function invocation wasn not being recognized.

With this fix, tests 21 and 22 now pass.

This causes test 16 to pass. Tests 17-20 are also passing now, (though
they would probably have passed before this change and simply weren't
being run yet).

This makes tests 16 - 19 pass.

This is what gcc does, and it's actually less work to do
this. Previously we were having to save the contents of space tokens
as a string, but we don't need to do that now.

We extend test #0 to exercise this feature here.

This makes test 15 pass and also dramatically simplifies the lexer.

We were previously using a CONTROL state in the lexer to only emit
SPACE tokens when on text lines. But that's not actually what we
want. We need SPACE tokens in the replacement lists as well. Instead
of a lexer state for this, we now simply set a "space_tokens" flag
whenever we start constructing a pp_tokens list and clear the flag
whenever we see a '#' introducing a directive.

Much cleaner this way.

This supports function-like macro invocation but without any argument
substitution. This now makes test 11 through 14 pass.

Which is as simple as copying the former action back from the git
history.

Now all tests through test 11 pass.

For this we add an "active" string_list_t to the parser. This makes
the current expansion_list_t in the parser obsolete, but we don't
remove that yet.

With this change we can now start passing some actual tests, so we
turn on real testing in the test suite again. I expect to implement
things more or less in the same order as before, so the test suite now
halts on first error.

With this change the first 8 tests in the suite pass, (object-like
macros with chaining and recursion).

With this change, we can recreate the original text-line input
exactly. Previously we were inserting a space between every pair of
tokens so our output had a lot more whitespace than our input.

With this change, we can drop the "-b" option to diff and match the
input exactly.

Still not doing any macro expansion just yet. But it should be fairly
easy from here.

This pernicious stuff managed to sneak in on us.

This is a fresh start with a much simpler approach for the flex/bison
portions of the preprocessor. This isn't functional yet, (produces no
output), but can at least read all of our test cases without any parse
errors.

The grammar here is based on the grammar provided for the preprocessor
in the C99 specification.

This is what the C99 specification demands. And the GLSL specification
says that we should follow the "standard C++" rules for #if condition
expressions rather than the GLSL rules, (which only support a 32-bit
integer).

The operator coverage here is quite complete. The one big thing
missing is that we are not yet doing macro expansion in #if
lines. This makes the whole support fairly useless, so we plan to fix
that shortcoming right away.

So far the only expression implemented is a single integer literal,
but obviously that's easy to extend. Various things including nesting
are tested here.

This is *very* easy to implement now that macro arguments are pre-expanded.

Previously, we were using the same lexing stack as we use for macro
expansion to also expand macro arguments. Instead, we now do this
earlier by simply recursing over the macro-invocations replacement
list and constructing a new expanded list, (and pushing only *that*
onto the stack).

This is simpler, and also allows us to more easily implement token
pasting in the future.

The last remaining thing here was that when a line ended with a macro,
and the parser looked ahead to the newline token, the lexer was
printing that newline before the parser printed the expansion of the
macro.

The fix is simple, just make the lexer tell the parser that a newline
is needed, and the parser can wait until reducing a production to
print that newline.

With this, we now pass the entire test suite with simply "diff -u", so
we no longer have any diff options hiding whitespace bugs from
us. Hurrah!

This fixes more differences compared to "gcc -E" so removes several
cases of erroneously failing test cases. The implementation isn't very
elegant, but it is functional.

We fix this by moving printing up to the top-level "input" action and
tracking whether a space is needed between one token and the next.

This fixes all actual bugs in test-suite output, but does leave some
tests failing due to differences in the amount of whitespace produced,
(which aren't actual bugs per se).

The only good dead code is non-existing dead code.

The fix here is quite simple (and actually only deletes code). When
expanding a macro, we don't return a ',' as a unique token type, but
simply let it fall through to the generic case.

The specification says that commas within a parenthesized group,
(that's not a function-like macro invocation), are passed through
literally and not considered argument separators in any outer macro
invocation.

Add support and a test for this case. This support makes a third
occurrence of the same "FUNC_MACRO (" shift/reduce conflict appear, so
expect that.

This change does introduce a fairly large copy/paste block in the
grammar which is unfortunate. Perhaps if I were more clever I'd find a
way to share the common pieces between argument and argument_or_comma.

The specification of the preprocessor in C99 says that when we see a
macro name that we are already expanding that we refuse to expand it
now, (which we've done for a while), but also that we refuse to ever
expand it later if seen in other contexts at which it would be
legitimate to expand.

We add a test case for that here, and fix it to work. The fix takes
advantage of a new token_t value for tokens and argument words along
with the recently added IDENTIFIER_FINALIZED token type which
instructs the parser to not even look for another expansion.

There's not yet any change in functionality here, (at least according
to the test suite). But we now have the option of specifying a type
for each string in the token list. This will allow us to finalize an
unexpanded macro name so that it won't be subjected to excess
expansion later.

Previously, we would pass original strings back to the original lexer
whenever we needed to re-lex something, (such as an expanded macro or
a macro argument). Now, we instead parse the macro or argument
originally to a string list, and then re-lex by simply returning each
string from this list in turn.

We do this in the recently added glcpp_parser_lex function that sits
on top of the lower-level glcpp_lex that only deals with text.

This doesn't change any behavior (at least according to the existing
test suite which all still passes) but it brings us much closer to
being able to "finalize" an unexpanded macro as required by the
specification.

We fixed the lexer a while back to never return a NEWLINE token, but
negelcted to clean up this declaration.

I'm not sure where this came from, but it's clearly not needed.

Much cleaner this way, (and now our custom lex function has access to
all the parser state which it will need).

We rename the generated lexer from yylex to glcpp_lex. Then we
implement our own yylex function in glcpp-parse.y that calls
glcpp_lex. This doesn't change the behavior at all yet, but gives us a
place where we can do implement alternate lexing in the future.

(We want this because instead of re-lexing from strings for macro
expansion, we want to lex from pre-parsed token lists. We need this so
that when we terminate recursion due to an already active macro
expansion, we can ensure that that symbol never gets expanded again
later.)

The support for an object-like amcro within a macro-invocation
argument was also implemented at one level too high in the
grammar. Fortunately, this is a very simple fix.

The previous fix added FUNC_MACRO to a production one higher in teh
grammar than it should have. So it prevented a FUNC_MACRO from
appearing as part of a mutli-token argument rather than just alone as
an argument. Fix this (and add a test).

This adds a second shift/reduce conflict to our grammar. It's basically the
same conflict we had previously, (deciding to shift a '(' after a FUNC_MACRO)
but this time in the "argument" context rather than the "content" context.

It would be nice to not have these, but I think they are unavoidable
(withotu a lot of pain at least) given the preprocessor specification.