hokein marked 7 inline comments as done.
hokein added inline comments.
================
Comment at: clang/include/clang/Tooling/Syntax/Pseudo/Grammar.h:130
+
+ // Returns the SymbolID of the augmented symbol '_'
+ SymbolID augmentedSymbol() const { return 0; }
----------------
sammccall wrote:
> this "augmented symbol" name doesn't seem widely used. (search for `lr
> "augmented symbol"` produces few results, mostly unrelated). It's also a
> confusing name, because it's IIUC it's not the symbol that's augmented, but
> rather the grammar has been augmented with the symbol...
>
> I'd suggest just calling it the start symbol, unless the distinction is
> critical (I don't yet understand why it's important - I added it in the
> prototype just to avoid having the language-specific name "translation-unit"
> hardcoded).
>
> Otherwise it's hard to suggest a good name without understanding what it's
> for, but it should be descriptive...
yeah, it is about augmented grammar. Strictly speaking, it is a start symbol of
augmented symbol. Maybe we should not speak augmented stuff in the code, it is
not a well-known term, and causes confusion. rename it to start symbol instead.
It looks like using augmented grammar is a "standard" LR technique, it
introduces a converged start state and accepting state in the LR graph, which
makes it easier for the implementation. And it is a good fit for support
multiple start symbols.
================
Comment at: clang/include/clang/Tooling/Syntax/Pseudo/Grammar.h:133
+
+ // Computes the FIRST(X) for all non-terminal symbol X.
+ std::vector<llvm::DenseSet<SymbolID>> firstSets() const;
----------------
sammccall wrote:
> sammccall wrote:
> > In about the same number of words you could explain what this actually is
> > :-)
> >
> > // Computes the set of terminals that could appear at the start of each
> > non-terminal.
> is there some reason these functions need to be part of the grammar class?
>
> They seem like part of the LR building to me, it could be local to
> LRBuilder.cpp, or exposed from LRTable.h or so for testing
as discussed, made them as free functions in Grammar.h. Separate the first and
follow set changes to https://reviews.llvm.org/D118990, comments around them
should be addressed there.
================
Comment at: clang/lib/Tooling/Syntax/Pseudo/Grammar.cpp:88
+ for (const auto &R : T->Rules) {
+ // Rule 2: for a rule X := ...Yz, we add all symbols from FIRST(z) to
+ // FOLLOW(Y).
----------------
sammccall wrote:
> nit: `... Y Z`, with consistent spaces/capitalization
> Unless case is meant to imply something here?
Y was for nonterminal while z was for nonterminal or terminals. They are not
super important, changed all to Uppercase.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D118196/new/
https://reviews.llvm.org/D118196
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