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i am trying to consume a large grammer file (postgresql) which is in Bison format.
Bison is supposed to be the GNU implementation/extension of Yacc but I think it has some differences since I got a syntax error. I have not spent time to find out the differences between Yacc/Bison related to this. Maybe you can comment on that.

The section that cause the error is

OptSchemaEltList:
            OptSchemaEltList schema_stmt
                {
                    if (@$ < 0)         /* see comments for YYLLOC_DEFAULT */
                        @$ = @2;
                    $$ = lappend($1, $2);
                }
            | /* EMPTY */
                { $$ = NIL; }
        ;

The @$ causes: strconv.ParseInt: parsing "": invalid syntax:

Type of $$ gets overwrtitten by the type of last $n used.

They should be sorted. Also, some of the defaults are documented after the flag while others after the description: make it uniform.

Cf. #2

The error list is scanner.ErrorList. The Error() method of scanner.ErrorList returns only the first error.

See cznic/golex#13 (comment).

Probably only in parsers with conflicts. It never occured to me test such cases, but it must work and must produce stable, best-effort parsers as the original yacc does.

I have a *.y file to generate a parser for sql, but I found there was different output between MacOS(10.13) and Linux(CentOS 6.3).
Ant the output parser from MacOS not working good. I had to generate the parser on linux and send the parser file to mac to continue my work.
There are lost of different between to parser.

I use the command like this:

goyacc -o sql.go sql.y
gofmt -w sql.go

hi
How build goyacc tool in GO?

i have goyacc -h package in my system.
but want install go tool yacc on go 1.8
how can do this?

$ make

go fmt
go test
PASS
ok github.com/cznic/goyacc 0.002s
go install
go tool vet -printfuncs "Log:0,Logf:1" *.go
golint .
make todo
make[1]: Entering directory '/home/guest/go/src/github.com/cznic/goyacc'
main.go:554: _ = yyerrok
main.go:706: _ = yypt // guard against "declared and not used"
main.go:791: _ = oNoLines //TODO Ignored for now
all_test.go:37:func TODO(...interface{}) string {
all_test.go:39: return fmt.Sprintf("TODO: %s:%d:\n", path.Base(fn), fl)
main.go:791: _ = oNoLines //TODO Ignored for now
make[1]: Leaving directory '/home/guest/go/src/github.com/cznic/goyacc'

I was trying to parse cockroachdb's sql.y and hit a bug:

sql.y:454:9: unexpected '*', expected identifier

https://github.com/cockroachdb/cockroach/blob/9cf7b53242e4680af2755102da33f6c558ae501e/pkg/sql/parser/sql.y#L454

It appears this doesn't like the * in %token <*tree.NumVal> ICONST FCONST.

Hi,

parser.y:36:41: $$ of declarations has no declared type (and 30 more errors)
what does it complain?

program: declarations 
{
}

declarations: declaration
{
  declarationNode := newDeclarationNode($$.funcDecl)
  $$.node = declarationNode

  cast(yylex).SetAstRoot($$.node)
}

goyacc inherited issue 9099.

• Explain the advantages.
• Show which grammars won't work or will work differently without $default.

Should produce at least the non formatted version in such case.

$ cat bug.y
%union{
    val  int
    vals []int
}

%token  I
%type   <vals>  L

%%

S:  L

L:
    {
        $$ = []int(nil)
    }
|   L I
    {
        $$ = append($$, $2)
    }
$ goyacc -o /dev/stdout bug.y | grep yypt-0
Parse table entries: 5 of 24, x 8 bits == 5 bytes
        yyVAL.vals = append(yyVAL.vals, yyS[yypt-0].)
$ 

Token I should have been declared as %token <val> I, but the missing type of $2 gets undetected by the y package. Goyacc then renders invalid Go code.

Token values are assigned when ranging a map. Make the order of assigning the values stable to improve VCS diffs.

It's always yyDebug but the prefix should come from the -p option value.

The documented order is rule, state, ... but the actual order is incorrectly state, rule, ....

Hello,

how is this different from https://golang.org/cmd/yacc/?

-Gerald

... as -1, but the value generated by cznic/y should be used instead.

And one more bug in error recovery - instead of proper stem there's a hardcoded yy.

Use the go/format.Source, Luke.

Not yet implemented as of now.

I have a parser that has the following basic structure:

program
    : statements
    ;
statements
    : statement
    | statement statements
    ;

And I am getting the following error: y.go:348:12: duplicate index in array literal: 5
I opened up y.go and lines 345-349 look like this:

yyParseTab = [83][]uint8{
    // 0
    {4: 46, 14: 50, 49, 25: 47, 32: 48, 45, 44, 36: 43},
    {5: 42, 5: 42, 5: 42, 5: 42, 5: 42},
    {1: 41, 5: 41, 41, 12: 41, 41},
    ...
}

If I'm not mistaken, it looks like the error corresponds to state 1. But I'm not a yacc expert, by any means. Looking at y.output for state 1 gives the following:

state 1 // NAME SEMICOLON [$end]
    
    0 $accept: program .  [$end, AND, ARROW, LCURLY, OR]

    $end    accept
    AND     accept
    ARROW   accept
    LCURLY  accept
    OR      accept

So, I think I'm reading this correctly as "we just reduced program, so check whether the next token is $end, AND, ARROW, LCURLY, or OR." I'm not sure why it would be checking that though because there is no valid token other than $end that can occur after reducing to program, which is making me think this may be an issue with goyacc. It appears to work if I manually alter the entry to just {5: 42}. Thoughts?

The problem propagates from $go tool yacc used by cznic/parser/yacc, see issue #2

I feel as though I should not have had to write this:

// Tokname returns the string name of a token type (for testing purposes).
func Tokname(i int) string {
	if i < 128 {
		return string([]byte{byte(i & 0xff)})
	}
	return cparseTokname(i - 57342)
}

That magic number is particularly annoying.

Would you please make something equivalent a public method?

Hi,

could you upload some examples which uses goyacc together with golex?

Thanks,
Gerald

It always start with yy but the prefix should come from the -p option value.