我在Lemon中整理了一个语法（与YACC相似），但产生了S / R冲突。我不习惯LALR解析，也不了解问题是什么，也不知道如何解决。语法是：
%right EQUALS.
%right RIGHT_ASSIGN LEFT_ASSIGN MOD_ASSIGN DIV_ASSIGN MUL_ASSIGN.
%right QUESTION COLON.
%left EQ_OP.
%left NE_OP LE_OP GE_OP LCARET RCARET.
%left PLUS MINUS.
%left STAR PERCENT FSLASH.
%right UNA.
%left DOT PTR_OP.
%left UN.
%left LBRACKET LSBRACKET RBRACKET RSBRACKET.
%right DOTACCESS.
file ::= statement_list EOF.
statement_break ::= EOL.
statement_list ::= statement statement_break.
statement_list ::= statement_list statement statement_break.
statement ::= expr.
statement ::= assign_expr argument_expr_list. [UN]
primary_expr
::= IDENTIFIER.
primary_expr
::= CONSTANT.
primary_expr
::= STRING_LITERAL.
primary_expr
::= LBRACKET expr RBRACKET.
postfix_expr
::= primary_expr.
postfix_expr
::= postfix_expr LSBRACKET expr RSBRACKET. [UN]
postfix_expr
::= postfix_expr LBRACKET RBRACKET. [UN]
postfix_expr
::= postfix_expr LBRACKET argument_expr_list RBRACKET. [UN]
postfix_expr
::= postfix_expr DOT IDENTIFIER. [DOTACCESS]
postfix_expr
::= postfix_expr PTR_OP IDENTIFIER. [DOTACCESS]
postfix_expr
::= postfix_expr INC_OP.
postfix_expr
::= postfix_expr DEC_OP.
argument_expr_list
::= assign_expr.
argument_expr_list
::= argument_expr_list COMMA assign_expr.
unary_expr
::= postfix_expr.
unary_expr
::= unary_operator cast_expr. [UNA]
unary_expr
::= SIZEOF unary_expr. [UN]
unary_expr
::= SIZEOF LBRACKET type_name RBRACKET. [UN]
unary_operator
::= EXCLAMATION.
cast_expr
::= unary_expr.
cast_expr
::= LBRACKET type_name RBRACKET cast_expr. [UNA]
mul_expr
::= cast_expr.
mul_expr
::= mul_expr STAR cast_expr.
mul_expr
::= mul_expr FSLASH cast_expr.
mul_expr
::= mul_expr PERCENT cast_expr.
add_expr
::= mul_expr.
add_expr
::= add_expr PLUS mul_expr.
add_expr
::= add_expr MINUS mul_expr.
shift_expr
::= add_expr.
shift_expr
::= shift_expr LEFT_OP add_expr.
shift_expr
::= shift_expr RIGHT_OP add_expr.
rel_expr
::= shift_expr.
rel_expr
::= rel_expr LCARET shift_expr.
rel_expr
::= rel_expr RCARET shift_expr.
rel_expr
::= rel_expr LE_OP shift_expr.
rel_expr
::= rel_expr GE_OP shift_expr.
eq_expr
::= rel_expr.
eq_expr
::= eq_expr EQ_OP rel_expr.
eq_expr
::= eq_expr NE_OP rel_expr.
and_expr
::= eq_expr.
and_expr
::= and_expr AND eq_expr.
excl_or_expr
::= and_expr.
excl_or_expr
::= excl_or_expr HAT and_expr.
incl_or_expr
::= excl_or_expr.
incl_or_expr
::= incl_or_expr BAR excl_or_expr.
log_and_expr
::= incl_or_expr.
log_and_expr
::= log_and_expr AND_OP incl_or_expr.
log_or_expr
::= log_and_expr.
log_or_expr
::= log_or_expr OR_OP log_and_expr.
cond_expr
::= log_or_expr.
cond_expr
::= log_or_expr QUESTION expr COLON cond_expr.
assign_expr
::= cond_expr.
assign_expr
::= unary_expr assign_op assign_expr.
assign_op
::= EQUALS. [EQUALS]
assign_op
::= MUL_ASSIGN. [EQUALS]
assign_op
::= DIV_ASSIGN. [EQUALS]
assign_op
::= MOD_ASSIGN. [EQUALS]
assign_op
::= ADD_ASSIGN. [EQUALS]
assign_op
::= SUB_ASSIGN. [EQUALS]
assign_op
::= LEFT_ASSIGN. [EQUALS]
assign_op
::= RIGHT_ASSIGN. [EQUALS]
assign_op
::= AND_ASSIGN. [EQUALS]
assign_op
::= XOR_ASSIGN. [EQUALS]
assign_op
::= OR_ASSIGN. [EQUALS]
expr
::= assign_expr.
expr
::= expr COMMA assign_expr.
type_name
::= TYPE.
Lemon的输出是：
State 4:
primary_expr ::= * IDENTIFIER
primary_expr ::= * CONSTANT
primary_expr ::= * STRING_LITERAL
primary_expr ::= * LBRACKET expr RBRACKET
postfix_expr ::= * primary_expr
postfix_expr ::= * postfix_expr LSBRACKET expr RSBRACKET
postfix_expr ::= * postfix_expr LBRACKET RBRACKET
postfix_expr ::= postfix_expr LBRACKET * RBRACKET
postfix_expr ::= * postfix_expr LBRACKET argument_expr_list RBRACKET
postfix_expr ::= postfix_expr LBRACKET * argument_expr_list RBRACKET
postfix_expr ::= * postfix_expr DOT IDENTIFIER
postfix_expr ::= * postfix_expr PTR_OP IDENTIFIER
postfix_expr ::= * postfix_expr INC_OP
postfix_expr ::= * postfix_expr DEC_OP
argument_expr_list ::= * assign_expr
argument_expr_list ::= * argument_expr_list COMMA assign_expr
unary_expr ::= * postfix_expr
unary_expr ::= * unary_operator cast_expr
unary_expr ::= * SIZEOF unary_expr
unary_expr ::= * SIZEOF LBRACKET type_name RBRACKET
unary_operator ::= * EXCLAMATION
cast_expr ::= * unary_expr
cast_expr ::= * LBRACKET type_name RBRACKET cast_expr
mul_expr ::= * cast_expr
mul_expr ::= * mul_expr STAR cast_expr
mul_expr ::= * mul_expr FSLASH cast_expr
mul_expr ::= * mul_expr PERCENT cast_expr
add_expr ::= * mul_expr
add_expr ::= * add_expr PLUS mul_expr
add_expr ::= * add_expr MINUS mul_expr
shift_expr ::= * add_expr
shift_expr ::= * shift_expr LEFT_OP add_expr
shift_expr ::= * shift_expr RIGHT_OP add_expr
rel_expr ::= * shift_expr
rel_expr ::= * rel_expr LCARET shift_expr
rel_expr ::= * rel_expr RCARET shift_expr
rel_expr ::= * rel_expr LE_OP shift_expr
rel_expr ::= * rel_expr GE_OP shift_expr
eq_expr ::= * rel_expr
eq_expr ::= * eq_expr EQ_OP rel_expr
eq_expr ::= * eq_expr NE_OP rel_expr
and_expr ::= * eq_expr
and_expr ::= * and_expr AND eq_expr
excl_or_expr ::= * and_expr
excl_or_expr ::= * excl_or_expr HAT and_expr
incl_or_expr ::= * excl_or_expr
incl_or_expr ::= * incl_or_expr BAR excl_or_expr
log_and_expr ::= * incl_or_expr
log_and_expr ::= * log_and_expr AND_OP incl_or_expr
log_or_expr ::= * log_and_expr
log_or_expr ::= * log_or_expr OR_OP log_and_expr
cond_expr ::= * log_or_expr
cond_expr ::= * log_or_expr QUESTION expr COLON cond_expr
assign_expr ::= * cond_expr
assign_expr ::= * unary_expr assign_op assign_expr
LBRACKET shift 2
RBRACKET shift-reduce 12 postfix_expr ::= postfix_expr LBRACKET RBRACKET
IDENTIFIER shift-reduce 6 primary_expr ::= IDENTIFIER
CONSTANT shift-reduce 7 primary_expr ::= CONSTANT
STRING_LITERAL shift-reduce 8 primary_expr ::= STRING_LITERAL
SIZEOF shift 32
EXCLAMATION shift-reduce 24 unary_operator ::= EXCLAMATION
assign_expr shift 43 /* because assign_expr==argument_expr_list */
argument_expr_list shift 43
primary_expr shift 36 /* because primary_expr==postfix_expr */
postfix_expr shift 36
unary_expr shift 33
unary_operator shift 31
cast_expr shift 42 /* because cast_expr==mul_expr */
mul_expr shift 42
add_expr shift 55
shift_expr shift 54
rel_expr shift 39
eq_expr shift 47
and_expr shift 69
excl_or_expr shift 68
incl_or_expr shift 66
log_and_expr shift 64
log_or_expr shift 45
cond_expr shift 43 /* because cond_expr==assign_expr */
State 20:
primary_expr ::= * IDENTIFIER
primary_expr ::= * CONSTANT
primary_expr ::= * STRING_LITERAL
primary_expr ::= * LBRACKET expr RBRACKET
postfix_expr ::= * primary_expr
postfix_expr ::= * postfix_expr LSBRACKET expr RSBRACKET
postfix_expr ::= * postfix_expr LBRACKET RBRACKET
postfix_expr ::= * postfix_expr LBRACKET argument_expr_list RBRACKET
postfix_expr ::= * postfix_expr DOT IDENTIFIER
postfix_expr ::= * postfix_expr PTR_OP IDENTIFIER
postfix_expr ::= * postfix_expr INC_OP
postfix_expr ::= * postfix_expr DEC_OP
unary_expr ::= * postfix_expr
unary_expr ::= * unary_operator cast_expr
unary_expr ::= * SIZEOF unary_expr
unary_expr ::= * SIZEOF LBRACKET type_name RBRACKET
unary_operator ::= * EXCLAMATION
cast_expr ::= * unary_expr
cast_expr ::= * LBRACKET type_name RBRACKET cast_expr
mul_expr ::= * cast_expr
mul_expr ::= * mul_expr STAR cast_expr
mul_expr ::= * mul_expr FSLASH cast_expr
mul_expr ::= * mul_expr PERCENT cast_expr
add_expr ::= * mul_expr
add_expr ::= * add_expr PLUS mul_expr
add_expr ::= * add_expr MINUS mul_expr
shift_expr ::= * add_expr
shift_expr ::= * shift_expr LEFT_OP add_expr
shift_expr ::= * shift_expr RIGHT_OP add_expr
rel_expr ::= rel_expr LE_OP * shift_expr
LBRACKET shift 2
IDENTIFIER shift-reduce 6 primary_expr ::= IDENTIFIER
CONSTANT shift-reduce 7 primary_expr ::= CONSTANT
STRING_LITERAL shift-reduce 8 primary_expr ::= STRING_LITERAL
SIZEOF shift 32
EXCLAMATION shift-reduce 24 unary_operator ::= EXCLAMATION
primary_expr shift 36 /* because primary_expr==postfix_expr */
postfix_expr shift 36
unary_expr shift 42 /* because unary_expr==mul_expr */
unary_operator shift 31
cast_expr shift 42 /* because cast_expr==mul_expr */
mul_expr shift 42
add_expr shift 55
shift_expr shift 49
State 36:
postfix_expr ::= postfix_expr * LSBRACKET expr RSBRACKET
postfix_expr ::= postfix_expr * LBRACKET RBRACKET
postfix_expr ::= postfix_expr * LBRACKET argument_expr_list RBRACKET
postfix_expr ::= postfix_expr * DOT IDENTIFIER
postfix_expr ::= postfix_expr * PTR_OP IDENTIFIER
postfix_expr ::= postfix_expr * INC_OP
postfix_expr ::= postfix_expr * DEC_OP
(20) unary_expr ::= postfix_expr *
DOT shift 61
PTR_OP shift 60
LBRACKET shift 4
LBRACKET reduce 20 ** Parsing conflict **
LSBRACKET shift 7
INC_OP shift-reduce 16 postfix_expr ::= postfix_expr INC_OP
DEC_OP shift-reduce 17 postfix_expr ::= postfix_expr DEC_OP
{default} reduce 20 unary_expr ::= postfix_expr
您可以在“状态36”中找到冲突（我剔除了多余的输出）。我认为应该可以使用优先规则来解决，但我不知道如何解决。
冲突来自规则
statement ::= assign_expr argument_expr_list. [UN]
在我看来，这完全没有必要。任何来自此产品的statement也可以源自
statement: expr.
所以语法是模棱两可的：
assign_expr的示例为a = b（unary_expr assign_op assign_expr）。另一个例子是a = sin(0.5)。由于我们也有statement ::= expr（和expr ::= assign_expr），因此可以通过两种方式将a = sin(0.5)解析为statement：作为assign_expr a = sin(0.5)，直接还原为expr或作为assign_expr a = sin，然后是argument_expr_list。在我看来，第二种情况从没有用过，应该只从语法中删除产生式。但是也许您会想到一些特定的语义。
您的语法充满了优先声明，这可能不会造成任何伤害，但是我怀疑这些优先声明中的任何一个是否有任何作用。当然，无法通过任何优先声明来解决所报告的特定移位/减少冲突，因为可能的减少是没有声明优先的单位规则。 （unary_expr ::= postfix_expr.）给它一个任意的优先级可能会解决冲突，但是在我看来，它不太可能以一种有用的方式解决它；但是，您解决了这个问题，则其他规则将变得不可用，这是一个不好的信号。