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Merge pull request #36 from nyalldawson/precedence

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Setup operator precedence for parser to avoid ambiguity and fix shift/reduce warnings
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Evan Miller 2020-08-22 18:28:23 -04:00 committed by GitHub
commit 8b40423f65
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2 changed files with 22 additions and 7 deletions
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11
src/sql/lexer.l
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@ -50,25 +50,28 @@ struct sql_context;
%%
select { return SELECT; }
select { return SELECT; }
from { return FROM; }
connect { return CONNECT; }
disconnect { return DISCONNECT; }
to { return TO; }
list { return LIST; }
where { return WHERE; }
tables { return TABLES; }
table { return TABLE; }
tables { return TABLES; }
table { return TABLE; }
describe { return DESCRIBE; }
and { return AND; }
or { return OR; }
not { return NOT; }
is { return IS; }
null { return NUL; }
"=" { return EQ; }
(<=) { return LTEQ; }
(>=) { return GTEQ; }
"<" { return LT; }
">" { return GT; }
like { return LIKE; }
limit { return LIMIT; }
limit { return LIMIT; }
count { return COUNT; }
strptime { return STRPTIME; }
[ \t\r] ;

18
src/sql/parser.y
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@ -71,6 +71,18 @@ typedef struct sql_context
%type <ival> nulloperator
%type <name> identifier
//
// operator precedence
//
// left associativity means that 1+2+3 translates to (1+2)+3
// the order of operators here determines their precedence
%left OR
%left AND
%right NOT
%left EQ LTEQ GTEQ LT GT LIKE IS
%%
stmt:
@ -142,9 +154,9 @@ identifier:
;
operator:
'=' { $$ = MDB_EQUAL; }
| '>' { $$ = MDB_GT; }
| '<' { $$ = MDB_LT; }
EQ { $$ = MDB_EQUAL; }
| GT { $$ = MDB_GT; }
| LT { $$ = MDB_LT; }
| LTEQ { $$ = MDB_LTEQ; }
| GTEQ { $$ = MDB_GTEQ; }
| LIKE { $$ = MDB_LIKE; }