SQL Parser Listener
Applies to ❌ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
In order to implement custom parser behaviour, it is possible to provide your Configuration with a set of custom org.jooq.ParseListener
implementations.
The current SPI offers hooking into the parsing of 3 types of syntactic elements (see also the parser grammar):
-
term
to parseorg.jooq.Field
expressions -
predicate
to parseorg.jooq.Condition
expressions -
tableFactor
to parseorg.jooq.Table
expressions
The idea is that any listener implementation you provide the parser with may be able to parse functions, top-level-precedence operators, etc. without having to deal with all the lower level precedence operators, such as AND
, OR
, NOT
, +
, -
, etc. etc.
For example, assuming you want to add support for a logical LOGICAL_XOR
operator as a function:
Query query = configuration .derive(ParseListener.onParseCondition(ctx -> { if (ctx.parseFunctionNameIf("LOGICAL_XOR")) { ctx.parse('('); Condition c1 = ctx.parseCondition(); ctx.parse(','); Condition c2 = ctx.parseCondition(); ctx.parse(')'); return c1.andNot(c2).or(c2.andNot(c1)); } // Let the parser take over if we don't know the token return null; }) .dsl() .parser() .parseQuery("select * from t where logical_xor(t.a = 1, t.b = 2)");
The above will just translate the convenience function LOGICAL_XOR(c1, c2)
into its formal definition c1 AND NOT c2 OR c2 AND NOT c1
. But we can do even better than this. If a dialect has native XOR
support, why not support that?
Query query = configuration .derive(ParseListener.onParseCondition(ctx -> { if (ctx.parseFunctionNameIf("LOGICAL_XOR")) { ctx.parse('('); Condition c1 = ctx.parseCondition(); ctx.parse(','); Condition c2 = ctx.parseCondition(); ctx.parse(')'); return CustomCondition.of(c -> { switch (c.family()) { case MARIADB: case MYSQL: c.visit(condition("{0} xor {1}", c1, c2)); break; default: c.visit(c1.andNot(c2).or(c2.andNot(c1))); break; } }); } // Let the parser take over if we don't know the token return null; })) .dsl() .parser() .parseQuery("select * from t where logical_xor(t.a = 1, t.b = 2)"); System.out.println(DSL.using(SQLDialect.MYSQL).render(query)); System.out.println(DSL.using(SQLDialect.ORACLE).render(query));
The output of the above is now:
-- MYSQL: select * from t where (t.a = 1 xor t.b = 2); -- ORACLE: select * from t where (t.a = 1 and not (t.b = 2)) or (t.b = 2 and not (t.a = 1));
This way, with a modest effort, you can parse and/or translate arbitrary column expressions, table expressions, or conditional expressions that jOOQ does not support natively, or override the default behaviour of the parser in this area.
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