Postgres Array Operators are unsupported expressions

[richard-merrick]

Parsing postgres dialect SQL which contains array operators returns ValueError (Unsupported expression type)

Tested in sqlglot ==20.11.0
Affects at least ArrayOverlaps and ArrayContains

(https://www.postgresql.org/docs/current/functions-array.html)

from sqlglot import parse_one 

sql = "SELECT ARRAY[1,2,3] && ARRAY[2,3,4] FROM table_xyz;"

x = parse_one(sql, read='postgres')

print(x)

Traceback (most recent call last):
  File "./temp.py", line 8, in <module>
    print(x)
  File "./env/lib/python3.10/site-packages/sqlglot/expressions.py", line 501, in __str__
    return self.sql()
  File "./env/lib/python3.10/site-packages/sqlglot/expressions.py", line 526, in sql
    return Dialect.get_or_raise(dialect).generate(self, **opts)
  File "./env/lib/python3.10/site-packages/sqlglot/dialects/dialect.py", line 452, in generate
    return self.generator(**opts).generate(expression, copy=copy)
  File "./env/lib/python3.10/site-packages/sqlglot/generator.py", line 492, in generate
    sql = self.sql(expression).strip()
  File "./env/lib/python3.10/site-packages/sqlglot/generator.py", line 650, in sql
    sql = getattr(self, exp_handler_name)(expression)
  File "./env/lib/python3.10/site-packages/sqlglot/generator.py", line 2062, in select_sql
    expressions = self.expressions(expression)
  File "./env/lib/python3.10/site-packages/sqlglot/generator.py", line 2978, in expressions
    sql = self.sql(e, comment=False)
  File "./env/lib/python3.10/site-packages/sqlglot/generator.py", line 656, in sql
    raise ValueError(f"Unsupported expression type {expression.__class__.__name__}")
ValueError: Unsupported expression type ArrayOverlaps