Fix: is true for presto closes #1740

tobymao · Jun 7, 2023 · 0cc09cf · 0cc09cf
1 parent d2e46c3
commit 0cc09cf
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Showing 3 changed files with 29 additions and 0 deletions.
diff --git a/sqlglot/dialects/presto.py b/sqlglot/dialects/presto.py
@@ -242,6 +242,7 @@ class Generator(generator.Generator):
         INTERVAL_ALLOWS_PLURAL_FORM = False
         JOIN_HINTS = False
         TABLE_HINTS = False
+        IS_BOOL = False
         STRUCT_DELIMITER = ("(", ")")
 
         PROPERTIES_LOCATION = {

diff --git a/sqlglot/generator.py b/sqlglot/generator.py
@@ -237,6 +237,7 @@ class Generator:
 
     JOIN_HINTS = True
     TABLE_HINTS = True
+    IS_BOOL = True
 
     RESERVED_KEYWORDS: t.Set[str] = set()
     WITH_SEPARATED_COMMENTS = (exp.Select, exp.From, exp.Where, exp.With)
@@ -2127,6 +2128,10 @@ def ilikeany_sql(self, expression: exp.ILikeAny) -> str:
         return self.binary(expression, "ILIKE ANY")
 
     def is_sql(self, expression: exp.Is) -> str:
+        if not self.IS_BOOL and isinstance(expression.expression, exp.Boolean):
+            return self.sql(
+                expression.this if expression.expression.this else exp.not_(expression.this)
+            )
         return self.binary(expression, "IS")
 
     def like_sql(self, expression: exp.Like) -> str:

diff --git a/tests/dialects/test_redshift.py b/tests/dialects/test_redshift.py
@@ -18,6 +18,29 @@ def test_redshift(self):
             },
         )
 
+        self.validate_all(
+            "x is true",
+            write={
+                "redshift": "x IS TRUE",
+                "presto": "x",
+            },
+        )
+        self.validate_all(
+            "x is false",
+            write={
+                "redshift": "x IS FALSE",
+                "presto": "NOT x",
+            },
+        )
+
+        self.validate_all(
+            "x is not false",
+            write={
+                "redshift": "NOT x IS FALSE",
+                "presto": "NOT NOT x",
+            },
+        )
+
         self.validate_all(
             "SELECT SYSDATE",
             write={