Fix parsing of booleanLiterals in cql2-text

pygeofilter/parsers/cql2_text/grammar.lark

@@ -126,7 +126,7 @@ func.2: attribute "(" expression ("," expression)* ")" -> function
 
 envelope: "ENVELOPE"i "(" number number number number ")"
 
-BOOLEAN: ( "TRUE" | "FALSE" )
+BOOLEAN.2: ( "TRUE"i | "FALSE"i)
 
 DOUBLE_QUOTED: "\"" /.*?/ "\""
 SINGLE_QUOTED: "'" /.*?/ "'"

pygeofilter/parsers/cql2_text/parser.py

@@ -178,8 +178,8 @@ def INT(self, value):
     def FLOAT(self, value):
         return float(value)
 
-    def boolean(self, value):
-        return value in ("TRUE", "true", "T", "t", "1")
+    def BOOLEAN(self, value):
+        return value.lower() == "true"
 
     def DOUBLE_QUOTED(self, token):
         return token[1:-1]

tests/parsers/cql2_text/test_parser.py

@@ -0,0 +1,33 @@
+from pygeofilter import ast
+from pygeofilter.parsers.cql2_text import parse
+
+
+def test_attribute_eq_true_uppercase():
+    result = parse("attr = TRUE")
+    assert result == ast.Equal(
+        ast.Attribute("attr"),
+        True,
+    )
+
+def test_attribute_eq_true_lowercase():
+    result = parse("attr = true")
+    assert result == ast.Equal(
+        ast.Attribute("attr"),
+        True,
+    )
+
+
+def test_attribute_eq_false_uppercase():
+    result = parse("attr = FALSE")
+    assert result == ast.Equal(
+        ast.Attribute("attr"),
+        False,
+    )
+
+
+def test_attribute_eq_false_lowercase():
+    result = parse("attr = false")
+    assert result == ast.Equal(
+        ast.Attribute("attr"),
+        False,
+    )