Fix #228 by removing invalid sanity check. (#230)

This sanity check threw an exception from SqlParser whenever a data type
reference that included more than one argument was encountered.  The
check appears to have been completely erroneous from the start and on
removing it, no other modifications were needed.  However, note that 
at this time we do not actually do anything with those arguments.  At this
time their presence is simply tolerated to improve SQL-92 
compatibility.  See #231 for one way we could use these arguments.

This commit also adds a few tests to SqlParserTests to cover this
scenario and prevent regressions.

lang/src/org/partiql/lang/syntax/SqlParser.kt

@@ -718,9 +718,6 @@ class SqlParser(private val ion: IonSystem) : Parser {
         if(type != TYPE) {
             errMalformedParseTree("Expected ParseType.TYPE instead of $type")
         }
-        if(children.size > 1) {
-            errMalformedParseTree("Apparently DataType needs multiple lengths, sizes, etc")
-        }
         val sqlDataType = SqlDataType.forTypeName(token!!.keywordText!!)
         if(sqlDataType == null) {
             errMalformedParseTree("Invalid DataType: ${token.keywordText!!}")

lang/test/org/partiql/lang/syntax/SqlParserTest.kt

@@ -909,22 +909,116 @@ class SqlParserTest : SqlParserTestBase() {
         "(term (exp (cast (term (exp (lit 5))) (term (exp (type character_varying))))))"
     )
 
+
+    @Test
+    fun castASVarChar() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type character_varying)
+           )
+        """,
+        "CAST(a AS VARCHAR)",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type character_varying)))
+           )))
+        """
+    )
+
     @Test
-    fun castArg() = assertExpression(
+    fun castASVarCharWithLength() = assertExpression(
         """(cast
-             (+ (lit 5) (id a case_insensitive))
+             (id a case_insensitive)
              (type character_varying 1)
            )
         """,
-        "CAST(5 + a AS VARCHAR(1))",
-        """(term (exp (cast (term (exp (+ (term (exp (lit 5)))
-                                          (term (exp (id a case_insensitive)))
-                            )))
+        "CAST(a AS VARCHAR(1))",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
                             (term (exp (type character_varying 1)))
            )))
         """
     )
 
+    @Test
+    fun castAsDecimal() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type decimal)
+           )
+        """,
+        "CAST(a AS DECIMAL)",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type decimal)))
+           )))
+        """
+    )
+
+    @Test
+    fun castAsDecimalScaleOnly() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type decimal 1)
+           )
+        """,
+        "CAST(a AS DECIMAL(1))",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type decimal 1)))
+           )))
+        """
+    )
+    @Test
+    fun castAsDecimalScaleAndPrecision() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type decimal 1 2)
+           )
+        """,
+        "CAST(a AS DECIMAL(1, 2))",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type decimal 1 2)))
+           )))
+        """
+    )
+    @Test
+    fun castAsNumeric() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type numeric)
+           )
+        """,
+        "CAST(a AS NUMERIC)",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type numeric)))
+           )))
+        """
+    )
+
+    @Test
+    fun castAsNumericScaleOnly() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type numeric 1)
+           )
+        """,
+        "CAST(a AS NUMERIC(1))",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type numeric 1)))
+           )))
+        """
+    )
+    @Test
+    fun castAsNumericScaleAndPrecision() = assertExpression(
+        """(cast
+             (id a case_insensitive)
+             (type numeric 1 2)
+           )
+        """,
+        "CAST(a AS NUMERIC(1, 2))",
+        """(term (exp (cast (term (exp (id a case_insensitive)))
+                            (term (exp (type numeric 1 2)))
+           )))
+        """
+    )
+
     //****************************************
     // searched CASE
     //****************************************