Use a regex to detect correctly match function

Author: carlosdelest

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/fulltext/Match.java

@@ -132,7 +132,7 @@ public String functionName() {
 
     private boolean isOperator() {
         if (isOperator == null) {
-            isOperator = source().text().toUpperCase(Locale.ROOT).startsWith(super.functionName()) == false;
+            isOperator = source().text().toUpperCase(Locale.ROOT).matches("^" + super.functionName() + "\\s*\\(.*\\)") == false;
         }
         return isOperator;
     }

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/VerifierTests.java

@@ -1145,6 +1145,19 @@ public void testMatchFunctionNotAllowedAfterCommands() throws Exception {
         );
     }
 
+    public void testMatchFunctionAndOperatorHaveCorrectErrorMessages() throws Exception {
+        assertEquals(
+            "1:24: [MATCH] function cannot be used after LIMIT",
+            error("from test | limit 10 | where match(first_name, \"Anna\")")
+        );
+        assertEquals(
+            "1:24: [MATCH] function cannot be used after LIMIT",
+            error("from test | limit 10 | where match ( first_name, \"Anna\" ) ")
+        );
+        assertEquals("1:24: [:] operator cannot be used after LIMIT", error("from test | limit 10 | where first_name:\"Anna\""));
+        assertEquals("1:24: [:] operator cannot be used after LIMIT", error("from test | limit 10 | where first_name : \"Anna\""));
+    }
+
     public void testQueryStringFunctionsNotAllowedAfterCommands() throws Exception {
         // Source commands
         assertEquals("1:13: [QSTR] function cannot be used after SHOW", error("show info | where qstr(\"8.16.0\")"));