Add support for additional Oracle SQL functions and enhance token management

Author: xterao

src/main/java/org/domaframework/doma/intellij/SqlTokenHelper.java

@@ -26,22 +26,36 @@
 
 public class SqlTokenHelper {
 
+  static final Set<String> KEYWORD_TOKENS = new HashSet<>();
+  static final Set<String> DATA_TYPE_TOKENS = new HashSet<>();
+  static final Set<String> FUNCTION_TOKENS = new HashSet<>();
+
+  static {
+    // Initialize keyword tokens
+    KEYWORD_TOKENS.addAll(SqlKeywordTokenUtil.getTokens());
+
+    // Initialize DataType tokens
+    DATA_TYPE_TOKENS.addAll(SqlDataTypeTokenUtil.getTokens());
+
+    // Initialize function tokens
+    FUNCTION_TOKENS.addAll(SqlFunctionToken.getTokens());
+    FUNCTION_TOKENS.addAll(PostgresSqlFunctionToken.getTokens());
+    FUNCTION_TOKENS.addAll(MySqlFunctionToken.getTokens());
+    FUNCTION_TOKENS.addAll(OracleFunctionToken.getTokens());
+  }
+
+  // Keywords
   public static Set<String> getKeyword() {
-    return SqlKeywordTokenUtil.getTokens();
+    return KEYWORD_TOKENS;
   }
 
+  // Data Types
   public static Set<String> getDataTypeTokens() {
-    return SqlDataTypeTokenUtil.getTokens();
+    return DATA_TYPE_TOKENS;
   }
 
   // Functions
   public static Set<String> getFunctionTokens() {
-    Set<String> tokens = new HashSet<>(SqlFunctionToken.getTokens());
-    tokens.addAll(SqlFunctionToken.getTokens());
-    tokens.addAll(PostgresSqlFunctionToken.getTokens());
-    tokens.addAll(MySqlFunctionToken.getTokens());
-    tokens.addAll(OracleFunctionToken.getTokens());
-
-    return tokens;
+    return FUNCTION_TOKENS;
   }
 }

src/main/java/org/domaframework/doma/intellij/tokens/OracleFunctionToken.java

@@ -23,22 +23,88 @@ public class OracleFunctionToken {
   static final Set<String> TOKENS = new HashSet<>();
 
   static {
-    TOKENS.addAll(
-        Set.of(
-            "abs",
-            "ceil",
-            "floor",
-            "round",
-            "power",
-            "sqrt",
-            "exp",
-            "log",
-            "to_char",
-            "to_date",
-            "to_number",
-            "current_date",
-            "current_timestamp",
-            "sysdate"));
+    // Mathematical Functions
+    {
+      TOKENS.addAll(
+          Set.of(
+              "abs",
+              "ceil",
+              "floor",
+              "mod",
+              "power",
+              "sqrt",
+              "sign",
+              "trunc"
+          ));
+    }
+    // Conversion Functions
+    {
+      TOKENS.addAll(
+          Set.of(
+              "asciistr",
+              "instr",
+              "instrb",
+              "instr4",
+              "length",
+              "lengthb",
+              "length4",
+              "cast",
+              "numtodsinterval",
+              "numtoyminterval",
+              "to_char",
+              "to_date",
+              "to_number",
+              "unistr"
+          ));
+    }
+    // String Functions
+    {
+      TOKENS.addAll(
+          Set.of(
+              "substr",
+              "substrb",
+              "substr4"
+          ));
+    }
+    // Lob Functions
+    {
+      TOKENS.addAll(
+          Set.of(
+              "empty_blob",
+              "empty_clob",
+              "to_blob",
+              "to_clob",
+              "to_lob",
+              "to_nclob"
+          ));
+    }
+    // Comparison functions
+    {
+      TOKENS.addAll(
+          Set.of(
+              "decode",
+              "greatest",
+              "least",
+              "coalesce",
+              "nullif",
+              "nvl"
+          ));
+    }
+    // Date/Time Functions
+    {
+      TOKENS.addAll(
+          Set.of(
+              "add_months",
+              "extract",
+              "months_between",
+              "round",
+              "sysdate",
+              "getdate",
+              "timestampadd",
+              "timestampdiff",
+              "to_date"
+          ));
+    }
   }
 
   public static Set<String> getTokens() {