Create local variable for whether we're in PostgreSQL mode, remove…

Create local variable for whether we're in PostgreSQL mode, remove implementation details from doco, add compiler/IDE hint for falling-through switch statement

h2/src/docsrc/html/features.html

@@ -954,7 +954,7 @@ or the SQL statement <code>SET MODE PostgreSQL</code>.
     <ul>
     <li>Uses \ for back-references</li>
     <li>Will not throw an exception when the <code>flagsString</code> parameter contains a 'g'</li>
-    <li>Will use Java's <code>String.replaceFirst()</code> method (instead of <code>String.replaceAll()</code>) if the 'g' flag is not present in the <code>flagsString</code> parameter.</li>
+    <li>In the absence of the 'g' flag in the <code>flagsString</code> parameter, only the first-matched substring will be replaced</li>
     </ul>
 </li><li>Fixed-width strings are padded with spaces.
 </li><li>MONEY data type is treated like NUMERIC(19, 2) data type.

h2/src/main/org/h2/expression/Function.java

@@ -1370,9 +1370,10 @@ public class Function extends Expression implements FunctionCall {
             }
             String regexpMode = v3 == null || v3.getString() == null ? "" :
                     v3.getString();
-            int flags = makeRegexpFlags(regexpMode, Mode.ModeEnum.PostgreSQL.equals(database.getMode().getEnum()));
+            boolean isInPostgreSqlMode = Mode.ModeEnum.PostgreSQL.equals(database.getMode().getEnum())
+            int flags = makeRegexpFlags(regexpMode, isInPostgreSqlMode);
             try {
-                if(Mode.ModeEnum.PostgreSQL.equals(database.getMode().getEnum()) && !regexpMode.contains("g")) {
+                if(isInPostgreSqlMode && !regexpMode.contains("g")) {
                   result = ValueString.get(
                     Pattern.compile(regexp, flags).matcher(v0.getString())
                       .replaceFirst(replacement),
@@ -2060,6 +2061,7 @@ public class Function extends Expression implements FunctionCall {
                         if (ignoreGlobalFlag) {
                             break;
                         }
+                    //$FALL-THROUGH$
                     default:
                         throw DbException.get(ErrorCode.INVALID_VALUE_2, stringFlags);
                 }