Merge pull request #397 from Starch/getString

[Java] add new convenience methods to get char arrays as string.

Author: mjpt777

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/JavaGenerator.java

@@ -1621,6 +1621,23 @@ private CharSequence generatePrimitiveArrayPropertyDecode(final String propertyN
                 fieldLength,
                 generateArrayFieldNotPresentCondition(token.version(), indent),
                 offset));
+
+            sb.append(String.format(
+                "\n" +
+                indent + "    public String %s()\n" +
+                indent + "    {\n" +
+                "%s" +
+                indent + "        final byte[] dst = new byte[%d];\n" +
+                indent + "        buffer.getBytes(this.offset + %d, dst, 0, %d);\n\n" +
+                indent + "        int end = 0;\n" +
+                indent + "        for (; end < %d && dst[end] != 0; ++end);\n\n" +
+                indent + "        return new String(dst, 0, end, %s);\n" +
+                indent + "    }\n\n",
+                formatPropertyName(propertyName),
+                generateStringNotPresentCondition(token.version(), indent),
+                fieldLength, offset,
+                fieldLength, fieldLength,
+                charset(encoding.characterEncoding())));
         }
 
         return sb;
@@ -1695,6 +1712,30 @@ private CharSequence generatePrimitiveArrayPropertyEncode(
                 toUpperFirstChar(propertyName),
                 fieldLength,
                 offset));
+
+            sb.append(String.format(
+                indent + "    public %s %s(final String src)\n" +
+                indent + "    {\n" +
+                indent + "        final int length = %d;\n" +
+                indent + "        final byte[] bytes = src.getBytes(%s);\n" +
+                indent + "        if (bytes.length > length)\n" +
+                indent + "        {\n" +
+                indent + "            throw new IndexOutOfBoundsException(" +
+                                          "\"string too large for copy: byte length=\" + bytes.length);\n" +
+                indent + "        }\n\n" +
+                indent + "        buffer.putBytes(this.offset + %d, bytes, 0, bytes.length);\n\n" +
+                indent + "        for (int start = bytes.length; start < length; ++start)\n" +
+                indent + "        {\n" +
+                indent + "            buffer.putByte(this.offset + %d + start, (byte) 0);\n" +
+                indent + "        }\n\n" +
+                indent + "        return this;\n" +
+                indent + "    }\n",
+                formatClassName(containingClassName),
+                propertyName,
+                fieldLength,
+                charset(encoding.characterEncoding()),
+                offset,
+                offset));
         }
 
         return sb;

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/JavaUtil.java

@@ -19,7 +19,12 @@
 import uk.co.real_logic.sbe.SbeTool;
 import uk.co.real_logic.sbe.util.ValidationUtil;
 
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.EnumMap;
+import java.util.HashMap;
 import java.util.Map;
 
 /**
@@ -83,6 +88,30 @@ public String toString()
         TYPE_NAME_BY_PRIMITIVE_TYPE_MAP.put(PrimitiveType.DOUBLE, "double");
     }
 
+    /** Indexes known charset aliases to the name of the instance in {@link StandardCharsets}. */
+    private static final Map<String, String> STD_CHARSETS = new HashMap<>();
+
+    static
+    {
+        try
+        {
+            for (Field f : StandardCharsets.class.getDeclaredFields())
+            {
+                if (Charset.class.isAssignableFrom(f.getType())
+                        && ((f.getModifiers() & Modifier.STATIC) == Modifier.STATIC))
+                {
+                    final Charset c = (Charset) f.get(null);
+                    STD_CHARSETS.put(c.name(), f.getName());
+                    c.aliases().forEach(alias -> STD_CHARSETS.put(alias, f.getName()));
+                }
+            }
+        }
+        catch (IllegalAccessException e)
+        {
+            throw new RuntimeException(e);
+        }
+    }
+
     /**
      * Map the name of a {@link uk.co.real_logic.sbe.PrimitiveType} to a Java primitive type name.
      *
@@ -168,4 +197,22 @@ public static void append(final StringBuilder builder, final String indent, fina
     {
         builder.append(indent).append(line).append('\n');
     }
+
+    /**
+     * Return java code to fetch an instance of {@link java.nio.charset.Charset} corresponding to the given encoding.
+     * @param encoding the encoding (eg. UTF-8).
+     * @return the code to fetch the assiciated charset.
+     */
+    public static String charset(String encoding)
+    {
+        final String charset = STD_CHARSETS.get(encoding);
+        if (charset != null)
+        {
+            return "java.nio.charset.StandardCharsets." + charset;
+        }
+        else
+        {
+            return "java.nio.charset.Charset.forName(\"" + encoding + "\")";
+        }
+    }
 }

sbe-tool/src/test/java/uk/co/real_logic/sbe/generation/java/JavaGeneratorTest.java

@@ -351,6 +351,25 @@ public void shouldGenerateEnumCodecs() throws Exception
         assertThat(get(decoder, "code"), hasToString("B"));
     }
 
+    @Test
+    public void shouldGenerateGetString() throws Exception
+    {
+        final UnsafeBuffer buffer = new UnsafeBuffer(new byte[4096]);
+        generator().generate();
+
+        final Object encoder = wrap(buffer, compileCarEncoder().newInstance());
+        final Object decoder = getCarDecoder(buffer, encoder);
+
+        set(encoder, "vehicleCode", String.class, "R11");
+        assertThat(get(decoder, "vehicleCode"), is("R11"));
+
+        set(encoder, "vehicleCode", String.class, "");
+        assertThat(get(decoder, "vehicleCode"), is(""));
+
+        set(encoder, "vehicleCode", String.class, "R11R12");
+        assertThat(get(decoder, "vehicleCode"), is("R11R12"));
+    }
+
     private Class<?> getModelClass(final Object encoder) throws ClassNotFoundException
     {
         final String className = "Model";