[Rust] updated codegen to create additional function for primitive arrays that will accept an "impl Iterator". This allows an arbitrary number of items to be passed in, which will guarantee the correct number of items are encoded (defined 'nullValue' will be used where appropriate)

Author: Michael Ward

rust/tests/extension_test.rs

@@ -187,7 +187,7 @@ fn encode_car_from_scratch() -> SbeResult<(usize, Vec<u8>)> {
     car.available(BooleanType::T);
     car.code(Model::A);
     car.some_numbers(&[0, 1, 2, 3]);
-    car.vehicle_code(b"abcdef_extra_is_ignored"); // abcdef
+    car.vehicle_code_from_iter(b"abcdef_extra_is_ignored".iter().map(|x| *x)); // abcdef
 
     extras.set_cruise_control(true);
     extras.set_sports_pack(true);

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

@@ -361,7 +361,23 @@ static void generateEncoderVarData(
         }
     }
 
-    private static void generatePrimitiveEncoder(
+    private static void generateRustDoc(
+        final StringBuilder sb,
+        final int level,
+        final Token typeToken,
+        final Encoding encoding) throws IOException
+    {
+        indent(sb, level, "/// - min value: %s\n", encoding.applicableMinValue());
+        indent(sb, level, "/// - max value: %s\n", encoding.applicableMaxValue());
+        indent(sb, level, "/// - null value: %s\n", encoding.applicableNullValue());
+        indent(sb, level, "/// - characterEncoding: %s\n", encoding.characterEncoding());
+        indent(sb, level, "/// - semanticType: %s\n", encoding.semanticType());
+        indent(sb, level, "/// - encodedOffset: %d\n", typeToken.offset());
+        indent(sb, level, "/// - encodedLength: %d\n", typeToken.encodedLength());
+        indent(sb, level, "/// - version: %d\n", typeToken.version());
+    }
+
+    private static void generatePrimitiveArrayEncoder(
         final StringBuilder sb,
         final int level,
         final Token typeToken,
@@ -371,37 +387,29 @@ private static void generatePrimitiveEncoder(
         final PrimitiveType primitiveType = encoding.primitiveType();
         final String rustPrimitiveType = rustTypeName(primitiveType);
         final int arrayLength = typeToken.arrayLength();
-        if (arrayLength > 1)
-        {
-            indent(sb, level, "/// primitive array field '%s'\n", name);
-            indent(sb, level, "/// - min value: %s\n", encoding.applicableMinValue());
-            indent(sb, level, "/// - max value: %s\n", encoding.applicableMaxValue());
-            indent(sb, level, "/// - null value: %s\n", encoding.applicableNullValue());
-            indent(sb, level, "/// - characterEncoding: %s\n", encoding.characterEncoding());
-            indent(sb, level, "/// - semanticType: %s\n", encoding.semanticType());
-            indent(sb, level, "/// - encodedOffset: %d\n", typeToken.offset());
-            indent(sb, level, "/// - encodedLength: %d\n", typeToken.encodedLength());
-            indent(sb, level, "/// - version: %d\n", typeToken.version());
-            indent(sb, level, "#[inline]\n");
-            indent(sb, level, "pub fn %s(&mut self, value: &[%s]) {\n",
-                formatFunctionName(name),
-                rustPrimitiveType);
 
-            // NB: must create variable 'offset' before calling mutable self.get_buf_mut()
-            indent(sb, level + 1, "let offset = self.%s;\n", getBufOffset(typeToken));
-            indent(sb, level + 1, "let buf = self.get_buf_mut();\n");
+        indent(sb, level, "/// primitive array field '%s'\n", name);
+        generateRustDoc(sb, level, typeToken, encoding);
+        indent(sb, level, "#[inline]\n");
+        indent(sb, level, "pub fn %s(&mut self, value: &[%s]) {\n",
+            formatFunctionName(name), rustPrimitiveType);
 
-            if (rustPrimitiveType.equals("u8"))
-            {
-                indent(sb, level + 1, "let mid = %d.min(value.len());\n", arrayLength);
-                indent(sb, level + 1, "buf.put_slice_at(offset, value.split_at(mid).0);\n");
-                indent(sb, level + 1, "for i in mid..%d {\n", arrayLength);
-                indent(sb, level + 2, "buf.put_u8_at(offset + (i * 1), %s_u8);\n", encoding.applicableNullValue());
-                indent(sb, level + 1, "}\n");
-                indent(sb, level, "}\n\n");
-                return;
-            }
+        // NB: must create variable 'offset' before calling mutable self.get_buf_mut()
+        indent(sb, level + 1, "debug_assert_eq!(%d, value.len());\n", arrayLength);
+        indent(sb, level + 1, "let offset = self.%s;\n", getBufOffset(typeToken));
+        indent(sb, level + 1, "let buf = self.get_buf_mut();\n");
 
+        if (rustPrimitiveType.equals("u8"))
+        {
+            indent(sb, level + 1, "let mid = %d.min(value.len());\n", arrayLength);
+            indent(sb, level + 1, "buf.put_slice_at(offset, value.split_at(mid).0);\n");
+            indent(sb, level + 1, "for i in mid..%d {\n", arrayLength);
+            indent(sb, level + 2, "buf.put_u8_at(offset + (i * 1), %s_u8);\n", encoding.applicableNullValue());
+            indent(sb, level + 1, "}\n");
+            indent(sb, level, "}\n\n");
+        }
+        else
+        {
             for (int i = 0; i < arrayLength; i++)
             {
                 if (i == 0)
@@ -419,34 +427,59 @@ private static void generatePrimitiveEncoder(
 
             indent(sb, level, "}\n\n");
         }
-        else
+
+        indent(sb, level, "/// primitive array field '%s' from an Iterator\n", name);
+        generateRustDoc(sb, level, typeToken, encoding);
+        indent(sb, level, "#[inline]\n");
+        indent(sb, level, "pub fn %s_from_iter(&mut self, iter: impl Iterator<Item = %s>) {\n",
+            formatFunctionName(name), rustPrimitiveType);
+
+        indent(sb, level + 1, "let offset = self.%s;\n", getBufOffset(typeToken));
+        indent(sb, level + 1, "let buf = self.get_buf_mut();\n");
+        indent(sb, level + 1, "let iter = iter.chain(std::iter::repeat(%s_%s)).take(%d);\n",
+            encoding.applicableNullValue(), rustPrimitiveType, arrayLength);
+
+        indent(sb, level + 1, "for (i, v) in iter.enumerate() {\n");
+        indent(sb, level + 2, "buf.put_%s_at(offset + (i * %d), v);\n",
+            rustPrimitiveType, primitiveType.size());
+        indent(sb, level + 1, "}\n");
+        indent(sb, level, "}\n\n");
+    }
+
+    private static void generatePrimitiveEncoder(
+        final StringBuilder sb,
+        final int level,
+        final Token typeToken,
+        final String name) throws IOException
+    {
+        final int arrayLength = typeToken.arrayLength();
+        if (arrayLength > 1)
         {
-            if (encoding.presence() == Encoding.Presence.CONSTANT)
-            {
-                indent(sb, level, "// skipping CONSTANT %s\n\n", name);
-            }
-            else
-            {
-                indent(sb, level, "/// primitive field '%s'\n", name);
-                indent(sb, level, "/// - min value: %s\n", encoding.applicableMinValue());
-                indent(sb, level, "/// - max value: %s\n", encoding.applicableMaxValue());
-                indent(sb, level, "/// - null value: %s\n", encoding.applicableNullValue());
-                indent(sb, level, "/// - characterEncoding: %s\n", encoding.characterEncoding());
-                indent(sb, level, "/// - semanticType: %s\n", encoding.semanticType());
-                indent(sb, level, "/// - encodedOffset: %d\n", typeToken.offset());
-                indent(sb, level, "/// - encodedLength: %d\n", typeToken.encodedLength());
-                indent(sb, level, "/// - version: %d\n", typeToken.version());
-                indent(sb, level, "#[inline]\n");
-                indent(sb, level, "pub fn %s(&mut self, value: %s) {\n",
-                    formatFunctionName(name),
-                    rustPrimitiveType);
-
-                // NB: must create variable 'offset' before calling mutable self.get_buf_mut()
-                indent(sb, level + 1, "let offset = self.%s;\n", getBufOffset(typeToken));
-                indent(sb, level + 1, "self.get_buf_mut().put_%s_at(offset, value);\n", rustPrimitiveType);
-                indent(sb, level, "}\n\n");
-            }
+            generatePrimitiveArrayEncoder(sb, level, typeToken, name);
+            return;
+        }
+
+        final Encoding encoding = typeToken.encoding();
+        if (encoding.presence() == Encoding.Presence.CONSTANT)
+        {
+            indent(sb, level, "// skipping CONSTANT %s\n\n", name);
+            return;
         }
+
+        final PrimitiveType primitiveType = encoding.primitiveType();
+        final String rustPrimitiveType = rustTypeName(primitiveType);
+
+        indent(sb, level, "/// primitive field '%s'\n", name);
+        generateRustDoc(sb, level, typeToken, encoding);
+        indent(sb, level, "#[inline]\n");
+        indent(sb, level, "pub fn %s(&mut self, value: %s) {\n",
+            formatFunctionName(name), rustPrimitiveType);
+
+        // NB: must create variable 'offset' before calling mutable self.get_buf_mut()
+        indent(sb, level + 1, "let offset = self.%s;\n", getBufOffset(typeToken));
+        indent(sb, level + 1, "self.get_buf_mut().put_%s_at(offset, value);\n", rustPrimitiveType);
+        indent(sb, level, "}\n\n");
+
     }
 
     private static void generateEnumEncoder(