Merge pull request #685 from ian-p-cooke/streaming_rust

enhancements to Rust generator

Author: mjpt777

.gitignore

@@ -13,7 +13,7 @@
 # Build tools
 build-local.properties
 deps
-/bin
+*/bin
 build
 .gradle
 target
@@ -23,6 +23,7 @@ GPATH
 prop
 out
 .vs/
+.vscode
 
 # cmake
 

build.gradle

@@ -569,7 +569,8 @@ def cargo_exists() {
     try {
         def result = project.exec {
             executable = 'cargo'
-            args = '-v'
+            args = [ '-V' ]
+            standardOutput = new ByteArrayOutputStream()
         }
         return result.exitValue == 0
     }

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

@@ -173,7 +173,7 @@ void appendWrapMethod(final Appendable appendable, final String structName)
         throws IOException
     {
         appendable.append("\n").append(INDENT).append(String.format(
-            "fn wrap(%s: %s) -> %s {%n", scratchProperty(), RustGenerator.withLifetime(scratchType()),
+            "pub fn wrap(%s: %s) -> %s {%n", scratchProperty(), RustGenerator.withLifetime(scratchType()),
             RustGenerator.withLifetime(structName)));
         indent(appendable, 2, "%s { %s: %s }\n",
             structName, scratchProperty(), scratchProperty());

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

@@ -53,6 +53,8 @@ public RustGenerator(final Ir ir, final OutputManager outputManager)
 
     public void generate() throws IOException
     {
+        final int headerSize = totalByteSize(ir.headerStructure());
+
         generateSharedImports(outputManager);
         generateResultEnums(outputManager);
         generateDecoderScratchStruct(outputManager);
@@ -61,7 +63,7 @@ public void generate() throws IOException
         generateEnums(ir, outputManager);
         generateComposites(ir, outputManager);
         generateBitSets(ir, outputManager);
-        final int headerSize = totalByteSize(ir.headerStructure());
+        generateMessageHeaderDecoder(outputManager, headerSize);
 
         for (final List<Token> tokens : ir.messages())
         {
@@ -285,6 +287,27 @@ private static void generateEntryPoint(
         }
     }
 
+    static void generateMessageHeaderDecoder(
+        final OutputManager outputManager,
+        final int headerSize) throws IOException
+    {
+        final String messageTypeName = "MessageHeader";
+        final RustCodecType codecType = RustCodecType.Decoder;
+        try (Writer writer = outputManager.createOutput(messageTypeName + format(" %s entry point", codecType.name())))
+        {
+            final String gerund = codecType.gerund();
+            writer.append(format("pub fn start_%s_%s<%s>(data: &%s%s [u8]) -> CodecResult<(&%s %s, %s)> {\n", gerund,
+                formatMethodName(messageTypeName), DATA_LIFETIME, DATA_LIFETIME,
+                codecType == RustCodecType.Encoder ? " mut" : "",
+                DATA_LIFETIME, messageTypeName,
+                withLifetime(codecType.scratchType())));
+            indent(writer, 1, format("let mut scratch = %s { data: data, pos: 0 };\n", codecType.scratchType()));
+            indent(writer, 1, format("let v = scratch.read_type::<%s>(%s)?;\n", messageTypeName, headerSize));
+            indent(writer, 1, "Ok((v, scratch))\n");
+            writer.append("}\n");
+        }
+    }
+
     static String withLifetime(final String typeName)
     {
         return format("%s<%s>", typeName, DATA_LIFETIME);
@@ -1163,7 +1186,7 @@ static void generateEncoderScratchStruct(final OutputManager outputManager) thro
         try (Writer writer = outputManager.createOutput("Scratch Encoder Data Wrapper - codec internal use only"))
         {
             writer.append("#[derive(Debug)]\n");
-            writer.append(format("struct %s<%s> {\n", SCRATCH_ENCODER_TYPE, DATA_LIFETIME));
+            writer.append(format("pub struct %s<%s> {\n", SCRATCH_ENCODER_TYPE, DATA_LIFETIME));
             indent(writer, 1, "data: &%s mut [u8],\n", DATA_LIFETIME);
             indent(writer).append("pos: usize,\n");
             writer.append("}\n");
@@ -1291,7 +1314,7 @@ private static void generateDecoderScratchStruct(final OutputManager outputManag
         try (Writer writer = outputManager.createOutput("Scratch Decoder Data Wrapper - codec internal use only"))
         {
             writer.append("#[derive(Debug)]\n");
-            writer.append(format("struct %s<%s> {\n", SCRATCH_DECODER_TYPE, DATA_LIFETIME));
+            writer.append(format("pub struct %s<%s> {\n", SCRATCH_DECODER_TYPE, DATA_LIFETIME));
             indent(writer, 1, "data: &%s [u8],\n", DATA_LIFETIME);
             indent(writer).append("pos: usize,\n");
             writer.append("}\n");
@@ -1798,6 +1821,18 @@ private void generateMessageHeaderDefault(
             indent(writer, 1, "pub message_header: MessageHeader\n");
             writer.append("}\n");
 
+            final String blockLength = Integer.toString(messageToken.encodedLength());
+            final String templateId = Integer.toString(messageToken.id());
+            final String schemaId = Integer.toString(ir.id());
+            final String version = Integer.toString(ir.version());
+
+            indent(writer, 0, "impl %s {\n", wrapperName);
+            indent(writer, 1, "pub const BLOCK_LENGTH : u16 = " + blockLength + ";\n");
+            indent(writer, 1, "pub const TEMPLATE_ID : u16 = " + templateId + ";\n");
+            indent(writer, 1, "pub const SCHEMA_ID : u16 = " + schemaId + ";\n");
+            indent(writer, 1, "pub const VERSION : u16 = " + version + ";\n");
+            indent(writer, 0, "}\n");
+
             indent(writer, 0, "impl Default for %s {\n", wrapperName);
             indent(writer, 1, "fn default() -> %s {\n", wrapperName);
             indent(writer, 2, "%s {\n", wrapperName);
@@ -1807,10 +1842,10 @@ private void generateMessageHeaderDefault(
                 new HashMap<String, String>()
                 {
                     {
-                        put("block_length", Integer.toString(messageToken.encodedLength()));
-                        put("template_id", Integer.toString(messageToken.id()));
-                        put("schema_id", Integer.toString(ir.id()));
-                        put("version", Integer.toString(ir.version()));
+                        put("block_length", blockLength);
+                        put("template_id", templateId);
+                        put("schema_id", schemaId);
+                        put("version", version);
                     }
                 });
 

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

@@ -237,7 +237,7 @@ private static boolean cargoExists()
     {
         try
         {
-            final ProcessBuilder builder = new ProcessBuilder("cargo", "-v");
+            final ProcessBuilder builder = new ProcessBuilder("cargo", "-V");
             final Process process = builder.start();
             process.waitFor(5, TimeUnit.SECONDS);
             return process.exitValue() == 0;