[Rust] Elide explicit ActingVersion lifetime. (aeron-io#1053)

Author: gierlachg

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

@@ -26,7 +26,7 @@
 
 import static uk.co.real_logic.sbe.generation.rust.RustGenerator.CodecType.Encoder;
 import static uk.co.real_logic.sbe.generation.rust.RustGenerator.CodecType.Decoder;
-import static uk.co.real_logic.sbe.generation.rust.RustGenerator.withLifetime;
+import static uk.co.real_logic.sbe.generation.rust.RustGenerator.withBufLifetime;
 import static uk.co.real_logic.sbe.generation.rust.RustUtil.*;
 
 class MessageCoderDef implements RustGenerator.ParentDef
@@ -171,8 +171,8 @@ void appendMessageStruct(final Appendable out, final String structName) throws I
             indent(out, 1, "#[derive(Debug, Default)]\n");
         }
 
-        indent(out, 1, "pub struct %s {\n", withLifetime(structName));
-        indent(out, 2, "buf: %s,\n", withLifetime(this.codecType.bufType()));
+        indent(out, 1, "pub struct %s {\n", withBufLifetime(structName));
+        indent(out, 2, "buf: %s,\n", withBufLifetime(this.codecType.bufType()));
         indent(out, 2, "initial_offset: usize,\n");
         indent(out, 2, "offset: usize,\n");
         indent(out, 2, "limit: usize,\n");
@@ -190,7 +190,7 @@ void appendWrapFn(final Appendable out) throws IOException
         {
             indent(out, 2, "pub fn wrap(\n");
             indent(out, 3, "mut self,\n");
-            indent(out, 3, "buf: %s,\n", withLifetime(this.codecType.bufType()));
+            indent(out, 3, "buf: %s,\n", withBufLifetime(this.codecType.bufType()));
             indent(out, 3, "offset: usize,\n");
             indent(out, 3, "acting_block_length: %s,\n", blockLengthType());
             indent(out, 3, "acting_version: %s,\n", schemaVersionType());
@@ -200,7 +200,7 @@ void appendWrapFn(final Appendable out) throws IOException
         else
         {
             indent(out, 2, "pub fn wrap(mut self, buf: %s, offset: usize) -> Self {\n",
-                withLifetime(this.codecType.bufType()));
+                withBufLifetime(this.codecType.bufType()));
             indent(out, 3, "let limit = offset + SBE_BLOCK_LENGTH as usize;\n");
         }
 

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

@@ -52,6 +52,7 @@ public class RustGenerator implements CodeGenerator
 {
     static final String WRITE_BUF_TYPE = "WriteBuf";
     static final String READ_BUF_TYPE = "ReadBuf";
+    static final String ANONYMOUS_LIFETIME = "'_";
     static final String BUF_LIFETIME = "'a";
 
     enum CodecType
@@ -189,9 +190,19 @@ String schemaVersionType()
         return rustTypeName(ir.headerStructure().schemaVersionType());
     }
 
-    static String withLifetime(final String typeName)
+    static String withAnonymousLifetime(final String typeName)
     {
-        return format("%s<%s>", typeName, BUF_LIFETIME);
+        return withLifetime(typeName, ANONYMOUS_LIFETIME);
+    }
+
+    static String withBufLifetime(final String typeName)
+    {
+        return withLifetime(typeName, BUF_LIFETIME);
+    }
+
+    private static String withLifetime(final String typeName, final String lifetime)
+    {
+        return format("%s<%s>", typeName, lifetime);
     }
 
     static void appendImplWithLifetimeHeader(
@@ -1281,14 +1292,14 @@ static void appendImplEncoderTrait(
         final Appendable out,
         final String typeName) throws IOException
     {
-        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withLifetime("Writer"), withLifetime(typeName));
+        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withBufLifetime("Writer"), withBufLifetime(typeName));
         indent(out, 2, "#[inline]\n");
         indent(out, 2, "fn get_buf_mut(&mut self) -> &mut WriteBuf<'a> {\n");
         indent(out, 3, "&mut self.buf\n");
         indent(out, 2, "}\n");
         indent(out, 1, "}\n\n");
 
-        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withLifetime("Encoder"), withLifetime(typeName));
+        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withBufLifetime("Encoder"), withBufLifetime(typeName));
         indent(out, 2, "#[inline]\n");
         indent(out, 2, "fn get_limit(&self) -> usize {\n");
         indent(out, 3, "self.limit\n");
@@ -1306,21 +1317,21 @@ static void appendImplDecoderTrait(
         final Appendable out,
         final String typeName) throws IOException
     {
-        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, "ActingVersion", withLifetime(typeName));
+        indent(out, 1, "impl %s for %s {\n", "ActingVersion", withAnonymousLifetime(typeName));
         indent(out, 2, "#[inline]\n");
         indent(out, 2, "fn acting_version(&self) -> %s {\n", schemaVersionType);
         indent(out, 3, "self.acting_version\n");
         indent(out, 2, "}\n");
         indent(out, 1, "}\n\n");
 
-        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withLifetime("Reader"), withLifetime(typeName));
+        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withBufLifetime("Reader"), withBufLifetime(typeName));
         indent(out, 2, "#[inline]\n");
         indent(out, 2, "fn get_buf(&self) -> &ReadBuf<'a> {\n");
         indent(out, 3, "&self.buf\n");
         indent(out, 2, "}\n");
         indent(out, 1, "}\n\n");
 
-        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withLifetime("Decoder"), withLifetime(typeName));
+        indent(out, 1, "impl<%s> %s for %s {\n", BUF_LIFETIME, withBufLifetime("Decoder"), withBufLifetime(typeName));
         indent(out, 2, "#[inline]\n");
         indent(out, 2, "fn get_limit(&self) -> usize {\n");
         indent(out, 3, "self.limit\n");