Feature: support for coding of aggregates

CMakeLists.txt

@@ -8,6 +8,7 @@ cmake_minimum_required(VERSION 3.12)
 
 option(JAM_COMPATIBLE "Build compatible with JAM-codec" OFF)
 option(CUSTOM_CONFIG_SUPPORT "Support custom config of streams" OFF)
+set(MAX_AGGREGATE_FIELDS 20 CACHE STRING "Max number of aggregates fields (1..1000); for generation")
 
 option(BUILD_TESTS "Whether to include the test suite in build" OFF)
 

include/scale/detail/.gitignore

@@ -0,0 +1,5 @@
+# Ignored because part of this file is generated by CMake.
+# If changes to the base content need to be committed, they must be committed explicitly,
+# except for the section between `-BEGIN-GENERATED-SECTION-` and `-END-GENERATED-SECTION-`,
+# which is automatically generated and should not be committed.
+aggregate.hpp

include/scale/detail/aggregate.hpp

@@ -9,73 +9,14 @@
 
 namespace scale::detail {
 
-  template <typename T, typename F>
-    requires SimpleCodeableAggregate<T>
-  auto &as_decomposed(T &&v, const F &f) {
+  template <SimpleCodeableAggregate T, typename F>
+  decltype(auto) decompose_and_apply(T &&v, const F &f) {
     constexpr auto N = field_number_of<T>;
     // clang-format off
     if constexpr (N == 0) {
       return f();
-    } else if constexpr (N == 1) {
-      auto &[v1] = v;
-      return f(v1);
-    } else if constexpr (N == 2) {
-      auto &[v1, v2] = v;
-      return f(v1, v2);
-    } else if constexpr (N == 3) {
-      auto &[v1, v2, v3] = v;
-      return f(v1, v2, v3);
-    } else if constexpr (N == 4) {
-      auto &[v1, v2, v3, v4] = v;
-      return f(v1, v2, v3, v4);
-    } else if constexpr (N == 5) {
-      auto &[v1, v2, v3, v4, v5] = v;
-     return f(v1, v2, v3, v4, v5);
-    } else if constexpr (N == 6) {
-      auto &[v1, v2, v3, v4, v5, v6] = v;
-      return f(v1, v2, v3, v4, v5, v6);
-    } else if constexpr (N == 7) {
-      auto &[v1, v2, v3, v4, v5, v6, v7] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7);
-    } else if constexpr (N == 8) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8);
-    } else if constexpr (N == 9) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9);
-    } else if constexpr (N == 10) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10);
-    } else if constexpr (N == 11) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11);
-    } else if constexpr (N == 12) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12);
-    } else if constexpr (N == 13) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13);
-    } else if constexpr (N == 14) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14);
-    } else if constexpr (N == 15) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15);
-    } else if constexpr (N == 16) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16);
-    } else if constexpr (N == 17) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17);
-    } else if constexpr (N == 18) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18);
-    } else if constexpr (N == 19) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19);
-    } else if constexpr (N == 20) {
-      auto &[v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20] = v;
-      return f(v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20);
+    // -BEGIN-GENERATED-SECTION-
+    // -END-GENERATED-SECTION-
     } else {
       // We mustn't fall in here
       static_assert(N <= MAX_FIELD_NUM, "Inconsistent value of MAX_FIELD_NUM");

include/scale/scale_decoder_stream.hpp

@@ -74,10 +74,10 @@ namespace scale {
      * @return reference to stream
      */
     ScaleDecoderStream &operator>>(SimpleCodeableAggregate auto &v) {
-      return detail::as_decomposed(v,
-                                   [&](auto &...args) -> ScaleDecoderStream & {
-                                     return (*this >> ... >> args);
-                                   });
+      return detail::decompose_and_apply(
+          v, [&](auto &...args) -> ScaleDecoderStream & {
+            return (*this >> ... >> args);
+          });
     }
 
     /**

include/scale/scale_encoder_stream.hpp

@@ -93,7 +93,7 @@ namespace scale {
      * @return reference to stream
      */
     ScaleEncoderStream &operator<<(const SimpleCodeableAggregate auto &v) {
-      return detail::as_decomposed(
+      return detail::decompose_and_apply(
           v, [&](const auto &...args) -> ScaleEncoderStream & {
             return (*this << ... << args);
           });

scripts/generate_aggregate_hpp.sh

@@ -0,0 +1,96 @@
+#!/bin/sh
+
+# This script modifies a specified C++ source file by replacing a generated section.
+# It reads the file, finds the markers '-BEGIN-GENERATED-SECTION-' and '-END-GENERATED-SECTION-',
+# generates C++ code based on a given integer N, and writes the modified content back to the file.
+# If the markers are not found, the script exits with an error without modifying the file.
+# If the file is modified, the specified stamp file is updated (if provided).
+# Usage: ./generate_aggregate_hpp.sh <filename> <N> [stampfile]
+# Where <filename> is the path to the C++ source file, <N> is an integer between 0 and 1000,
+# and [stampfile] is an optional path to the stamp file to be updated.
+
+# Validate input
+if [ "$#" -lt 2 ] || [ "$#" -gt 3 ]; then
+    echo "Usage: $0 <filename> <N> [stampfile]"
+    exit 1
+fi
+
+FILENAME="$1"
+N="$2"
+STAMPFILE="$3"
+
+if [ ! -f "$FILENAME" ]; then
+    echo "Error: File '$FILENAME' not found."
+    exit 1
+fi
+
+if echo "$N" | grep -q "[^0-9]" || [ "$N" -lt 0 ] || [ "$N" -gt 1000 ]; then
+    echo "N must be an integer between 0 and 1000"
+    exit 1
+fi
+
+# Find the section markers
+BEGIN_LINE=$(awk '/-BEGIN-GENERATED-SECTION-/ {print NR; exit}' "$FILENAME")
+END_LINE=$(awk '/-END-GENERATED-SECTION-/ {print NR; exit}' "$FILENAME")
+
+if [ -z "$BEGIN_LINE" ] || [ -z "$END_LINE" ]; then
+    echo "Error: Required markers not found in the file."
+    exit 1
+fi
+
+# Create temporary file
+tempfile=$(mktemp) || { echo "Failed to create temporary file"; exit 1; }
+
+# Trap to ensure the temporary file is deleted in case of errors
+trap 'rm -f "$tempfile"' EXIT
+
+# Write the modified content to the temporary file
+awk -v begin="$BEGIN_LINE" -v end="$END_LINE" -v n="$N" '
+BEGIN { in_generated_section = 0; }
+{
+    if (NR == begin) {
+        print; # Print the BEGIN marker
+        in_generated_section = 1;
+        for (i = 1; i <= n; i++) {
+            printf "    } else if constexpr (N == %d) {\n", i;
+            printf "      auto &[";
+            for (j = 1; j <= i; j++) {
+                printf "v%d%s", j, (j < i ? ", " : "");
+            }
+            printf "] = v;\n";
+            printf "      return f(";
+            for (j = 1; j <= i; j++) {
+                printf "v%d%s", j, (j < i ? ", " : "");
+            }
+            printf ");\n";
+        }
+        next;
+    }
+    if (NR == end) {
+        print; # Print the END marker
+        in_generated_section = 0;
+        next;
+    }
+    if (!in_generated_section) {
+        print;
+    }
+}' "$FILENAME" > "$tempfile" || { echo "Error processing file"; exit 1; }
+
+# Check if the file has changed before overwriting
+if ! cmp -s "$tempfile" "$FILENAME"; then
+    mv "$tempfile" "$FILENAME"
+    if [ -n "$STAMPFILE" ]; then
+        touch "$STAMPFILE"
+        echo "File '$FILENAME' successfully updated. Stamp file '$STAMPFILE' modified."
+    else
+        echo "File '$FILENAME' successfully updated."
+    fi
+else
+    rm -f "$tempfile"
+    echo "No changes detected."
+fi
+
+# Remove trap on success
+trap - EXIT
+
+exit 0

src/CMakeLists.txt

@@ -1,3 +1,16 @@
+set(SCRIPT_PATH "${CMAKE_SOURCE_DIR}/scripts/generate_aggregate_hpp.sh")
+set(TARGET_FILE "${CMAKE_SOURCE_DIR}/include/scale/detail/aggregate.hpp")
+set(STAMP_FILE "${CMAKE_BINARY_DIR}/include/scale/detail/aggregate.hpp.stamp")
+add_custom_command(
+    OUTPUT  ${STAMP_FILE}
+    COMMAND ${CMAKE_COMMAND} -E echo "Running: ${SCRIPT_PATH} '${TARGET_FILE}' '${MAX_AGGREGATE_FIELDS}' '${STAMP_FILE}'"
+    COMMAND ${SCRIPT_PATH} ${TARGET_FILE} ${MAX_AGGREGATE_FIELDS} ${STAMP_FILE}
+    DEPENDS ${SCRIPT_PATH} ${TARGET_FILE}
+    COMMENT "Generating include/scale/detail/aggregate.hpp"
+    VERBATIM
+)
+add_custom_target(generate_aggregate_hpp ALL DEPENDS ${STAMP_FILE})
+
 add_library(scale
     encode_append.cpp
     scale_decoder_stream.cpp