feat: postgreact: hello world

package/c/postgreact/default.nix

@@ -0,0 +1,41 @@
+{
+  lib,
+  stdenv,
+  postgresql,
+  ...
+}: 
+
+stdenv.mkDerivation {
+  pname = "postgreact";
+  version = "0.1";
+  
+  src = ./.;
+
+  buildInputs = [
+    postgresql
+  ];
+
+  buildPhase = ''
+    mkdir -p target
+    sh ./make.sh build
+  '';
+
+  installPhase = ''
+    mkdir -p $out/lib/postgresql $out/share/postgresql/extension
+    
+    # Install compiled library
+    install -m 755 -D target/postgreact.so $out/lib/postgresql/postgreact.so
+    
+    # Install control and SQL files
+    install -m 644 -D postgreact.control $out/share/postgresql/extension/postgreact.control
+    install -m 644 -D postgreact--0.1.sql $out/share/postgresql/extension/postgreact--0.1.sql
+  '';
+
+  meta = with lib; {
+    description = "PostgreSQL extension for reactive functions";
+    homepage = "https://github.com/yukkop/util.nix";
+    license = licenses.mit;
+    platforms = postgresql.meta.platforms;
+    maintainers = with maintainers; [ ];
+  };
+} 

package/c/postgreact/make.sh

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+#!/bin/sh
+# Usage: make.sh [build|watch] [--debug] [--color]
+# Options:
+#   build         Build the postgres extension (default if no mode is provided).
+#   watch         Build the extension and watch for changes.
+#   --debug       Build with -O0 (debug mode).
+#   --color       Pass -fdiagnostics-color=always to compiler.
+#   help, --help  Show this help message.
+
+check_dependencies() {
+  for dep in gcc pg_config; do
+    if ! command -v "$dep" >/dev/null 2>&1; then
+      echo "Error: Required dependency '$dep' not found." >&2
+      exit 1
+    fi
+  done
+  
+  # Check for either fswatch or inotifywait for watch mode
+  if [ "$MODE" = "watch" ] && ! command -v fswatch >/dev/null 2>&1 && ! command -v inotifywait >/dev/null 2>&1; then
+    echo "Error: Neither fswatch nor inotifywait found. Please install one of them." >&2
+    echo "  On macOS: brew install fswatch" >&2
+    echo "  On Linux: sudo apt install inotify-tools" >&2
+    exit 1
+  fi
+}
+
+print_help() {
+  cat <<EOF
+Usage: $0 [build|watch] [--debug] [--color]
+  build         Build the postgres extension (default).
+  watch         Build the extension and watch for changes.
+  --debug       Build with debug flags (-O0).
+  --color       Force colored compiler diagnostics.
+  help, --help  Display this help message.
+EOF
+}
+
+# Show help if requested
+case "$1" in
+  help|--help)
+    print_help
+    exit 0
+    ;;
+esac
+
+# Default flags
+OPTFLAGS="-O2"
+CFLAGS="-Wall -Wextra -pedantic -fPIC"
+COLOR_FLAG=""
+DEBUG=0
+
+# Process options
+while [ $# -gt 0 ]; do
+  case "$1" in
+    --debug)
+      OPTFLAGS="-O0 -gdwarf-2 -g3 -Wno-error"
+      DEBUG=1
+      ;;
+    --color)
+      COLOR_FLAG="-fdiagnostics-color=always"
+      ;;
+    *)
+      break
+      ;;
+  esac
+  shift
+done
+
+MODE="${1:-build}"
+shift 2> /dev/null
+
+if [ -n "$COLOR_FLAG" ]; then
+  CFLAGS="$CFLAGS $COLOR_FLAG"
+fi
+
+check_dependencies
+
+# Get PostgreSQL include directory
+PG_INCLUDE=$(pg_config --includedir-server)
+PG_LIBDIR=$(pg_config --libdir)
+
+case "$MODE" in
+  watch)
+    find . -type d | nix run .#watch -- 'sh ./make.sh build' -p '*.c' -p '*.h' 2>&1
+    ;;
+  build)
+    mkdir -p target
+    echo "# Building PostgreSQL extension"
+    # shellcheck disable=SC2086
+    gcc $CFLAGS $OPTFLAGS -I$PG_INCLUDE -shared -o target/postgreact.so postgreact.c
+    
+    # Copy extension files to target directory
+    cp postgreact.control target/
+    cp postgreact--0.1.sql target/
+    
+    echo "Build complete. Files available in target/ directory."
+    ;;
+  *)
+    print_help
+    exit 1
+    ;;
+esac

package/c/postgreact/postgreact--0.1.sql

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+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION postgreact" to load this file. \quit
+
+-- Define the hello function that uses our C implementation
+CREATE FUNCTION hello()
+RETURNS text
+AS 'postgreact', 'hello'
+LANGUAGE C STRICT;

package/c/postgreact/postgreact.c

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+#include "postgres.h"
+#include "fmgr.h"
+#include "utils/builtins.h" /* for text_to_cstring and cstring_to_text */
+
+#ifdef PG_MODULE_MAGIC
+PG_MODULE_MAGIC;
+#endif
+
+/* Define the function hello */
+PG_FUNCTION_INFO_V1(hello);
+
+/* Implement the function */
+Datum hello(PG_FUNCTION_ARGS) 
+{
+    PG_RETURN_TEXT_P(cstring_to_text("Hello, world!"));
+}

package/c/postgreact/postgreact.control

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+comment = 'My first extension'
+default_version = '0.1'
+module_pathname = '$libdir/postgreact'