New dependency readline for better REPL UX.

Author: nos1dot618

CMakeLists.txt

@@ -36,18 +36,22 @@ target_link_libraries(lbd PRIVATE
     lbdRuntime
 )
 
+find_package(PkgConfig REQUIRED)
+# Readline.
+pkg_check_modules(READLINE REQUIRED readline)
+target_include_directories(lbd PRIVATE ${READLINE_INCLUDE_DIRS})
+target_link_libraries(lbd PRIVATE ${READLINE_LIBRARIES})
+
 # Fully static build (platform dependent).
 option(LBD_STATIC_BUILD "Build fully static binary" OFF)
-if(LBD_STATIC_BUILD)
+if (LBD_STATIC_BUILD)
     target_link_options(lbd PRIVATE -static)
-endif()
+    # Readline depends upon ncurses.
+    target_link_libraries(lbd PRIVATE ncurses tinfo)
+endif ()
 
 # Warnings.
-if(MSVC)
-    target_compile_options(lbd PRIVATE /W4)
-else()
-    target_compile_options(lbd PRIVATE -Wall -Wextra -Wpedantic)
-endif()
+target_compile_options(lbd PRIVATE -Wall -Wextra -Wpedantic)
 
 # Tests.
 enable_testing()

README.md

@@ -14,34 +14,16 @@
 
 ### Setup
 
-#### GNU/Linux
-
 ```bash
 bash ./scripts/setup.sh
 ```
 
-#### Windows (PowerShell)
-
-```powershell
-. .\scripts\setup.ps1
-```
-
 ### Run Golden Tests
 
-#### GNU/Linux
-
 ```bash
 bash ./tests/run_tests.sh
 ```
 
-#### Windows
-
-```powershell
-python .\tests\tests.py
-```
-
-> Depricated.
-
 ## Samples
 
 Booleans and If-Then construct built entirely using Lambda Expressions.
@@ -132,3 +114,7 @@ lbd [options]
 ## Editor Plugins
 
 1. [GNU Emacs](./editor-plugins/emacs)
+
+## Dependencies
+
+1. [readline](https://tiswww.case.edu/php/chet/readline/rltop.html): For better REPL user experience.

TODO.txt

@@ -1,4 +1,8 @@
 - [EXAMPLES] Add better examples (e.g., Advent of Code snippets).
 - [DOCS] Fix tests output in README.
-- [TOOLING] Step debug kind of functionality in REPL. Inside REPL, while loading a file, load one expression at a time and provide user with some feedback and actions to perform.
 - [DEV TOOLING] Make a pre-commit-hook which does not allow to push to master, if the tests are failing. Additionally, test whether the `docs/SIGNATURE.txt` is up-to-date or not.
+
+# REPL
+- Add support for step-debugging while loading a file (load single expression at a time).
+  Provide user feedback and actions to perform (gdb kind of).
+- Support auto-completion using readline.

scripts/setup.sh

@@ -3,24 +3,31 @@
 # and creating a Python environment for development.
 # Should be run from within the PROJECT ROOT.
 
-set -e
+set -eu
 
-# --- CMake Project Setup ---
-BuildDir="cmake-build-debug"
-if [[ ! -d "$BuildDir" ]]; then
-    mkdir "$BuildDir"
-fi
-cd "$BuildDir"
-cmake ..
-cmake --build .
-cd ..
+SCRIPTS_DIR_PATH=$(dirname "${BASH_SOURCE[0]}")
+ROOT_PATH=$(dirname "$SCRIPTS_DIR_PATH")
+BUILD_DIR="$ROOT_PATH/cmake-build-debug"
+
+# Install dependencies.
+# TODO: Support installing dependencies in a cross platform manner.
+sudo apt-get install -y libreadline-dev
+
+# CMake Project Setup.
+mkdir -p "$BUILD_DIR"
+cd "$BUILD_DIR"
+cmake "$ROOT_PATH"
+cmake --build "$BUILD_DIR"
 
-# --- Python Environment Setup ---
-VenvDir="venv"
-if [[ ! -d "$VenvDir" ]]; then
-    python3 -m venv "$VenvDir"
+# Python Environment Setup.
+cd "$ROOT_PATH"
+
+VENV_DIR="venv"
+if [[ ! -d "$VENV_DIR" ]]; then
+    python3 -m venv "$VENV_DIR"
 fi
-source "$VenvDir/bin/activate"
+
+source "$VENV_DIR/bin/activate"
 python -m pip install --upgrade pip
 if [[ -f "requirements.txt" ]]; then
     pip install -r requirements.txt

src/repl.cpp

@@ -7,8 +7,11 @@
 #include <lbd/frontend/parser.h>
 #include <lbd/runtime/interpreter.h>
 #include <lbd/exceptions.h>
+#include <readline/readline.h>
+#include <readline/history.h>
 
-#define onOrOff(val) ((val) ? "on " : "off")
+#define ON_OR_OFF(val) ((val) ? "on " : "off")
+#define LBD_HISTORY ".lbd_history"
 
 // TODO: Option :t for display type information of a symbol.
 
@@ -64,10 +67,7 @@ namespace repl
                     (*sharedEnvironment)->bind(first, second);
                 }
             }
-            if (resultantOptions.sideEffects)
-            {
-                std::cout << std::endl;
-            }
+            if (resultantOptions.sideEffects) std::cout << std::endl;
         }
 
         subOptions.logger.info("info: file loaded ", filepath);
@@ -97,6 +97,9 @@ namespace repl
     {
         enableVirtualTerminal();
 
+        using_history();
+        read_history(LBD_HISTORY);
+
         static logs::Logger logger(false, true, false);
         optionsValue = {.ownExpression = true, .forceOnEnvironmentDump = false, .debug = debug, .logger = logger};
 
@@ -110,18 +113,15 @@ namespace repl
         {
             try
             {
-                // Prompt depends on whether we are continuing a buffer
-                if (buffer.empty())
-                {
-                    std::cout << colors::CYAN << "\n>> " << colors::RESET;
-                }
-                else
-                {
-                    std::cout << colors::CYAN << ".. " << colors::RESET;
-                }
+                // Prompt depends on whether we are continuing a buffer or not.
+                std::string prompt = colors::CYAN + std::string(buffer.empty() ? "\n>> " : ".. ") + colors::RESET;
                 for (size_t i = 0; i < indentLevel; i++) std::cout << "  ";
 
-                if (!std::getline(std::cin, line)) break; // EOF (C-d / C-z)
+                char* input = readline(prompt.c_str());
+                if (!input) break; // EOF (C-d / C-z)
+                if (*input) add_history(input);
+                line = std::string(input);
+                free(input);
 
                 // REPL arguments parsing
                 {
@@ -159,9 +159,9 @@ namespace repl
                                    }, colors::GREEN);
                         std::cout << std::endl;
                         printTable({"Options", "State", "Help"}, {
-                                       {"debug", onOrOff(optionsValue.debug), "use :debug to toggle"},
+                                       {"debug", ON_OR_OFF(optionsValue.debug), "use :debug to toggle"},
                                        {
-                                           "force-on-env-dump", onOrOff(optionsValue.forceOnEnvironmentDump),
+                                           "force-on-env-dump", ON_OR_OFF(optionsValue.forceOnEnvironmentDump),
                                            "use :force to toggle"
                                        }
                                    }, colors::GREEN);
@@ -275,5 +275,7 @@ namespace repl
                 optionsValue.logger.error({}, "error: ", ex.what());
             }
         }
+
+        write_history(LBD_HISTORY);
     }
 }