From 87b7bddd71740f255ce4257659aa69038408d329 Mon Sep 17 00:00:00 2001
From: olari <olari@mm.st>
Date: Sat, 25 May 2019 19:06:58 +0300
Subject: [PATCH] Add brainfuck.cpp

---
 cpp/brainfuck/Makefile      |  2 +
 cpp/brainfuck/brainfuck.cpp | 87 +++++++++++++++++++++++++++++++++++++
 cpp/brainfuck/cat.bf        |  1 +
 cpp/brainfuck/helloworld.bf |  1 +
 4 files changed, 91 insertions(+)
 create mode 100644 cpp/brainfuck/Makefile
 create mode 100644 cpp/brainfuck/brainfuck.cpp
 create mode 100644 cpp/brainfuck/cat.bf
 create mode 100644 cpp/brainfuck/helloworld.bf

diff --git a/cpp/brainfuck/Makefile b/cpp/brainfuck/Makefile
new file mode 100644
index 0000000..37345b0
--- /dev/null
+++ b/cpp/brainfuck/Makefile
@@ -0,0 +1,2 @@
+all:
+	g++ -std=c++17 -O2 brainfuck.cpp -lstdc++fs -o brainfuck
diff --git a/cpp/brainfuck/brainfuck.cpp b/cpp/brainfuck/brainfuck.cpp
new file mode 100644
index 0000000..2215d79
--- /dev/null
+++ b/cpp/brainfuck/brainfuck.cpp
@@ -0,0 +1,87 @@
+#include <cstdint>
+
+#include <string>
+#include <array>
+#include <stack>
+
+#include <fstream>
+#include <iostream>
+
+#include <filesystem>
+
+std::string get_file_contents(std::ifstream& file_stream) {
+    std::string file_string;
+
+    file_stream.seekg(0, std::ios::end);
+    file_string.resize(file_stream.tellg());
+    file_stream.seekg(0, std::ios::beg);
+
+    file_stream.read(&file_string[0], file_string.size());
+
+    return file_string;
+}
+
+std::string get_brainfuck_code(const std::string& file) {
+    std::string code;
+
+    for (auto c : file) {
+        switch (c) {
+        case '>': case '<':
+        case '+': case '-':
+        case '.': case ',':
+        case '[': case ']':
+            code.push_back(c);
+        }
+    }
+
+    return code;
+}
+
+template<typename value_type, std::size_t size>
+struct bf_context_t {
+    std::array<value_type, size> cells;
+    std::stack<std::size_t> scope;
+    std::uintptr_t ptr;
+};
+
+int main(int argc, char* argv[]) {
+    if (argc < 2) {
+        std::cout << "Usage: " << argv[0] << std::endl;
+        return 1;
+    }
+
+    const std::string file_path = argv[1];
+
+    if (!std::filesystem::exists(file_path)) {
+        std::cout << "Could not find file." << std::endl;
+        return 1;
+    }
+
+    std::ifstream file_stream(file_path);
+
+    if (!file_stream) {
+        std::cout << "Could not open file." << std::endl;
+        return 1;
+    }
+
+    const std::string file_contents = get_file_contents(file_stream);
+    const std::string bf_code = get_brainfuck_code(file_contents);
+
+    // by default, std::cin skips whitespace
+    std::cin >> std::noskipws;
+
+    auto ctx = bf_context_t<std::uint8_t, 30'000>{};
+
+    for (auto ip = 0; ip < bf_code.length(); ++ip) {
+        switch (bf_code[ip]) {
+            case '>': ++ctx.ptr; break;
+            case '<': --ctx.ptr; break;
+            case '+': ++ctx.cells[ctx.ptr]; break;
+            case '-': --ctx.cells[ctx.ptr]; break;
+            case '.': std::cout << (char)ctx.cells[ctx.ptr]; break;
+            case ',': std::cin >> ctx.cells[ctx.ptr]; break;
+            case '[': ctx.scope.push(ip); break;
+            case ']': if (ctx.cells[ctx.ptr]) ip = ctx.scope.top() - 1; ctx.scope.pop(); break;
+        }
+    }
+}
diff --git a/cpp/brainfuck/cat.bf b/cpp/brainfuck/cat.bf
new file mode 100644
index 0000000..58e93e5
--- /dev/null
+++ b/cpp/brainfuck/cat.bf
@@ -0,0 +1 @@
+,[.[-],]
diff --git a/cpp/brainfuck/helloworld.bf b/cpp/brainfuck/helloworld.bf
new file mode 100644
index 0000000..8fa0f72
--- /dev/null
+++ b/cpp/brainfuck/helloworld.bf
@@ -0,0 +1 @@
+++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.