added BF interpreter homework (#59)

1 files changed, 68 insertions, 0 deletions

diff --git a/homework/81489/bf_interpreter/main.cpp b/homework/81489/bf_interpreter/main.cpp
new file mode 100644
index 0000000..fc065aa
--- /dev/null
+++ b/homework/81489/bf_interpreter/main.cpp
@@ -0,0 +1,68 @@
+#include <stdio.h>
+#include <stack>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <string>
+
+using namespace std;
+
+class Brainfuck {
+    private:
+        static const int init_length = 1024;
+        char *tape;
+        stack<int> loop_stack;
+        char *tape_pos;
+
+    public:
+        Brainfuck() : tape(new char[init_length]), tape_pos(tape + (init_length / 2)) {}
+        Brainfuck(int _length): tape(new char [_length]), tape_pos(tape + (_length / 2)) {}
+
+        void interpret(string& code) {
+            for (int i = 0; code[i]; ++i) {
+                switch (code[i]) {
+                    case '\n': break;
+                    case '<': --(this->tape_pos); break;
+                    case '>': ++(this->tape_pos); break;
+                    case '-': -- *(this->tape_pos); break;
+                    case '+': ++ *(this->tape_pos); break;
+                    case '[': this->loop_stack.push(i); break;
+                    case ']':
+                        if (*(this->tape_pos)) {
+                            i = this->loop_stack.top();
+                        } else {
+                            this->loop_stack.pop();
+                        }
+                        break;
+                    case '.': putchar(*this->tape_pos); break;
+                    case ',': *(this->tape_pos) = (char)getchar();
+                    default: break;
+                }
+            }
+        }
+};
+
+int main(int argc, char *argv[])
+{
+    Brainfuck bf;
+    if (argc != 2) {
+        printf("Usage: <executable> <text_file_name>\n");
+        return 1;
+    }
+
+    int fd;
+    if (!(fd = open(argv[1], O_RDONLY))) {
+        printf("Error opening file \"%s\"\n", argv[1]);
+        return 1;
+    };
+
+    char buff[128];
+    string code;
+    while (int lth = read(fd, buff, 128)) {
+        buff[lth] = '\0';
+        code += buff;
+    }
+
+    bf.interpret(code);
+    return 0;
+}
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