From fdd2fa736155f9a1f5792dfd477b41d11ce21708 Mon Sep 17 00:00:00 2001
From: Sebastian Lohff <seba@someserver.de>
Date: Mon, 3 Jan 2022 16:19:37 +0100
Subject: [PATCH] Initial commit

---
 .gitignore  |   3 ++
 Cargo.lock  |   7 +++
 Cargo.toml  |   8 ++++
 src/main.rs | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 149 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.lock
 create mode 100644 Cargo.toml
 create mode 100644 src/main.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..355560c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/target
+*.swp
+*.swo
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..e2fc507
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "brainfuck"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..a1564a8
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "brainfuck"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..9cfb749
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,131 @@
+
+fn check_brainfuck(prog: &str) -> bool {
+    /*
+    let valid_bf_chars = "<>+-.,[]";
+    for (n, c) in prog.char_indices() {
+        if ! valid_bf_chars.contains(c) {
+            println!("Invalid character '{}' on pos {}", c, n);
+        }
+    }
+    */
+    let mut brackets = 0;
+    let mut borked = false;
+    for (n, c) in prog.char_indices() {
+        match c {
+            '[' => brackets += 1,
+            ']' => {
+                if brackets > 0 {
+                    brackets -= 1;
+                } else {
+                    println!("Closing bracket without matching opening bracket in pos {}", n);
+                    borked = true;
+                }
+            },
+            '<' | '>' | '+' | '-' | '.' | ',' => (),
+            _ => {
+                println!("Invalid character '{}' on pos {}", c, n);
+                borked = true;
+            },
+        }
+    }
+    return ! borked;
+}
+
+fn run_brainfuck(prog: &str, debug: bool) {
+    println!("Running programm {}", prog);
+
+    let mut data = vec![];
+    data.push(0);
+    let mut data_ptr = 0;
+    let mut pc = 0;
+
+    loop {
+        let c = prog.chars().nth(pc).unwrap();
+        if debug {
+            println!("At pos {} char {} with data {} at {} (data {:?})", pc, c, data[data_ptr], data_ptr, data);
+        }
+        let mut inc_pc = true;
+        match c {
+            '+' => data[data_ptr] += 1,
+            '-' => data[data_ptr] -= 1,
+            '>' => {
+                data_ptr += 1;
+                if data_ptr == data.len() {
+                    data.push(0)
+                }
+            },
+            '<' => {
+                if data_ptr > 0 {
+                    data_ptr -= 1;
+                } else {
+                    data.insert(0, 0);
+                }
+            },
+            '.' => print!("{}", std::char::from_u32(data[data_ptr]).unwrap()),
+            ',' => println!("<input not implemented>"),
+            '[' => {
+                if data[data_ptr] == 0 {
+                    let mut brackets = 0;
+                    loop {
+                        match prog.chars().nth(pc).unwrap() {
+                            '[' => brackets += 1,
+                            ']' => {
+                                brackets -= 1;
+                                if brackets == 0 {
+                                    break;
+                                }
+                            },
+                            _ => (),
+                        }
+                        pc += 1;
+                    }
+                    inc_pc = false;
+                    if debug {
+                        println!("Executed conditional [ jump to pos {}", pc);
+                    }
+                }
+            },
+            ']' => {
+                if data[data_ptr] != 0 {
+                    let mut brackets = 1;
+                    loop {
+                        pc -= 1;
+                        match prog.chars().nth(pc).unwrap() {
+                            ']' => brackets += 1,
+                            '[' => {
+                                brackets -= 1;
+                                if brackets == 0 {
+                                    break;
+                                }
+                            },
+                            _ => (),
+                        }
+                    }
+                    if debug {
+                        println!("Executed conditional ] jump to pos {}", pc + 1);
+                    }
+                }
+            }
+            _ => (),
+        }
+
+        if inc_pc {
+            pc += 1
+        }
+        if pc == prog.len() {
+            break;
+        }
+    }
+}
+
+fn main() {
+    println!("Welcome to rust BF!");
+
+    //let prog = "xxx]]";
+    let prog = "++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.";
+    if ! check_brainfuck(prog) {
+        println!("Invalid program, aborting");
+        return;
+    }
+    run_brainfuck(prog, false);
+}