wrote interpreter source code

src/main.rs

@@ -1,3 +1,97 @@
-fn main() {
+use anyhow::Result;
-    println!("Hello, world!");
+use anyhow::anyhow;
+use std::collections::HashMap;
+use std::io::{self, Read, Write};
+use std::fs;
+fn clean_code(code: &str) -> Vec<char> {
+    let vec: Vec<char> = code.chars().collect();
+    let clean = vec
+        .into_iter()
+        .filter(|b| "+-<>,.[]".contains(*b))
+        .collect();
+    clean
+}
+fn precompute_jump_table(code: &[char]) -> Result<HashMap<usize, usize>> {
+    let mut jump_table = HashMap::new();
+    let mut stack = Vec::new();
+    for (i, &char) in code.iter().enumerate() {
+        if char == '[' {
+            stack.push(i);
+        } else if char == ']' {
+            match stack.pop() {
+                Some(start_index) => {
+                    jump_table.insert(start_index, i);
+                    jump_table.insert(i, start_index);
+                }
+                None => {
+                    return Err(anyhow!("miss matching closing brackets at index {}", i));
+                }
+            }
+        }
+    }
+    if !stack.is_empty() {
+        return Err(anyhow!("open brackets unclosed"));
+    }
+    Ok(jump_table)
+}
+fn execute(raw_code: &str) -> Result<()> {
+    let clean = clean_code(raw_code);
+    let jump_table = precompute_jump_table(&clean)?;
+    let mut tape: [u8; 30000] = [0; 30000];
+    let mut data_ptr: usize = 0;
+    let mut exec_ptr: usize = 0;
+    while exec_ptr < clean.len() {
+        let cmd = clean[exec_ptr];
+        match cmd {
+            '+' => {
+                tape[data_ptr] = tape[data_ptr].wrapping_add(1);
+            }
+            '-' => {
+                tape[data_ptr] = tape[data_ptr].wrapping_sub(1);
+            }
+            '>' => {
+                data_ptr += 1;
+                if data_ptr > 29999 {
+                    data_ptr = 0;
+                }
+            }
+            '<' => {
+                if data_ptr == 0 {
+                    data_ptr = 29999;
+                }
+                else {
+                    data_ptr -= 1;
+                }
+            }
+            ',' => {
+                let mut buf = [0; 1];
+if io::stdin().read_exact(&mut buf).is_ok() {
+    tape[data_ptr] = buf[0];
+}
+            }
+            '.' => {
+                print!("{}", tape[data_ptr] as char);
+                let _ = io::stdout().flush();
+            }
+            '[' => {
+                if tape[data_ptr] == 0 {
+                    exec_ptr = *jump_table.get(&exec_ptr).unwrap();
+                }
+            }
+            ']' => {
+                if tape[data_ptr] != 0 {
+                    exec_ptr = *jump_table.get(&exec_ptr).unwrap();
+                }
+            }
+            _ => {}
+        }
+        exec_ptr += 1;
+    }
+    Ok(())
+}
+fn main() -> Result<()> {
+    let code_path = std::env::args().nth(1).ok_or_else(|| anyhow!("Usage: bf <path to file.bf>"))?;
+    let code = fs::read_to_string(&code_path)?;
+    execute(&code)?;
+    Ok(())
 }