seperate files

bfi-rust/src/interpreter/o1.rs

@@ -0,0 +1,110 @@
+/*!
+ # optimization time
+
+ first parse the bf so that it can be executed faster
+ most importantly: loop jumps should be immediate
+*/
+
+use std::io::{Read, stdin};
+
+use crate::interpreter::{MEM_SIZE, Memory, minify, parse, Statement};
+
+pub fn run(pgm: &str) -> String {
+    let pgm = minify(pgm);
+    let pgm = parse(pgm.chars().collect());
+    let out = interpret(&pgm);
+    out
+}
+
+fn interpret(pgm: &Vec<Statement>) -> String {
+    let mut out = String::new();
+    let mut pointer: usize = 0;
+    let mut mem: [u8; MEM_SIZE] = [0; MEM_SIZE];
+
+    for s in pgm {
+        execute(s, &mut mem, &mut pointer, &mut out)
+    }
+
+    out
+}
+
+fn execute(statement: &Statement, mem: &mut Memory, pointer: &mut usize, out: &mut String) {
+    match statement {
+        Statement::R => if *pointer == MEM_SIZE - 1 { *pointer = 0 } else { *pointer += 1 },
+        Statement::L => if *pointer == 0 { *pointer = MEM_SIZE - 1 } else { *pointer -= 1 },
+        Statement::Inc => mem[*pointer] = mem[*pointer].wrapping_add(1),
+        Statement::Dec => mem[*pointer] = mem[*pointer].wrapping_sub(1),
+        Statement::Out => out.push(mem[*pointer] as u8 as char),
+        Statement::In => {
+            let mut in_buffer = [0, 1];
+            stdin().read(&mut in_buffer).unwrap();
+            mem[*pointer] = in_buffer[0] as u8;
+        }
+        Statement::Loop(vec) => {
+            while mem[*pointer] != 0 {
+                for s in vec {
+                    execute(&s, mem, pointer, out);
+                }
+            }
+        }
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use crate::interpreter::o1::{execute, run, Statement};
+
+    #[test]
+    fn execute_simple() {
+        let mut pointer: usize = 0;
+        let mut mem: [u8; 65535] = [0; 65535];
+        let mut out = String::new();
+
+        execute(&Statement::R, &mut mem, &mut pointer, &mut out);
+        assert_eq!(pointer, 1);
+        execute(&Statement::L, &mut mem, &mut pointer, &mut out);
+        assert_eq!(pointer, 0);
+        execute(&Statement::Inc, &mut mem, &mut pointer, &mut out);
+        assert_eq!(mem[pointer], 1);
+        execute(&Statement::Dec, &mut mem, &mut pointer, &mut out);
+        assert_eq!(mem[pointer], 0);
+    }
+
+    #[test]
+    fn execute_false_loop() {
+        let statement = Statement::Loop(vec![Statement::Inc, Statement::Inc, Statement::R]);
+        let mut pointer: usize = 0;
+        let mut mem: [u8; 65535] = [0; 65535];
+
+        execute(&statement, &mut mem, &mut pointer, &mut String::new());
+        assert_eq!(mem[0], 0);
+        assert_eq!(mem[1], 0);
+    }
+
+    #[test]
+    fn execute_loop() {
+        let statement = Statement::Loop(vec![Statement::Inc, Statement::Inc, Statement::R]);
+        let mut pointer: usize = 0;
+        let mut mem: [u8; 65535] = [0; 65535];
+        mem[0] = 1;
+
+        execute(&statement, &mut mem, &mut pointer, &mut String::new());
+        assert_eq!(mem[0], 3);
+        assert_eq!(mem[1], 0);
+    }
+
+    #[test]
+    fn run_loop() {
+        let program = "++++++++++[>++++++++++<-]>.";
+        let out = run(program);
+        assert_eq!(out, String::from("d"));
+    }
+
+    #[test]
+    fn hello_world() {
+        let program = "++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.";
+        let out = run(program);
+        assert_eq!(out, String::from("Hello World!\n"));
+    }
+}