From 329c33f3cbe353c2fd159d0a4f3c0df351e66169 Mon Sep 17 00:00:00 2001
From: Nilstrieb <nilstrieb@gmail.com>
Date: Sun, 25 Apr 2021 10:35:28 +0200
Subject: [PATCH] experimental pattern matching

---
 bfi-rust/src/interpreter/optimized/mod.rs     | 10 ++++-
 .../src/interpreter/optimized/patterns.rs     | 41 +++++++++++++++++--
 bfi-rust/src/main.rs                          |  2 +-
 3 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/bfi-rust/src/interpreter/optimized/mod.rs b/bfi-rust/src/interpreter/optimized/mod.rs
index 9745171..7df4ab4 100644
--- a/bfi-rust/src/interpreter/optimized/mod.rs
+++ b/bfi-rust/src/interpreter/optimized/mod.rs
@@ -24,6 +24,7 @@ enum ExStatement {
     Loop(Vec<ExStatement>),
     SetNull,
     Repeat(Box<ExStatement>, usize),
+    ForLoop(usize, Box<ExStatement>),
 }
 
 impl From<Statement> for ExStatement {
@@ -177,6 +178,12 @@ fn execute(statement: &ExStatement, mem: &mut Memory, pointer: &mut usize, out:
                 }
             }
         }
+        ExStatement::ForLoop(offset, statement) => {
+            *pointer += offset;
+            while mem[*pointer - offset] != 0 {
+                execute(statement, mem, pointer, out);
+            }
+        }
     };
 }
 
@@ -184,8 +191,7 @@ fn execute(statement: &ExStatement, mem: &mut Memory, pointer: &mut usize, out:
 #[cfg(test)]
 mod test {
     use crate::interpreter::optimized::{run, o_repeat};
-    use crate::interpreter::optimized::ExStatement::{Inc, Repeat, R, L};
-    use crate::interpreter::Statement::Dec;
+    use crate::interpreter::optimized::ExStatement::{Inc, Repeat, R, L, Dec};
 
     #[test]
     fn run_loop() {
diff --git a/bfi-rust/src/interpreter/optimized/patterns.rs b/bfi-rust/src/interpreter/optimized/patterns.rs
index 0d9ebf4..ffe4bb9 100644
--- a/bfi-rust/src/interpreter/optimized/patterns.rs
+++ b/bfi-rust/src/interpreter/optimized/patterns.rs
@@ -1,8 +1,43 @@
 //!
 //! # Patterns find and replace
 //! Pattern-match ExStatements and replace them with optimizations like add, multiply etc
-//!
-//! A pattern might look a bit like this: `Loop(Dec)` -> `SetNull`
 
 
-struct Pattern {}
\ No newline at end of file
+use crate::interpreter::optimized::ExStatement;
+
+///
+/// Replace this: `[>>x<<-]` or `[->>x<<]` with `WhileAdd(2, x)`
+fn for_loop(to_test: ExStatement) -> ExStatement {
+    match to_test {
+        ExStatement::Loop(v) => {
+            match v[..] {
+                [ExStatement::R, ExStatement::Inc, ExStatement::L, ExStatement::Dec] => {
+                    ExStatement::ForLoop(1, Box::from(ExStatement::Inc))
+                }
+                _ => ExStatement::Loop(v)
+            }
+        },
+        s => s
+    }
+}
+
+
+
+
+#[cfg(test)]
+mod test {
+    use crate::interpreter::optimized::ExStatement::{Out, Loop, Inc, R, L, Dec, ForLoop};
+    use crate::interpreter::optimized::patterns::for_loop;
+
+    #[test]
+    fn for_loop_false() {
+        let statement = Loop(vec![Out, Inc]);
+        assert_eq!(statement.clone(), for_loop(statement));
+    }
+
+    #[test]
+    fn for_loop_simplest() {
+        let statement = Loop(vec![R, Inc, L, Dec]);
+        assert_eq!(ForLoop(1, Box::from(Inc)), for_loop(statement));
+    }
+}
\ No newline at end of file
diff --git a/bfi-rust/src/main.rs b/bfi-rust/src/main.rs
index c6099cd..222a01c 100644
--- a/bfi-rust/src/main.rs
+++ b/bfi-rust/src/main.rs
@@ -30,7 +30,7 @@ fn run(program: String) {
     let out = interpreter::o1::run(&*program);
     let end1 = start1.elapsed().unwrap();*/
     let start2 = SystemTime::now();
-    let out2 = interpreter::o2::run(&*program, false).unwrap();
+    let out2 = interpreter::optimized::run(&*program, false).unwrap();
     let end2 = start2.elapsed().unwrap();
     //assert_eq!(out, out2);
     //println!("{}\nFinished execution. Took o1: 18008ms (for hanoi), o2: {}ms", out2/*, end1.as_millis()*/, end2.as_millis());