From 4a2674a035814a737a4e7a8d1d667b36d3d0599a Mon Sep 17 00:00:00 2001
From: ondra05 <ondra@ondra05.cz>
Date: Fri, 1 Jul 2022 22:56:22 +0200
Subject: [PATCH] Implemented finally

---
 ablescript/src/ast.rs       |  1 +
 ablescript/src/interpret.rs | 19 ++++++++++++++++---
 ablescript/src/lexer.rs     |  4 ++++
 ablescript/src/parser.rs    | 14 +++-----------
 ablescript/src/value/mod.rs |  9 ++-------
 5 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/ablescript/src/ast.rs b/ablescript/src/ast.rs
index 3e62941..9ab00fe 100644
--- a/ablescript/src/ast.rs
+++ b/ablescript/src/ast.rs
@@ -142,6 +142,7 @@ pub enum Stmt {
     },
     Read(Assignable),
     Melo(Spanned<String>),
+    Finally(Block),
     Rlyeh,
     Rickroll,
 }
diff --git a/ablescript/src/interpret.rs b/ablescript/src/interpret.rs
index b0d7444..aef62ea 100644
--- a/ablescript/src/interpret.rs
+++ b/ablescript/src/interpret.rs
@@ -9,7 +9,7 @@
 #![deny(missing_docs)]
 
 use crate::{
-    ast::{Assignable, AssignableKind, Expr, Spanned, Stmt},
+    ast::{Assignable, AssignableKind, Block, Expr, Spanned, Stmt},
     consts::ablescript_consts,
     error::{Error, ErrorKind},
     value::{Functio, Value, ValueRef, Variable},
@@ -37,6 +37,9 @@ pub struct ExecEnv {
     /// (via the `read` statement). We store each of those bits as
     /// booleans to facilitate easy manipulation.
     read_buf: VecDeque<bool>,
+
+    /// Vector of blocks to be executed at the end of the program
+    finalisers: Vec<Block>,
 }
 
 /// A set of visible variable and function definitions in a single
@@ -51,6 +54,7 @@ impl Default for ExecEnv {
         Self {
             stack: vec![Default::default()],
             read_buf: Default::default(),
+            finalisers: vec![],
         }
     }
 }
@@ -99,7 +103,7 @@ impl ExecEnv {
 
         Self {
             stack: vec![scope],
-            read_buf: Default::default(),
+            ..Default::default()
         }
     }
 
@@ -115,7 +119,13 @@ impl ExecEnv {
                 kind: ErrorKind::TopLevelEnough,
                 span,
             }),
+        }?;
+
+        for block in std::mem::take(&mut self.finalisers) {
+            self.eval_stmts_hs(&block, true)?;
         }
+
+        Ok(())
     }
 
     /// The same as `eval_stmts`, but report "enough" and "and again"
@@ -302,6 +312,7 @@ impl ExecEnv {
                     }
                 }
             },
+            Stmt::Finally(block) => self.finalisers.push(block.clone()),
             Stmt::Rlyeh => {
                 // Maybe print a creepy error message or something
                 // here at some point. ~~Alex
@@ -468,7 +479,9 @@ impl ExecEnv {
                     }
                 };
             }
-            Functio::Eval(code) => self.eval_stmts(&crate::parser::parse(&code)?)?,
+            Functio::Eval(code) => {
+                self.eval_stmts_hs(&crate::parser::parse(&code)?, false)?;
+            }
         }
         Ok(())
     }
diff --git a/ablescript/src/lexer.rs b/ablescript/src/lexer.rs
index cb39439..ca5e67c 100644
--- a/ablescript/src/lexer.rs
+++ b/ablescript/src/lexer.rs
@@ -101,6 +101,10 @@ pub enum Token {
     #[token("and again")]
     AndAgain,
 
+    /// Run at the end of the program
+    #[token("finally")]
+    Finally,
+    
     /// Crash with random error (see discussion #17)
     #[token("rlyeh")]
     Rlyeh,
diff --git a/ablescript/src/parser.rs b/ablescript/src/parser.rs
index 4967275..22003ce 100644
--- a/ablescript/src/parser.rs
+++ b/ablescript/src/parser.rs
@@ -70,9 +70,10 @@ impl<'source> Parser<'source> {
             Token::Functio => self.functio_flow(),
             Token::Bff => self.bff_flow(),
             Token::Melo => self.melo_flow(),
-            Token::Loop => self.loop_flow(),
+            Token::Loop => self.get_block().map(|body| Stmt::Loop { body }),
             Token::Enough => self.semicolon_terminated(Stmt::Enough),
             Token::AndAgain => self.semicolon_terminated(Stmt::AndAgain),
+            Token::Finally => self.get_block().map(Stmt::Finally),
             Token::Rlyeh => self.semicolon_terminated(Stmt::Rlyeh),
             Token::Rickroll => self.semicolon_terminated(Stmt::Rickroll),
 
@@ -149,7 +150,7 @@ impl<'source> Parser<'source> {
                 let next = self.checked_next()?;
                 Ok(Expr::Aint(Box::new(self.parse_expr(next, buf)?)))
             }
-            
+
             Token::Plus
             | Token::Minus
             | Token::Star
@@ -558,15 +559,6 @@ impl<'source> Parser<'source> {
         self.semicolon_terminated(Stmt::Melo(ident))
     }
 
-    /// Parse loop flow
-    ///
-    /// `loop` is an infinite loop, no condition, only body
-    fn loop_flow(&mut self) -> Result<Stmt, Error> {
-        Ok(Stmt::Loop {
-            body: self.get_block()?,
-        })
-    }
-
     /// Perform lang -> script substitution if in T-Dark block
     fn tdark_subst(&self, mut string: String) -> String {
         if self.tdark {
diff --git a/ablescript/src/value/mod.rs b/ablescript/src/value/mod.rs
index c7998a0..3c1dfe7 100644
--- a/ablescript/src/value/mod.rs
+++ b/ablescript/src/value/mod.rs
@@ -18,8 +18,9 @@ use std::{
 pub type Cart = HashMap<Value, ValueRef>;
 
 /// AbleScript Value
-#[derive(Debug, Clone)]
+#[derive(Debug, Default, Clone)]
 pub enum Value {
+    #[default]
     Nul,
     Undefined,
     Str(String),
@@ -29,12 +30,6 @@ pub enum Value {
     Cart(Cart),
 }
 
-impl Default for Value {
-    fn default() -> Self {
-        Self::Nul
-    }
-}
-
 impl Hash for Value {
     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
         discriminant(self).hash(state);