From 7b89f4c10cbae465cf3bc54e9d65d2829f4cdd93 Mon Sep 17 00:00:00 2001
From: darcy <acednes@gmail.com>
Date: Wed, 4 Dec 2024 21:32:50 +1100
Subject: [PATCH] feat: parse `eval` instruction

---
 src/debugger/eval.rs | 30 +++++++++++++++++++++
 src/debugger/mod.rs  |  5 ++--
 src/parser.rs        | 64 +++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 src/debugger/eval.rs

diff --git a/src/debugger/eval.rs b/src/debugger/eval.rs
new file mode 100644
index 0000000..aeb0ca5
--- /dev/null
+++ b/src/debugger/eval.rs
@@ -0,0 +1,30 @@
+use miette::Result;
+
+use crate::{
+    air::AirStmt,
+    lexer::{cursor::Cursor, TokenKind},
+    runtime::RunState,
+    symbol::InstrKind,
+    AsmParser,
+};
+
+pub fn run(state: &mut RunState, line: String) {
+    let stmt = parse(line);
+
+    println!("{:#?}", stmt);
+
+    todo!();
+}
+
+fn parse(line: String) -> Result<AirStmt> {
+    // TODO(fix): This is a TERRIBLE solution. Ideally cursor doesn't take &'static str ??
+    let line = Box::leak(line.into_boxed_str());
+
+    let mut parser = AsmParser::new_simple(line)?;
+
+    let stmt = parser.parse_simple()?;
+
+    println!("{:#?}", stmt);
+
+    todo!();
+}
diff --git a/src/debugger/mod.rs b/src/debugger/mod.rs
index 10e8aba..83269a9 100644
--- a/src/debugger/mod.rs
+++ b/src/debugger/mod.rs
@@ -1,4 +1,5 @@
 mod command;
+mod eval;
 mod parse;
 mod source;
 
@@ -339,8 +340,8 @@ impl Debugger {
 
             Command::Eval { instruction } => {
                 self.was_pc_changed = true;
-                dprintln!(Always, "<{}>", instruction);
-                dprintln!(Always, "unimplemented: eval")
+                dprintln!(Always, "Eval: <{}>", instruction);
+                eval::run(state, instruction);
             }
 
             Command::BreakAdd { location } => {
diff --git a/src/parser.rs b/src/parser.rs
index 15e5e48..7489377 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -81,6 +81,33 @@ pub fn preprocess(src: &'static str) -> Result<Vec<Token>> {
     Ok(res)
 }
 
+fn preprocess_simple(src: &'static str) -> Result<Vec<Token>> {
+    let mut res: Vec<Token> = Vec::new();
+    let mut cur = Cursor::new(src);
+
+    loop {
+        let token = cur.advance_real()?;
+        match token.kind {
+            TokenKind::Instr(_) | TokenKind::Trap(_) => res.push(token),
+
+            TokenKind::Comment | TokenKind::Whitespace => continue,
+            TokenKind::Eof => break,
+
+            TokenKind::Dir(_)
+            | TokenKind::Label
+            | TokenKind::Lit(_)
+            | TokenKind::Reg(_)
+            | TokenKind::Byte(_)
+            | TokenKind::Breakpoint => {
+                // TODO(feat): Handle error
+                panic!("unexpected token `{:?}`", token.kind);
+            }
+        }
+    }
+
+    Ok(res)
+}
+
 fn unescape(s: &str) -> Cow<str> {
     if s.find('\\').is_none() {
         return Cow::Borrowed(s);
@@ -137,6 +164,16 @@ impl AsmParser {
         })
     }
 
+    pub fn new_simple(src: &'static str) -> Result<Self> {
+        let toks = preprocess_simple(src)?;
+        Ok(AsmParser {
+            src,
+            toks: toks.into_iter().peekable(),
+            air: Air::new(),
+            line: 1,
+        })
+    }
+
     fn get_span(&self, span: Span) -> &str {
         &self.src[span.offs()..span.end()]
     }
@@ -200,6 +237,31 @@ impl AsmParser {
         Ok(self.air)
     }
 
+    pub fn parse_simple(&mut self) -> Result<AirStmt> {
+        let Some(tok) = self.toks.next() else {
+            // TODO(feat): Handle error
+            panic!("unexpected eof (possibly unreachable)");
+        };
+
+        match tok.kind {
+            TokenKind::Instr(instr_kind) => self.parse_instr(instr_kind),
+            TokenKind::Trap(trap_kind) => self.parse_trap(trap_kind),
+
+            // Does not exist in preprocessed token stream
+            TokenKind::Comment
+            | TokenKind::Whitespace
+            | TokenKind::Eof
+            | TokenKind::Dir(_)
+            | TokenKind::Label
+            | TokenKind::Lit(_)
+            | TokenKind::Reg(_)
+            | TokenKind::Byte(_)
+            | TokenKind::Breakpoint => {
+                unreachable!("Found invalid token kind in preprocessed stream");
+            }
+        }
+    }
+
     /// Return label or leave iter untouched and return None
     fn optional_label(&mut self) -> Option<Token> {
         match self.toks.peek() {
@@ -209,7 +271,7 @@ impl AsmParser {
     }
 
     /// Process several tokens to form valid AIR statement
-    fn parse_instr(&mut self, kind: InstrKind) -> Result<AirStmt> {
+    pub fn parse_instr(&mut self, kind: InstrKind) -> Result<AirStmt> {
         use crate::symbol::InstrKind;
         match kind {
             InstrKind::Push => {