From 4d066acda3186cf1b160dc5410beabad1bd24ef5 Mon Sep 17 00:00:00 2001
From: Toni <antpiasecki@gmail.com>
Date: Thu, 29 May 2025 18:47:21 +0200
Subject: [PATCH] codegen

---
 src/codegen.rs | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs    | 11 ++++++--
 2 files changed, 80 insertions(+), 2 deletions(-)
 create mode 100644 src/codegen.rs

diff --git a/src/codegen.rs b/src/codegen.rs
new file mode 100644
index 0000000..53189aa
--- /dev/null
+++ b/src/codegen.rs
@@ -0,0 +1,71 @@
+use std::{error::Error, fmt::Write};
+
+use crate::{parser::Expr, tokenizer::TokenType};
+
+pub struct Codegen {
+    output: String,
+}
+
+impl Codegen {
+    pub fn new() -> Codegen {
+        Codegen {
+            output: String::new(),
+        }
+    }
+
+    pub fn emit_prologue(&mut self) -> Result<(), Box<dyn Error>> {
+        writeln!(&mut self.output, "section .data")?;
+        writeln!(&mut self.output, "format db \"%d\", 10, 0")?;
+        writeln!(&mut self.output, "section .text")?;
+        writeln!(&mut self.output, "global main")?;
+        writeln!(&mut self.output, "main:")?;
+        writeln!(&mut self.output, "    extern printf")?;
+        Ok(())
+    }
+
+    pub fn emit_epilogue(&mut self) -> Result<(), Box<dyn Error>> {
+        writeln!(&mut self.output, "    mov rdi, format")?;
+        writeln!(&mut self.output, "    mov rsi, rax")?;
+        writeln!(&mut self.output, "    xor rax, rax")?;
+        writeln!(&mut self.output, "    call printf")?;
+        writeln!(&mut self.output, "    mov rax, 0")?;
+        writeln!(&mut self.output, "    ret")?;
+        writeln!(&mut self.output, "section .note.GNU-stack")?;
+        writeln!(&mut self.output, "    db 0")?;
+        Ok(())
+    }
+
+    pub fn get_output(self) -> String {
+        self.output
+    }
+
+    pub fn compile_expr(&mut self, expr: Expr) -> Result<(), Box<dyn Error>> {
+        match expr {
+            Expr::Binary { left, op, right } => {
+                self.compile_expr(*left)?;
+                writeln!(&mut self.output, "    push rax")?;
+                self.compile_expr(*right)?;
+                writeln!(&mut self.output, "    mov rbx, rax")?;
+                writeln!(&mut self.output, "    pop rax")?;
+
+                match op.token_type {
+                    TokenType::Plus => writeln!(&mut self.output, "    add rax, rbx")?,
+                    TokenType::Minus => writeln!(&mut self.output, "    sub rax, rbx")?,
+                    TokenType::Star => writeln!(&mut self.output, "    imul rax, rbx")?,
+                    TokenType::Slash => {
+                        writeln!(&mut self.output, "    cqo")?;
+                        writeln!(&mut self.output, "    idiv rbx")?;
+                    }
+                    _ => todo!(),
+                }
+            }
+            Expr::Grouping(expr) => self.compile_expr(*expr)?,
+            Expr::Literal(token) => match token.token_type {
+                TokenType::Number => writeln!(&mut self.output, "    mov rax, {}", token.lexeme)?,
+                _ => todo!(),
+            },
+            Expr::Unary { op, right } => todo!(),
+        }
+        Ok(())
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index d4f317e..13e8d2b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+mod codegen;
 mod parser;
 mod tokenizer;
 
@@ -9,9 +10,15 @@ fn compile_file(path: String) -> Result<(), Box<dyn Error>> {
     // TODO: basename
     let tokenizer = tokenizer::Tokenizer::new(path, source);
     let tokens = tokenizer.tokenize()?;
-    let parser = parser::Parser::new(tokens);
 
-    println!("{:#?}", parser.parse());
+    let parser = parser::Parser::new(tokens);
+    let expr = parser.parse()?;
+
+    let mut codegen = codegen::Codegen::new();
+    codegen.emit_prologue()?;
+    codegen.compile_expr(expr)?;
+    codegen.emit_epilogue()?;
+    println!("{}", codegen.get_output());
 
     Ok(())
 }