Code generation

src/ast.rs

@@ -1,4 +1,6 @@
 use serde::{Deserialize, Serialize};
+use ron::from_str;
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub enum AstNodeKind {
     // Primitives
@@ -23,6 +25,7 @@ pub enum AstNodeKind {
     FunctionReturn,
     FunctionDefinition,
     VariableDefinition,
+    VariableDeclaration,
     Assign,
     // Blank node
     Null,
@@ -42,48 +45,112 @@ impl AstNode {
             subnodes,
         }
     }
-    pub fn emit(&self, f: &mut dyn std::fmt::Write) -> std::fmt::Result {
+    pub fn emit(&self) -> String {
         use AstNodeKind::*;
         match self.kind {
-            Integer => write!(f, "i32.const {}\n", self.value),
+            // Primitives
-            Identifier => write!(f, "get_local ${}\n", self.value),
+            Integer => format!("(i32.const {})", self.value),
-            Add => {
+            Identifier => format!("(get_local ${})", self.value),
-                self.subnodes[0].emit(f)?;
+            // Unary operators
-                self.subnodes[1].emit(f)?;
+            Not => format!("(i32.eq (i32.const 0) {})", self.subnodes[1].emit()),
-                write!(f, "i32.add\n")
+            // Infix operators
+            NotEqual => format!("(i32.ne {} {})", self.subnodes[0].emit(), self.subnodes[1].emit()),
+            Equal => format!("(i32.eq {} {})", self.subnodes[0].emit(), self.subnodes[1].emit()),
+            Add => format!("(i32.add {} {})", self.subnodes[0].emit(), self.subnodes[1].emit()),
+            Subtract => format!("(i32.sub {} {})", self.subnodes[0].emit(), self.subnodes[1].emit()),
+            Multiply => format!("(i32.mul {} {})", self.subnodes[0].emit(), self.subnodes[1].emit()),
+            Divide => format!("(i32.div_s {} {})", self.subnodes[0].emit(), self.subnodes[1].emit()),
+            // Control flow
+            Block => {
+                let mut out = String::new();
+                for node in &self.subnodes {
+                    out += "";
+                    out += &node.emit();
+                }
+                out
+            }
+            IfStatement => {
+                let mut out = String::new();
+                out += &format!("(if {} (then {})", self.subnodes[0].emit(), self.subnodes[1].emit()); // Emit the conditional and consequence.
+                if let Some(alternative) = self.subnodes.get(2) {
+                    out += &format!(" (else {})", alternative.emit()); // Emit the alternative.
+                }
+                out += ")";
+                out
+            }
+            WhileLoop => {
+                let loop_symbol = "while_loop"; // TODO: Make generate unique symbol for nested loops.
+                let mut out = String::new();
+                out += &format!("(block ${}_wrapper", loop_symbol);
+                out += &format!(" (loop ${}_loop", loop_symbol);
+                out += &format!(" {}", self.subnodes[1].emit());
+                out += &format!(" (br_if ${}_wrapper (i32.eq (i32.const 0) {}))", loop_symbol, self.subnodes[0].emit());
+                out += &format!(" (br ${}_loop)", loop_symbol);
+                out += "))";
+                out
             }
             Program => {
-                write!(f, "(module\n")?;
+                let mut out = String::new();
+                out += "(module";
                 let mut exported = vec![];
                 for node in &self.subnodes {
-                    node.emit(f)?;
+                    out += " ";
+                    out += &node.emit();
                     if node.kind == FunctionDefinition {
                         exported.push(node.value.clone());
                     }
                 }
                 for export in exported {
-                    write!(f, "(export \"{0}\" (func ${0}))\n", export)?;
+                    out += &format!(" (export \"{0}\" (func ${0}))", export);
                 }
-                write!(f, ")")
+                out += ")";
+                out
             }
+            // Functions and variables
+            FunctionCall => {
+                let mut out = String::new();
+                out += &format!("(call ${}", from_str::<AstNode>(&self.value).unwrap().value);
+                for n in &self.subnodes {
+                    out += " ";
+                    out += &n.emit();
+                }
+                out += ")";
+                out
+            },
+            FunctionReturn => format!("{} (return)", self.subnodes[0].emit()),
             FunctionDefinition => {
-                write!(f, "(func ${}", self.value)?;
+                let mut out = String::new();
-                // let body = self.subnodes[0];
+                out += &format!("(func ${}", self.value);
-                for a in &self.subnodes[1..] {
+                let body = self.subnodes[0].clone();
-                    write!(f, " (param ${} i32)", a.value)?;
+                for n in &self.subnodes[1..] {
+                    out += &format!(" (param ${} i32)", n.value);
                 }
-                write!(f, " (result i32)\n")?;
+                let mut func_returns_value = false;
-                self.subnodes[0].emit(f)?;
+                let mut index = 0;
-                write!(f, ")\n")
+                loop {
-            }
+                    if index >= body.subnodes.len() {
-            Block => {
+                        break;
-                for node in &self.subnodes {
+                    }
-                    node.emit(f)?;
+                    match body.subnodes[index].kind {
+                        AstNodeKind::FunctionReturn => func_returns_value = true,
+                        _ => {}
+                    }
+                    index += 1;
                 }
-                write!(f, "")
+                if func_returns_value {
+                    out += " (result i32)";
+                }
+                for n in &body.subnodes {
+                    out += " ";
+                    out += &n.emit();
+                }
+                out += ")";
+                out
             }
-            FunctionReturn => self.subnodes[0].emit(f),
+            VariableDeclaration => format!("(local ${} i32)", self.value),
-            _ => Ok(()),
+            Assign => format!("(set_local ${} {})", self.value, self.subnodes[0].emit()),
+            // Blank node / other
+            Null | _ => "".into(),
         }
     }
 
@@ -219,6 +286,13 @@ impl AstNode {
             subnodes: vec![value],
         }
     }
+    pub fn variable_declaration(name: String) -> AstNode {
+        AstNode {
+            kind: AstNodeKind::VariableDeclaration,
+            value: name,
+            subnodes: vec![],
+        }
+    }
     pub fn assign(name: String, value: AstNode) -> AstNode {
         AstNode {
             kind: AstNodeKind::Assign,

src/main.rs

@@ -4,13 +4,19 @@ use std::fs::File;
 use std::io::prelude::*;
 
 fn main() -> std::io::Result<()> {
-    let src = r#"function add(left, right) { return left + right; }"#;
+    let src = r#"
+        function a(num) {
+            return num;
+        }
+        function main(num) {
+            var amt = a(2);
+            return num + amt;
+        }"#;
     let ast = pivot::parse(src);
-    // println!("{}", ast);
+    println!("{}", ast);
-    let mut code = String::new();
+    let code = ast.emit();
-    ast.emit(&mut code);
     println!("{}", code);
     let binary = wat::parse_str(code).unwrap();
-    let mut file = File::create("out.wasm")?.write_all(&binary)?;
+    File::create("out.wasm")?.write_all(&binary)?;
     Ok(())
 }

src/parse/mod.rs

@@ -1,15 +1,22 @@
 mod combinators;
 
-use crate::ast::AstNode;
+use crate::ast::{AstNode, AstNodeKind};
 use combinators::Parser;
 use ron::{from_str, to_string};
 
 pub fn parse<T: Into<String>>(src: T) -> AstNode {
     let src: String = src.into();
-    let parse_program = Parser::custom(parse_statement)
+    let whitespace = Parser::regex(r"[ \n\r\t]+");
+    let comments = Parser::regex(r"[/][/].*").or(Parser::regex(r"[/][*].*[*][/]"));
+    let ignored = whitespace.or(comments).repeat_range(0..usize::MAX);
+    let statement = ignored.optional().ignore().and(Parser::custom(parse_statement));
+    let parse_program = statement.clone()
         .repeat_range(0..usize::MAX)
         .map(|matched| {
             let data = from_str::<Vec<String>>(&matched)?;
+            for d in &data {
+                println!("{}", d);
+            }
             let mut statements = vec![];
             for d in data {
                 statements.push(from_str::<AstNode>(&d)?);
@@ -159,29 +166,31 @@ fn parse_statement(src: String) -> Result<(String, String), String> {
         .and(block_statement.clone())
         .map(|matched| {
             let data = from_str::<Vec<String>>(&matched)?;
-            for d in &data {
+            let mut body = from_str::<AstNode>(&data[1])?;
-                println!("{}", d);
-            }
-            let body = from_str::<AstNode>(&data[1])?;
-            println!("body: {}", body);
             let data = from_str::<Vec<String>>(&data[0])?;
-            for d in &data {
-                println!("{}", d);
-            }
             let name = from_str::<AstNode>(&data[0])?.value;
-            println!("name: {}", name);
             let params = from_str::<Vec<String>>(&data[1])?;
             let mut parameters = vec![];
-            for p in from_str::<Vec<String>>(&params[0])? {
+            if params.len() != 0 {
-                parameters.push(from_str::<AstNode>(&p)?);
+                for p in from_str::<Vec<String>>(&params[0])? {
+                    parameters.push(from_str::<AstNode>(&p)?);
+                }
             }
-            println!("{:?}", parameters);
+            // Hoist variable definitions.
+            let mut vars = vec![];
+            let mut others = vec![];
+            for node in &body.subnodes {
+                match node.kind {
+                    AstNodeKind::VariableDefinition => {
+                        vars.push(AstNode::variable_declaration(node.value.clone()));
+                        others.push(AstNode::assign(node.value.clone(), node.subnodes[0].clone()))
+                    },
+                    _ => others.push(node.clone()),
+                }
+            }
+            vars.append(&mut others);
+            body.subnodes = vars;
             Ok(to_string(&AstNode::function_definition(name, parameters, body))?)
-        })
-        .map(|matched| {
-            let function_definition = from_str::<AstNode>(&matched)?;
-            println!("{}", function_definition);
-            Ok(matched)
         });
     return_statement.clone()
         .or(if_statement.clone())
@@ -283,8 +292,11 @@ fn parse_expression(src: String) -> Result<(String, String), String> {
             let callee = data[0].clone();
             let args = from_str::<Vec<String>>(&data[1])?;
             let mut ast_args = vec![];
-            for arg in &args {
+            if let Some(args) = args.get(0) {
-                ast_args.push(from_str::<AstNode>(arg)?);
+                let args = from_str::<Vec<String>>(&args)?;
+                for arg in &args {
+                    ast_args.push(from_str::<AstNode>(arg)?);
+                }
             }
             Ok(to_string(
                 &AstNode::function_call(callee, ast_args),

test.js

@@ -1,5 +1,5 @@
 require("webassembly")
   .load("out.wasm")
   .then(module => {
-    console.log("2 + 2 is " + module.exports.add(2, 2));
+    console.log("3 + 2 is " + module.exports.main(3));
   });