Add transpiler

compiler/erg_compiler/lib.rs

@@ -21,5 +21,6 @@ pub mod mod_cache;
 pub mod optimize;
 pub mod ownercheck;
 pub mod reorder;
+pub mod transpile;
 pub mod ty;
 pub mod varinfo;

compiler/erg_compiler/main.rs

@@ -10,6 +10,7 @@ use erg_common::traits::Runnable;
 
 use erg_compiler::build_hir::HIRBuilder;
 use erg_compiler::lower::ASTLowerer;
+use erg_compiler::transpile::Transpiler;
 use erg_compiler::ty::deserialize::Deserializer;
 use erg_compiler::Compiler;
 
@@ -31,6 +32,9 @@ fn run() {
         "check" => {
             HIRBuilder::run(cfg);
         }
+        "transpile" => {
+            Transpiler::run(cfg);
+        }
         "compile" | "exec" => {
             Compiler::run(cfg);
         }

compiler/erg_compiler/transpile.rs

@@ -0,0 +1,233 @@
+use std::fs::File;
+use std::io::Write;
+
+use erg_common::config::ErgConfig;
+use erg_common::log;
+use erg_common::traits::{Runnable, Stream};
+use erg_common::Str;
+
+use erg_parser::ast::ParamPattern;
+
+use crate::build_hir::HIRBuilder;
+use crate::desugar_hir::HIRDesugarer;
+use crate::error::{CompileError, CompileErrors};
+use crate::hir::{Accessor, Block, Call, Expr, Identifier, Params, Signature, HIR};
+use crate::link::Linker;
+use crate::mod_cache::SharedModuleCache;
+
+#[derive(Debug, Clone)]
+pub struct PyScript {
+    pub filename: Str,
+    pub code: String,
+}
+
+/// Generates a `PyScript` from an String or other File inputs.
+#[derive(Debug, Default)]
+pub struct Transpiler {
+    pub cfg: ErgConfig,
+    builder: HIRBuilder,
+    mod_cache: SharedModuleCache,
+    script_generator: ScriptGenerator,
+}
+
+impl Runnable for Transpiler {
+    type Err = CompileError;
+    type Errs = CompileErrors;
+    const NAME: &'static str = "Erg transpiler";
+
+    fn new(cfg: ErgConfig) -> Self {
+        let mod_cache = SharedModuleCache::new();
+        let py_mod_cache = SharedModuleCache::new();
+        Self {
+            builder: HIRBuilder::new_with_cache(
+                cfg.copy(),
+                "<module>",
+                mod_cache.clone(),
+                py_mod_cache,
+            ),
+            script_generator: ScriptGenerator::new(),
+            mod_cache,
+            cfg,
+        }
+    }
+
+    #[inline]
+    fn cfg(&self) -> &ErgConfig {
+        &self.cfg
+    }
+
+    #[inline]
+    fn finish(&mut self) {}
+
+    fn clear(&mut self) {
+        // self.builder.clear();
+    }
+
+    fn exec(&mut self) -> Result<i32, Self::Errs> {
+        let path = self.input().filename().replace(".er", ".py");
+        let script = self.transpile(self.input().read(), "exec")?;
+        let mut f = File::create(&path).unwrap();
+        f.write_all(script.code.as_bytes()).unwrap();
+        Ok(0)
+    }
+
+    fn eval(&mut self, src: String) -> Result<String, CompileErrors> {
+        let script = self.transpile(src, "eval")?;
+        Ok(script.code)
+    }
+}
+
+impl Transpiler {
+    pub fn transpile(&mut self, src: String, mode: &str) -> Result<PyScript, CompileErrors> {
+        log!(info "the transpiling process has started.");
+        let hir = self.build_link_desugar(src, mode)?;
+        let script = self.script_generator.transpile(hir);
+        log!(info "code:\n{}", script.code);
+        log!(info "the transpiling process has completed");
+        Ok(script)
+    }
+
+    fn build_link_desugar(&mut self, src: String, mode: &str) -> Result<HIR, CompileErrors> {
+        let artifact = self
+            .builder
+            .build(src, mode)
+            .map_err(|artifact| artifact.errors)?;
+        let linker = Linker::new(&self.cfg, &self.mod_cache);
+        let hir = linker.link(artifact.hir);
+        Ok(HIRDesugarer::desugar(hir))
+    }
+}
+
+#[derive(Debug, Default)]
+pub struct ScriptGenerator {
+    level: usize,
+}
+
+impl ScriptGenerator {
+    pub const fn new() -> Self {
+        Self { level: 0 }
+    }
+
+    pub fn transpile(&mut self, hir: HIR) -> PyScript {
+        let mut code = String::new();
+        for chunk in hir.module.into_iter() {
+            code += &self.transpile_expr(chunk);
+            code.push('\n');
+        }
+        PyScript {
+            filename: hir.name,
+            code,
+        }
+    }
+
+    pub fn transpile_expr(&mut self, expr: Expr) -> String {
+        match expr {
+            Expr::Lit(lit) => lit.token.content.to_string(),
+            Expr::Call(call) => self.transpile_call(call),
+            Expr::Accessor(acc) => match acc {
+                Accessor::Ident(ident) => Self::transpile_ident(ident),
+                Accessor::Attr(attr) => {
+                    format!(
+                        "{}.{}",
+                        self.transpile_expr(*attr.obj),
+                        Self::transpile_ident(attr.ident)
+                    )
+                }
+            },
+            Expr::Def(mut def) => match def.sig {
+                Signature::Var(var) => {
+                    let mut code = format!("{} = ", Self::transpile_ident(var.ident));
+                    if def.body.block.len() > 1 {
+                        todo!("transpile instant blocks")
+                    }
+                    let expr = def.body.block.remove(0);
+                    code += &self.transpile_expr(expr);
+                    code
+                }
+                Signature::Subr(subr) => {
+                    let mut code = format!(
+                        "def {}({}):\n",
+                        Self::transpile_ident(subr.ident),
+                        self.transpile_params(subr.params)
+                    );
+                    code += &self.transpile_block(def.body.block);
+                    code
+                }
+            },
+            other => todo!("transpile {other}"),
+        }
+    }
+
+    fn transpile_call(&mut self, mut call: Call) -> String {
+        match call.obj.local_name() {
+            Some("assert") => {
+                let mut code = format!("assert {}", self.transpile_expr(call.args.remove(0)));
+                if let Some(msg) = call.args.try_remove(0) {
+                    code += &format!(", {}", self.transpile_expr(msg));
+                }
+                code
+            }
+            _ => self.transpile_simple_call(call),
+        }
+    }
+
+    fn transpile_simple_call(&mut self, mut call: Call) -> String {
+        let mut code = self.transpile_expr(*call.obj);
+        code.push('(');
+        while let Some(arg) = call.args.try_remove_pos(0) {
+            code += &self.transpile_expr(arg.expr);
+            code.push(',');
+        }
+        while let Some(arg) = call.args.try_remove_kw(0) {
+            code += &format!("{}={},", arg.keyword, self.transpile_expr(arg.expr));
+        }
+        code.push(')');
+        code
+    }
+
+    fn transpile_ident(ident: Identifier) -> String {
+        if let Some(py_name) = ident.vi.py_name {
+            py_name.to_string()
+        } else if ident.dot.is_some() {
+            ident.name.into_token().content.to_string()
+        } else {
+            let name = ident.name.into_token().content;
+            let name = name.replace('!', "__erg_proc__");
+            let name = name.replace('$', "__erg_shared__");
+            format!("__{name}")
+        }
+    }
+
+    fn transpile_params(&mut self, params: Params) -> String {
+        let mut code = String::new();
+        for non_default in params.non_defaults {
+            let ParamPattern::VarName(param) = non_default.pat else { todo!() };
+            code += &format!("{},", param.into_token().content);
+        }
+        for default in params.defaults {
+            let ParamPattern::VarName(param) = default.sig.pat else { todo!() };
+            code += &format!(
+                "{}={},",
+                param.into_token().content,
+                self.transpile_expr(default.default_val)
+            );
+        }
+        code
+    }
+
+    fn transpile_block(&mut self, block: Block) -> String {
+        self.level += 1;
+        let mut code = String::new();
+        let last = block.len() - 1;
+        for (i, chunk) in block.into_iter().enumerate() {
+            code += &"    ".repeat(self.level);
+            if i == last {
+                code += "return ";
+            }
+            code += &self.transpile_expr(chunk);
+            code.push('\n');
+        }
+        self.level -= 1;
+        code
+    }
+}