refactor: 拆分 statement emit 分发逻辑

crates/oxide_compiler/src/emitter/stmt/declaration.rs

@@ -0,0 +1,105 @@
+use super::*;
+
+impl Compiler {
+    pub(in crate::emitter) fn emit_variable_declaration_statement(
+        &self, stmt: &Statement, ctx: &mut CompileCtx,
+    ) -> Result<Option<u8>, String> {
+        let Statement::VariableDeclaration(decl) = stmt else {
+            return Ok(None);
+        };
+        let mut r = None;
+        for d in &decl.declarations {
+            let is_const = matches!(decl.kind, VariableDeclarationKind::Const);
+            if is_const && d.init.is_none() {
+                return Err("const declaration must have an initializer".into());
+            }
+            if let Some(init) = &d.init {
+                let val_reg = self.emit_expression(init, ctx)?;
+                self.emit_binding_pattern(&d.id, val_reg, decl.kind, is_const, ctx)?;
+                if let BindingPattern::BindingIdentifier(bi) = &d.id {
+                    if matches!(*init, Expression::ArrowFunctionExpression(_)) {
+                        if let Some(sub_mod) = ctx.sub_modules.last_mut() {
+                            sub_mod.function_name = Some(bi.name.to_string());
+                        }
+                    }
+                }
+                r = Some(val_reg);
+            } else {
+                let BindingPattern::BindingIdentifier(bi) = &d.id else {
+                    return Err("destructuring declaration requires an initializer".into());
+                };
+                let idx = ctx.add_constant(Constant::Undefined);
+                let tmp = ctx.alloc_reg();
+                ctx.emit_load_const(tmp, idx);
+                let var_reg = ctx.alloc_reg();
+                ctx.declare(bi.name.as_str(), var_reg, decl.kind, is_const)?;
+                ctx.emit(opcode::encode(OpCode::STORE_VAR, var_reg, tmp, 0));
+                ctx.init_var(bi.name.as_str());
+                r = Some(var_reg);
+            }
+        }
+        Ok(r)
+    }
+
+    pub(in crate::emitter) fn emit_function_declaration_statement(
+        &self, stmt: &Statement, ctx: &mut CompileCtx,
+    ) -> Result<Option<u8>, String> {
+        let Statement::FunctionDeclaration(fd) = stmt else {
+            return Ok(None);
+        };
+        let name = if let Some(id) = &fd.id {
+            id.name.to_string()
+        } else {
+            return Err("FunctionDeclaration without name".into());
+        };
+
+        let mut param_names = Vec::new();
+        for (idx, param) in fd.params.items.iter().enumerate() {
+            match &param.pattern {
+                oxide_parser::BindingPattern::BindingIdentifier(bi) => {
+                    param_names.push(ParamSpec::Identifier(bi.name.to_string()));
+                }
+                pattern => {
+                    param_names.push(ParamSpec::Pattern {
+                        synthetic_name: format!("@@param_{idx}"),
+                        pattern,
+                    });
+                }
+            }
+        }
+
+        let body_stmts: &[Statement] = if let Some(body) = &fd.body { &body.statements } else { &[] };
+
+        let mut sub_module = self.compile_function_body(&param_names, body_stmts, ctx, false, false)?;
+        sub_module.function_name = Some(name.clone());
+        ctx.sub_modules.push(sub_module);
+        let sub_idx = ctx.sub_modules.len() as u32;
+
+        let var_reg = ctx.lookup(&name)?;
+        ctx.reserve_reg(var_reg);
+        let const_idx = ctx.add_constant(Constant::BytecodeFunc(sub_idx));
+        ctx.emit_load_const(var_reg, const_idx);
+        ctx.emit(opcode::encode(OpCode::STORE_VAR, var_reg, var_reg, 0));
+
+        Ok(None)
+    }
+
+    pub(in crate::emitter) fn emit_class_declaration_statement(
+        &self, stmt: &Statement, ctx: &mut CompileCtx,
+    ) -> Result<Option<u8>, String> {
+        let Statement::ClassDeclaration(class) = stmt else {
+            return Ok(None);
+        };
+        let name = class
+            .id
+            .as_ref()
+            .map(|id| id.name.to_string())
+            .ok_or_else(|| "ClassDeclaration without name".to_string())?;
+        let var_reg = ctx.alloc_reg();
+        ctx.declare(&name, var_reg, VariableDeclarationKind::Let, false)?;
+        ctx.init_var(&name);
+        let ctor_reg = self.emit_class(class, ctx)?;
+        ctx.emit(opcode::encode(OpCode::STORE_VAR, var_reg, ctor_reg, 0));
+        Ok(None)
+    }
+}