lab2: rebuild semantic analysis for current SysY grammar

include/sem/Sema.h

@@ -1,30 +1,69 @@
 // 基于语法树的语义检查与名称绑定。
 #pragma once
 
+#include <string>
 #include <unordered_map>
+#include <vector>
 
 #include "SysYParser.h"
 
+enum class SemanticType {
+  Void,
+  Int,
+  Float,
+};
+
+struct ScalarConstant {
+  SemanticType type = SemanticType::Int;
+  double number = 0.0;
+};
+
+struct ObjectBinding {
+  enum class DeclKind {
+    Var,
+    Const,
+    Param,
+  };
+
+  std::string name;
+  SemanticType type = SemanticType::Int;
+  DeclKind decl_kind = DeclKind::Var;
+  bool is_array_param = false;
+  std::vector<int> dimensions;
+  const SysYParser::VarDefContext* var_def = nullptr;
+  const SysYParser::ConstDefContext* const_def = nullptr;
+  const SysYParser::FuncFParamContext* func_param = nullptr;
+  bool has_const_value = false;
+  ScalarConstant const_value;
+};
+
+struct FunctionBinding {
+  std::string name;
+  SemanticType return_type = SemanticType::Int;
+  std::vector<ObjectBinding> params;
+  const SysYParser::FuncDefContext* func_def = nullptr;
+  bool is_builtin = false;
+};
+
 class SemanticContext {
  public:
-  void BindVarUse(SysYParser::VarContext* use,
-                  SysYParser::VarDefContext* decl) {
-    var_uses_[use] = decl;
-  }
+  void BindObjectUse(const SysYParser::LValContext* use, ObjectBinding binding);
+  const ObjectBinding* ResolveObjectUse(
+      const SysYParser::LValContext* use) const;
+
+  void BindFunctionCall(const SysYParser::UnaryExpContext* call,
+                        FunctionBinding binding);
+  const FunctionBinding* ResolveFunctionCall(
+      const SysYParser::UnaryExpContext* call) const;
 
-  SysYParser::VarDefContext* ResolveVarUse(
-      const SysYParser::VarContext* use) const {
-    auto it = var_uses_.find(use);
-    return it == var_uses_.end() ? nullptr : it->second;
-  }
+  void RegisterFunction(FunctionBinding binding);
+  const FunctionBinding* ResolveFunction(const std::string& name) const;
 
  private:
-  std::unordered_map<const SysYParser::VarContext*,
-                     SysYParser::VarDefContext*>
-      var_uses_;
+  std::unordered_map<const SysYParser::LValContext*, ObjectBinding> object_uses_;
+  std::unordered_map<const SysYParser::UnaryExpContext*, FunctionBinding>
+      function_calls_;
+  std::unordered_map<std::string, FunctionBinding> functions_;
 };
 
-// 目前仅检查：
-// - 变量先声明后使用
-// - 局部变量不允许重复定义
 SemanticContext RunSema(SysYParser::CompUnitContext& comp_unit);

include/sem/SymbolTable.h

@@ -1,17 +1,25 @@
-// 极简符号表：记录局部变量定义点。
+// 维护对象符号的多层作用域。
 #pragma once
 
 #include <string>
+#include <string_view>
 #include <unordered_map>
+#include <vector>
 
-#include "SysYParser.h"
+#include "sem/Sema.h"
 
 class SymbolTable {
  public:
-  void Add(const std::string& name, SysYParser::VarDefContext* decl);
-  bool Contains(const std::string& name) const;
-  SysYParser::VarDefContext* Lookup(const std::string& name) const;
+  SymbolTable();
+
+  void EnterScope();
+  void ExitScope();
+
+  bool Add(const ObjectBinding& symbol);
+  bool ContainsInCurrentScope(std::string_view name) const;
+  const ObjectBinding* Lookup(std::string_view name) const;
+  size_t Depth() const;
 
  private:
-  std::unordered_map<std::string, SysYParser::VarDefContext*> table_;
+  std::vector<std::unordered_map<std::string, ObjectBinding>> scopes_;
 };

src/sem/SymbolTable.cpp

@@ -1,17 +1,39 @@
-// 维护局部变量声明的注册与查找。
+// 维护对象符号的注册与按作用域查找。
 
 #include "sem/SymbolTable.h"
 
-void SymbolTable::Add(const std::string& name,
-                      SysYParser::VarDefContext* decl) {
-  table_[name] = decl;
+#include <stdexcept>
+
+SymbolTable::SymbolTable() : scopes_(1) {}
+
+void SymbolTable::EnterScope() { scopes_.emplace_back(); }
+
+void SymbolTable::ExitScope() {
+  if (scopes_.size() <= 1) {
+    throw std::runtime_error("symbol table scope underflow");
+  }
+  scopes_.pop_back();
 }
 
-bool SymbolTable::Contains(const std::string& name) const {
-  return table_.find(name) != table_.end();
+bool SymbolTable::Add(const ObjectBinding& symbol) {
+  auto& scope = scopes_.back();
+  return scope.emplace(symbol.name, symbol).second;
 }
 
-SysYParser::VarDefContext* SymbolTable::Lookup(const std::string& name) const {
-  auto it = table_.find(name);
-  return it == table_.end() ? nullptr : it->second;
+bool SymbolTable::ContainsInCurrentScope(std::string_view name) const {
+  const auto& scope = scopes_.back();
+  return scope.find(std::string(name)) != scope.end();
 }
+
+const ObjectBinding* SymbolTable::Lookup(std::string_view name) const {
+  const std::string key(name);
+  for (auto it = scopes_.rbegin(); it != scopes_.rend(); ++it) {
+    auto found = it->find(key);
+    if (found != it->end()) {
+      return &found->second;
+    }
+  }
+  return nullptr;
+}
+
+size_t SymbolTable::Depth() const { return scopes_.size(); }