flowchart TD
  Start([EvalCtx::eval]) --> Eval[EvalContext::eval]
  Eval --> AddNode[为本即将求值表达式分配 ValueId，添加至图中]
  AddNode --> CheckType{检查表达式类型}

  CheckType -->|AttrSet| A_EvalKeys[强制求值所有键]
  A_EvalKeys --> A_Construct[构造 AttrSet]
  A_Construct --> End
  A_EvalKeys -.->|eval| Eval

  CheckType -->|List| L_Construct[构造列表]
  L_Construct --> End

  CheckType -->|HasAttr| HA_ForceAttrSet[强制求值 AttrSet]
  HA_ForceAttrSet --> HA_ForceAttrPath[强制求值 AttrPath]
  HA_ForceAttrPath --> HA_Result[求出结果]
  HA_Result --> End
  HA_ForceAttrSet -.->|eval| Eval
  HA_ForceAttrPath -.->|eval| Eval

  CheckType -->|BinOp| B_ForceLeft[强制求值左操作数]
  B_ForceLeft --> B_ForceRight[强制求值右操作数]
  B_ForceRight --> B_Apply[应用操作符]
  B_Apply --> End
  B_ForceLeft -.->|eval| Eval
  B_ForceRight -.->|eval| Eval

  CheckType -->|UnOp| U_ForceOperand[强制求值操作数]
  U_ForceOperand --> U_Apply[应用操作符]
  U_Apply --> End
  U_ForceOperand -.->|eval| Eval

  CheckType -->|Select| S_ForceAttrSet[强制求值 AttrSet]
  S_ForceAttrSet --> S_ForceAttrPath[强制求值 AttrPath]
  S_ForceAttrPath --> S_Result[获取结果]
  S_Result --> End
  S_ForceAttrSet -.->|eval| Eval
  S_ForceAttrPath -.->|eval| Eval

  CheckType -->|If| I_ForceCond[强制求值条件]
  I_ForceCond --> I_Cond{判断条件}
  I_Cond -->|true| I_Consq[返回 then]
  I_Cond -->|false| I_Alter[返回 else]
  I_Consq --> End
  I_Alter --> End
  I_ForceCond -.->|eval| Eval

  CheckType -->|Call| C_RegArg[注册函数参数]
  C_RegArg --> C_ForceBody[强制求值函数体]
  C_ForceBody --> End
  C_ForceBody -.->|eval| Eval

  CheckType -->|With| W_ForceNameSpace[强制求值命名空间]
  W_ForceNameSpace --> W_EnterWith[进入命名空间]
  W_EnterWith --> W_ForceBody[强制求值表达式]
  W_ForceBody --> W_ExitWith[退出命名空间]
  W_ExitWith --> End
  W_ForceNameSpace -.->|eval| Eval
  W_ForceBody -.->|eval| Eval

  CheckType -->|Assert| As_ForceCond[强制求值断言]
  As_ForceCond --> As_Cond{判断断言}
  As_Cond -->|true| As_ForceBody[强制求值表达式]
  As_Cond -->|false| As_Throw[抛出 Catchable]
  As_ForceBody --> End
  As_ForceCond -.->|eval| Eval
  As_ForceBody -.->|eval| Eval

  CheckType -->|ConcatStrings| CS_ForceParts[强制求值所有字符串片段]
  CS_ForceParts --> CS_Construct[构造字符串]
  CS_Construct --> End
  CS_ForceParts -.->|eval| Eval

  CheckType -->|Const| Co_Construct[构造常量]
  Co_Construct --> End

  CheckType -->|Str| St_Construct[构造字符串]
  St_Construct --> End

  CheckType -->|Var| V_Lookup[动态查找变量]
  V_Lookup --> End

  CheckType -->|Arg| Ar_Lookup[查找参数]
  Ar_Lookup --> End

  CheckType -->|Func| F_Construct[构造函数]
  F_Construct --> End

  CheckType -->|StrictRef| SR_Eval[求值被引用表达式]
  SR_Eval --> Eval

  CheckType -->|LazyRef| LR_Resolve[解析动态变量引用]
  LR_Resolve --> LR_Contruct[构造惰性引用]
  LR_Contruct --> End

  End([返回结果])