feat: WIP

TODO.md

@@ -11,17 +11,145 @@
 阻拦变量解析的是 `with import` 而不是一般的 `with`
 解析阶段可以解决除涉及非字符串常量拼接路径导入之外的问题
 
-# 工作流程
+静态分析图与求值期图分离，动态生成求值期图
+
+依赖类型：
+1. 强依赖 (x!)
+  - builtins.toString x => x!
+  - x + y => x! y!
+  - { x = 1; ${sym} = 2; } => sym!
+2. 弱依赖 a.k.a. thunk (x?)
+  - builtins.seq x y => x! y?
+3. 递归依赖 (x!!)
+  - builtins.deepSeq x y => x!! y?
+
+e.g.
+- let a? = { inherit a?; }; in a! => a!
+  - a! => { a = <THUNK> }
+- f: let x? = f! x?; in x! => f! x!
+- let ret? = (self: { x? = 1; y? = self.x! + 1; }) ret?; in ret.y! => ret! x! y!
+
+工作流程：
+1. string -> AST
+2. AST -> HIR (alloc ExprId)
+3. HIR -> LIR (resolve var, build graph)
+4. LIR -> Value
+
 ```mermaid
 flowchart TD
-  Start --> CtxNew[Context::new]
-  CtxNew --> CtxEval[Context::eval]
-  CtxEval --> DCtxNew[DowngradeCtx::new]
-  DCtxNew --> DCtxDowngradeRoot[DowngradeCtx::downgrade_root]
-  DCtxDowngradeRoot --> RCtxNew[ResolveCtx::new]
-  RCtxNew --> RCtxResolveRoot[ResolveCtx::resolve_root]
-  RCtxResolveRoot --> ECtxNew[EvalCtx::new]
-  ECtxNew --> ECtxEvalRoot[EvalCtx::eval_root]
-  ECtxEvalRoot --> ECtxEvalDeps[EvalCtx::eval_deps]
-  ECtxEvalDeps --> ECtxEval[EvalCtx::eval]
+  Start([Context::eval]) --> Eval[EvalContext::eval]
+  Eval --> AddNode[add node to graph]
+  AddNode --> CheckType{check expression type}
+
+  CheckType -->|AttrSet| A_EvalKeys[eval keys]
+  A_EvalKeys --> A_Construct[construct attrset]
+  A_Construct --> A_Return[return attrset]
+  A_Return --> End
+  A_EvalKeys -.->|eval| Eval
+
+  CheckType -->|List| L_Construct[construct list]
+  L_Construct --> L_Return[return list]
+  L_Return --> End
+
+  CheckType -->|HasAttr| HA_ForceAttrSet[force attrset]
+  HA_ForceAttrSet --> HA_ForceAttrPath[force attrpath]
+  HA_ForceAttrPath --> HA_Return[return bool]
+  HA_Return --> End
+  HA_ForceAttrSet -.->|eval| Eval
+  HA_ForceAttrPath -.->|eval| Eval
+
+  CheckType -->|BinOp| B_ForceLeft[force left operand]
+  B_ForceLeft --> B_ForceRight[force right operand]
+  B_ForceRight --> B_Apply[apply operator]
+  B_Apply --> B_Return[return value]
+  B_Return --> End
+  B_ForceLeft -.->|eval| Eval
+  B_ForceRight -.->|eval| Eval
+
+  CheckType -->|UnOp| U_ForceOperand[force operand]
+  U_ForceOperand --> U_Apply[apply operator]
+  U_Apply --> U_Return[return value]
+  U_Return --> End
+  U_ForceOperand -.->|eval| Eval
+
+  CheckType -->|Select| S_ForceAttrSet[force attrset]
+  S_ForceAttrSet --> S_ForceAttrPath[force attrpath]
+  S_ForceAttrPath --> S_CallEval[call eval on value]
+  S_CallEval --> S_Return[return value]
+  S_Return --> End
+  S_ForceAttrSet -.->|eval| Eval
+  S_ForceAttrPath -.->|eval| Eval
+  S_CallEval -.-> Eval
+
+  CheckType -->|If| I_ForceCond[force condition]
+  I_ForceCond --> I_Cond{condition}
+  I_Cond -->|true| I_ForceConsq[force consequence]
+  I_Cond -->|false| I_ForceAlter[force alternative]
+  I_ForceConsq --> I_CallEvalConsq[call eval on consequence]
+  I_ForceAlter --> I_CallEvalAlter[call eval on alternative]
+  I_CallEvalConsq --> I_ReturnConsq[return value]
+  I_CallEvalAlter --> I_ReturnAlter[return value]
+  I_ReturnConsq --> End
+  I_ReturnAlter --> End
+  I_ForceCond -.->|eval| Eval
+  I_ForceConsq -.->|eval| Eval
+  I_ForceAlter -.->|eval| Eval
+  I_CallEvalConsq -.-> Eval
+  I_CallEvalAlter -.-> Eval
+
+  CheckType -->|Call| C_RegArg[register argument]
+  C_RegArg --> C_ForceBody[force body]
+  C_ForceBody --> C_CallEval[call eval on body]
+  C_CallEval --> C_Return[return value]
+  C_Return --> End
+  C_ForceBody -.->|eval| Eval
+  C_CallEval -.-> Eval
+
+  CheckType -->|With| W_EnterWith[enter with]
+  W_EnterWith --> W_ForceBody[force body]
+  W_ForceBody --> W_CallEval[call eval on body]
+  W_CallEval --> W_Return[return value]
+  W_Return --> End
+  W_ForceBody -.->|eval| Eval
+  W_CallEval -.-> Eval
+
+  CheckType -->|Assert| As_ForceCond[force condition]
+  As_ForceCond --> As_Cond{condition}
+  As_Cond -->|true| As_ForceBody[force body]
+  As_Cond -->|false| As_Throw[throw Catchable]
+  As_ForceBody --> As_CallEval[call eval on body]
+  As_CallEval --> End
+  As_ForceCond -.->|eval| Eval
+  As_ForceBody -.->|eval| Eval
+  As_CallEval -.-> Eval
+
+  CheckType -->|ConcatStrings| CS_ForceParts[force string parts]
+  CS_ForceParts --> CS_Construct[construct string]
+  CS_Construct --> End
+  CS_ForceParts -.->|eval| Eval
+
+  CheckType -->|Const| Co_Return[return constant]
+  Co_Return --> End
+
+  CheckType -->|Str| St_Return[return string]
+  St_Return --> End
+
+  CheckType -->|Var| V_Lookup[lookup var]
+  V_Lookup --> V_Return[return value]
+  V_Return --> End
+
+  CheckType -->|Arg| Ar_Lookup[lookup arg]
+  Ar_Lookup --> End
+
+  CheckType -->|Func| F_Construct[construct function]
+  F_Construct --> End
+
+  CheckType -->|StrictRef| SR_Eval[eval referenced expr]
+  SR_Eval --> Eval
+
+  CheckType -->|LazyRef| LR_Resolve[resolve dynamic variable lookups of the referenced expr]
+  LR_Resolve --> LR_Contruct[construct lazy reference]
+  LR_Contruct --> End
+
+  End([return result])
 ```