typedef struct PStmnt PStmnt;

typedef PStmnt *AST;

typedef enum {
	PExprIntLit,    // 17
	PExprStrLit,    // "17"
	PExprAssign,    // x=y
	PExprModAssign, // x op= y, for op in +-*/%«»&^|
	PExprMemberget, // x.y
	                //  -> is forthcoming
	PExprIndex,     // x[y]
	PExprId,        // x
	PExprRef,       // &x
	PExprLabelRef,  // &&x
	PExprMonad,     // op x, for op in *+-!~
	PExprDyad,      // x op y, for op in +-*/%«»&^|
	PExprLogDyad,   // x op y, for op in || &&
	PExprCmp,       // x op y, for op in < <= == >= > !=
	PExprTernaryIf, // x ? y : z
	PExprFnCall,    // f(x)
	PExprPreInc,    // ++x
	PExprPreDec,    // --x
	PExprPostInc,   // x++
	PExprPostDec,   // x--
	PExprStmnt,     /* ({statements;expr;}) * actually statement expression */
} PExprType;

typedef enum {
	PLogDyadOr,
	PLogDyadAnd,
} PLogDyad;

typedef enum {
	PCmpLt,
	PCmpLe,
	PCmpEq,
	PCmpGe,
	PCmpGt,
	PCmpNe,
} PCmp;

typedef enum {
	PMonadDeref,
	PMonadPlus, // identity; ignore
	PMonadNeg,
	PMonadLogNot,
	PMonadBitNot,
} PMonad;
typedef enum {
	PDyadAdd,
	PDyadSub,
	PDyadMul,
	PDyadDiv,
	PDyadMod,
	PDyadLShift,
	PDyadRShift,
	PDyadBitAnd,
	PDyadBitXor,
	PDyadBitOr,
} PDyad;

typedef struct PExpr PExpr;
struct PExpr {
	Pos pos;
	PExprType type;

	union {
		s8 int_lit;
		Cc1 *id;
		Cc1 *str_lit;
		struct {
			PDyad op;
			PExpr *lhs, *rhs;
		} dyad; // reused by assign, modassign
		struct {
			PLogDyad op;
			PExpr *lhs, *rhs;
		} ldyad;
		struct {
			PCmp cmp;
			PExpr *lhs, *rhs;
		} cmp;
		struct { PExpr *c, *t, *f; } ternary; //todo : pos
		struct {
			PExpr *fn;
			PExpr *params;
		} call;

		struct {
			PMonad op;
			PExpr *operand; //generic for monadic operator application
		} monad;

		AST stmnt_expr;

		struct {
			PExpr *structure;
			Cc1 *membername;
		} memberget;
		struct {
			PExpr *array, *subscript;
		} index;
	};
};



/// 'Forest': collection of syntax trees
typedef struct {
	PStmnt *ast;

	// (t)ype environment
	struct {
		Cc1 **map;

		usz *stack;
	} tenv;
} Forest;

typedef enum {
	PStmntFnProto, // int f(int); / also uses the 'fn' member, but with unspecified contents for 'body'
	PStmntFnDecl,  // int f(int v) { ... }
	PStmntVDecl,   // int x,y=x;
	PStmntRet,     // return x
	PStmntExpr,    // expr; / actually expression statement
	PStmntGoto,    // goto x
	PStmntCompound,// {x;y;}
	PStmntIf,      // if(x)y;
	PStmntIfElse,  // if(x)y;else z;
	PStmntWhile,   // while(x)y;
	PStmntDoWhile, // do x;while(y);
	PStmntFor,     // for(x;y;z)w;
	PStmntSwitch,  // switch(x)y;
	PStmntTypedef, // typedef int x, y;
	               // reuses vdecl member
	PStmntContinue,// self-explanatory
	PStmntBreak,   // break;
	PStmntEmpty,   // ;
} PStmntType;
struct PStmnt {
	Pos pos;
	PStmntType type;

	struct {
		Cc1 *name;
		Pos pos;
	} *labels;

	struct {
		PExpr expr; // for 'default', the position here will be valid
		bool isdefault;
	} *switch_labels;

	union {
		struct {
			Cc1 *name;
			PTypeId ret;
			PTypeSig sig;
			AST body;
		} fn;

		struct {
			StorageClass storage_class;

			struct {
				PTypeId type;
				Pos tpos;     // T pose!
				Cc1 *name;
				//Pos npos;
				Pos eqpos;
				bool is_init;
				PExpr init;
			} *decls;
		} vdecl;

		AST compound;

		PExpr expr;

		struct {
			PExpr cond;
			PStmnt *branch;
		} sif;
		struct {
			PExpr cond;
			PStmnt *body;
		} sbody;
		struct {
			PExpr cond;
			PStmnt *branch1, *branch2;
		} sifelse;
		struct {
			PExpr cond;
			PStmnt *body;
		} swhile; //while and do-while
		struct {
			PStmnt *init;
			PExpr *cond, *post; //all these can be null if not present
			PStmnt *body;
		} sfor;
		struct {
			PExpr control;
			PStmnt *body;
		} sswitch;
	};
};

bool parse(TokenList *tl, Forest *out);