CmdFrame - tcl/tkコードリーディング

概要

コマンドフレームを定義する構造体

     /*
      * Data needed for Eval vs TEBC
      *
      * EXECUTION CONTEXTS and usage of CmdFrame
      *
      * Field	  TEBC		  EvalEx	  EvalObjEx
      * =======	  ====		  ======	  =========
      * level	  yes		  yes		  yes
      * type	  BC/PREBC	  SRC/EVAL	  EVAL_LIST
      * line0	  yes		  yes		  yes
      * framePtr	  yes		  yes		  yes
      * =======	  ====		  ======	  =========
      *
      * =======	  ====		  ======	  ========= union data
      * line1	  -		  yes		  -
      * line3	  -		  yes		  -
      * path	  -		  yes		  -
      * -------	  ----		  ------	  ---------
      * codePtr	  yes		  -		  -
      * pc	  yes		  -		  -
      * =======	  ====		  ======	  =========
      *
      * =======	  ====		  ======	  ========= | union cmd
      * listPtr	  -		  -		  yes	    |
      * -------	  ----		  ------	  --------- |
      * cmd	  yes		  yes		  -	    |
      * cmdlen	  yes		  yes		  -	    |
      * -------	  ----		  ------	  --------- |
      */
 

tcl/generic/tclInt.h

メンバー

• int type; /* Values see below. */
• int level; スタック内のフレーム数
• int *line; コマンドが始まるワードのライン /* Lines the words of the command start on. */
• int nline;
• CallFrame *framePtr; activation record の手続き。may be NULL
• struct CmdFrame *nextPtr;
• union {

 	struct {
 	    [[Tcl_Obj]] *path; コマンドが入っているファイルへのパス
 	} eval;
 	struct {
 	    const void *codePtr;　実行中のバイトコード
 	    const char *pc;	命令カウンター
 	} tebc;
     } data;
     union {
 	struct {
 	    const char *cmd;	実行されたコマンドと長さ
 	    int len;		
 	} str;
 	[[Tcl_Obj]] *listPtr;	/* Tcl_EvalObjEx, cmd list. */
     } cmd;

ソース

 /*
  * TIP #280
  * The structure below defines a command frame. A command frame provides
  * location information for all commands executing a tcl script (source, eval,
  * uplevel, procedure bodies, ...). The runtime structure essentially contains
  * the stack trace as it would be if the currently executing command were to
  * throw an error.
  *
  * For commands where it makes sense it refers to the associated CallFrame as
  * well.
  *
  * The structures are chained in a single list, with the top of the stack
  * anchored in the Interp structure.
  *
  * Instances can be allocated on the C stack, or the heap, the former making
  * cleanup a bit simpler.
  */
 
 typedef struct CmdFrame {
     /*
      * General data. Always available.
      */
 
     int type;			/* Values see below. */
     int level;			/* Number of frames in stack, prevent O(n)
 				 * scan of list. */
     int *line;			/* Lines the words of the command start on. */
     int nline;
     [[CallFrame]] *framePtr;	/* Procedure activation record, may be
 				 * NULL. */
     struct CmdFrame *nextPtr;	/* Link to calling frame. */
     /*
      * Data needed for Eval vs TEBC
      *
      * EXECUTION CONTEXTS and usage of CmdFrame
      *
      * Field	  TEBC		  EvalEx	  EvalObjEx
      * =======	  ====		  ======	  =========
      * level	  yes		  yes		  yes
      * type	  BC/PREBC	  SRC/EVAL	  EVAL_LIST
      * line0	  yes		  yes		  yes
      * framePtr	  yes		  yes		  yes
      * =======	  ====		  ======	  =========
      *
      * =======	  ====		  ======	  ========= union data
      * line1	  -		  yes		  -
      * line3	  -		  yes		  -
      * path	  -		  yes		  -
      * -------	  ----		  ------	  ---------
      * codePtr	  yes		  -		  -
      * pc	  yes		  -		  -
      * =======	  ====		  ======	  =========
      *
      * =======	  ====		  ======	  ========= | union cmd
      * listPtr	  -		  -		  yes	    |
      * -------	  ----		  ------	  --------- |
      * cmd	  yes		  yes		  -	    |
      * cmdlen	  yes		  yes		  -	    |
      * -------	  ----		  ------	  --------- |
      */
 
     union {
 	struct {
 	    Tcl_Obj *path;	/* Path of the sourced file the command is
 				 * in. */
 	} eval;
 	struct {
 	    const void *codePtr;/* Byte code currently executed... */
 	    const char *pc;	/* ... and instruction pointer. */
 	} tebc;
     } data;
     union {
 	struct {
 	    const char *cmd;	/* The executed command, if possible... */
 	    int len;		/* ... and its length. */
 	} str;
 	Tcl_Obj *listPtr;	/* Tcl_EvalObjEx, cmd list. */
     } cmd;
 } CmdFrame;