Comments

 

Unlike fortran statements and expressions, there exist no specific node variant to describe comments. A comment is attached to a statement; not as a child but as an attribute. Let us consider the comment in following fortran statement:

    print *,1
C I am fortran comment 
    i=1
    print *,2

The AST   attribute applied to the assignment generates the following AST structure:

ass(name i, int_cst 1){^prefix comment_s[comment I am fortran comment]}

So, comments need some specific functionalities in TSF.

  $\blacktriangleright$ s.NBCOMMENT

 
The expression   returns the number of comments associated to the AST statement s.

  $\blacktriangleright$ s.COMMENT

 
The expression   returns the string concatenation of all comments associated to the AST statement s.

  $\blacktriangleright$ s.COMMENT(n)

 
The expression   returns the string of the comment of rank n associated to the AST statement s. The rank of the first comment is 1. The strings "first" and "last" can be used to access to the first and the last comment.

  $\blacktriangleright$ s.PUREINST

 
The   expression returns a copy of the AST statement s buy without the comments associated to its root node. This attribute does not remove comments in the body of an iterative or conditional statement (see EXPURGATECOMMENT for an example)

  $\blacktriangleright$ s.EXPURGATECOMMENT

 
The   expression returns a copy of the AST s without any comment in any subpart of s.
$\vartriangleright$ Example 41:The following script removes the comments associated to a IF statement and to the THEN part of the IF statement. The comments in the ELSE clause are preserved.

     

  SCRIPT RemoveIfComment(stat)
    IF (stat.VARIANT=="struct_if") THEN
      // Remove the comment of the IF statement
      newstat := stat.PUREINST 
      //Remove the comments i n the THEN part 
      newstat.THENCLAUSE <- newstat.THENCLAUSE.EXPURGATECOMMENT 
      stat <- newstat
    ENDIF 
  ENDSCRIPT

  $\blacktriangleright$ INSERTCOMMENT(s,c,op,p)

 
The statement   adds the comment specified by the string c to the statement s at the position p with the operation op. The position p can be an integer index (i.e. the first index is 1) or one of the string "first" or "last". The operation op must be one of the following keywords (i.e. string):

• "insert" - The comment is inserted at the specified position.
• "replace" - The comment at the specified position is replaced by the new comment. The position "all" can be used to replace all the comments by the new one.
• "delete" - The comment at the specified position is deleted. The position "all" can be used to delete all the comments. The argument c is not used here.

 

$\vartriangleright$ Example 42:The following script replaces the comments of the selected statement by the result of the AST attribute applied to the statement. A comment "$$ AST" is added before this comment. If it is found, then the new comment does not replace the last comment but it is inserted after.      

 
  SCRIPT InsertASTComment () 
    stat := $cstat 
    IF (stat) THEN
      IF (stat.COMMENT(1)=="$$ AST") THEN
        INSERTCOMMENT(stat,"  "+stat.AST,"insert","last") 
      ELSE      
        INSERTCOMMENT(stat,"  "+stat.AST,"replace","all") 
        INSERTCOMMENT(stat,"$$ AST","insert",1) 
      ENDIF
    ENDIF
  ENDSCRIPT

  $\blacktriangleright$ INSERTCOMMENT(s,c)

 
The statement   adds the comment specified by the string c to the statement s. This is a shortcut to INSERTCOMMENT(s,c,"insert","last").