Add to tokens comments and whitespaces if Y2EXPORTCOMMENTS is set

it is needed for exporting comments from ycp code to ruby one. It is enclosed in
env variable to avoid performance regression in common run.

libycp/src/Scanner.cc

@@ -324,6 +324,18 @@ Scanner::scannedType () const
     return m_scannedType;
 }
 
+void
+Scanner::setCommentBefore (const string & comment_before)
+{
+    m_commentBefore = comment_before;
+}
+
+std::string
+Scanner::commentBefore () const
+{
+    return m_commentBefore;
+}
+
 
 int
 Scanner::lineNumber () const

libycp/src/include/ycp/Scanner.h

@@ -120,6 +120,11 @@ class Scanner : public yyFlexLexer, public Logger
      */
     constTypePtr m_scannedType;
 
+    /**
+     * Holds the comment before the most recent token
+     */
+    std::string m_commentBefore;
+
     /**
      * Holds the line number of scanned_value
      */
@@ -263,6 +268,8 @@ class Scanner : public yyFlexLexer, public Logger
      */
     constTypePtr scannedType() const;
 
+    std::string commentBefore () const;
+
     /**
      * Gets the line number of the latest scanned token.
      */
@@ -309,6 +316,8 @@ class Scanner : public yyFlexLexer, public Logger
      */
     void setScannedToken (const tokenValue & value, constTypePtr type);
 
+    void setCommentBefore (const string & comment_before);
+
     /**
      * Internal helper function that deals with strings of arbitrary
      * length

libycp/src/parser.yy

@@ -19,12 +19,13 @@
 
    Implementation rules
 
-   yystype is a struct with four elements
+   yystype is a struct with five elements
 
     YCodePtr c		pointer to code (where applicable)
     tokenValue v	value of token (where applicable)
     constTypePtr t	type of current syntactic element
     int l		line number of syntactic element
+    string com          comment preceding the token
 
    c and v somehow represent a similar kind of information and are
    mostly valid alternating.
@@ -33,13 +34,19 @@
    identifiers, etc.
    c is used for the 'high level' (parser) syntax like expressions,
    statements, blocks, etc.
+   NOTE that the distinction is mostly between terminals and nonterminals,
+   but notably the 'type' nonterminal noes not have YCode and holds a Type
+   tree instead.
 
    t is valid everywhere since every syntactic element has a type.
 
    ** t == 0 means 'error', all other yystype are undefined in this case.
 
    l is valid everywhere since every syntactic element appears at a
    distinctive line number in the source file.
+
+   com is valid for scanner tokens. As soon as there is an YCode, we
+   move it off com to c.
 /-*/
 %{
 #include <stdio.h>
@@ -85,6 +92,7 @@ struct yystype_type {
     tokenValue v;		// token (for scanner level syntax)
     constTypePtr t;		// type (NULL for error)
     int l;
+    std::string com;		// comment before the token
 };
 #define YYSTYPE yystype_type