[stringtemplate-interest] Problem with fixed-length custom objectrenderer

[Rabea Gransberger]

Hello,

if you are registering a renderer for String you should use an explicit
format tag to ensure only those strings you like to render are rendered.
Your code applied the renderer also to the line seperator.

Try this one:

public class TestStringTemplate_FixedLength {
	/** Renders a string by appending with spaces to get a minimal size
*/
	public static class FixesLengthRenderer implements AttributeRenderer
{
		private final int length;

		public FixesLengthRenderer(int length) {
			this.length = length;
		}

		public String toString(Object o) {
			return o.toString();
		}

		private String doFormat(Object o) {
			final String s = o.toString();
			if (s.length() == length) {
				return s;
			}
			else if (s.length() > length) {
				return s.substring(0, length);
			}
			else {
				int toAdd = length - s.length();
				return prepend(s, toAdd);
			}
		}

		private String prepend(final String s, int toAdd) {
			char[] c = new char[toAdd];
			Arrays.fill(c, ' ');
			StringBuilder b = new StringBuilder();
			b.append(c);
			b.append(s);
			return b.toString();
		}

		public String toString(Object o, String formatName) {
			if ("fixedLength".equals(formatName)) {
				return doFormat(o);
			}
			return toString(o);
		}
	}

	public static void main(String[] args) {
		StringTemplate st = new StringTemplate(
				"$elems:{$it;format=\"fixedLength\"$ foo};
separator=\"\n\"$");
		st.registerRenderer(String.class, new
FixesLengthRenderer(6));
		st.setAttribute("elems", new String[] { "ABC", "DEFG" });
		System.out.println(st.toString());
	}
}  

> -----Ursprüngliche Nachricht-----
> Von: stringtemplate-interest-bounces at antlr.org 
> [mailto:stringtemplate-interest-bounces at antlr.org] Im Auftrag 
> von Frédéric Delanoy
> Gesendet: Donnerstag, 26. Februar 2009 11:44
> An: stringtemplate-interest at antlr.org
> Betreff: [stringtemplate-interest] Problem with fixed-length 
> custom objectrenderer
> 
> Hi All,
> 
> I'm trying to implement a custom object renderer to ouput 
> fixed-length data. I set an attribute to a list of strings, 
> and output it using a newline separator.
> However, only the first line is correctly indented
> 
> Here's what I used:
> 
> public class TestStringTemplate_FixedLength {
>     /** Renders a string by appending with spaces to get a 
> minimal size */
>     public static class FixesLengthRenderer implements 
> AttributeRenderer {
>         private final int length;
>         public FixesLengthRenderer(int length) {
>             this.length = length;
>         }
> 
>         /** returns a char[] composed of n copies of 
> character c, or empty string if n < 1 */
>         private char[] times(int n, char c) {
>             if (n < 1) return new char[0];
>             char[] cc = new char[n];
>             for (int i = 0; i < cc.length; i++) cc[i] = c;
>             return cc;
>         }
> 
>         /** Returns a copy of s of size n; string value is 
> truncated or white-space-appended if needed */
>         private String adaptStringToSize(String s, int size) {
>             if (size < 1) return "";
>             int len = s.length();
>             StringBuilder sb = new StringBuilder(size);
>             sb.append(s.substring(0, Math.min(len, size)));
>             sb.append(times(size - len, ' '));
>             return sb.toString();
>         }
>         public String toString(Object o) { return
> adaptStringToSize((String) o, length); }
>         public String toString(Object o, String formatName) { 
> return toString(o); }
>     }
> 
>     public static void main(String[] args) {
>         StringTemplate st= new StringTemplate("$elems:{$it$ 
> foo}; separator=\"\n\"$");
>         st.registerRenderer(String.class, new FixesLengthRenderer(6));
>         st.setAttribute("elems", new String[] { "ABC", "DEFG" });
>         System.out.println(st.toString());
>     }
> }
> 
> The output I have is:
> ABC    foo
>      DEFG   foo
> 
> Can s.o. please help?
> 
> Thanks in advance,
> 
> Frédéric Delanoy
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