Extend documentation of ParserState

commonmark/src/main/java/org/commonmark/internal/DocumentParser.java

@@ -21,12 +21,12 @@ public class DocumentParser implements ParserState {
     private CharSequence line;
 
     /**
-     * current index (offset) in input line
+     * current index (offset) in input line (0-based)
      */
     private int index = 0;
 
     /**
-     * current column of input line (tab causes column to go to next 4-space tab stop)
+     * current column of input line (tab causes column to go to next 4-space tab stop) (0-based)
      */
     private int column = 0;
 

commonmark/src/main/java/org/commonmark/parser/block/ParserState.java

@@ -12,22 +12,26 @@ public interface ParserState {
     CharSequence getLine();
 
     /**
-     * @return the current index within the line
+     * @return the current index within the line (0-based)
      */
     int getIndex();
 
     /**
-     * @return the index of the next non-space character starting from {@link #getIndex()} (may be the same)
+     * @return the index of the next non-space character starting from {@link #getIndex()} (may be the same) (0-based)
      */
     int getNextNonSpaceIndex();
 
     /**
-     * @return the current column within the line
+     * The column is the position within the line after tab characters have been processed as 4-space tab stops.
+     * If the line doesn't contain any tabs, it's the same as the {@link #getIndex()}. If the line starts with a tab,
+     * followed by text, then the column for the first character of the text is 4 (the index is 1).
+     *
+     * @return the current column within the line (0-based)
      */
     int getColumn();
 
     /**
-     * @return the indentation (either by spaces or tab stop of 4), starting from {@link #getColumn()}
+     * @return the indentation in columns (either by spaces or tab stop of 4), starting from {@link #getColumn()}
      */
     int getIndent();