Function print_with_source 

pub fn print_with_source<O, T, F>(
    o: O,
    tree: &Tree<T, F>,
    source: &str,
) -> Result<(), Error>
where
    O: Write,
    T: Copy + Debug,
    F: Flavor<Index: Display>,

Pretty-print a tree with the source spans printed.

This prints like print, except that the source reference of each element without children is the text of source covered by its span. If the span is out of range of source or does not fall on character boundaries, + is printed instead.

Elements are told apart by whether they have children, so a node without children is printed exactly like a token.

Examples

#[derive(Debug, Clone, Copy)]
enum Syntax {
    NUMBER,
    WHITESPACE,
    OPERATOR,
    PLUS,
}

use Syntax::*;

let source = "128 + 64";

let tree = syntree::tree! {
    NUMBER => {
        (NUMBER, 3),
    },
    (WHITESPACE, 1),
    OPERATOR => {
        (PLUS, 1)
    },
    (WHITESPACE, 1),
    NUMBER => {
        (NUMBER, 2),
    },
};

let mut s = Vec::new();
syntree::print::print_with_source(&mut s, &tree, source)?;

This would write:

NUMBER@0..3
  NUMBER@0..3 "128"
WHITESPACE@3..4 " "
OPERATOR@4..5
  PLUS@4..5 "+"
WHITESPACE@5..6 " "
NUMBER@6..8
  NUMBER@6..8 "64"