oneOrMore

Tries to match subrule 'r' one or more times. If 'r' fails from the very beginning, it fails and else succeeds.

Its matches are those of its subrules (they might be different for each match) and its children are all the parse trees returned by the successive application of 'r'.

alias oneOrMore!(or!(literal!"abc", literal!"d")) rule; // in PEG-speak:  '("abc" / "d")*'
ParseTree input = ParseTree("",false,[], "abcdabce");

ParseTree result = rule(input);

assert(result.successful);
assert(result.matches == ["abc", "d", "abc"]);
assert(result.end == 7); // matched "abcdabce"[0..7] => "abcdabc". "e" at the end is not part of the parse tree.
assert(result.children.length == 3);
writeln(result);
/+
writes:
oneOrMore  [0, 7]["abc", "d", "abc"]
 +-or  [0, 3]["abc"]
 |  +-literal(abc)  [0, 3]["abc"]
 +-or  [3, 4]["d"]
 |  +-literal(d)  [3, 4]["d"]
 +-or  [4, 7]["abc"]
    +-literal(abc)  [4, 7]["abc"]
+/

So we know the first child used the 'literal!"abc"' sub-rule and matched input[0..3]. The second matched input[3..4] and the third input[4..7].

input = ParseTree("",false,[], "efgh");
result = rule(input);
assert(!result.successful); // fails, since it failed on the first try.