Editing Left recursion (section)

=== Direct left recursion ===
Direct left recursion occurs when the definition can be satisfied with only one substitution.  It requires a rule of the form
:<math>A \to A\alpha</math>
where <math>\alpha</math> is a sequence of nonterminals and terminals . For example, the rule
:<math>\mathit{Expression} \to \mathit{Expression} + \mathit{Term}</math>
is directly left-recursive. A left-to-right [[recursive descent parser]] for this rule might look like
<syntaxhighlight lang="cpp">
void Expression() {
  Expression();
  match('+');
  Term();
}
</syntaxhighlight>
and such code would fall into infinite recursion when executed.