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Using Laravel for Advanced String Manipulation in PHP

A Gherkin Lexer

Explore how to build a Gherkin lexer in Laravel by managing text indentation to structure and simplify parsing. Understand how breaking a Gherkin document into lines with relative indentation helps streamline parser implementation, making it easier to handle scenarios and features accurately.

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A lexer is an interesting topic when parsing text because it can often be confused with the parser itself. If we look at the Gherkin example in the code snippet below, we can see that there are a lot of individual characters and words, and it might be difficult to even figure out where we should start parsing this:

C++
Feature: Overdue tasks
  Let users know when tasks are overdue, even when using other
  features of the app
  Rule: Users are notified about overdue tasks on first use of the day
    Background:
      Given I have overdue tasks
    Example: First use of the day
      Given I last used the app yesterday
      When I use the app
      Then I am notified about overdue tasks

Operating directly on individual characters or entire words can be complicated from a parser’s perspective. It would be much more helpful if we could work on a higher-level structure instead. This is where a lexer comes in.

Because Gherkin is an ...