MarkupAnalyzer Lint Rule

Description

Markup Analyzer is a customizable lint rule for the custom_lint package in Dart/Flutter. It allows you to prohibit specific types of string expressions in the parameters of Flutter widgets.

This rule enables you to control the usage of string expressions such as simple string literals, interpolations, binary expressions, and others based on your configuration.

• MarkupAnalyzer Lint Rule
  • Description
  • Installation
  • Configuration
  • Usage
  • Examples
    • 1. Simple String Literals (simple)
    • 2. Prefixed Identifiers (prefixed_identifier)
    • 3. String Interpolation (interpolation)
    • 4. Binary Expressions (binary)
    • 5. Adjacent Strings (adjacent)
    • 6. Method Invocations (method)
    • 7. Simple Identifiers (simple_identifier)
    • 8. Function Invocations (function)

Installation

1. Add the package to your project's dependencies:

   Add the following to your project's pubspec.yaml under dev_dependencies:

   dev_dependencies:
     custom_lint: 
     markup_analyzer: ^latest_version

2. Get the dependencies:

   flutter pub get

3. Activate the plugin in analysis_options.yaml:

   Create or update the analysis_options.yaml file at the root of your project:

   analyzer:
     plugins:
       - custom_lint
   
   custom_lint:
     rules:
       - markup_analyzer

Configuration

You can configure the MarkupAnalyzer rule via analysis_options.yaml by specifying which types of string expressions should be prohibited and the severity level of the error.

Example of a full configuration:

custom_lint:
  rules:
    - markup_analyzer:
      simple: error
      interpolation: warning
      binary: warning
      adjacent: warning
      prefixed_identifier: none
      method: none
      simple_identifier: none
      function: none

Usage

After setting up the plugin and configuring the rules, run the analyzer on your project:

dart run custom_lint

All rule violations will be displayed in the console and highlighted in your IDE if it supports custom_lint.

Examples

1. Simple String Literals (simple)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    simple: error

// BAD
Text('Hello, world!'); // Simple string literal is prohibited.

// OR GOOD
Text(AppLocalizations.of(context).greeting)

2. Prefixed Identifiers (prefixed_identifier)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    prefixed_identifier: error

// ERROR
Text(widget.title); // Prefixed identifier is prohibited.

3. String Interpolation (interpolation)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    interpolation: error

// BAD
Text('Hello, $name!'); // String interpolation is prohibited.

// GOOD
Text(AppLocalizations.of(context).helloWithName(name)); // Use string concatenation instead.

4. Binary Expressions (binary)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    binary: error

// ERROR
Text('Hello, ' + 'world!'); // Binary expression with '+' is prohibited.

5. Adjacent Strings (adjacent)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    adjacent: error

// ERROR
Text(
'Hello, '
'world!'
); // Adjacent strings are prohibited.

6. Method Invocations (method)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    method: error

// BAD
Text('hello'.tr()); // Method invocation is prohibited.

//GOOD
Text(AppLocalizations.of(context).hello)

7. Simple Identifiers (simple_identifier)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    simple_identifier: error

// ERROR
Text(title); // Simple identifier is prohibited.

8. Function Invocations (function)

Configuration:

custom_lint:
rules:
  markup_analyzer:
    function: error

// ERROR
Text(() { return 'Hello' } ()); // Function invocation is prohibited.