为自定义领域特定语言开发JavaScript Lint工具的通用规范咨询

Great question! When integrating syntax checking into your CodeMirror-based DSL editor, there are well-established patterns, helper libraries, and best practices to follow for building a robust lint tool. Let’s break this down:

1. Universal Interface Requirements (for CodeMirror Integration) #

First, CodeMirror’s lint system expects your custom lint function to adhere to a specific output format. At a minimum, your tool should expose a function that:

• Takes a string of your DSL code as input
• Returns an array of error objects, where each object includes:
  • from: A CodeMirror position object ({line: number, ch: number}) marking the start of the error
  • to: A position object marking the end of the error
  • message: A human-readable description of the issue
  • Optional: severity: A string ("error" or "warning") to categorize the issue

Here’s a simplified example of this function structure:

function lintMyDSL(code) {
  const errors = [];
  // Your parsing/validation logic here
  if (/* detect an error */) {
    errors.push({
      from: {line: 2, ch: 5},
      to: {line: 2, ch: 10},
      message: "Invalid permission action: 'write' is not allowed here",
      severity: "error"
    });
  }
  return errors;
}

To hook this into CodeMirror, register it as a lint helper:

CodeMirror.registerHelper("lint", "my-dsl", lintMyDSL);

2. Helper Libraries to Simplify Development #

Building a full lint tool from scratch can be tedious—these libraries can handle heavy lifting:

• Parser Generators: Use these to build a formal parser for your DSL, which will automatically catch syntax errors:
  • PEG.js: A simple, expressive parser generator that outputs JavaScript parsers. It throws detailed errors with line/column positions that you can map to CodeMirror’s format.
  • Chevrotain: A powerful, modular parser toolkit with built-in error recovery and position tracking.
  • Nearley.js: A parser generator based on Earley algorithms, great for complex grammars.
• CodeMirror Utilities: Use CodeMirror’s built-in functions to convert character indices to line/column positions (e.g., CodeMirror.Pos or editor context methods for range-aware checks).
• ESLint Plugin Architecture (Inspiration): While ESLint is for JavaScript, its pattern of separating rules into reusable modules is a great reference for organizing your DSL’s validation rules (e.g., separate modules for syntax checks, semantic checks, and style guidelines).

3. Established Guidelines & Best Practices #

• Start with Syntax Validation First: Use your parser to catch basic syntax errors (unclosed brackets, invalid keywords, missing tokens) before moving to semantic checks. Most parser generators will throw errors with precise position data that you can directly map to CodeMirror’s error format.
• Separate Syntax and Semantic Checks:
  • Syntax checks: Validate the structure of the code (e.g., "Every policy block must have a subject field").
  • Semantic checks: Validate the meaning of the code (e.g., "This subject reference doesn’t exist in the defined roles").
• Optimize for Performance: For large DSL files, consider incremental linting—only re-check the parts of the code that were modified, instead of re-parsing the entire file. CodeMirror’s change events can help you track modified ranges.
• Write Test Cases: Create a suite of test files covering valid code, syntax errors, and semantic errors. Use these to validate your lint tool’s output and catch regressions.
• Make Errors Actionable: Include specific suggestions in error messages (e.g., "Did you mean 'read' instead of 'write'?") to help users fix issues faster.

Example Workflow with PEG.js #

1. Define your DSL’s grammar in a PEG.js file, including error handling for invalid syntax.
2. Generate a JavaScript parser from the grammar.
3. In your lint function, run the parser on the input code. If it throws an error, extract the line/column position and convert it to CodeMirror’s from/to positions.
4. Add additional semantic checks (e.g., validate references against a symbol table) and push those errors to the result array.

内容的提问来源于stack exchange，提问作者hsluoyz