no-trailing-spaces.ts

import type { AST } from "svelte-eslint-parser"
import { createRule } from "../utils"

export default createRule("no-trailing-spaces", {
  meta: {
    type: "layout",
    docs: {
      description: "disallow trailing whitespace at the end of lines",
      category: "Extension Rules",
      recommended: false,
      extensionRule: "no-trailing-spaces",
      conflictWithPrettier: true,
    },
    fixable: "whitespace",
    schema: [
      {
        type: "object",
        properties: {
          skipBlankLines: { type: "boolean" },
          ignoreComments: { type: "boolean" },
        },
        additionalProperties: false,
      },
    ],
    messages: {
      trailingSpace: "Trailing spaces not allowed.",
    },
  },
  create(context) {
    const options:
      | { skipBlankLines?: boolean; ignoreComments?: boolean }
      | undefined = context.options[0]
    const skipBlankLines = options?.skipBlankLines || false
    const ignoreComments = options?.ignoreComments || false

    const sourceCode = context.getSourceCode()

    const ignoreLineNumbers = new Set<number>()
    if (ignoreComments) {
      for (const { type, loc } of sourceCode.getAllComments()) {
        const endLine = type === "Block" ? loc.end.line - 1 : loc.end.line
        for (let i = loc.start.line; i <= endLine; i++) {
          ignoreLineNumbers.add(i)
        }
      }
    }

    /**
     * Reports a given location.
     */
    function report(loc: AST.SourceLocation) {
      context.report({
        loc,
        messageId: "trailingSpace",
        fix(fixer) {
          return fixer.removeRange([
            sourceCode.getIndexFromLoc(loc.start),
            sourceCode.getIndexFromLoc(loc.end),
          ])
        },
      })
    }

    /**
     * Collects the location of the given node as the ignore line numbers.
     */
    function collectIgnoreLineNumbers({ loc }: { loc: AST.SourceLocation }) {
      const endLine = loc.end.line - 1
      for (let i = loc.start.line; i <= endLine; i++) {
        ignoreLineNumbers.add(i)
      }
    }

    return {
      TemplateElement: collectIgnoreLineNumbers,
      ...(ignoreComments
        ? {
            SvelteHTMLComment: collectIgnoreLineNumbers,
          }
        : {}),
      "Program:exit"() {
        const lines = sourceCode.lines
        for (let lineIndex = 0; lineIndex < lines.length; lineIndex++) {
          const line = lines[lineIndex]
          if (skipBlankLines && !line.trim()) {
            continue
          }
          const lineNumber = lineIndex + 1
          if (ignoreLineNumbers.has(lineNumber)) {
            continue
          }
          const trimmed = line.trimEnd()
          if (trimmed === line) {
            continue
          }
          report({
            start: { line: lineNumber, column: trimmed.length },
            end: { line: lineNumber, column: line.length },
          })
        }
      },
    }
  },
})