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node_modules/eslint/lib/rules/lines-between-class-members.js

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+/**
+ * @fileoverview Rule to check empty newline between class members
+ * @author 薛定谔的猫<hh_2013@foxmail.com>
+ */
+"use strict";
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "layout",
+
+        docs: {
+            description: "require or disallow an empty line between class members",
+            category: "Stylistic Issues",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/lines-between-class-members"
+        },
+
+        fixable: "whitespace",
+
+        schema: [
+            {
+                enum: ["always", "never"]
+            },
+            {
+                type: "object",
+                properties: {
+                    exceptAfterSingleLine: {
+                        type: "boolean",
+                        default: false
+                    }
+                },
+                additionalProperties: false
+            }
+        ],
+        messages: {
+            never: "Unexpected blank line between class members.",
+            always: "Expected blank line between class members."
+        }
+    },
+
+    create(context) {
+
+        const options = [];
+
+        options[0] = context.options[0] || "always";
+        options[1] = context.options[1] || { exceptAfterSingleLine: false };
+
+        const sourceCode = context.getSourceCode();
+
+        /**
+         * Checks if there is padding between two tokens
+         * @param {Token} first The first token
+         * @param {Token} second The second token
+         * @returns {boolean} True if there is at least a line between the tokens
+         */
+        function isPaddingBetweenTokens(first, second) {
+            const comments = sourceCode.getCommentsBefore(second);
+            const len = comments.length;
+
+            // If there is no comments
+            if (len === 0) {
+                const linesBetweenFstAndSnd = second.loc.start.line - first.loc.end.line - 1;
+
+                return linesBetweenFstAndSnd >= 1;
+            }
+
+
+            // If there are comments
+            let sumOfCommentLines = 0; // the numbers of lines of comments
+            let prevCommentLineNum = -1; // line number of the end of the previous comment
+
+            for (let i = 0; i < len; i++) {
+                const commentLinesOfThisComment = comments[i].loc.end.line - comments[i].loc.start.line + 1;
+
+                sumOfCommentLines += commentLinesOfThisComment;
+
+                /*
+                 * If this comment and the previous comment are in the same line,
+                 * the count of comment lines is duplicated. So decrement sumOfCommentLines.
+                 */
+                if (prevCommentLineNum === comments[i].loc.start.line) {
+                    sumOfCommentLines -= 1;
+                }
+
+                prevCommentLineNum = comments[i].loc.end.line;
+            }
+
+            /*
+             * If the first block and the first comment are in the same line,
+             * the count of comment lines is duplicated. So decrement sumOfCommentLines.
+             */
+            if (first.loc.end.line === comments[0].loc.start.line) {
+                sumOfCommentLines -= 1;
+            }
+
+            /*
+             * If the last comment and the second block are in the same line,
+             * the count of comment lines is duplicated. So decrement sumOfCommentLines.
+             */
+            if (comments[len - 1].loc.end.line === second.loc.start.line) {
+                sumOfCommentLines -= 1;
+            }
+
+            const linesBetweenFstAndSnd = second.loc.start.line - first.loc.end.line - 1;
+
+            return linesBetweenFstAndSnd - sumOfCommentLines >= 1;
+        }
+
+        return {
+            ClassBody(node) {
+                const body = node.body;
+
+                for (let i = 0; i < body.length - 1; i++) {
+                    const curFirst = sourceCode.getFirstToken(body[i]);
+                    const curLast = sourceCode.getLastToken(body[i]);
+                    const nextFirst = sourceCode.getFirstToken(body[i + 1]);
+                    const isPadded = isPaddingBetweenTokens(curLast, nextFirst);
+                    const isMulti = !astUtils.isTokenOnSameLine(curFirst, curLast);
+                    const skip = !isMulti && options[1].exceptAfterSingleLine;
+
+
+                    if ((options[0] === "always" && !skip && !isPadded) ||
+                        (options[0] === "never" && isPadded)) {
+                        context.report({
+                            node: body[i + 1],
+                            messageId: isPadded ? "never" : "always",
+                            fix(fixer) {
+                                return isPadded
+                                    ? fixer.replaceTextRange([curLast.range[1], nextFirst.range[0]], "\n")
+                                    : fixer.insertTextAfter(curLast, "\n");
+                            }
+                        });
+                    }
+                }
+            }
+        };
+    }
+};