Fix: edge-cases of semi-style (#9560)

* Fix: edge-cases of semi-style * Fix: remove EmptyStatement entirely
eslint · Nov 7, 2017 · 7e3bf6a · 7e3bf6a
1 parent e5a37ce
commit 7e3bf6a
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Showing 2 changed files with 130 additions and 20 deletions.
diff --git a/lib/rules/semi-style.js b/lib/rules/semi-style.js
@@ -18,13 +18,51 @@ const astUtils = require("../ast-utils");
 const SELECTOR = `:matches(${
     [
         "BreakStatement", "ContinueStatement", "DebuggerStatement",
-        "DoWhileStatement", "EmptyStatement", "ExportAllDeclaration",
+        "DoWhileStatement", "ExportAllDeclaration",
         "ExportDefaultDeclaration", "ExportNamedDeclaration",
         "ExpressionStatement", "ImportDeclaration", "ReturnStatement",
         "ThrowStatement", "VariableDeclaration"
     ].join(",")
 })`;
 
+/**
+ * Get the child node list of a given node.
+ * This returns `Program#body`, `BlockStatement#body`, or `SwitchCase#consequent`.
+ * This is used to check whether a node is the first/last child.
+ * @param {Node} node A node to get child node list.
+ * @returns {Node[]|null} The child node list.
+ */
+function getChildren(node) {
+    const t = node.type;
+
+    if (t === "BlockStatement" || t === "Program") {
+        return node.body;
+    }
+    if (t === "SwitchCase") {
+        return node.consequent;
+    }
+    return null;
+}
+
+/**
+ * Check whether a given node is the last statement in the parent block.
+ * @param {Node} node A node to check.
+ * @returns {boolean} `true` if the node is the last statement in the parent block.
+ */
+function isLastChild(node) {
+    const t = node.parent.type;
+
+    if (t === "IfStatement" && node.parent.consequent === node && node.parent.alternate) { // before `else` keyword.
+        return true;
+    }
+    if (t === "DoWhileStatement") { // before `while` keyword.
+        return true;
+    }
+    const nodeList = getChildren(node.parent);
+
+    return nodeList !== null && nodeList[nodeList.length - 1] === node; // before `}` or etc.
+}
+
 module.exports = {
     meta: {
         docs: {
@@ -40,23 +78,6 @@ module.exports = {
         const sourceCode = context.getSourceCode();
         const option = context.options[0] || "last";
 
-        /**
-         * Check whether comments exist between the given 2 tokens.
-         * @param {Token} left The left token to check.
-         * @param {Token} right The right token to check.
-         * @returns {boolean} `true` if comments exist between the given 2 tokens.
-         */
-        function commentsExistBetween(left, right) {
-            return sourceCode.getFirstTokenBetween(
-                left,
-                right,
-                {
-                    includeComments: true,
-                    filter: astUtils.isCommentToken
-                }
-            ) !== null;
-        }
-
         /**
          * Check the given semicolon token.
          * @param {Token} semiToken The semicolon token to check.
@@ -79,7 +100,7 @@ module.exports = {
                             : "the beginning of the next line"
                     },
                     fix(fixer) {
-                        if (prevToken && nextToken && commentsExistBetween(prevToken, nextToken)) {
+                        if (prevToken && nextToken && sourceCode.commentsExistBetween(prevToken, nextToken)) {
                             return null;
                         }
 
@@ -95,6 +116,10 @@ module.exports = {
 
         return {
             [SELECTOR](node) {
+                if (option === "first" && isLastChild(node)) {
+                    return;
+                }
+
                 const lastToken = sourceCode.getLastToken(node);
 
                 if (astUtils.isSemicolonToken(lastToken)) {

diff --git a/tests/lib/rules/semi-style.js b/tests/lib/rules/semi-style.js
@@ -27,18 +27,103 @@ ruleTester.run("semi-style", rule, {
         "for(a;\nb;\nc);",
         "for((a\n);\n(b\n);\n(c));",
         "if(a)foo;\nbar",
+        { code: ";", options: ["last"] },
         { code: ";foo;bar;baz;", options: ["last"] },
         { code: "foo;\nbar;", options: ["last"] },
         { code: "for(a;b;c);", options: ["last"] },
         { code: "for(a;\nb;\nc);", options: ["last"] },
         { code: "for((a\n);\n(b\n);\n(c));", options: ["last"] },
         { code: "if(a)foo;\nbar", options: ["last"] },
+        { code: ";", options: ["first"] },
         { code: ";foo;bar;baz;", options: ["first"] },
         { code: "foo\n;bar;", options: ["first"] },
         { code: "for(a;b;c);", options: ["first"] },
         { code: "for(a;\nb;\nc);", options: ["first"] },
         { code: "for((a\n);\n(b\n);\n(c));", options: ["first"] },
-        { code: "if(a)foo\n;bar", options: ["first"] }
+
+        // edge cases
+        {
+            code: `
+                {
+                    ;
+                }
+            `,
+            options: ["first"]
+        },
+        {
+            code: `
+                while (a)
+                    ;
+                foo
+            `,
+            options: ["first"]
+        },
+        {
+            code: `
+                do
+                    ;
+                while (a)
+            `,
+            options: ["first"]
+        },
+        {
+            code: `
+                do
+                    foo;
+                while (a)
+            `,
+            options: ["first"]
+        },
+        {
+            code: `
+                if (a)
+                    foo;
+                else
+                    bar
+            `,
+            options: ["first"]
+        },
+        {
+            code: `
+                if (a)
+                    foo
+                ;bar
+            `,
+            options: ["first"]
+        },
+        {
+            code: `
+                {
+                    ;
+                }
+            `,
+            options: ["last"]
+        },
+        {
+            code: `
+                switch (a) {
+                    case 1:
+                        ;foo
+                }
+            `,
+            options: ["last"]
+        },
+        {
+            code: `
+                while (a)
+                    ;
+                foo
+            `,
+            options: ["last"]
+        },
+        {
+            code: `
+                do
+                    ;
+                while (a)
+            `,
+            options: ["last"]
+        }
     ],
     invalid: [
         {