Add isNonEmptyArray (#9902)

scripts/tools/eslint-plugin-prettier-internal-rules/index.js

@@ -7,6 +7,7 @@ module.exports = {
     "jsx-identifier-case": require("./jsx-identifier-case"),
     "no-node-comments": require("./no-node-comments"),
     "prefer-fast-path-each": require("./prefer-fast-path-each"),
+    "prefer-is-non-empty-array": require("./prefer-is-non-empty-array"),
     "require-json-extensions": require("./require-json-extensions"),
   },
 };

scripts/tools/eslint-plugin-prettier-internal-rules/prefer-is-non-empty-array.js

@@ -0,0 +1,152 @@
+"use strict";
+
+const getLengthSelector = (path) =>
+  `[${path}.type="MemberExpression"][${path}.property.type="Identifier"][${path}.property.name="length"]`;
+const selector = [
+  "LogicalExpression",
+  ':not(FunctionDeclaration[id.name="isNonEmptyArray"] *)',
+  '[operator="&&"]',
+  `:matches(${[
+    // `&& foo.length`
+    getLengthSelector("right"),
+    // `&& foo.length !== 0`
+    // `&& foo.length > 0`
+    [
+      '[right.type="BinaryExpression"]',
+      ':matches([right.operator="!=="], [right.operator=">"])',
+      getLengthSelector("right.left"),
+      '[right.right.type="Literal"]',
+      '[right.right.raw="0"]',
+    ].join(""),
+  ].join(", ")})`,
+].join("");
+
+const negativeSelector = [
+  "LogicalExpression",
+  '[operator="||"]',
+  `:matches(${[
+    // `|| !foo.length`
+    [
+      '[right.type="UnaryExpression"]',
+      '[right.operator="!"]',
+      getLengthSelector("right.argument"),
+    ].join(""),
+    // `|| foo.length === 0`
+    [
+      '[right.type="BinaryExpression"]',
+      '[right.operator="==="]',
+      getLengthSelector("right.left"),
+      '[right.right.type="Literal"]',
+      '[right.right.raw="0"]',
+    ].join(""),
+  ].join(", ")})`,
+].join("");
+
+const isArrayIsArrayCall = (node) =>
+  node.type === "CallExpression" &&
+  node.callee.type === "MemberExpression" &&
+  node.callee.object.type === "Identifier" &&
+  node.callee.object.name === "Array" &&
+  node.callee.property.type === "Identifier" &&
+  node.callee.property.name === "isArray";
+
+const MESSAGE_ID = "prefer-is-non-empty-array";
+
+module.exports = {
+  meta: {
+    type: "suggestion",
+    docs: {
+      url:
+        "https://github.com/prettier/prettier/blob/master/scripts/eslint-plugin-prettier-internal-rules/prefer-is-non-empty-array.js",
+    },
+    messages: {
+      [MESSAGE_ID]: "Please use `isNonEmptyArray()`.",
+    },
+    fixable: "code",
+  },
+  create(context) {
+    const sourceCode = context.getSourceCode();
+
+    return {
+      [selector](node) {
+        let { left, right } = node;
+
+        while (left.type === "LogicalExpression" && left.operator === "&&") {
+          left = left.right;
+        }
+
+        let leftObject = left;
+        // `Array.isArray(foo)`
+        if (isArrayIsArrayCall(leftObject)) {
+          leftObject = leftObject.arguments[0];
+        }
+
+        const rightObject =
+          right.type === "BinaryExpression" ? right.left.object : right.object;
+        const objectText = sourceCode.getText(rightObject);
+        // Simple compare with code
+        if (sourceCode.getText(leftObject) !== objectText) {
+          return;
+        }
+
+        const [start] = left.range;
+        const [, end] = node.range;
+        context.report({
+          loc: {
+            start: sourceCode.getLocFromIndex(start),
+            end: sourceCode.getLocFromIndex(end),
+          },
+          messageId: MESSAGE_ID,
+          fix(fixer) {
+            return fixer.replaceTextRange(
+              [start, end],
+              `isNonEmptyArray(${objectText})`
+            );
+          },
+        });
+      },
+      [negativeSelector](node) {
+        let { left, right } = node;
+
+        while (left.type === "LogicalExpression" && left.operator === "||") {
+          left = left.right;
+        }
+
+        if (!left.type === "UnaryExpression" || left.operator !== "!") {
+          return;
+        }
+
+        const rightObject =
+          right.type === "UnaryExpression"
+            ? right.argument.object
+            : right.left.object;
+        let leftObject = left.argument;
+        if (isArrayIsArrayCall(leftObject)) {
+          leftObject = leftObject.arguments[0];
+        }
+
+        const objectText = sourceCode.getText(rightObject);
+        // Simple compare with code
+        if (sourceCode.getText(leftObject) !== objectText) {
+          return;
+        }
+
+        const [start] = left.range;
+        const [, end] = node.range;
+        context.report({
+          loc: {
+            start: sourceCode.getLocFromIndex(start),
+            end: sourceCode.getLocFromIndex(end),
+          },
+          messageId: MESSAGE_ID,
+          fix(fixer) {
+            return fixer.replaceTextRange(
+              [start, end],
+              `!isNonEmptyArray(${objectText})`
+            );
+          },
+        });
+      },
+    };
+  },
+};