first commit

app_vue/node_modules/eslint/lib/rules/no-this-before-super.js

@@ -0,0 +1,304 @@
+/**
+ * @fileoverview A rule to disallow using `this`/`super` before `super()`.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Checks whether or not a given node is a constructor.
+ * @param {ASTNode} node A node to check. This node type is one of
+ *   `Program`, `FunctionDeclaration`, `FunctionExpression`, and
+ *   `ArrowFunctionExpression`.
+ * @returns {boolean} `true` if the node is a constructor.
+ */
+function isConstructorFunction(node) {
+    return (
+        node.type === "FunctionExpression" &&
+        node.parent.type === "MethodDefinition" &&
+        node.parent.kind === "constructor"
+    );
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "problem",
+
+        docs: {
+            description: "disallow `this`/`super` before calling `super()` in constructors",
+            category: "ECMAScript 6",
+            recommended: true,
+            url: "https://eslint.org/docs/rules/no-this-before-super"
+        },
+
+        schema: [],
+
+        messages: {
+            noBeforeSuper: "'{{kind}}' is not allowed before 'super()'."
+        }
+    },
+
+    create(context) {
+
+        /*
+         * Information for each constructor.
+         * - upper:      Information of the upper constructor.
+         * - hasExtends: A flag which shows whether the owner class has a valid
+         *   `extends` part.
+         * - scope:      The scope of the owner class.
+         * - codePath:   The code path of this constructor.
+         */
+        let funcInfo = null;
+
+        /*
+         * Information for each code path segment.
+         * Each key is the id of a code path segment.
+         * Each value is an object:
+         * - superCalled:  The flag which shows `super()` called in all code paths.
+         * - invalidNodes: The array of invalid ThisExpression and Super nodes.
+         */
+        let segInfoMap = Object.create(null);
+
+        /**
+         * Gets whether or not `super()` is called in a given code path segment.
+         * @param {CodePathSegment} segment A code path segment to get.
+         * @returns {boolean} `true` if `super()` is called.
+         */
+        function isCalled(segment) {
+            return !segment.reachable || segInfoMap[segment.id].superCalled;
+        }
+
+        /**
+         * Checks whether or not this is in a constructor.
+         * @returns {boolean} `true` if this is in a constructor.
+         */
+        function isInConstructorOfDerivedClass() {
+            return Boolean(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends);
+        }
+
+        /**
+         * Checks whether or not this is before `super()` is called.
+         * @returns {boolean} `true` if this is before `super()` is called.
+         */
+        function isBeforeCallOfSuper() {
+            return (
+                isInConstructorOfDerivedClass() &&
+                !funcInfo.codePath.currentSegments.every(isCalled)
+            );
+        }
+
+        /**
+         * Sets a given node as invalid.
+         * @param {ASTNode} node A node to set as invalid. This is one of
+         *      a ThisExpression and a Super.
+         * @returns {void}
+         */
+        function setInvalid(node) {
+            const segments = funcInfo.codePath.currentSegments;
+
+            for (let i = 0; i < segments.length; ++i) {
+                const segment = segments[i];
+
+                if (segment.reachable) {
+                    segInfoMap[segment.id].invalidNodes.push(node);
+                }
+            }
+        }
+
+        /**
+         * Sets the current segment as `super` was called.
+         * @returns {void}
+         */
+        function setSuperCalled() {
+            const segments = funcInfo.codePath.currentSegments;
+
+            for (let i = 0; i < segments.length; ++i) {
+                const segment = segments[i];
+
+                if (segment.reachable) {
+                    segInfoMap[segment.id].superCalled = true;
+                }
+            }
+        }
+
+        return {
+
+            /**
+             * Adds information of a constructor into the stack.
+             * @param {CodePath} codePath A code path which was started.
+             * @param {ASTNode} node The current node.
+             * @returns {void}
+             */
+            onCodePathStart(codePath, node) {
+                if (isConstructorFunction(node)) {
+
+                    // Class > ClassBody > MethodDefinition > FunctionExpression
+                    const classNode = node.parent.parent.parent;
+
+                    funcInfo = {
+                        upper: funcInfo,
+                        isConstructor: true,
+                        hasExtends: Boolean(
+                            classNode.superClass &&
+                            !astUtils.isNullOrUndefined(classNode.superClass)
+                        ),
+                        codePath
+                    };
+                } else {
+                    funcInfo = {
+                        upper: funcInfo,
+                        isConstructor: false,
+                        hasExtends: false,
+                        codePath
+                    };
+                }
+            },
+
+            /**
+             * Removes the top of stack item.
+             *
+             * And this traverses all segments of this code path then reports every
+             * invalid node.
+             * @param {CodePath} codePath A code path which was ended.
+             * @returns {void}
+             */
+            onCodePathEnd(codePath) {
+                const isDerivedClass = funcInfo.hasExtends;
+
+                funcInfo = funcInfo.upper;
+                if (!isDerivedClass) {
+                    return;
+                }
+
+                codePath.traverseSegments((segment, controller) => {
+                    const info = segInfoMap[segment.id];
+
+                    for (let i = 0; i < info.invalidNodes.length; ++i) {
+                        const invalidNode = info.invalidNodes[i];
+
+                        context.report({
+                            messageId: "noBeforeSuper",
+                            node: invalidNode,
+                            data: {
+                                kind: invalidNode.type === "Super" ? "super" : "this"
+                            }
+                        });
+                    }
+
+                    if (info.superCalled) {
+                        controller.skip();
+                    }
+                });
+            },
+
+            /**
+             * Initialize information of a given code path segment.
+             * @param {CodePathSegment} segment A code path segment to initialize.
+             * @returns {void}
+             */
+            onCodePathSegmentStart(segment) {
+                if (!isInConstructorOfDerivedClass()) {
+                    return;
+                }
+
+                // Initialize info.
+                segInfoMap[segment.id] = {
+                    superCalled: (
+                        segment.prevSegments.length > 0 &&
+                        segment.prevSegments.every(isCalled)
+                    ),
+                    invalidNodes: []
+                };
+            },
+
+            /**
+             * Update information of the code path segment when a code path was
+             * looped.
+             * @param {CodePathSegment} fromSegment The code path segment of the
+             *      end of a loop.
+             * @param {CodePathSegment} toSegment A code path segment of the head
+             *      of a loop.
+             * @returns {void}
+             */
+            onCodePathSegmentLoop(fromSegment, toSegment) {
+                if (!isInConstructorOfDerivedClass()) {
+                    return;
+                }
+
+                // Update information inside of the loop.
+                funcInfo.codePath.traverseSegments(
+                    { first: toSegment, last: fromSegment },
+                    (segment, controller) => {
+                        const info = segInfoMap[segment.id];
+
+                        if (info.superCalled) {
+                            info.invalidNodes = [];
+                            controller.skip();
+                        } else if (
+                            segment.prevSegments.length > 0 &&
+                            segment.prevSegments.every(isCalled)
+                        ) {
+                            info.superCalled = true;
+                            info.invalidNodes = [];
+                        }
+                    }
+                );
+            },
+
+            /**
+             * Reports if this is before `super()`.
+             * @param {ASTNode} node A target node.
+             * @returns {void}
+             */
+            ThisExpression(node) {
+                if (isBeforeCallOfSuper()) {
+                    setInvalid(node);
+                }
+            },
+
+            /**
+             * Reports if this is before `super()`.
+             * @param {ASTNode} node A target node.
+             * @returns {void}
+             */
+            Super(node) {
+                if (!astUtils.isCallee(node) && isBeforeCallOfSuper()) {
+                    setInvalid(node);
+                }
+            },
+
+            /**
+             * Marks `super()` called.
+             * @param {ASTNode} node A target node.
+             * @returns {void}
+             */
+            "CallExpression:exit"(node) {
+                if (node.callee.type === "Super" && isBeforeCallOfSuper()) {
+                    setSuperCalled();
+                }
+            },
+
+            /**
+             * Resets state.
+             * @returns {void}
+             */
+            "Program:exit"() {
+                segInfoMap = Object.create(null);
+            }
+        };
+    }
+};