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app_vue/node_modules/eslint/lib/rules/constructor-super.js

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+/**
+ * @fileoverview A rule to verify `super()` callings in constructor.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Checks whether a given code path segment is reachable or not.
+ * @param {CodePathSegment} segment A code path segment to check.
+ * @returns {boolean} `true` if the segment is reachable.
+ */
+function isReachable(segment) {
+    return segment.reachable;
+}
+
+/**
+ * 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"
+    );
+}
+
+/**
+ * Checks whether a given node can be a constructor or not.
+ * @param {ASTNode} node A node to check.
+ * @returns {boolean} `true` if the node can be a constructor.
+ */
+function isPossibleConstructor(node) {
+    if (!node) {
+        return false;
+    }
+
+    switch (node.type) {
+        case "ClassExpression":
+        case "FunctionExpression":
+        case "ThisExpression":
+        case "MemberExpression":
+        case "CallExpression":
+        case "NewExpression":
+        case "ChainExpression":
+        case "YieldExpression":
+        case "TaggedTemplateExpression":
+        case "MetaProperty":
+            return true;
+
+        case "Identifier":
+            return node.name !== "undefined";
+
+        case "AssignmentExpression":
+            if (["=", "&&="].includes(node.operator)) {
+                return isPossibleConstructor(node.right);
+            }
+
+            if (["||=", "??="].includes(node.operator)) {
+                return (
+                    isPossibleConstructor(node.left) ||
+                    isPossibleConstructor(node.right)
+                );
+            }
+
+            /**
+             * All other assignment operators are mathematical assignment operators (arithmetic or bitwise).
+             * An assignment expression with a mathematical operator can either evaluate to a primitive value,
+             * or throw, depending on the operands. Thus, it cannot evaluate to a constructor function.
+             */
+            return false;
+
+        case "LogicalExpression":
+
+            /*
+             * If the && operator short-circuits, the left side was falsy and therefore not a constructor, and if
+             * it doesn't short-circuit, it takes the value from the right side, so the right side must always be a
+             * possible constructor. A future improvement could verify that the left side could be truthy by
+             * excluding falsy literals.
+             */
+            if (node.operator === "&&") {
+                return isPossibleConstructor(node.right);
+            }
+
+            return (
+                isPossibleConstructor(node.left) ||
+                isPossibleConstructor(node.right)
+            );
+
+        case "ConditionalExpression":
+            return (
+                isPossibleConstructor(node.alternate) ||
+                isPossibleConstructor(node.consequent)
+            );
+
+        case "SequenceExpression": {
+            const lastExpression = node.expressions[node.expressions.length - 1];
+
+            return isPossibleConstructor(lastExpression);
+        }
+
+        default:
+            return false;
+    }
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "problem",
+
+        docs: {
+            description: "require `super()` calls in constructors",
+            category: "ECMAScript 6",
+            recommended: true,
+            url: "https://eslint.org/docs/rules/constructor-super"
+        },
+
+        schema: [],
+
+        messages: {
+            missingSome: "Lacked a call of 'super()' in some code paths.",
+            missingAll: "Expected to call 'super()'.",
+
+            duplicate: "Unexpected duplicate 'super()'.",
+            badSuper: "Unexpected 'super()' because 'super' is not a constructor.",
+            unexpected: "Unexpected 'super()'."
+        }
+    },
+
+    create(context) {
+
+        /*
+         * {{hasExtends: boolean, scope: Scope, codePath: CodePath}[]}
+         * Information for each constructor.
+         * - upper:      Information of the upper constructor.
+         * - hasExtends: A flag which shows whether own class has a valid `extends`
+         *               part.
+         * - scope:      The scope of own class.
+         * - codePath:   The code path object of the constructor.
+         */
+        let funcInfo = null;
+
+        /*
+         * {Map<string, {calledInSomePaths: boolean, calledInEveryPaths: boolean}>}
+         * Information for each code path segment.
+         * - calledInSomePaths:  A flag of be called `super()` in some code paths.
+         * - calledInEveryPaths: A flag of be called `super()` in all code paths.
+         * - validNodes:
+         */
+        let segInfoMap = Object.create(null);
+
+        /**
+         * Gets the flag which shows `super()` is called in some paths.
+         * @param {CodePathSegment} segment A code path segment to get.
+         * @returns {boolean} The flag which shows `super()` is called in some paths
+         */
+        function isCalledInSomePath(segment) {
+            return segment.reachable && segInfoMap[segment.id].calledInSomePaths;
+        }
+
+        /**
+         * Gets the flag which shows `super()` is called in all paths.
+         * @param {CodePathSegment} segment A code path segment to get.
+         * @returns {boolean} The flag which shows `super()` is called in all paths.
+         */
+        function isCalledInEveryPath(segment) {
+
+            /*
+             * If specific segment is the looped segment of the current segment,
+             * skip the segment.
+             * If not skipped, this never becomes true after a loop.
+             */
+            if (segment.nextSegments.length === 1 &&
+                segment.nextSegments[0].isLoopedPrevSegment(segment)
+            ) {
+                return true;
+            }
+            return segment.reachable && segInfoMap[segment.id].calledInEveryPaths;
+        }
+
+        return {
+
+            /**
+             * Stacks a constructor information.
+             * @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;
+                    const superClass = classNode.superClass;
+
+                    funcInfo = {
+                        upper: funcInfo,
+                        isConstructor: true,
+                        hasExtends: Boolean(superClass),
+                        superIsConstructor: isPossibleConstructor(superClass),
+                        codePath
+                    };
+                } else {
+                    funcInfo = {
+                        upper: funcInfo,
+                        isConstructor: false,
+                        hasExtends: false,
+                        superIsConstructor: false,
+                        codePath
+                    };
+                }
+            },
+
+            /**
+             * Pops a constructor information.
+             * And reports if `super()` lacked.
+             * @param {CodePath} codePath A code path which was ended.
+             * @param {ASTNode} node The current node.
+             * @returns {void}
+             */
+            onCodePathEnd(codePath, node) {
+                const hasExtends = funcInfo.hasExtends;
+
+                // Pop.
+                funcInfo = funcInfo.upper;
+
+                if (!hasExtends) {
+                    return;
+                }
+
+                // Reports if `super()` lacked.
+                const segments = codePath.returnedSegments;
+                const calledInEveryPaths = segments.every(isCalledInEveryPath);
+                const calledInSomePaths = segments.some(isCalledInSomePath);
+
+                if (!calledInEveryPaths) {
+                    context.report({
+                        messageId: calledInSomePaths
+                            ? "missingSome"
+                            : "missingAll",
+                        node: node.parent
+                    });
+                }
+            },
+
+            /**
+             * Initialize information of a given code path segment.
+             * @param {CodePathSegment} segment A code path segment to initialize.
+             * @returns {void}
+             */
+            onCodePathSegmentStart(segment) {
+                if (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
+                    return;
+                }
+
+                // Initialize info.
+                const info = segInfoMap[segment.id] = {
+                    calledInSomePaths: false,
+                    calledInEveryPaths: false,
+                    validNodes: []
+                };
+
+                // When there are previous segments, aggregates these.
+                const prevSegments = segment.prevSegments;
+
+                if (prevSegments.length > 0) {
+                    info.calledInSomePaths = prevSegments.some(isCalledInSomePath);
+                    info.calledInEveryPaths = prevSegments.every(isCalledInEveryPath);
+                }
+            },
+
+            /**
+             * 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 (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
+                    return;
+                }
+
+                // Update information inside of the loop.
+                const isRealLoop = toSegment.prevSegments.length >= 2;
+
+                funcInfo.codePath.traverseSegments(
+                    { first: toSegment, last: fromSegment },
+                    segment => {
+                        const info = segInfoMap[segment.id];
+                        const prevSegments = segment.prevSegments;
+
+                        // Updates flags.
+                        info.calledInSomePaths = prevSegments.some(isCalledInSomePath);
+                        info.calledInEveryPaths = prevSegments.every(isCalledInEveryPath);
+
+                        // If flags become true anew, reports the valid nodes.
+                        if (info.calledInSomePaths || isRealLoop) {
+                            const nodes = info.validNodes;
+
+                            info.validNodes = [];
+
+                            for (let i = 0; i < nodes.length; ++i) {
+                                const node = nodes[i];
+
+                                context.report({
+                                    messageId: "duplicate",
+                                    node
+                                });
+                            }
+                        }
+                    }
+                );
+            },
+
+            /**
+             * Checks for a call of `super()`.
+             * @param {ASTNode} node A CallExpression node to check.
+             * @returns {void}
+             */
+            "CallExpression:exit"(node) {
+                if (!(funcInfo && funcInfo.isConstructor)) {
+                    return;
+                }
+
+                // Skips except `super()`.
+                if (node.callee.type !== "Super") {
+                    return;
+                }
+
+                // Reports if needed.
+                if (funcInfo.hasExtends) {
+                    const segments = funcInfo.codePath.currentSegments;
+                    let duplicate = false;
+                    let info = null;
+
+                    for (let i = 0; i < segments.length; ++i) {
+                        const segment = segments[i];
+
+                        if (segment.reachable) {
+                            info = segInfoMap[segment.id];
+
+                            duplicate = duplicate || info.calledInSomePaths;
+                            info.calledInSomePaths = info.calledInEveryPaths = true;
+                        }
+                    }
+
+                    if (info) {
+                        if (duplicate) {
+                            context.report({
+                                messageId: "duplicate",
+                                node
+                            });
+                        } else if (!funcInfo.superIsConstructor) {
+                            context.report({
+                                messageId: "badSuper",
+                                node
+                            });
+                        } else {
+                            info.validNodes.push(node);
+                        }
+                    }
+                } else if (funcInfo.codePath.currentSegments.some(isReachable)) {
+                    context.report({
+                        messageId: "unexpected",
+                        node
+                    });
+                }
+            },
+
+            /**
+             * Set the mark to the returned path as `super()` was called.
+             * @param {ASTNode} node A ReturnStatement node to check.
+             * @returns {void}
+             */
+            ReturnStatement(node) {
+                if (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
+                    return;
+                }
+
+                // Skips if no argument.
+                if (!node.argument) {
+                    return;
+                }
+
+                // Returning argument is a substitute of 'super()'.
+                const segments = funcInfo.codePath.currentSegments;
+
+                for (let i = 0; i < segments.length; ++i) {
+                    const segment = segments[i];
+
+                    if (segment.reachable) {
+                        const info = segInfoMap[segment.id];
+
+                        info.calledInSomePaths = info.calledInEveryPaths = true;
+                    }
+                }
+            },
+
+            /**
+             * Resets state.
+             * @returns {void}
+             */
+            "Program:exit"() {
+                segInfoMap = Object.create(null);
+            }
+        };
+    }
+};