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app_vue/node_modules/eslint/lib/rules/strict.js

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+/**
+ * @fileoverview Rule to control usage of strict mode directives.
+ * @author Brandon Mills
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Gets all of the Use Strict Directives in the Directive Prologue of a group of
+ * statements.
+ * @param {ASTNode[]} statements Statements in the program or function body.
+ * @returns {ASTNode[]} All of the Use Strict Directives.
+ */
+function getUseStrictDirectives(statements) {
+    const directives = [];
+
+    for (let i = 0; i < statements.length; i++) {
+        const statement = statements[i];
+
+        if (
+            statement.type === "ExpressionStatement" &&
+            statement.expression.type === "Literal" &&
+            statement.expression.value === "use strict"
+        ) {
+            directives[i] = statement;
+        } else {
+            break;
+        }
+    }
+
+    return directives;
+}
+
+/**
+ * Checks whether a given parameter is a simple parameter.
+ * @param {ASTNode} node A pattern node to check.
+ * @returns {boolean} `true` if the node is an Identifier node.
+ */
+function isSimpleParameter(node) {
+    return node.type === "Identifier";
+}
+
+/**
+ * Checks whether a given parameter list is a simple parameter list.
+ * @param {ASTNode[]} params A parameter list to check.
+ * @returns {boolean} `true` if the every parameter is an Identifier node.
+ */
+function isSimpleParameterList(params) {
+    return params.every(isSimpleParameter);
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "require or disallow strict mode directives",
+            category: "Strict Mode",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/strict"
+        },
+
+        schema: [
+            {
+                enum: ["never", "global", "function", "safe"]
+            }
+        ],
+
+        fixable: "code",
+        messages: {
+            function: "Use the function form of 'use strict'.",
+            global: "Use the global form of 'use strict'.",
+            multiple: "Multiple 'use strict' directives.",
+            never: "Strict mode is not permitted.",
+            unnecessary: "Unnecessary 'use strict' directive.",
+            module: "'use strict' is unnecessary inside of modules.",
+            implied: "'use strict' is unnecessary when implied strict mode is enabled.",
+            unnecessaryInClasses: "'use strict' is unnecessary inside of classes.",
+            nonSimpleParameterList: "'use strict' directive inside a function with non-simple parameter list throws a syntax error since ES2016.",
+            wrap: "Wrap {{name}} in a function with 'use strict' directive."
+        }
+    },
+
+    create(context) {
+
+        const ecmaFeatures = context.parserOptions.ecmaFeatures || {},
+            scopes = [],
+            classScopes = [];
+        let mode = context.options[0] || "safe";
+
+        if (ecmaFeatures.impliedStrict) {
+            mode = "implied";
+        } else if (mode === "safe") {
+            mode = ecmaFeatures.globalReturn ? "global" : "function";
+        }
+
+        /**
+         * Determines whether a reported error should be fixed, depending on the error type.
+         * @param {string} errorType The type of error
+         * @returns {boolean} `true` if the reported error should be fixed
+         */
+        function shouldFix(errorType) {
+            return errorType === "multiple" || errorType === "unnecessary" || errorType === "module" || errorType === "implied" || errorType === "unnecessaryInClasses";
+        }
+
+        /**
+         * Gets a fixer function to remove a given 'use strict' directive.
+         * @param {ASTNode} node The directive that should be removed
+         * @returns {Function} A fixer function
+         */
+        function getFixFunction(node) {
+            return fixer => fixer.remove(node);
+        }
+
+        /**
+         * Report a slice of an array of nodes with a given message.
+         * @param {ASTNode[]} nodes Nodes.
+         * @param {string} start Index to start from.
+         * @param {string} end Index to end before.
+         * @param {string} messageId Message to display.
+         * @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
+         * @returns {void}
+         */
+        function reportSlice(nodes, start, end, messageId, fix) {
+            nodes.slice(start, end).forEach(node => {
+                context.report({ node, messageId, fix: fix ? getFixFunction(node) : null });
+            });
+        }
+
+        /**
+         * Report all nodes in an array with a given message.
+         * @param {ASTNode[]} nodes Nodes.
+         * @param {string} messageId Message id to display.
+         * @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
+         * @returns {void}
+         */
+        function reportAll(nodes, messageId, fix) {
+            reportSlice(nodes, 0, nodes.length, messageId, fix);
+        }
+
+        /**
+         * Report all nodes in an array, except the first, with a given message.
+         * @param {ASTNode[]} nodes Nodes.
+         * @param {string} messageId Message id to display.
+         * @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
+         * @returns {void}
+         */
+        function reportAllExceptFirst(nodes, messageId, fix) {
+            reportSlice(nodes, 1, nodes.length, messageId, fix);
+        }
+
+        /**
+         * Entering a function in 'function' mode pushes a new nested scope onto the
+         * stack. The new scope is true if the nested function is strict mode code.
+         * @param {ASTNode} node The function declaration or expression.
+         * @param {ASTNode[]} useStrictDirectives The Use Strict Directives of the node.
+         * @returns {void}
+         */
+        function enterFunctionInFunctionMode(node, useStrictDirectives) {
+            const isInClass = classScopes.length > 0,
+                isParentGlobal = scopes.length === 0 && classScopes.length === 0,
+                isParentStrict = scopes.length > 0 && scopes[scopes.length - 1],
+                isStrict = useStrictDirectives.length > 0;
+
+            if (isStrict) {
+                if (!isSimpleParameterList(node.params)) {
+                    context.report({ node: useStrictDirectives[0], messageId: "nonSimpleParameterList" });
+                } else if (isParentStrict) {
+                    context.report({ node: useStrictDirectives[0], messageId: "unnecessary", fix: getFixFunction(useStrictDirectives[0]) });
+                } else if (isInClass) {
+                    context.report({ node: useStrictDirectives[0], messageId: "unnecessaryInClasses", fix: getFixFunction(useStrictDirectives[0]) });
+                }
+
+                reportAllExceptFirst(useStrictDirectives, "multiple", true);
+            } else if (isParentGlobal) {
+                if (isSimpleParameterList(node.params)) {
+                    context.report({ node, messageId: "function" });
+                } else {
+                    context.report({
+                        node,
+                        messageId: "wrap",
+                        data: { name: astUtils.getFunctionNameWithKind(node) }
+                    });
+                }
+            }
+
+            scopes.push(isParentStrict || isStrict);
+        }
+
+        /**
+         * Exiting a function in 'function' mode pops its scope off the stack.
+         * @returns {void}
+         */
+        function exitFunctionInFunctionMode() {
+            scopes.pop();
+        }
+
+        /**
+         * Enter a function and either:
+         * - Push a new nested scope onto the stack (in 'function' mode).
+         * - Report all the Use Strict Directives (in the other modes).
+         * @param {ASTNode} node The function declaration or expression.
+         * @returns {void}
+         */
+        function enterFunction(node) {
+            const isBlock = node.body.type === "BlockStatement",
+                useStrictDirectives = isBlock
+                    ? getUseStrictDirectives(node.body.body) : [];
+
+            if (mode === "function") {
+                enterFunctionInFunctionMode(node, useStrictDirectives);
+            } else if (useStrictDirectives.length > 0) {
+                if (isSimpleParameterList(node.params)) {
+                    reportAll(useStrictDirectives, mode, shouldFix(mode));
+                } else {
+                    context.report({ node: useStrictDirectives[0], messageId: "nonSimpleParameterList" });
+                    reportAllExceptFirst(useStrictDirectives, "multiple", true);
+                }
+            }
+        }
+
+        const rule = {
+            Program(node) {
+                const useStrictDirectives = getUseStrictDirectives(node.body);
+
+                if (node.sourceType === "module") {
+                    mode = "module";
+                }
+
+                if (mode === "global") {
+                    if (node.body.length > 0 && useStrictDirectives.length === 0) {
+                        context.report({ node, messageId: "global" });
+                    }
+                    reportAllExceptFirst(useStrictDirectives, "multiple", true);
+                } else {
+                    reportAll(useStrictDirectives, mode, shouldFix(mode));
+                }
+            },
+            FunctionDeclaration: enterFunction,
+            FunctionExpression: enterFunction,
+            ArrowFunctionExpression: enterFunction
+        };
+
+        if (mode === "function") {
+            Object.assign(rule, {
+
+                // Inside of class bodies are always strict mode.
+                ClassBody() {
+                    classScopes.push(true);
+                },
+                "ClassBody:exit"() {
+                    classScopes.pop();
+                },
+
+                "FunctionDeclaration:exit": exitFunctionInFunctionMode,
+                "FunctionExpression:exit": exitFunctionInFunctionMode,
+                "ArrowFunctionExpression:exit": exitFunctionInFunctionMode
+            });
+        }
+
+        return rule;
+    }
+};