diff options
Diffstat (limited to 'tools/node_modules/eslint/lib/rules/utils/ast-utils.js')
| -rw-r--r-- | tools/node_modules/eslint/lib/rules/utils/ast-utils.js | 210 |
1 files changed, 203 insertions, 7 deletions
diff --git a/tools/node_modules/eslint/lib/rules/utils/ast-utils.js b/tools/node_modules/eslint/lib/rules/utils/ast-utils.js index ecde099fa02..f919f5a26c8 100644 --- a/tools/node_modules/eslint/lib/rules/utils/ast-utils.js +++ b/tools/node_modules/eslint/lib/rules/utils/ast-utils.js @@ -32,6 +32,7 @@ const thisTagPattern = /^[\s*]*@this/mu; const COMMENTS_IGNORE_PATTERN = /^\s*(?:eslint|jshint\s+|jslint\s+|istanbul\s+|globals?\s+|exported\s+|jscs)/u; +const ESLINT_DIRECTIVE_PATTERN = /^(?:eslint[- ]|(?:globals?|exported) )/u; const LINEBREAKS = new Set(["\r\n", "\r", "\n", "\u2028", "\u2029"]); // A set of node types that can contain a list of statements @@ -788,6 +789,203 @@ function getModuleExportName(node) { return node.value; } +/** + * Returns literal's value converted to the Boolean type + * @param {ASTNode} node any `Literal` node + * @returns {boolean | null} `true` when node is truthy, `false` when node is falsy, + * `null` when it cannot be determined. + */ +function getBooleanValue(node) { + if (node.value === null) { + + /* + * it might be a null literal or bigint/regex literal in unsupported environments . + * https://github.com/estree/estree/blob/14df8a024956ea289bd55b9c2226a1d5b8a473ee/es5.md#regexpliteral + * https://github.com/estree/estree/blob/14df8a024956ea289bd55b9c2226a1d5b8a473ee/es2020.md#bigintliteral + */ + + if (node.raw === "null") { + return false; + } + + // regex is always truthy + if (typeof node.regex === "object") { + return true; + } + + return null; + } + + return !!node.value; +} + +/** + * Checks if a branch node of LogicalExpression short circuits the whole condition + * @param {ASTNode} node The branch of main condition which needs to be checked + * @param {string} operator The operator of the main LogicalExpression. + * @returns {boolean} true when condition short circuits whole condition + */ +function isLogicalIdentity(node, operator) { + switch (node.type) { + case "Literal": + return (operator === "||" && getBooleanValue(node) === true) || + (operator === "&&" && getBooleanValue(node) === false); + + case "UnaryExpression": + return (operator === "&&" && node.operator === "void"); + + case "LogicalExpression": + + /* + * handles `a && false || b` + * `false` is an identity element of `&&` but not `||` + */ + return operator === node.operator && + ( + isLogicalIdentity(node.left, operator) || + isLogicalIdentity(node.right, operator) + ); + + case "AssignmentExpression": + return ["||=", "&&="].includes(node.operator) && + operator === node.operator.slice(0, -1) && + isLogicalIdentity(node.right, operator); + + // no default + } + return false; +} + +/** + * Checks if an identifier is a reference to a global variable. + * @param {Scope} scope The scope in which the identifier is referenced. + * @param {ASTNode} node An identifier node to check. + * @returns {boolean} `true` if the identifier is a reference to a global variable. + */ +function isReferenceToGlobalVariable(scope, node) { + const reference = scope.references.find(ref => ref.identifier === node); + + return Boolean( + reference && + reference.resolved && + reference.resolved.scope.type === "global" && + reference.resolved.defs.length === 0 + ); +} + + +/** + * Checks if a node has a constant truthiness value. + * @param {Scope} scope Scope in which the node appears. + * @param {ASTNode} node The AST node to check. + * @param {boolean} inBooleanPosition `true` if checking the test of a + * condition. `false` in all other cases. When `false`, checks if -- for + * both string and number -- if coerced to that type, the value will + * be constant. + * @returns {boolean} true when node's truthiness is constant + * @private + */ +function isConstant(scope, node, inBooleanPosition) { + + // node.elements can return null values in the case of sparse arrays ex. [,] + if (!node) { + return true; + } + switch (node.type) { + case "Literal": + case "ArrowFunctionExpression": + case "FunctionExpression": + return true; + case "ClassExpression": + case "ObjectExpression": + + /** + * In theory objects like: + * + * `{toString: () => a}` + * `{valueOf: () => a}` + * + * Or a classes like: + * + * `class { static toString() { return a } }` + * `class { static valueOf() { return a } }` + * + * Are not constant verifiably when `inBooleanPosition` is + * false, but it's an edge case we've opted not to handle. + */ + return true; + case "TemplateLiteral": + return (inBooleanPosition && node.quasis.some(quasi => quasi.value.cooked.length)) || + node.expressions.every(exp => isConstant(scope, exp, false)); + + case "ArrayExpression": { + if (!inBooleanPosition) { + return node.elements.every(element => isConstant(scope, element, false)); + } + return true; + } + + case "UnaryExpression": + if ( + node.operator === "void" || + node.operator === "typeof" && inBooleanPosition + ) { + return true; + } + + if (node.operator === "!") { + return isConstant(scope, node.argument, true); + } + + return isConstant(scope, node.argument, false); + + case "BinaryExpression": + return isConstant(scope, node.left, false) && + isConstant(scope, node.right, false) && + node.operator !== "in"; + + case "LogicalExpression": { + const isLeftConstant = isConstant(scope, node.left, inBooleanPosition); + const isRightConstant = isConstant(scope, node.right, inBooleanPosition); + const isLeftShortCircuit = (isLeftConstant && isLogicalIdentity(node.left, node.operator)); + const isRightShortCircuit = (inBooleanPosition && isRightConstant && isLogicalIdentity(node.right, node.operator)); + + return (isLeftConstant && isRightConstant) || + isLeftShortCircuit || + isRightShortCircuit; + } + case "NewExpression": + return inBooleanPosition; + case "AssignmentExpression": + if (node.operator === "=") { + return isConstant(scope, node.right, inBooleanPosition); + } + + if (["||=", "&&="].includes(node.operator) && inBooleanPosition) { + return isLogicalIdentity(node.right, node.operator.slice(0, -1)); + } + + return false; + + case "SequenceExpression": + return isConstant(scope, node.expressions[node.expressions.length - 1], inBooleanPosition); + case "SpreadElement": + return isConstant(scope, node.argument, inBooleanPosition); + case "CallExpression": + if (node.callee.type === "Identifier" && node.callee.name === "Boolean") { + if (node.arguments.length === 0 || isConstant(scope, node.arguments[0], true)) { + return isReferenceToGlobalVariable(scope, node.callee); + } + } + return false; + case "Identifier": + return node.name === "undefined" && isReferenceToGlobalVariable(scope, node); + + // no default + } + return false; +} + //------------------------------------------------------------------------------ // Public Interface //------------------------------------------------------------------------------ @@ -908,12 +1106,8 @@ module.exports = { const comment = node.value.trim(); return ( - node.type === "Line" && comment.indexOf("eslint-") === 0 || - node.type === "Block" && ( - comment.indexOf("global ") === 0 || - comment.indexOf("eslint ") === 0 || - comment.indexOf("eslint-") === 0 - ) + node.type === "Line" && comment.startsWith("eslint-") || + node.type === "Block" && ESLINT_DIRECTIVE_PATTERN.test(comment) ); }, @@ -1905,6 +2099,7 @@ module.exports = { return OCTAL_OR_NON_OCTAL_DECIMAL_ESCAPE_PATTERN.test(rawString); }, + isReferenceToGlobalVariable, isLogicalExpression, isCoalesceExpression, isMixedLogicalAndCoalesceExpressions, @@ -1918,5 +2113,6 @@ module.exports = { isSameReference, isLogicalAssignmentOperator, getSwitchCaseColonToken, - getModuleExportName + getModuleExportName, + isConstant }; |