diff options
Diffstat (limited to 'tools/node_modules/eslint/lib/rules/no-sequences.js')
-rw-r--r-- | tools/node_modules/eslint/lib/rules/no-sequences.js | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-sequences.js b/tools/node_modules/eslint/lib/rules/no-sequences.js new file mode 100644 index 0000000000..5e746dfa88 --- /dev/null +++ b/tools/node_modules/eslint/lib/rules/no-sequences.js @@ -0,0 +1,112 @@ +/** + * @fileoverview Rule to flag use of comma operator + * @author Brandon Mills + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const astUtils = require("../ast-utils"); + +//------------------------------------------------------------------------------ +// Rule Definition +//------------------------------------------------------------------------------ + +module.exports = { + meta: { + docs: { + description: "disallow comma operators", + category: "Best Practices", + recommended: false + }, + + schema: [] + }, + + create(context) { + const sourceCode = context.getSourceCode(); + + /** + * Parts of the grammar that are required to have parens. + */ + const parenthesized = { + DoWhileStatement: "test", + IfStatement: "test", + SwitchStatement: "discriminant", + WhileStatement: "test", + WithStatement: "object", + ArrowFunctionExpression: "body" + + /* + * Omitting CallExpression - commas are parsed as argument separators + * Omitting NewExpression - commas are parsed as argument separators + * Omitting ForInStatement - parts aren't individually parenthesised + * Omitting ForStatement - parts aren't individually parenthesised + */ + }; + + /** + * Determines whether a node is required by the grammar to be wrapped in + * parens, e.g. the test of an if statement. + * @param {ASTNode} node - The AST node + * @returns {boolean} True if parens around node belong to parent node. + */ + function requiresExtraParens(node) { + return node.parent && parenthesized[node.parent.type] && + node === node.parent[parenthesized[node.parent.type]]; + } + + /** + * Check if a node is wrapped in parens. + * @param {ASTNode} node - The AST node + * @returns {boolean} True if the node has a paren on each side. + */ + function isParenthesised(node) { + return astUtils.isParenthesised(sourceCode, node); + } + + /** + * Check if a node is wrapped in two levels of parens. + * @param {ASTNode} node - The AST node + * @returns {boolean} True if two parens surround the node on each side. + */ + function isParenthesisedTwice(node) { + const previousToken = sourceCode.getTokenBefore(node, 1), + nextToken = sourceCode.getTokenAfter(node, 1); + + return isParenthesised(node) && previousToken && nextToken && + astUtils.isOpeningParenToken(previousToken) && previousToken.range[1] <= node.range[0] && + astUtils.isClosingParenToken(nextToken) && nextToken.range[0] >= node.range[1]; + } + + return { + SequenceExpression(node) { + + // Always allow sequences in for statement update + if (node.parent.type === "ForStatement" && + (node === node.parent.init || node === node.parent.update)) { + return; + } + + // Wrapping a sequence in extra parens indicates intent + if (requiresExtraParens(node)) { + if (isParenthesisedTwice(node)) { + return; + } + } else { + if (isParenthesised(node)) { + return; + } + } + + const child = sourceCode.getTokenAfter(node.expressions[0]); + + context.report({ node, loc: child.loc.start, message: "Unexpected use of comma operator." }); + } + }; + + } +}; |