node/tools/eslint/lib/rules/semi.js

/**
 * @fileoverview Rule to flag missing semicolons.
 * @author Nicholas C. Zakas
 * @copyright 2013 Nicholas C. Zakas. All rights reserved.
 * See LICENSE file in root directory for full license.
 */
"use strict";

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

module.exports = function(context) {

    var OPT_OUT_PATTERN = /[\[\(\/\+\-]/; // One of [(/+-
    var options = context.options[1];
    var never = context.options[0] === "never",
        exceptOneLine = options && options.omitLastInOneLineBlock === true,
        sourceCode = context.getSourceCode();

    //--------------------------------------------------------------------------
    // Helpers
    //--------------------------------------------------------------------------

    /**
     * Reports a semicolon error with appropriate location and message.
     * @param {ASTNode} node The node with an extra or missing semicolon.
     * @param {boolean} missing True if the semicolon is missing.
     * @returns {void}
     */
    function report(node, missing) {
        var message,
            fix,
            lastToken = sourceCode.getLastToken(node),
            loc = lastToken.loc;

        if (!missing) {
            message = "Missing semicolon.";
            loc = loc.end;
            fix = function(fixer) {
                return fixer.insertTextAfter(lastToken, ";");
            };
        } else {
            message = "Extra semicolon.";
            loc = loc.start;
            fix = function(fixer) {
                return fixer.remove(lastToken);
            };
        }

        context.report({
            node: node,
            loc: loc,
            message: message,
            fix: fix
        });

    }

    /**
     * Checks whether a token is a semicolon punctuator.
     * @param {Token} token The token.
     * @returns {boolean} True if token is a semicolon punctuator.
     */
    function isSemicolon(token) {
        return (token.type === "Punctuator" && token.value === ";");
    }

    /**
     * Check if a semicolon is unnecessary, only true if:
     *   - next token is on a new line and is not one of the opt-out tokens
     *   - next token is a valid statement divider
     * @param {Token} lastToken last token of current node.
     * @returns {boolean} whether the semicolon is unnecessary.
     */
    function isUnnecessarySemicolon(lastToken) {
        var isDivider, isOptOutToken, lastTokenLine, nextToken, nextTokenLine;

        if (!isSemicolon(lastToken)) {
            return false;
        }

        nextToken = context.getTokenAfter(lastToken);

        if (!nextToken) {
            return true;
        }

        lastTokenLine = lastToken.loc.end.line;
        nextTokenLine = nextToken.loc.start.line;
        isOptOutToken = OPT_OUT_PATTERN.test(nextToken.value);
        isDivider = (nextToken.value === "}" || nextToken.value === ";");

        return (lastTokenLine !== nextTokenLine && !isOptOutToken) || isDivider;
    }

    /**
     * Checks a node to see if it's in a one-liner block statement.
     * @param {ASTNode} node The node to check.
     * @returns {boolean} whether the node is in a one-liner block statement.
     */
    function isOneLinerBlock(node) {
        var nextToken = context.getTokenAfter(node);
        if (!nextToken || nextToken.value !== "}") {
            return false;
        }

        var parent = node.parent;
        return parent && parent.type === "BlockStatement" &&
          parent.loc.start.line === parent.loc.end.line;
    }

    /**
     * Checks a node to see if it's followed by a semicolon.
     * @param {ASTNode} node The node to check.
     * @returns {void}
     */
    function checkForSemicolon(node) {
        var lastToken = context.getLastToken(node);

        if (never) {
            if (isUnnecessarySemicolon(lastToken)) {
                report(node, true);
            }
        } else {
            if (!isSemicolon(lastToken)) {
                if (!exceptOneLine || !isOneLinerBlock(node)) {
                    report(node);
                }
            } else {
                if (exceptOneLine && isOneLinerBlock(node)) {
                    report(node, true);
                }
            }
        }
    }

    /**
     * Checks to see if there's a semicolon after a variable declaration.
     * @param {ASTNode} node The node to check.
     * @returns {void}
     */
    function checkForSemicolonForVariableDeclaration(node) {
        var ancestors = context.getAncestors(),
            parentIndex = ancestors.length - 1,
            parent = ancestors[parentIndex];

        if ((parent.type !== "ForStatement" || parent.init !== node) &&
            (!/^For(?:In|Of)Statement/.test(parent.type) || parent.left !== node)
        ) {
            checkForSemicolon(node);
        }
    }

    //--------------------------------------------------------------------------
    // Public API
    //--------------------------------------------------------------------------

    return {
        "VariableDeclaration": checkForSemicolonForVariableDeclaration,
        "ExpressionStatement": checkForSemicolon,
        "ReturnStatement": checkForSemicolon,
        "ThrowStatement": checkForSemicolon,
        "DoWhileStatement": checkForSemicolon,
        "DebuggerStatement": checkForSemicolon,
        "BreakStatement": checkForSemicolon,
        "ContinueStatement": checkForSemicolon,
        "ImportDeclaration": checkForSemicolon,
        "ExportAllDeclaration": checkForSemicolon,
        "ExportNamedDeclaration": function(node) {
            if (!node.declaration) {
                checkForSemicolon(node);
            }
        },
        "ExportDefaultDeclaration": function(node) {
            if (!/(?:Class|Function)Declaration/.test(node.declaration.type)) {
                checkForSemicolon(node);
            }
        }
    };

};

module.exports.schema = {
    "anyOf": [
        {
            "type": "array",
            "items": [
                {
                    "enum": ["never"]
                }
            ],
            "minItems": 0,
            "maxItems": 1
        },
        {
            "type": "array",
            "items": [
                {
                    "enum": ["always"]
                },
                {
                    "type": "object",
                    "properties": {
                        "omitLastInOneLineBlock": {"type": "boolean"}
                    },
                    "additionalProperties": false
                }
            ],
            "minItems": 0,
            "maxItems": 2
        }
    ]
};