Function genHandler

vue.js:14507–14572

(
        name,
        handler
    )

    }

    function genHandler(
        name,
        handler
    ) {
        if (!handler) {
            return 'function(){}'
        }

        if (Array.isArray(handler)) {
            return ("[" + (handler.map(function (handler) {
                return genHandler(name, handler);
            }).join(',')) + "]")
        }

        var isMethodPath = simplePathRE.test(handler.value);
        var isFunctionExpression = fnExpRE.test(handler.value);

        if (!handler.modifiers) {
            if (isMethodPath || isFunctionExpression) {
                return handler.value
            }
            /* istanbul ignore if */
            return ("function($event){" + (handler.value) + "}") // inline statement
        } else {
            var code = '';
            var genModifierCode = '';
            var keys = [];
            for (var key in handler.modifiers) {
                if (modifierCode[key]) {
                    genModifierCode += modifierCode[key];
                    // left/right
                    if (keyCodes[key]) {
                        keys.push(key);
                    }
                } else if (key === 'exact') {
                    var modifiers = (handler.modifiers);
                    genModifierCode += genGuard(
                        ['ctrl', 'shift', 'alt', 'meta']
                            .filter(function (keyModifier) {
                                return !modifiers[keyModifier];
                            })
                            .map(function (keyModifier) {
                                return ("$event." + keyModifier + "Key");
                            })
                            .join('||')
                    );
                } else {
                    keys.push(key);
                }
            }
            if (keys.length) {
                code += genKeyFilter(keys);
            }
            // Make sure modifiers like prevent and stop get executed after key filtering
            if (genModifierCode) {
                code += genModifierCode;
            }
            var handlerCode = isMethodPath