Limit number of special characters

There is also a more advanced attempt that allows more, but I've commented it out because it doesn't quite work yet. Special characters now always count for 12.

Contributes to issue CURA-2652.

cura/Settings/MachineNameValidator.py

@@ -1,18 +1,45 @@
 # Copyright (c) 2016 Ultimaker B.V.
 # Cura is released under the terms of the AGPLv3 or higher.
 
+from PyQt5.QtCore import pyqtSlot, pyqtProperty, QObject, pyqtSignal, QRegExp
+from PyQt5.QtGui import QValidator
+import os #For statvfs.
+import urllib #To escape machine names for how they're saved to file.
+
 import UM.Resources
 import UM.Settings.ContainerRegistry
 import UM.Settings.InstanceContainer
 
-from PyQt5.QtGui import QValidator
-import os #For statvfs.
-import urllib #To escape machine names for how they're saved to file.
-
 ##  Are machine names valid?
 #
 #   Performs checks based on the length of the name.
-class MachineNameValidator(QValidator):
+class MachineNameValidator(QObject):
+    def __init__(self, parent = None):
+        super().__init__(parent)
+
+        #Compute the validation regex for printer names. This is limited by the maximum file name length.
+        try:
+            filename_max_length = os.statvfs(UM.Resources.getDataStoragePath()).f_namemax
+        except AttributeError: #Doesn't support statvfs. Probably because it's not a Unix system.
+            filename_max_length = 255 #Assume it's Windows on NTFS.
+        machine_name_max_length = filename_max_length - len("_current_settings.") - len(UM.Settings.ContainerRegistry.getMimeTypeForContainer(UM.Settings.InstanceContainer).preferredSuffix)
+        # Characters that urllib.parse.quote_plus escapes count for 3! So now we
+        # must devise a regex that allows only 3 normal characters or 1 special
+        # character, and that up to [machine_name_max_length / 3] times.
+        maximum_special_characters = int(machine_name_max_length / 12)
+        unescaped = r"[a-zA-Z0-9_\-\.\/]"
+        #single_length = r"[\u0000-\u007F]"
+        #double_length = r"[\u0080-\u07FF]"
+        #triple_length = r"[\u0800-\uFFFF]"
+        #quadruple_length = r"[\u10000-\u10FFFF]"
+        #self.machine_name_regex = r"((((" + unescaped + r"{0,3}|" + single_length + r"){0,2}" \
+        #                          + r"|" + double_length + r"){0,2}" \
+        #                          + r"|" + triple_length + r"){0,2}" \
+        #                          + r"|" + quadruple_length + r"){0," + str(maximum_special_characters) + r"}"
+        self.machine_name_regex = r"((" + unescaped + "){0,12}|.){0," + str(maximum_special_characters) + r"}"
+
+    validationChanged = pyqtSignal()
+
     ##  Check if a specified machine name is allowed.
     #
     #   \param name The machine name to check.
@@ -22,12 +49,29 @@ class MachineNameValidator(QValidator):
     def validate(self, name, position):
         #Check for file name length of the current settings container (which is the longest file we're saving with the name).
         try:
-            filename_max_length = os.statvfs(UM.Resources.getDataStoragePath())
+            filename_max_length = os.statvfs(UM.Resources.getDataStoragePath()).f_namemax
         except AttributeError: #Doesn't support statvfs. Probably because it's not a Unix system.
             filename_max_length = 255 #Assume it's Windows on NTFS.
         escaped_name = urllib.parse.quote_plus(name)
         current_settings_filename = escaped_name + "_current_settings." + UM.Settings.ContainerRegistry.getMimeTypeForContainer(UM.Settings.InstanceContainer).preferredSuffix
-        if current_settings_filename > filename_max_length:
+        if len(current_settings_filename) > filename_max_length:
             return QValidator.Invalid
 
         return QValidator.Acceptable #All checks succeeded.
+
+    ##  Updates the validation state of a machine name text field.
+    @pyqtSlot(str)
+    def updateValidation(self, new_name):
+        is_valid = self.validate(new_name, 0)
+        if is_valid == QValidator.Acceptable:
+            print("VALID")
+            self.validation_regex = "^.*$" #Matches anything.
+        else:
+            print("BROKEN!")
+            self.validation_regex = "a^" #Never matches (unless you manage to get "a" before the start of the string... good luck).
+        self.validationChanged.emit()
+
+    @pyqtProperty("QRegExp", notify=validationChanged)
+    def machineNameRegex(self):
+        print(self.machine_name_regex)
+        return QRegExp(self.machine_name_regex)

resources/qml/AddMachineDialog.qml

@@ -175,6 +175,14 @@ UM.Dialog
         text: getMachineName()
         implicitWidth: UM.Theme.getSize("standard_list_input").width
         maximumLength: 40
+        //validator: Cura.MachineNameValidator { } //TODO: Gives a segfault in PyQt5.6. For now, we must use a signal on text changed.
+        validator: RegExpValidator
+        {
+            regExp: {
+                machineName.machine_name_validator.machineNameRegex
+            }
+        }
+        property var machine_name_validator: Cura.MachineNameValidator { }
         anchors.bottom:parent.bottom
     }