Implement minlength for <input> and <textarea>.

Source/core/html/HTMLInputElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 44 matching lines @@
 
     virtual bool shouldAutocomplete() const override final;
 
     // For ValidityState
     virtual bool hasBadInput() const override final;
     virtual bool patternMismatch() const override final;
     virtual bool rangeUnderflow() const override final;
     virtual bool rangeOverflow() const override final;
     virtual bool stepMismatch() const override final;
     virtual bool tooLong() const override final;
+    virtual bool tooShort() const override final;
     virtual bool typeMismatch() const override final;
     virtual bool valueMissing() const override final;
     virtual String validationMessage() const override final;
 
     // Returns the minimum value for type=date, number, or range.  Don't call this for other types.
     double minimum() const;
     // Returns the maximum value for type=date, number, or range.  Don't call this for other types.
     // This always returns a value which is >= minimum().
     double maximum() const;
     // Sets the "allowed value step" defined in the HTML spec to the specified double pointer.
@@ skipping 87 matching lines @@
     Vector<String> acceptMIMETypes();
     Vector<String> acceptFileExtensions();
     const AtomicString& alt() const;
 
     void setSize(unsigned);
     void setSize(unsigned, ExceptionState&);
 
     KURL src() const;
 
     int maxLength() const;
+    int minLength() const;
     void setMaxLength(int, ExceptionState&);
+    void setMinLength(int, ExceptionState&);
 
     bool multiple() const;
 
     FileList* files();
     void setFiles(FileList*);
 
     // Returns true if the given DragData has more than one dropped files.
     bool receiveDroppedFiles(const DragData*);
 
     String droppedFileSystemId();
@@ skipping 126 matching lines @@
     virtual void* preDispatchEventHandler(Event*) override final;
     virtual void postDispatchEventHandler(Event*, void* dataFromPreDispatch) override final;
 
     virtual bool isURLAttribute(const Attribute&) const override final;
     virtual bool hasLegalLinkAttribute(const QualifiedName&) const override final;
     virtual const QualifiedName& subResourceAttributeName() const override final;
     virtual bool isInRange() const override final;
     virtual bool isOutOfRange() const override final;
 
     bool tooLong(const String&, NeedsToCheckDirtyFlag) const;
+    bool tooShort(const String&, NeedsToCheckDirtyFlag) const;
 
     virtual bool supportsPlaceholder() const override final;
     virtual void updatePlaceholderText() override final;
     virtual bool isEmptyValue() const override final { return innerEditorValue().isEmpty(); }
     virtual bool isEmptySuggestedValue() const override final { return suggestedValue().isEmpty(); }
     virtual void handleFocusEvent(Element* oldFocusedElement, FocusType) override final;
     virtual void handleBlurEvent() override final;
     virtual void dispatchFocusInEvent(const AtomicString& eventType, Element* oldFocusedElement, FocusType) override final;
 
     virtual bool isOptionalFormControl() const override final { return !isRequiredFormControl(); }
     virtual bool isRequiredFormControl() const override final;
     virtual bool recalcWillValidate() const override final;
     virtual void requiredAttributeChanged() override final;
 
     void updateType();
 
     virtual void subtreeHasChanged() override final;
 
     void setListAttributeTargetObserver(PassOwnPtrWillBeRawPtr<ListAttributeTargetObserver>);
     void resetListAttributeTargetObserver();
     void parseMaxLengthAttribute(const AtomicString&);
+    void parseMinLengthAttribute(const AtomicString&);
     void updateValueIfNeeded();
 
     // Returns null if this isn't associated with any radio button group.
     RadioButtonGroupScope* radioButtonGroupScope() const;
     void addToRadioButtonGroup();
     void removeFromRadioButtonGroup();
 #if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
     virtual PassRefPtr<RenderStyle> customStyleForRenderer() override;
 #endif
 
     virtual bool shouldDispatchFormControlChangeEvent(String&, String&) override;
 
     AtomicString m_name;
     String m_valueIfDirty;
     String m_suggestedValue;
     int m_size;
     int m_maxLength;
+    int m_minLength;

[tkent, 2014/10/15 00:50:25]

I don't think we need new data member.  We should try to parse minlength
attribute value on demand.  If it has performance problems, we should introduce
m_minLength then.

[Bartek Nowierski, 2014/10/16 04:55:14]

Someone decided that it's worth doing for maxlength, so just for symmetry we
might as well do it for minlength. The advantage of this approach is that it's
obvious that if one is correct then the other is correct too.

     short m_maxResults;
     bool m_isChecked : 1;
     bool m_reflectsCheckedAttribute : 1;
     bool m_isIndeterminate : 1;
     bool m_isActivatedSubmit : 1;
     unsigned m_autocomplete : 2; // AutoCompleteSetting
     bool m_hasNonEmptyList : 1;
     bool m_stateRestored : 1;
     bool m_parsingInProgress : 1;
     bool m_valueAttributeWasUpdatedAfterParsing : 1;
     bool m_canReceiveDroppedFiles : 1;
     bool m_hasTouchEventHandler : 1;
     bool m_shouldRevealPassword : 1;
     bool m_needsToUpdateViewValue : 1;
     RefPtrWillBeMember<InputType> m_inputType;
     RefPtrWillBeMember<InputTypeView> m_inputTypeView;
     // The ImageLoader must be owned by this element because the loader code assumes
     // that it lives as long as its owning element lives. If we move the loader into
     // the ImageInput object we may delete the loader while this element lives on.
     OwnPtrWillBeMember<HTMLImageLoader> m_imageLoader;
     OwnPtrWillBeMember<ListAttributeTargetObserver> m_listAttributeTargetObserver;
 };
 
 } // namespace blink
 
 #endif // HTMLInputElement_h