Add MEL syntax highlighting for expression editor[给表达式编辑器添加mel的高光显示]

I don't use mel for years. But it would be great to have syntax highlighting in the expression editor. It's not that hard since maya build wiht Qt. Actually it's very easy to do it if you good at Qt. Here I'm gonna show you how to do it with PySide.
我n久没用过mel了，不过如果expression editor能有mel的高亮显示还是挺不错的。要添加这个并不难，因为maya是基于Qt的界面。实际上是一件很简单的事情，如果你擅长Qt的话。我在这里使用PySide来完成它。

Implementation[实现]

1. You need a QSyntaxHighlighter | 你需要一个QSyntaxHighlighte
2. apply the syntax highlighting rules to the expression editor's document | 把高亮显示的规则应用到expression editor的文档中

You can define your own mel QSyntaxHighlighter if you want. I not gonna do that I'll use the script editor's.
So the implementation should be
你也可以以定义你自己的mel QSyntaxHighlighter。我就直接使用脚本编辑器里的。我需要这么做

1. open a expression editor, find it with PySide, find the QTextEdit in the expression editor | 打开expression editor，使用PySide找到它，再找到它的QTextEdit
2. create a window with a mel cmdScrollFieldExecuter, this window will never show, and it'll create a mel QSyntaxHighlighter for you | 创建一个mel脚本编辑器窗口，这个窗口永远也不会显示，它会创建一个mel QSyntaxHighlighter
3. find the mel QSyntaxHighlighter | 找到mel QSyntaxHighlighter
4. apply it to the expression editor's document | 把它应用到expression editor的文档中

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from maya import cmds

from PySide import QtGui
#from PyQt4 import QtGui

def showExpEditor():
    """
    Add mel syntax highlighting for expression editor. Support Maya2011-2014
    """
    tempWin = "mytempmelwin_xxxxxxxxxx"
    # open expression editor
    cmds.ExpressionEditor()
    
    mapp = QtGui.QApplication.instance()
    if not mapp: return mapp
    mwin = mapp.activeWindow()
    if mwin.objectName() != "MayaWindow":
        mwin = mwin.parent()
    # finde expression editor
    expEditor = mwin.findChild(QtGui.QWidget, "expressionEditorWin")
    expTextEd = expEditor.findChild(QtGui.QTextEdit)
    
    # create a mel cmdScrollFieldExecuter
    if cmds.window(tempWin, ex=1): cmds.deleteUI(tempWin)
    cmds.window(tempWin)
    cmds.columnLayout()
    cmds.cmdScrollFieldExecuter(sourceType="mel")
    
    # find tempWin
    melWin = mwin.findChild(QtGui.QWidget, tempWin)
    # find the SyntaxHighlighter
    melHighlighter = melWin.findChild(QtGui.QSyntaxHighlighter)
    melHighlighter.setDocument(expTextEd.document())

showExpEditor()

How about the auto completions in the expression editor?[mel命令自动完成呢]
I can't find the QCompleter from the Script Editor. Autodesk may implement it on the QTextEdit or somewhere. So if you want the auto completions you have to do it yourslef.
我没找到QCompleter，Autodesk 应该是用过其它方式来实现的，所以你需要自己去实现了。

No desktop snapshot. Just try the code and have fun with it.