advanced linked lists addcharchar )inserts the given character into the buffer at the current position if the current entry mode is insertthe character is inserted and the following characters on that line are shifted downin overwrite modethe character at the current position is replaced if the cursor is currently at newline character and the entry mode is overwritethe new character is inserted at the end of the line the cursor is advanced one position if char is the newline characterthen line break occurswhich is the same as calling breakline(deletechar()removes the character at the current position and leaves the cursor at the same position ruboutchar()removes the character preceding the current position and moves the cursor left one position if the cursor is currently at the front of the linethe newline character on the preceding line is removed and the current line and the preceding line are merged into single line deleteall()deletes the entire contents of the buffer and resets it to the same state as in the constructor the definition of the adt includes the operations sufficient for use with simple text editor all of the information needed by an editor to display or manipulate the text is available through the defined operations implementation many different data structures can be used to implement the edit buffer adt the choice can depend on the type of editor with which the buffer will be used for examplewhen editing field within dialog box or web pagethe editing capabilities and the buffer size are usually limited but full-blown text edit like jedit or notepad requires dynamic bufferwhich can grow and shrink in size for our implementationwe are going to use doubly linked list of python listswhich provides dynamic capabilities in terms of growing and shrinking the buffer as needed while providing quick line insertions and deletions the individual lines of text will be stored in the nodes of the doubly linked list while the individual characters within the lines will be stored in python lists figure illustrates sample buffer using this organization the use of linked list provides fast line insertions and deletions as text is added and removed the doubly linked version allows for quick movement within the buffer both forward and backward as the user navigates among the lines of text the choice of the vector to store the individual characters allows for quick modifications as characters are added and deleted existing characters can be directly modified or deleted and new characters inserted without the overhead required when using strings although the python list does require resizingit' typical for individual lines of text on average to be relatively short