*JAVA*

Write a line-based text editor. The command syntax is similar to the Unix line editor ed. The internal copy of the file is maintained as a linked list of lines. To be able to go up and down in the file, you have to maintain a doubly linked list. Most commands are represented by a one-character string. Some are two characters and require an argument (or two). Support the commands shown below:

Command Function Go to the top. Add text after current line until on its own line Delete current line Delete several lines. Change name of the current file (for next write) Go to a numbered line. Get help Like append, but add lines before current line. Move current line after some other line. dr num num f name gnum m num mr num num num Move several lines as a unit after some other line Toggle whether line numbers are displayed. Print current line Print several lines. Abort without write. Read and paste another file into the current file. Substitute text with other text. Copy current line to after some other line. Copy several lines to after some other line. Write file to disk. Exit with write Go to the last line Go up one line. Go down one line Print current line number. Search forward for a pattern. Search backward for a pattern. Print number of lines and characters in file pr num num q! r name s text text t num tr num num num x! / text ? text Command Function Go to the top. Add text after current line until on its own line Delete current line Delete several lines. Change name of the current file (for next write) Go to a numbered line. Get help Like append, but add lines before current line. Move current line after some other line. dr num num f name gnum m num mr num num num Move several lines as a unit after some other line Toggle whether line numbers are displayed. Print current line Print several lines. Abort without write. Read and paste another file into the current file. Substitute text with other text. Copy current line to after some other line. Copy several lines to after some other line. Write file to disk. Exit with write Go to the last line Go up one line. Go down one line Print current line number. Search forward for a pattern. Search backward for a pattern. Print number of lines and characters in file pr num num q! r name s text text t num tr num num num x! / text ? text