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# 5. Editing Files

## 5.1. General Information

Source editing is one of the central parts of GPS, giving in turn access to many other functionalities, including extended source navigation and source analyzing tools.

The integrated source editor provides all the usual capabilities found in integrated environments, including:

Title bar
  Showing the full name of the file including path information.
Line number information
  This is the left area of the source editor. Line numbers can be disabled from the preferences. The Preferences Dialog. Note that this area can also display additional information, such as the current line of execution when debugging, or cvs annotations.
Scrollbar
  Located on the right of the editor, it allows you to scroll through the source file.
Speed column
  This column, when visible, is located on the left of the editor. It allows you to view all the highlighted lines in a file, at a glance. For example, all the lines containing compilation errors are displayed in the Speed Column. See The Preferences Dialog for information on how to customize the behavior of the Speed Column.
Status bar
  Giving information about the file. It is divided in two sections, one on the left and one on the right of the window.
The left section
  The first box on the left shows the current subprogram name for languages that support this capability. Currently Ada, C and C++ have this ability. See The Preferences Dialog to enable or disable this feature.
The right section

  If the file is maintained under version control, and version control is supported and enabled in GPS, the first box on the left will show VCS information on the file: the VCS kind (e.g. CVS), followed by the revision number, and if available, the status of the file.

  The second box shows the current editing mode. This is either Insert or Overwrite and can be changed using the insert keyboard keys by default.

  The third box shows the writable state of the file. You can change this state by clicking on the label directly: this will switch between Writable and Read Only. Note that this will not change the permissions of the file on disk, it will only change the writable state of the source editor within GPS.

  When trying to save a file which is read only on the disk, GPS will ask for confirmation, and if possible, will force saving of the file, keeping its read only state.

  The fourth box shows whether the file has been modified since the last save. The three possible states are:

Unmodified
  The file has not been modified since the file has been loaded or saved.
Modified
  The file has been modified since last load or save. Note that if you undo all the editing operations until the last save operation, this label will change to Unmodified.
Saved

  The file has been saved and not modified since.

  The fifth box displays the position of the cursor in the file by a line and a column number.

Contextual menu
  Displayed when you right-click on any area of the source editor. See in particular Contextual Menus for Source Navigation for more details.
Syntax highlighting

  Based on the programming language associated with the file, reserved words and languages constructs such as comments and strings are highlighted in different colors and fonts. See The Preferences Dialog for a list of settings that can be customized.

  By default, GPS knows about many languages. You can also easily add support for other languages through XML files. Most languages supported by GPS will provide syntax highlighting in the editor.

Automatic indentation

  When enabled, lines are automatically indented each time you press the `Enter` key, or by pressing the indentation key. The indentation key is `Ctrl-Tab` by default, and can be changed in the key manager dialog, The Key Manager Dialog.

  If a set of lines is selected when you press the indentation key, this whole set of lines will be indented.

Tooltips

  When you leave the mouse over a word in the source editor, a small window will automatically pop up if there are relevant contextual information to display about the word.

  The type of information displayed depends on the current state of GPS.

  In normal mode, the entity kind and the location of declaration is displayed when this information is available. That is, when the cross-reference information about the current file has been generated. If there is no relevant information, no tooltip is displayed. See Support for Cross-References for more information.

  In addition, the documentation for the entity is displayed. This is the block of comments just before or just after the entity’s declaration of body. There mustn’t be any blank line between the two. For instance, the following are valid documentation for Ada and C:

      --  A comment for A
      A : Integer;

      B : Integer;
      --  A comment for B

      C : Integer;

      --  Not a comment for C, there is a blank linke

  In debugging mode, the value of the variable under the mouse is displayed in the pop up window if the variable is known to the debugger. Otherwise, the normal mode information is displayed.

  You can disable the automatic pop up of tool tips in the Editor section of the preferences dialog. The Preferences Dialog.

Code completion

  GPS provides two kinds of code completion: a smart code completion based on semantic information, and a text completion.

  It is useful when editing a file and using often the same words to get automatic word completion. This is possible by typing the `Ctrl-/` key combination (customizable through the key manager dialog) after a partial word: the next possible completion will be inserted in the editor. Typing this key again will cycle through the list of possible completions.

  Text completions are searched in all currently open source files, by first looking at the closest words and then looking further in the source as needed.

Delimiter highlighting

  When the cursor is moved before an opening delimiter or after a closing delimiter, then both delimiters will be highlighted. The following characters are considered delimiters: ()[]{}. You can disable highlighting of delimiters in the preferences.

  You can also jump to a corresponding delimiter by using the `Ctrl-'` key, that can be configured in the preferences. Typing twice on this key will move the cursor back to its original position.

Current line highlighting

  You can configure the editor to highlight the current line with a certain color. The Preferences Dialog.

Current block highlighting

  If this preference is enabled, the editor will highlight the current block of code, e.g. the current begin...end block, or loop statement, etc...

  The block highlighting will also take into account the changes made in your source code, and will recompute automatically the current block when needed.

  This capability is currently implemented for Ada, C and C++ languages.

Block folding

  When enabled, the editor will display - icons on the left side, corresponding to the beginning of subprograms. If you click on one of these icons, all the lines corresponding to this subprogram are hidden, except the first one. As for the block highlighting, these icons are recomputed automatically when you modify your sources and are always kept up to date.

  This capability is currently implemented for Ada, C and C++ languages.

Auto save

  You can configure the editor to periodically save modified files. See Autosave delay for a full description of this capability.

Automatic highlighting of entities

  When the cursor is positioned on an entity in the source editor, GPS will highlight all references to this entity in the current editor.

  When the cursor moves away from the entity, the highlighting is removed.

  This is controlled by the plugin auto_highlight_occurrences.py: it can be deactivated by deactivating the plugin (The Plug-ins Editor).

  Details such as presence of indications in the Speed Column or highlighting color can be customized in the Plugins section of The Preferences Dialog.

GPS also integrates with existing third party editors such as Emacs or vi. Using an External Editor.

## 5.2. Editing Sources

### 5.2.1. Key bindings

In addition to the standard keys used to navigate in the editor (up, down, right, left, page up, page down), the integrated editor provides a number of key bindings allowing easy navigation in the file.

There are also several ways to define new key bindings, see Defining text aliases and Binding actions to keys.

Ctrl-Shift-u

  Pressing these three keys and then holding Ctrl-Shift allow you to enter characters using their hexadecimal value. For example, pressing `Ctrl-Shift-u-2-0` will insert a space character (ASCII 32, which is 20 in hexadecimal).

Ctrl-x / Shift-delete
  Cut to clipboard
Ctrl-c / Ctrl-insert
  Copy to clipboard
Ctrl-v / Shift-insert
  Paste from clipboard
Ctrl-s
  Save file to disk
Ctrl-z
  Undo previous insertion/deletion
Ctrl-r
  Redo previous insertion/deletion
Insert
  Toggle overwrite mode
Ctrl-a
  Select the whole file
Home / Ctrl-Pgup
  Go to the beginning of the line
End / Ctrl-Pgdown
  Go to the end of the line
Ctrl-Home
  Go to the beginning of the file
Ctrl-End
  Go to the end of the file
Ctrl-up
  Go to the beginning of the line, or to the previous line if already at the beginning of the line.
Ctrl-down
  Go to the end of the line, or to the beginning of the next line if already at the end of the line.
Ctrl-delete
  Delete end of the current word.
Ctrl-backspace
  Delete beginning of the current word.

## 5.3. The File Selector

The file selector is a dialog used to select a file. Under Windows, the default is to use the standard file selection widget. Under other platforms, the file selector is a built-in dialog:

This dialog provides the following areas and capabilities:

- A tool bar on the top composed of five buttons giving access to common navigation features:
- `left arrow` go back in the list of directories visited
- `right arrow` go forward
- `up arrow` go to parent directory
- `refresh` refresh the contents of the directory
- `home` go to home directory (value of the HOME environment variable, or / if not defined)
- A list with the current directory and the last directories explored. You can modify the current directory by modifying the text entry and hitting `Enter`, or by clicking on the right arrow and choose a previous directory in the pop down list displayed.
- A directory tree. You can open or close directories by clicking on the + and - icons on the left of the directories, or navigate using the keyboard keys: `up` and `down` to select the previous or the next directory, `+` and `-` to expand and collapse the current directory, and `backspace` to select the parent directory.
- A file list. This area lists the files contained in the selected directory. If a filter is selected in the filter area, only the relevant files for the given filter are displayed. Depending on the context, the list of files may include additional information about the files, e.g. the kind of a file, its size, etc...
- A filter area. Depending on the context, one or several filters are available to select only a subset of files to display. The filter All files which is always available will display all files in the directory selected.
- A file name area. This area will display the name of the current file selected, if any. You can also type a file or directory name directly, and complete the name automatically by using the `Tab` key.
- A button bar with the OK and Cancel buttons. When you have selected the right file, clock on OK to confirm, or click on Cancel at any time to cancel and close the file selection.

## 5.4. Menu Items

The main menus that give access to extended functionalities related to source editing are described in this section.

### 5.4.1. The File Menu

New

  Open a new untitled source editor. No syntax highlighting is performed until the file is saved, since GPS needs to know the file name in order to choose the programming language associated with a file.

  When you save a new file for the first time, GPS will ask you to enter the name of the file. In case you have started typing Ada code, GPS will try to guess based on the first main entity in the editor and on the current naming scheme, what should be the default name of this new file.

New View

  Create a new view of the current editor. The new view shares the same contents: if you modify one of the source views, the other view is updated at the same time. This is particularly useful when you want to display two separate parts of the same file, for example a function spec and its body.

  A new view can also be created by keeping the `shift` key pressed while drag-and-dropping the editor (see Moving Windows). This second method is preferred, since you can then specify directly where you want to put the new view. The default when using the menu is that the new view is put on top of the editor itself.

Open...

  Open a file selection dialog where you can select a file to edit. Under Windows, this is the standard file selector. Under other platforms, this is a built-in file selector described in The File Selector.

Open From Project...

  Open a dialog where you can easily and rapidly select a source file from your project.

  The first text area allows you to type a file name. You can start the beginning of a file name, and use the `Tab` key to complete the file name. If there are several possible completions, the common prefix will be displayed, and a list of all possible completions will be displayed in the second text area.

  You can then either complete the name by typing it, or continue hitting the `Tab` key to cycle through the possible completions, or click on one of the completions in the list displayed.

  If you press the down arrow key, the focus will move to the list of completions, so that you can select a file from this list without using the mouse.

  Once you have made your choice, click on the OK button to validate. Clicking on Cancel or hitting the `Esc` key will cancel the operation and close the dialog.

  This dialog will only show each file once. If you have extended projects in your hierarchy, some files may be redefined in some extending project. In this case, only the files from the extending project are shown, and you cannot have access through this dialog to the overridden files of the extended project. Of course, you can still use the project view or the standard File->Open menu to open these files.

Open From Host...

  Open a file selector dialog where you can specify a remote host, as defined in The remote configuration dialog. You have access to a remote host file system, can specify a file which can be edited in GPS. When you hit the save button or menu, the file will be saved on the remote host.

  See also Using GPS for Remote Development for a more efficient way to work locally on remote files.

Recent

  Open a sub menu containing a list of the ten most recent files opened in GPS, so that you can reopen them easily.

Save

  Save the current source editor if needed.

Save As...

  Same current file under a different name, using the file selector dialog. The File Selector.

Save More

  Give access to extra save capabilities.

All

  Save all items, including projects, etc...

Desktop

  Save the desktop to a file. The desktop includes information about files, graphs, ... and their window size and position in GPS. The desktop is saved per top level project, so that if you reload the same project you get back to the same situation you were in when you left GPS. Instead, if you load a different project another desktop will be loaded (or the default desktop). Through the preference “Save Desktop On Exit”, you can also automatically save this desktop when you quit GPS.

Change Directory...

  Open a directory selection dialog that lets you change the current working directory.

Messages

  This sub menu gives access to functionalities related to the Messages window. The Messages Window.

Clear

  Clear the contents of the Messages window.

Save As...

  Save the contents of the Messages window to a file. A file selector is displayed to choose the name and location of the file.

Load Contents...

  Open a file selector to load the contents of a file in the Messages window. Source locations are identified and loaded in The Locations View.

Export Locations to Editor

  List the contents of the Locations view in a standard text editor.

Close

  Close the current window. This applies to all GPS windows, not only source editors.

Print

  Print the current window contents, optionally saving it interactively if it has been modified. The Print Command specified in the preferences is used if it is defined. On Unix this command is required; on Windows it is optional.

  On Windows, if no command is specified in the preferences the standard Windows print dialog box is displayed. This dialog box allows the user to specify the target printer, the properties of the printer, which pages to print (all, or a specific range of pages), the number of copies to print, and, when more than one copy is specified, whether the pages should be collated. Pressing the Cancel button on the dialog box returns to GPS without printing the window contents; otherwise the specified pages and copies are printed on the selected printer. Each page is printed with a header containing the name of the file (if the window has ever been saved). The page number is printed on the bottom of each page.

  See also:ref:Print Command <Print_Command>.

Exit

  Exit GPS after confirmation and if needed, confirmation about saving modified windows and editors.

### 5.4.2. The Edit Menu

Undo

  Undo previous insertion/deletion in the current editor.

Redo

  Redo previous insertion/deletion in the current editor.

Cut

  Cut the current selection and store it in the clipboard.

Copy

  Copy the current selection to the clipboard.

Paste

  Paste the contents of the clipboard to the current cursor position.

Paste Previous

  GPS stores a list of all the text that was previously copied into the clipboard through the use of Copy or Cut.

  By default, if you press Paste, the newest text will be copied at the current position. But if you select Paste Previous immediately after (one or more times) you can instead paste text that was copied previously in the clipboard.

  For instance, if you copy through Edit->Copy the text “First”, then copy the text “Second”, you can then select Edit->Paste to insert “Second” at the current location. If you then select Edit->Paste Previous, “Second” will be replaced by “First”.

  Selecting this menu several times will replace the text previously pasted by the previous one in the list saved in the clipboard. When reaching the end of this list, GPS will started from the beginning, and insert again the last text copied into the clipboard.

  The size of this list is controlled by the Clipboard Size preference.

  For more information, The Clipboard View.

Select All

  Select the whole contents of the current source editor.

Rectangles...
  See the section Rectangles for more information on rectangles.
Insert File...
  Open a file selection dialog and insert the contents of this file in the current source editor, at the current cursor location.
Insert Shell Output...
  Open an input window at the bottom of the GPS window where you can specify any external command. The output of the command will be inserted at the current editor location in case of success. If text is selected, the text is passed to the external command and replaced by the command’s output.
Format Selection

  Indent and format the selection or the current line. The Preferences Dialog, for preferences related to source formatting.

Smart Completion

> Complete the identifier prefix under the cursor, and list the results in a pop-up list. Used with Ada sources this command can take advantage of an entity database as well as Ada parsers embedded in GPS which analyze the context, and offer completions from the entire project along with documentation extracted from comments surrounding declarations. To take full advantage of this feature, the smart completion preference must be enabled, which will imply the computation of the entity database at GPS startup.

> The support for C and C++ is not as powerful as the support for Ada since it relies completely on the xref information files generated by the compiler, does not have into account the C/C++ context around the cursor, and does not extract documentation from comments around candidate declarations. To take advantage of this feature, in addition to enable the smart completion preference, the C/C++ application must be built with -fdump-xref.

> In order to use this feature, open any Ada, C or C++ file, and begin to type an identifier. It has to be an identifier declared either in the current file (and accessible from the cursor location) or in one of the packages of the project loaded. Move the cursor right after the last character of the incomplete identifier and hit the completion key (which is `ctrl+space` by default). GPS will open a popup displaying all the known identifiers beginning with the prefix you typed. You can then browse among the various proposals by clicking on the `up` and `down` keys, or using the left scrollbar. For each entity, a documentation box is filled. If the location of the entity is known, it’s displayed as an hyperlink, and you can jump directly to its declaration by clicking on it.

> Typing new letters will reduce the range of proposal, as long as there remain solutions. Once you’ve selected the expected completion, you can validate by pressing `Enter`.

> Typing control characters (ie, characters which cannot be used in identifiers) will also validate the current selection.

> GPS is also able to complete automatically subprogram parameter or dotted notations. For example, if you type:

>     with Ada.

> the smart completion window will appear automatically, listing all the child and nested packages of Ada. You can configure the time interval after which the completion window appears (The Preferences Dialog).

> You can also write the beginning of the package, e.g.:

>     with Ada.Text

> pressing the completion key will offer you Text_IO.

> If you are in a code section, you will be able to complete the fields of a record, or the contents of a package, e.g.:

>      declare
>        type R is record
>           Field1 : Integer;
>           Field2 : Integer;
>        end record;

>        V : R;
>     begin
>        V.

> Completing V. will propose Field1 and Field2.

> The smart completion can also give you the possible parameters of a call you’re currently making. For example, in the following code:

>        procedure Proc (A, B, C : Integer);
>     begin
>        Proc (1,

> If you hit the completion key after the comma, the smart completion engine will propose you to complete with the named parameters “B =>”, “C =>” or directly to complete with all the remaining parameters, which in this case will be “B =>, C => )”.

> Limitations:

- This feature is currently only available for Ada, C and C++. Using the smart completion on sources of other languages behaves as the identifier completion does.

- Smart completion for C and C++ is based on the xref information generated by the compiler. Therefore, GPS has no knowledge on recently edited files. Use Build->Recompute Xref Info or rebuild with -fdump-xref to update the completion database.

- Smart completion for C and C++ is only triggered at the beginning of an expression (that is, it is not triggered on special characters such as ‘(‘, ‘->’, or the C++ operator ‘::’) and it may propose too much candidates since it does not have into account the C/C++ syntax context. Typing new letters will reduce the range of proposal, as long as there remain solutions.

- Smart completion of subprogram parameters, fields and dotted notation are not available yet for C and C++.

- More Completion .. index:: completion

  This submenu contains more ways to automatically complete code

  - Expand Alias Consider the current word as an alias and expand according to aliases defined in Defining text aliases.

  - Complete Identifier

    Complete the identifier prefix under the cursor. This command will cycle through all identifiers starting with the given prefix.

  - Complete Block .. index:: complete block

    Close the current statement (if, case, loop) or unit (procedure, function, package). This action works only on an Ada buffer.

Selection
  Comment Lines

    Comment the current selection or line based on the current programming language syntax.

  Uncomment Lines

    Remove the comment delimiters from the current selection or line.

  Refill

    Refill text on the selection or current line: rearrange line breaks in the paragraph so that line lengths do not exceed the maximum length, as set in the “Right margin” preference (The Preferences Dialog).

  Sort
    Sort the selected lines alphabetically. This is particularly useful when editing non source code, or for specific parts of the code, like with clauses in Ada.
  Sort Reverse
    Sort the selected lines in reverse alphabetical order
  Pipe in external program...
    Open an input window at the bottom of the GPS window where you can specify any external command, which will take the current selection as input. The output of the command will replace the contents of the selection on success.
  Serialize

    Increment a set of numbers found on adjacent lines. The exact behavior depends on whether there is a current selection or not.

    If there is no selection, then the set of lines considered is from the current line on and includes all adjacent lines that have at least one digit in the original columns. In the following example, ‘|’ marks the place where the cursor is at the beginning:

        AAA |10 AAA
        CCC 34567 CCC
        DDD DDD

    then only the first two lines will be modified, and will become:

        AAA 10 AAA
        CCC 11 CCC
        DDD DDD

    If there is a selection, all the lines in the selection are modified. For each line, the columns that had digits in the first line are modified, no matter what they actually contain. In the example above, if you select all three lines, the replacement becomes:

        AAA 10 AAA
        CCC 11567 CCC
        DDD 12D

    ie only the fifth and sixth columns are modified since only those columns contained digits in the first line. This feature assumes that you are selecting a relevant set of lines. But it allows you to transform blank lines more easily. For instance, if you have:

        AAA 1
        BBB
        CCC

    this is transformed into:

        AAA 1
        BBB 2
        CCC 3

  Untabify
    Replace all tabs in the current selection (or in the whole buffer if there is no selection) by the appropriate number of spaces
  Move Right and Move Left
    Shift the currently selected lines (or the current line if there is no selection) one character to the right or to the left
Fold all blocks

  Collapse all the blocks in the current file.

Unfold all blocks

  Uncollapse all the blocks in the current file.

Create Bookmark
  Creates a new Bookmark at cursor position. For more information, Bookmarks.
Pretty Print

  Pretty print the current source editor by calling the external tool gnatpp. It is possible to specify gnatpp switches in the switch editor. The Switches Editor.

Generate Body

  Generate Ada body stub for the current source editor by calling the external tool gnatstub.

Edit with external editor
  Using an External Editor.
Aliases

  Display the Aliases editor. Defining text aliases.

Key shortcuts

  Give access to the key manager dialog, to associate commands with special keys. The Key Manager Dialog.

Preferences

  Give access to the preferences dialog. The Preferences Dialog.

## 5.5. Rectangles

Rectangle commands operate on a rectangular area of the text, that is all the characters between two columns in a certain range of lines.

A rectangle is selected using the standard selection mechanism. You can therefore use either the mouse to highlight the proper region, or `shift` and the cursor keys to extend the selection, or the Emacs selection (with the mark and the current cursor location) if you have activated the `emacs.py` plugin.

Visually, a selected rectangle is exactly the same as the standard selection. In particular, the characters after the last column, on each line, will also be highlighted. The way the selection is interpreted (either as a full text or as a rectangle) depends on the command you then chose to manipulate the selection.

If you chose one of the commands from the /Edit/Rectangles menu, the actual rectangle will extend from the top-left corner down to the bottom-right corner. All characters to the right of the right-most column, although they are highlighted, are not part of the rectangle.

Consider for instance the following initial text:

    package A is
       procedure P;

       procedure Q;
    end A;

and assume we have selected from the character “p” in “procedure P”, down to the character “c” in “procedure Q”.

The following commands can then be used (either from the menu, or you can assign key shortcuts to them via the usual /Edit/Key shortcuts menu.

- Cut or Delete These commands will remove the selected text (and have no effect on empty lines within the rectangle). The former will in addition copy the rectangle to the clipboard, so that you can paste it later. In our example, we end up with:

      package A is
         edure P;

         edure Q;
      end A;

- Copy This command has no visual effect, but copies the contents of the rectangle into the clipboard.

- Paste Pastes the contents of the clipboard as a rectangle: each line from the clipboard is treated independently, and inserted on successive lines in the current editor. They all start in the same column (the one where the cursor is initially in), and existing text in the editor lines is shifted to the right). If for instance you now place the cursor in the second line, first column, and paste, we end up with:

      package A is
      proc   edure P;

      proc   edure Q;
      end A;

- Clear Replaces the contents of the selected rectangle with spaces. If we start from our initial exmaple, we end up with the following. Note the difference with Delete:

      package A is
             edure P;

             edure Q;
      end A;

- Open Replaces the contents of the selected rectangle with spaces, but shifts the lines to the right to do so. Note the difference with Clear:

      package A is
             procedure P;

             procedure Q;
      end A;

- Replace With Text This is similar to Clear, but the rectangle is replaced with user-defined text. The lines will be shifted left or right if the text you insert is shorter (resp. longer) than the width of the rectangle. If for instance we replace our initial rectangle with the text TMP, we end up with the following. Note that the character “c” has disappeared, since TMP is shorter than our rectangle width (4 characters). This command will impact lines that are empty in the initial rectangle:

      package A is
         TMPedure P;
         TMP
         TMPedure Q;
      end A;

- Insert Text This inserts a text to the left of the rectangle on each line. The following example inserts TMP. Note the difference with Replace With Text. This command will also insert the text on lines that are empty in the initial rectangle:

      package A is
         TMPprocedure P;
         TMP
         TMPprocedure Q;
      end A;

- Sort This sorts the selected lines according to the key which starts and ends on the corresponding rectangle’s columns:

      aaa 15 aa
      bbb 02 bb
      ccc 09 cc

  With a selection starting from the 1 on the first line and ending on the 9 on the last one, sorting will result with the following content:

      bbb 02 bb
      ccc 09 cc
      aaa 15 aa

- Sort reverse

  As above but in the reverse order.

## 5.6. Recording and replaying macros

It is often convenient to be able to repeat a given key sequence a number of times.

GPS supports this with several different methods:

- Repeat the next action

  If there is a single key press that you wish to repeat a number of times, you should first use the GPS action “Repeat Next” (bound by default to `control-u`, but this can be changed as usual through the /Edit/Key Shortcuts menu), then entering the number of times you wish to repeat, and finally pressing the key you want.

  For instance, the following sequence `control-u 79 -` will insert 79 characters ‘-‘ in the current editor. This proves often useful to insert separators.

  If you are using the emacs mode (see /Tools/Plug-ins menu), you can also use the sequence `control-u 30 control-k` to delete 30 lines.

- Recording macros

  If you wish to repeat a sequence of more than 1 key, you should record this sequence as a macro. All macro-related menus are found in /Tools/Macros, although it is often more convenient to use these through key bindings, which you can of course override.

  You must indicate to GPS that it should start recording the keys you are pressing. This is done through the /Tools/Macros/Start Keyboard Macro menu. As its name indicates, this only records keyboard events, not mouse events. Until you select /Tools/Macros/Stop Macro, GPS will keep recording the events.

  In Emacs mode, the macro actions are bound to `control-x (`, `control-x )` and `control-x e` key shortcuts. For instance, you can execute the following to create a very simple macro that deletes the current line, wherever your cursor initially is on that line:

  - `control-x (` start recording
  - `control-a` go to beginning of line
  - `control-k` delete line
  - `control-x )` stop recording

## 5.7. Contextual Menus for Editing Files

Whenever you ask for a contextual menu (using e.g. the third button on your mouse) on a source file, you will get access to a number of entries, displayed or not depending on the current context.

Menu entries include the following categories:

Source Navigation
  Contextual Menus for Source Navigation.
Dependencies
  Dependency Browser.
Entity browsing
  Entity Browser.
Project view
  The Project View.
Version control
  The Version Control Contextual Menu.
Debugger
  Using the Source Editor when Debugging.
Case exceptions
  Handling of case exceptions.
Refactoring
  Refactoring.

In addition, an entry Properties... is always visible in this contextual menu. When you select it, a dialog pops up that allows you to override the language used for the file, or the character set.

This can be used for instance if you want to open a file that does not belong to the current project, but where you want to benefit from the syntax highlighting that GPS knows how to.

It is not recommended to override the language for source files that belong to the project. Instead, you should use the Project Properties dialog and change the naming scheme if appropriate. This will ensure better consistency between GPS and the compiler in the way they manipulate the file.

## 5.8. Handling of case exceptions

GPS keeps a set of case exceptions that is used by all case insensitive languages. When editing or reformatting a buffer for such a language the case exception dictionary will be checked first. If an exception is found for this word or a substring of the word, it will be used; otherwise the specified casing for keywords or identifiers is used. A substring is defined as a part of the word separated by underscores.

Note that this feature is not activated for entities (keywords or identifiers) for which the casing is set to Unchanged. See The Preferences Dialog.

A contextual menu named Casing has the following entries:

Lower *entity*
  Set the selected entity in lower case.
Upper *entity*
  Set the selected entity in upper case.
Mixed *entity*
  Set the selected entity in mixed case (set the first letter and letters before an underscore in upper case, all other letters are set to lower case).
Smart Mixed *entity*
  Set the selected entity in smart mixed case. Idem as above except that upper case letters are kept unchanged.
Add exception for *entity*
  Add the current entity into the case exception dictionary.
Remove exception for *entity*
  Remove the current entity from the case exception dictionary.

To add or remove a substring exception into/from the dictionary you need to first select the substring on the editor. In this case the last two contextual menu entries will be:

Add substring exception for *str*
  Add the selected substring into the case substring exception dictionary.
Remove substring exception for *str*
  Remove the selected substring from the case substring exception dictionary.

## 5.9. Refactoring

GPS includes basic facilities for refactoring your code. Refactoring is the standard term used to describe manipulation of the source code that do not affect the behavior of the application, but help reorganize the source code to make it more readable, more extendable, ...

Refactoring technics are generally things that programmers are used to do by hand, but which are faster and more secure to do automatically through a tool.

One of the basic recommendations when you refactor your code is to recompile and test your application very regularly, to make sure that each of the small modifications you made to it didn’t break the behavior of your application. This is particularly true with GPS, since it relies on the cross-references information that is generated by the compiler. If some of the source files have not been recompiled recently, GPS will print warning messages indicating that the renaming operation might be dangerous and/or only partial.

One of the reference books that was used in the choice of refactoring methods to implement is “Refactoring”, by Martin Fowler (Addison Wesley).

### 5.9.1. Rename Entity

Clicking on an entity in a source file and selecting the Refactoring/Rename menu will open a dialog asking for the new name of the entity. GPS will rename all instances of the entity in your application. This includes the definition of the entity, its body, all calls to it, etc... Of course, no comment is updated, and you should probably check manually that the comment for the entity still applies.

GPS will handle primitive operations by also renaming the operations it overrides or that overrides it. This means that any dispatching call to that operation will also be renamed, and the application should still work as before. If you are renaming a parameter to a subprogram, GPS can also rename parameters with similar names in overriding or overridden subprograms.

The behavior when handling read-only files can be specified: by default, GPS will not do any refactoring in these files, and will display a dialog listing all of them; but you can also choose to make them writable just as if you had clicked on the “Read-Only” button in the status bar of the editor and then have GPS perform the renaming in them as well.

### 5.9.2. Name Parameters

If you are editing Ada code and click on a call to a subprogram, GPS will display a contextual menu Refactoring/Name parameters, which will replace all unnamed parameters by named parameters, as in:

       Call (1, 2)
    =>
       Call (Param1 => 1, Param2 => 2);

### 5.9.3. Extract Subprogram

This refactoring is used to move some code from one place to a separate subprogram. The goal is to simplify the original subprogram, by moving part of its code elsewhere.

Here is an example from the “Refactoring” book. The refactoring will take place in the body of the package `pkg.adb`, but the spec is needed so that you can compile the source code (a preliminary step mandatory before you can refactor the code):

    pragma Ada_05;

    with Ada.Containers.Indefinite_Doubly_Linked_Lists;
    with Ada.Strings.Unbounded;

    package Pkg is

       type Order is tagged null record;
       function Get_Amount (Self : Order) return Integer;

       package Order_Listsis new
          Ada.Containers.Indefinite_Doubly_Linked_Lists (Order);

       type Invoice is tagged record
          Orders : Order_Lists.List;
          Name   : Ada.Strings.Unbounded.Unbounded_String;
       end record;

       procedure Print_Owing (Self : Invoice);

    end Pkg;

The initial implementation for this code is given by the following code:

    pragma Ada_05;
    with Ada.Strings.Unbounded;  use Ada.Strings.Unbounded;
    with Ada.Text_IO;            use Ada.Text_IO;

    package body Pkg is
       use Order_Lists;

       ----------------
       -- Get_Amount --
       ----------------

       function Get_Amount (Self : Order) return Integer is
       begin
          return 0;
       end Get_Amount;

       -----------------
       -- Print_Owing --
       -----------------

       procedure Print_Owing (Self : Invoice) is
          E : Order_Lists.Cursor := First (Self.Orders);
          Outstanding : Natural := 0;
          Each : Order;
       begin
          --  <<< line 30
          --  Print Banner

          Put_Line ("");
          Put_Line (" Customer Owes         ");
          Put_Line ("");  --  << line 35

          --  Calculate Outstanding

          while Has_Element (E) loop
             Each := Element (E);
             Outstanding := Outstanding + Each.Get_Amount;
             Next (E);
          end loop;

          --  Print Details

          Put_Line ("Name: " & To_String (Self.Name));
          Put_Line ("Outstanding:" & Outstanding'Img);
       end Print_Owing;
    end Pkg;

The procedure Print_Owing is too long and does several independent actions. We will perform a series of three successive refactoring steps to extract the code and move it elsewhere.

The first is the code that prints the banner. Moving it is easy, since this code does not depend on any context. We could just do a copy-paste, but then we would have to create the new subprogram. Instead, we select lines 30 to 35, and then select the contextual menu Refactoring/Extract Subprogram. GPS will then automatically change Print_Owing and create a new procedure Print_Banner (the name is specified by the user, GPS does not try to guess it). Also, since the chunk of code that is extracted starts with a comment, GPS automatically uses that comment as the documentation for the new subprogram. Here is part of the resulting file:

    package body Pkg is

       procedure Print_Banner;
       --  Print Banner

       ------------------
       -- Print_Banner --
       ------------------

       procedure Print_Banner is
       begin
          Put_Line ("");
          Put_Line (" Customer Owes         ");
          Put_Line ("");
       end Print_Banner;

       ... (code not shown)

       procedure Print_Owing (Self : Invoice) is
          E : Order_Lists.Cursor := First (Self.Orders);
          Outstanding : Natural := 0;
          Each : Order;
       begin
          Print_Banner;

          --  Calculate Outstanding

          while Has_Element (E) loop
             Each := Element (E);
             Outstanding := Outstanding + Each.Get_Amount;
             Next (E);
          end loop;

          --  Print Details   <<< line  54

          Put_Line ("Name: " & To_String (Self.Name));
          Put_Line ("Outstanding:" & Outstanding'Img);  --  line 57
       end Print_Owing;
    end Pkg;

A more interesting example is when we want to extract the code to print the details of the invoice. This code depends on one local variable and the parameter to Print_Owing. When we select lines 54 to 57 and extract it into a new Print_Details subprogram, we get the following result. GPS automatically decides which variables to extract, and whether they should become parameters of the new subprogram, or local variables. In the former case, it will also automatically decide whether to create “in”, “out” or “in out” parameters. If there is a single “out” parameter, it will automatically create a function rather than a procedure.

GPS will use, for the parameters, the same name that was used for the local variable. Very often, it will make sense to recompile the new version of the source, and then apply the Rename Entity refactoring to have more specific names for the parameters, or the Name Parameters refactoring so that the call to the new method uses named parameters to further clarify the code:

    ... code not shown

    procedure Print_Details
      (Self : Invoice'Class;
       Outstanding : Natural);
    --  Print Details

    -------------------
    -- Print_Details --
    -------------------

    procedure Print_Details
      (Self : Invoice'Class;
       Outstanding : Natural)
    is
    begin
       Put_Line ("Name: " & To_String (Self.Name));
       Put_Line ("Outstanding:" & Outstanding'Img);
    end Print_Details;

    procedure Print_Owing (Self : Invoice) is
       E : Order_Lists.Cursor := First (Self.Orders);
       Outstanding : Natural := 0;
       Each : Order;
    begin
       Print_Banner;

       --  Calculate Outstanding

       while Has_Element (E) loop
          Each := Element (E);
          Outstanding := Outstanding + Each.Get_Amount;
          Next (E);
       end loop;

       Print_Details (Self, Outstanding);
    end Print_Owing;

Finally, we want to extract the code that computes the outstanding amount. When this code is moved, the variables E and Each become useless in Print_Owing and are moved into the new subprogram (which we will call Get_Outstanding. Here is the result of that last refactoring (the initial selection should include the blank lines before and after the code, to keep the resulting Print_Owing simpler). GPS will automatically ignore those blank lines:

    ... code not shown

    procedure Get_Outstanding (Outstanding : in out Natural);
    --  Calculate Outstanding

    ---------------------
    -- Get_Outstanding --
    ---------------------

    procedure Get_Outstanding (Outstanding : in out Natural) is
       E : Order_Lists.Cursor := First (Self.Orders);
       Each : Order;
    begin
       while Has_Element (E) loop
          Each := Element (E);
          Outstanding := Outstanding + Each.Get_Amount;
          Next (E);
       end loop;
    end Get_Outstanding;

    procedure Print_Owing (Self : Invoice) is
       Outstanding : Natural := 0;
    begin
       Print_Banner;
       Get_Outstanding (Outstanding);
       Print_Details (Self, Outstanding);
    end Print_Owing;

Note that the final version of Print_Owing is not perfect. For instance, passing the initial value 0 to Get_Outstanding is useless, and in fact that should probably be a function with no parameter. But GPS already saves a lot of time and manipulation.

Finally, a word of caution: this refactoring does not check that you are giving a valid input. For instance, if the text you select includes a declare block, you should always include the full block, not just a part of it (or select text between begin and end). Likewise, GPS does not expect you to select any part of the variable declarations, just the code.

## 5.10. Using an External Editor

GPS is integrated with a number of external editors, in particular Emacs and vi. The choice of the default external editor is done in the preferences. The Preferences Dialog.

The following values are recognized:

gnuclient

  This is the recommended client. It is based on Emacs, but needs an extra package to be installed. This is the only client that provides a full integration in GPS, since any extended lisp command can be sent to the Emacs server.

  By default, gnuclient will open a new Emacs frame for every file that is opened. You might want to add the following code to your `.emacs` file (create one if needed) so that the same Emacs frame is reused every time:

      (setq gnuserv-frame (car (frame-list)))

  See http://www.hpl.hp.com/personal/ange/gnuserv/home.html for more information.

emacsclient

  This is a program that is always available if you have installed Emacs. As opposed to starting a new Emacs every time, it will reuse an existing Emacs session. It is then extremely fast to open a file.

emacs

  This client will start a new Emacs session every time a file needs to be opened. You should use emacsclient instead, since it is much faster, and makes it easier to copy and paste between multiple files. Basically, the only reason to use this external editor is if your system doesn’t support emacsclient.

vim

  Vim is a vi-like editor that provides a number of enhancements, for instance syntax highlighting for all the languages supported by GPS. Selecting this external editor will start an xterm (or command window, depending on your system) with a running vim process editing the file.

  Note that one limitation of this editor is that if GPS needs to open the same file a second time, it will open a new editor, instead of reusing the existing one.

  To enable this capability, the xterm executable must be found in the PATH, and thus is not supported on Windows systems. Under Windows systems, you can use the custom editor instead.

vi

  This editor works exactly like vim, but uses the standard vi command instead of vim.

custom

  You can specify any external editor by choosing this item. The full command line used to call the editor can be specified in the preferences (see Custom Editor Command).

none
  No external editor is used, and the contextual menus simply won’t appear.

In the cases that require an Emacs server, GPS will try several solutions if no already running server was found. It will first try to spawn the glide environment distributed with GNAT. If not found in the PATH, it will then start a standard Emacs. The project file currently used in GPS will be set appropriately the first time Emacs is spawned. This means that if you load a new project in GPS, or modify the paths of the current project, you should kill any running Emacs, so that a new one is spawned by GPS with the appropriate project.

Alternatively, you can reload explicitly the project from Emacs itself by using the menu Project->Load

In the preferences, there are three settings that allow you to select the external editor (if left to an empty string, GPS will automatically select the first editor available on your system), to specify the custom editor command, in case you’ve selector this item, and whether this editor should always be used every time you double-click on a file, or whether you need to explicitly select the contextual menu to open the external editor.

## 5.11. Using the Clipboard

This section concerns X-Window users who are used to cutting and pasting with the middle mouse button. In the GPS text editor, as in many recent X applications, the GPS clipboard is set by explicit cut/copy/paste actions, either through menu items or keyboard shortcuts, and the primary clipboard (i.e. the ‘middle button’ clipboard) is set by the current selection.

Therefore, copy/paste between GPS and other X applications using the primary clipboard will still work, provided that there is some text currently selected. The GPS clipboard, when set, will override the primary clipboard.

By default, GPS overrides the X mechanism. To prevent this, add the following line: OVERRIDE_MIDDLE_CLICK_PASTE = no to your traces.cfg file. Note, however, that the X mechanism pastes all attributes of text, including coloring and editability, which can be confusing.

See http://standards.freedesktop.org/clipboards-spec/clipboards-latest.txt for more information.

## 5.12. Saving Files

After you have finished modifying your files, you need to save them. The basic method to do that is to select the menu File->Save, which saves the currently selected file.

You can also use the menu File->Save As... if you want to save the file with another name, or in another directory.

If you have multiple files to save, another possibility is to use the menu File->Save More->All. This will open a dialog listing all the currently modified editors that need saving. You can then select individually which one should be saved, and click on Save to do the actual saving.

When calling external commands, such as compiling a file, if the Auto save preference is disabled, this same dialog is also used, to make sure that e.g. the compiler will take into account your local changes. If the preference is enabled, the saving is performed automatically.

You can conveniently select or unselect all the files at once by clicking on the title of the first column (labeled Select). This will toggle the selection status of the first line, and have the same status for all other editors.

If you press Cancel instead of Save, no saving will take place, and the action that displayed this dialog is also canceled. Such actions can be for instance starting a compilation command, a VCS operation, or quitting GPS with unsaved files.

## 5.13. Remote Files

GPS has a basic support for working with files on remote hosts. This includes a number of protocols, described below, which allow you to read a file from a remote host, edit it locally, and then save it transparently to the remote machine.

For now, the support for remote files is only available through the GPS shell window. You start editing a remote file by typing a line similar to:

    Editor.edit protocol://user@machine/full/path

where “protocol” should be replaced by the name of the protocol you want to use, “user” is the login name you wish to use on the remote “machine”, and “/full/path” is the full path on the remote machine to access the file.

The user name is optional. If it is the same as on the local machine, you can omit the user name as well as the “@” sign.

Likewise, the machine name is optional, if you want to get a file from the local host. This can be used to access files belonging to another user. In this case, you need to specify the “@” sign, but do not insert a machine name right after it.

Remote files can also be used if you want to work with GPS, but the machine on which the files are found isn’t supported by GPS.

The following protocols are supported:

ssh

  This protocol is based on the ssh command line tool, which must therefore be available in the path. It provides encrypted and secure connections to the remote host. Files are transfered in-line, that is the connection is established the first time you access the remote host, and kept open for all further access.

  Although ssh can be setup not to require a password, GPS will automatically detect if a password is asked and open a dialog to query it.

  The remote system must be a Unix-like system with support for standard Unix commands like test, echo, rm and ls.

  In the sample shell command above, you would replace the word “protocol” with “ssh” to use this protocol.

rsh

  This protocol behaves like ssh, except that the connections are not encrypted. However, this protocol is generally available on all Unix machines by default.

  It has the same requirements that the ssh protocol. To use it, substitute the word “rsh” to “protocol” in the example above.

telnet

  This protocol is based on the standard telnet protocol. It behaves much like the two protocols above, with an unencrypted connection.

  To use it, substitute the word “telnet” to “protocol” in the example above.

scp

  This protocol is also based on one of the tools of the ssh suite. It provides encrypted connections, and uses a mixture of ssh and scp connections. Various commands like querying the time stamp of a file are executed through a permanent ssh connection, whereas files are downloaded and uploaded through a one-time scp command.

  It basically has the same behavior as the ssh protocol, although it might be slightly slower since a new connection has to be established every time a file is fetched from, or written to the remote host. However, it might work better than ssh if the file contains 8 bit characters.

  To use it, substitute the word “scp” to “protocol” in the example above.

rsync

  Just like scp is based on ssh, this protocol is based on either rsh or ssh. It depends on the external tool rsync, and uses a mixture of a rsh/ssh connection for commands like querying the time stamp of a file, and one-time connections with rsync to transfer the files.

  Rsync is specially optimized to transfer only the parts of a file that are different from the one already on the remote host. Therefore, it will generally provide the best performance when writing the file back to the remote host.

  If you set up the environment variable RSYNC_RSH to ssh before starting gps, the connection will then be encrypted when transferring the files, and the connection will be performed using ssh instead of rsh.

  To use this protocol, substitute the word “rsync” to “protocol” in the example above.

ftp

  This protocol provides only limited capabilities, but can be used to retrieve or write a file back through an ftp connection, possibly even through an anonymous ftp connection.

  To use this protocol, substitute the word “ftp” to “protocol” in the example above.

http
  This is the usual http protocol to download documents from the web. It is in particular useful for documentation

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