src/Doc/JEdit/JEdit.thy

some document antiquotations for Isabelle/jEdit elements;
modernized theory setup;

(*:wrap=hard:maxLineLen=78:*)

theory JEdit
imports Base
begin

chapter {* Introduction *}

section {* Concepts and terminology *}

text {* Isabelle/jEdit is a Prover IDE that integrates \emph{parallel
  proof checking} \cite{Wenzel:2009,Wenzel:2013:ITP} with
  \emph{asynchronous user interaction}
  \cite{Wenzel:2010,Wenzel:2012:UITP-EPTCS}, based on a
  document-oriented approach to \emph{continuous proof processing}
  \cite{Wenzel:2011:CICM,Wenzel:2012}. Many concepts and system
  components are fit together in order to make this work. The main
  building blocks are as follows.

  \begin{description}

  \item [PIDE] is a general framework for Prover IDEs based on
  Isabelle/Scala. It is built around a concept of parallel and
  asynchronous document processing, which is supported natively by the
  parallel proof engine that is implemented in Isabelle/ML. The prover
  discontinues the traditional TTY-based command loop, and supports
  direct editing of formal source text with rich formal markup for GUI
  rendering.

  \item [Isabelle/ML] is the implementation and extension language of
  Isabelle, see also \cite{isabelle-implementation}. It is integrated
  into the logical context of Isabelle/Isar and allows to manipulate
  logical entities directly. Arbitrary add-on tools may be implemented
  for object-logics such as Isabelle/HOL.

  \item [Isabelle/Scala] is the system programming language of
  Isabelle. It extends the pure logical environment of Isabelle/ML
  towards the ``real world'' of graphical user interfaces, text
  editors, IDE frameworks, web services etc.  Special infrastructure
  allows to transfer algebraic datatypes and formatted text easily
  between ML and Scala, using asynchronous protocol commands.

  \item [jEdit] is a sophisticated text editor implemented in
  Java.\footnote{@{url "http://www.jedit.org"}} It is easily extensible
  by plugins written in languages that work on the JVM, e.g.\
  Scala\footnote{@{url "http://www.scala-lang.org/"}}.

  \item [Isabelle/jEdit] is the main example application of the PIDE
  framework and the default user-interface for Isabelle. It targets
  both beginners and experts. Technically, Isabelle/jEdit combines a
  slightly modified version of the jEdit code base with a special
  plugin for Isabelle, integrated as standalone application for the
  main operating system platforms: Linux, Windows, Mac OS X.

  \end{description}

  The subtle differences of Isabelle/ML versus Standard ML,
  Isabelle/Scala versus Scala, Isabelle/jEdit versus jEdit need to be
  taken into account when discussing any of these PIDE building blocks
  in public forums, mailing lists, or even scientific publications.
  *}


section {* The Isabelle/jEdit Prover IDE *}

text {*
  \begin{figure}[htb]
  \begin{center}
  \includegraphics[width=\textwidth]{isabelle-jedit}
  \end{center}
  \caption{The Isabelle/jEdit Prover IDE}
  \label{fig:isabelle-jedit}
  \end{figure}

  Isabelle/jEdit (\figref{fig:isabelle-jedit}) consists of some
  plugins for the well-known jEdit text editor
  @{url "http://www.jedit.org"}, according to the following principles.

  \begin{itemize}

  \item The original jEdit look-and-feel is generally preserved,
  although some default properties are changed to accommodate Isabelle
  (e.g.\ the text area font).

  \item Formal Isabelle/Isar text is checked asynchronously while
  editing.  The user is in full command of the editor, and the prover
  refrains from locking portions of the buffer.

  \item Prover feedback works via colors, boxes, squiggly underline,
  hyperlinks, popup windows, icons, clickable output --- all based on
  semantic markup produced by Isabelle in the background.

  \item Using the mouse together with the modifier key @{verbatim
  CONTROL} (Linux, Windows) or @{verbatim COMMAND} (Mac OS X) exposes
  additional formal content via tooltips and/or hyperlinks.

  \item Formal output (in popups etc.) may be explored recursively,
  using the same techniques as in the editor source buffer.

  \item Additional panels (e.g.\ \emph{Output}, \emph{Symbols}) are
  organized by the Dockable Window Manager of jEdit, which also allows
  multiple floating instances of each window class.

  \item The prover process and source files are managed on the editor
  side.  The prover operates on timeless and stateless document
  content as provided via Isabelle/Scala.

  \item Plugin options of jEdit (for the \emph{Isabelle} plugin) give
  access to a selection of Isabelle/Scala options and its persistent
  preferences, usually with immediate effect on the prover back-end or
  editor front-end.

  \item The logic image of the prover session may be specified within
  Isabelle/jEdit.  The new image is provided automatically by the
  Isabelle build tool after restart of the application.

  \end{itemize}
*}


subsection {* Documentation *}

text {* Regular jEdit documentation is accessible via its @{verbatim
  Help} menu or @{verbatim F1} keyboard shortcut.  This includes a
  full \emph{User's Guide} and \emph{Frequently Asked Questions} for
  this sophisticated text editor.  The same can be browsed without the
  technical restrictions of the built-in Java HTML viewer here:
  @{url "http://www.jedit.org/index.php?page=docs"} (potentially for a
  different version of jEdit).

  Most of this information about jEdit is relevant for Isabelle/jEdit
  as well, but one needs to keep in mind that defaults sometimes
  differ, and the official jEdit documentation does not know about the
  Isabelle plugin with its special support for theory editing.
*}


subsection {* Plugins *}

text {* The \emph{Plugin Manager} of jEdit allows to augment editor
  functionality by JVM modules (jars) that are provided by the central
  plugin repository, which is accessible via various mirror sites.

  Connecting to the plugin server infrastructure of the jEdit project
  allows to update bundled plugins or to add further functionality.
  This needs to be done with the usual care for such an open bazaar of
  contributions. Arbitrary combinations of add-on features are apt to
  cause problems.  It is advisable to start with the default
  configuration of Isabelle/jEdit and develop some understanding how
  it is supposed to work, before loading additional plugins at a grand
  scale.

  \medskip The main \emph{Isabelle} plugin is an integral part of
  Isabelle/jEdit and needs to remain active at all times! A few
  additional plugins are bundled with Isabelle/jEdit for convenience
  or out of necessity, notably \emph{Console} with its Isabelle/Scala
  sub-plugin and \emph{SideKick} with some Isabelle-specific parsers
  for document tree structure.  The \emph{ErrorList} plugin is
  required by \emph{SideKick}, but not used specifically in
  Isabelle/jEdit. *}


subsection {* Options *}

text {* Both jEdit and Isabelle have distinctive management of
  persistent options.

  Regular jEdit options are accessible via the dialog for
  \emph{Plugins / Plugin Options}, which is also accessible via
  \emph{Utilities / Global Options}.  Changed properties are stored in
  @{file_unchecked "$ISABELLE_HOME_USER/jedit/properties"}.  In
  contrast, Isabelle system options are managed by Isabelle/Scala and
  changed values stored in @{file_unchecked
  "$ISABELLE_HOME_USER/etc/preferences"}, independently of the jEdit
  properties.  See also \cite{isabelle-sys}, especially the coverage
  of sessions and command-line tools like @{tool build} or @{tool
  options}.

  Those Isabelle options that are declared as \textbf{public} are
  configurable in jEdit via \emph{Plugin Options / Isabelle /
  General}.  Moreover, there are various options for rendering of
  document content, which are configurable via \emph{Plugin Options /
  Isabelle / Rendering}.  Thus \emph{Plugin Options / Isabelle} in
  jEdit provides a view on a subset of Isabelle system options.  Note
  that some of these options affect general parameters that are
  relevant outside Isabelle/jEdit as well, e.g.\ @{system_option
  threads} or @{system_option parallel_proofs} for the Isabelle build
  tool \cite{isabelle-sys}.

  \medskip All options are loaded on startup and saved on shutdown of
  Isabelle/jEdit.  Editing the machine-generated @{file_unchecked
  "$ISABELLE_HOME_USER/jedit/properties"} or @{file_unchecked
  "$ISABELLE_HOME_USER/etc/preferences"} manually while the
  application is running is likely to cause surprise due to lost
  update!  *}


subsection {* Keymaps *}

text {* Keyboard shortcuts used to be managed as jEdit properties in
  the past, but recent versions (2013) have a separate concept of
  \emph{keymap} that is configurable via \emph{Global Options /
  Shortcuts}.  The @{verbatim imported} keymap is derived from the
  initial environment of properties that is available at the first
  start of the editor; afterwards the keymap file takes precedence.

  This is relevant for Isabelle/jEdit due to various fine-tuning of
  default properties, and additional keyboard shortcuts for Isabelle
  specific functionality. Users may change their keymap later, but
  need to copy Isabelle-specific key bindings manually (see also
  @{file_unchecked "$ISABELLE_HOME_USER/jedit/keymaps"}).  *}


subsection {* Look-and-feel *}

text {* jEdit is a Java/AWT/Swing application with some ambition to
  support ``native'' look-and-feel on all platforms, within the limits
  of what Oracle as Java provider and major operating system
  distributors allow (see also \secref{sec:problems}).

  Isabelle/jEdit enables platform-specific look-and-feel by default as
  follows:

  \begin{description}

  \item[Linux] The platform-independent \emph{Nimbus} is used by
  default.

  \emph{GTK+} works under the side-condition that the overall GTK
  theme is selected in a Swing-friendly way.\footnote{GTK support in
  Java/Swing was once marketed aggressively by Sun, but never quite
  finished, and is today (2013) lagging a bit behind further
  development of Swing and GTK.  The graphics rendering performance
  can be worse than for other Swing look-and-feels.}

  \item[Windows] Regular \emph{Windows} is used by default, but
  \emph{Windows Classic} also works.

  \item[Mac OS X] Regular \emph{Mac OS X} is used by default.

  Moreover the bundled \emph{MacOSX} plugin provides various functions
  that are expected from applications on that particular platform:
  quit from menu or dock, preferences menu, drag-and-drop of text
  files on the application, full-screen mode for main editor windows
  etc.

  \end{description}

  Users may experiment with different look-and-feels, but need to keep
  in mind that this extra variance of GUI functionality is unlikely to
  work in arbitrary combinations.  The platform-independent
  \emph{Nimbus} and \emph{Metal} should always work.  The historic
  \emph{CDE/Motif} is better avoided.

  After changing the look-and-feel in \emph{Global Options /
  Appearance}, it is advisable to restart Isabelle/jEdit in order to
  take full effect.  *}


chapter {* Prover IDE functionality *}

section {* File-system access *}

text {* File specifications in jEdit follow various formats and
  conventions according to \emph{Virtual File Systems}, which may be
  also provided by additional plugins.  This allows to access remote
  files via the @{verbatim "http:"} protocol prefix, for example.
  Isabelle/jEdit attempts to work with the file-system access model of
  jEdit as far as possible.  In particular, theory sources are passed
  directly from the editor to the prover, without indirection via
  files.

  Despite the flexibility of URLs in jEdit, local files are
  particularly important and are accessible without protocol prefix.
  Here the path notation is that of the Java Virtual Machine on the
  underlying platform.  On Windows the preferred form uses
  backslashes, but happens to accept Unix/POSIX forward slashes, too.
  Further differences arise due to drive letters and network shares.

  The Java notation for files needs to be distinguished from the one
  of Isabelle, which uses POSIX notation with forward slashes on
  \emph{all} platforms.\footnote{Isabelle on Windows uses Cygwin
  file-system access.}  Moreover, environment variables from the
  Isabelle process may be used freely, e.g.\ @{file
  "$ISABELLE_HOME/etc/symbols"} or @{file_unchecked "$POLYML_HOME/README"}.
  There are special shortcuts: @{file "~"} for @{file "$USER_HOME"}
  and @{file "~~"} for @{file "$ISABELLE_HOME"}.

  \medskip Since jEdit happens to support environment variables within
  file specifications as well, it is natural to use similar notation
  within the editor, e.g.\ in the file-browser.  This does not work in
  full generality, though, due to the bias of jEdit towards
  platform-specific notation and of Isabelle towards POSIX.  Moreover,
  the Isabelle settings environment is not yet active when starting
  Isabelle/jEdit via its standard application wrapper (in contrast to
  @{verbatim "isabelle jedit"} run from the command line).

  For convenience, Isabelle/jEdit imitates at least @{verbatim
  "$ISABELLE_HOME"} and @{verbatim "$ISABELLE_HOME_USER"} within the
  Java process environment, in order to allow easy access to these
  important places from the editor.

  Moreover note that path specifications in prover input or output
  usually include formal markup that turns it into a hyperlink (see
  also \secref{sec:tooltips-hyperlinks}).  This allows to open the
  corresponding file in the text editor, independently of the path
  notation.  *}


section {* Text buffers and theories \label{sec:buffers-theories} *}

text {* As regular text editor, jEdit maintains a collection of open
  \emph{text buffers} to store source files; each buffer may be
  associated with any number of visible \emph{text areas}.  Buffers
  are subject to an \emph{edit mode} that is determined from the file
  type.  Files with extension \texttt{.thy} are assigned to the mode
  \emph{isabelle} and treated specifically.

  \medskip Isabelle theory files are automatically added to the formal
  document model of Isabelle/Scala, which maintains a family of
  versions of all sources for the prover.  The \emph{Theories} panel
  provides an overview of the status of continuous checking of theory
  sources.  Unlike batch sessions \cite{isabelle-sys}, theory nodes
  are identified by full path names; this allows to work with multiple
  (disjoint) Isabelle sessions simultaneously within the same editor
  session.

  Certain events to open or update buffers with theory files cause
  Isabelle/jEdit to resolve dependencies of \emph{theory imports}.
  The system requests to load additional files into editor buffers, in
  order to be included in the theory document model for further
  checking.  It is also possible to resolve dependencies
  automatically, depending on \emph{Plugin Options / Isabelle /
  General / Auto load}.

  \medskip The open text area views on theory buffers define the
  visible \emph{perspective} of Isabelle/jEdit.  This is taken as a
  hint for document processing: the prover ensures that those parts of
  a theory where the user is looking are checked, while other parts
  that are presently not required are ignored.  The perspective is
  changed by opening or closing text area windows, or scrolling within
  an editor window.

  The \emph{Theories} panel provides some further options to influence
  the process of continuous checking: it may be switched off globally
  to restrict the prover to superficial processing of command syntax.
  It is also possible to indicate theory nodes as \emph{required} for
  continuous checking: this means such nodes and all their imports are
  always processed independently of the visibility status (if
  continuous checking is enabled).  Big theory libraries that are
  marked as required can have significant impact on performance,
  though.

  \medskip Formal markup of checked theory content is turned into GUI
  rendering, based on a standard repertoire known from IDEs for
  programming languages: colors, icons, highlighting, squiggly
  underline, tooltips, hyperlinks etc.  For outer syntax of
  Isabelle/Isar there is some traditional syntax-highlighting via
  static keyword tables and tokenization within the editor.  In
  contrast, the painting of inner syntax (term language etc.)\ uses
  semantic information that is reported dynamically from the logical
  context.  Thus the prover can provide additional markup to help the
  user to understand the meaning of formal text, and to produce more
  text with some add-on tools (e.g.\ information messages by automated
  provers or disprovers running in the background).
*}


section {* Prover output \label{sec:prover-output} *}

text {* Prover output consists of \emph{markup} and \emph{messages}.
  Both are directly attached to the corresponding positions in the
  original source text, and visualized in the text area, e.g.\ as text
  colours for free and bound variables, or as squiggly underline for
  warnings, errors etc.\ (see also \figref{fig:output}).  In the
  latter case, the corresponding messages are shown by hovering with
  the mouse over the highlighted text --- although in many situations
  the user should already get some clue by looking at the position of
  the text highlighting.

  \begin{figure}[htb]
  \begin{center}
  \includegraphics[width=\textwidth]{output}
  \end{center}
  \caption{Multiple views on prover output: gutter area with icon,
    text area with popup, overview area, Theories panel, Output panel}
  \label{fig:output}
  \end{figure}

  The ``gutter area'' on the left-hand-side of the text area uses
  icons to provide a summary of the messages within the adjacent
  line of text.  Message priorities are used to prefer errors over
  warnings, warnings over information messages etc.  Plain output is
  ignored here.

  The ``overview area'' on the right-hand-side of the text area uses
  similar information to paint small rectangles for the overall status
  of the whole text buffer.  The graphics is scaled to fit the logical
  buffer length into the given window height.  Mouse clicks on the
  overview area position the cursor approximately to the corresponding
  line of text in the buffer.  Repainting the overview in real-time
  causes problems with big theories, so it is restricted to part of
  the text according to \emph{Plugin Options / Isabelle / General /
  Text Overview Limit} (in characters).

  Another course-grained overview is provided by the \emph{Theories}
  panel, but without direct correspondence to text positions.  A
  double-click on one of the theory entries with their status overview
  opens the corresponding text buffer, without changing the cursor
  position.

  \medskip In addition, the \emph{Output} panel displays prover
  messages that correspond to a given command, within a separate
  window.

  The cursor position in the presently active text area determines the
  prover commands whose cumulative message output is appended and
  shown in that window (in canonical order according to the processing
  of the command).  There are also control elements to modify the
  update policy of the output wrt.\ continued editor movements.  This
  is particularly useful with several independent instances of the
  \emph{Output} panel, which the Dockable Window Manager of jEdit can
  handle conveniently.

  Former users of the old TTY interaction model (e.g.\ Proof~General)
  might find a separate window for prover messages familiar, but it is
  important to understand that the main Prover IDE feedback happens
  elsewhere.  It is possible to do meaningful proof editing
  efficiently, using secondary output windows only rarely.

  The main purpose of the output window is to ``debug'' unclear
  situations by inspecting internal state of the prover.\footnote{In
  that sense, unstructured tactic scripts depend on continuous
  debugging with internal state inspection.} Consequently, some
  special messages for \emph{tracing} or \emph{proof state} only
  appear here, and are not attached to the original source.

  \medskip In any case, prover messages also contain markup that may
  be explored recursively via tooltips or hyperlinks (see
  \secref{sec:tooltips-hyperlinks}), or clicked directly to initiate
  certain actions (see \secref{sec:auto-tools} and
  \secref{sec:sledgehammer}).  *}


section {* Tooltips and hyperlinks \label{sec:tooltips-hyperlinks} *}

text {* Formally processed text (prover input or output) contains rich
  markup information that can be explored further by using the
  @{verbatim CONTROL} modifier key on Linux and Windows, or @{verbatim
  COMMAND} on Mac OS X.  Hovering with the mouse while the modifier is
  pressed reveals a \emph{tooltip} (grey box over the text with a
  yellow popup) and/or a \emph{hyperlink} (black rectangle over the
  text); see also \figref{fig:tooltip}.

  \begin{figure}[htb]
  \begin{center}
  \includegraphics[scale=0.3]{popup1}
  \end{center}
  \caption{Tooltip and hyperlink for some formal entity}
  \label{fig:tooltip}
  \end{figure}

  Tooltip popups use the same rendering principles as the main text
  area, and further tooltips and/or hyperlinks may be exposed
  recursively by the same mechanism; see \figref{fig:nested-tooltips}.

  \begin{figure}[htb]
  \begin{center}
  \includegraphics[scale=0.3]{popup2}
  \end{center}
  \caption{Nested tooltips over formal entities}
  \label{fig:nested-tooltips}
  \end{figure}

  The tooltip popup window provides some controls to \emph{close} or
  \emph{detach} the window, turning it into a separate \emph{Info}
  window managed by jEdit.  The @{verbatim ESCAPE} key closes
  \emph{all} popups, which is particularly relevant when nested
  tooltips are stacking up.

  \medskip A black rectangle in the text indicates a hyperlink that
  may be followed by a mouse click (while the @{verbatim CONTROL} or
  @{verbatim COMMAND} modifier key is still pressed). Presently
  (Isabelle2013-2) there is no systematic navigation within the
  editor to return to the original location.

  Also note that the link target may be a file that is itself not
  subject to formal document processing of the editor session and thus
  prevents further exploration: the chain of hyperlinks may end in
  some source file of the underlying logic image, or within the
  Isabelle/ML bootstrap sources of Isabelle/Pure. *}


section {* Text completion \label{sec:completion} *}

text {* \paragraph{Completion tables} are determined statically from
  the ``outer syntax'' of the underlying edit mode (for theory files
  this is the syntax of Isar commands), and specifications of Isabelle
  symbols (see also \secref{sec:symbols}).

  Symbols are completed in backslashed forms, e.g.\ @{verbatim
  "\\"}@{verbatim "forall"} or @{verbatim "\<forall>"} that both produce the
  Isabelle symbol @{text "\<forall>"} in its Unicode rendering.\footnote{The
  extra backslash avoids overlap with keywords of the buffer syntax,
  and allows to produce Isabelle symbols robustly in most syntactic
  contexts.}  Alternatively, symbol abbreviations may be used as
  specified in @{file "$ISABELLE_HOME/etc/symbols"}.

  \paragraph{Completion popups} are required in situations of
  ambiguous completion results or where explicit confirmation is
  demanded before inserting completed text into the buffer.

  The popup is some minimally invasive GUI component over the text
  area.  It interprets special keys @{verbatim TAB}, @{verbatim
  ESCAPE}, @{verbatim UP}, @{verbatim DOWN}, @{verbatim PAGE_UP},
  @{verbatim PAGE_DOWN}, but all other key events are passed to the
  underlying text area.  This allows to ignore unwanted completions
  most of the time and continue typing quickly.

  The meaning of special keys is as follows:

  \medskip
  \begin{tabular}{ll}
  \textbf{key} & \textbf{action} \\\hline
  @{verbatim "TAB"} & select completion \\
  @{verbatim "ESCAPE"} & dismiss popup \\
  @{verbatim "UP"} & move up one item \\
  @{verbatim "DOWN"} & move down one item \\
  @{verbatim "PAGE_UP"} & move up one page of items \\
  @{verbatim "PAGE_DOWN"} & move down one page of items \\
  \end{tabular}
  \medskip

  Movement within the popup is only active for multiple items.
  Otherwise the corresponding key event retains its standard meaning
  within the underlying text area.

  \paragraph{Explicit completion} is triggered by the keyboard
  shortcut @{verbatim "C+b"} (action @{action "isabelle.complete"}).
  This overrides the original jEdit binding for action @{verbatim
  "complete-word"}, but the latter is used as fall-back for
  non-Isabelle edit modes.  It is also possible to restore the
  original jEdit keyboard mapping of @{verbatim "complete-word"} via
  \emph{Global Options / Shortcuts}.

  Replacement text is inserted immediately into the buffer, unless
  ambiguous results demand an explicit popup.

  \paragraph{Implicit completion} is triggered by regular keyboard
  input events during of the editing process in the main jEdit text
  area (and a few additional text fields like the search criteria of
  the Find panel, see \secref{sec:find}).  Implicit completion depends
  on on further side-conditions:

  \begin{enumerate}

  \item The system option @{system_option jedit_completion} needs to
  be enabled (default).

  \item Completion of syntax keywords requires at least 3 relevant
  characters in the text.

  \item The system option @{system_option jedit_completion_delay}
  determines an additional delay (0.0 by default), before opening a
  completion popup.

  \item The system option @{system_option
  jedit_completion_dismiss_delay} determines an additional delay (0.0
  by default), before dismissing an earlier completion popup.  A value
  like 0.1 is occasionally useful to reduce the chance of loosing key
  strokes when the speed of typing exceeds that of repainting GUI
  components.

  \item The system option @{system_option jedit_completion_immediate}
  (disabled by default) controls whether replacement text should be
  inserted immediately without popup.  This is restricted to Isabelle
  symbols and their abbreviations (\secref{sec:symbols}) --- plain
  keywords always demand a popup for clarity.

  \item Completion of symbol abbreviations with only one relevant
  character in the text always enforces an explicit popup,
  independently of @{system_option jedit_completion_immediate}.

  \end{enumerate}

  These completion options may be configured in \emph{Plugin Options /
  Isabelle / General / Completion}.  The default is quite moderate in
  showing occasional popups and refraining from immediate insertion.
  An additional completion delay of 0.3 seconds will make it even less
  ambitious.

  In contrast, more aggressive completion works via @{system_option
  jedit_completion_delay}~@{verbatim "= 0.0"} and @{system_option
  jedit_completion_immediate}~@{verbatim "= true"}.  Thus the editing
  process becomes dependent on the system guessing correctly what the
  user had in mind.  It requires some practice (and study of the
  symbol abbreviation tables) to become productive in this advanced
  mode.

  In any case, unintended completions can be reverted by the regular
  @{verbatim undo} operation of jEdit.  When editing embedded
  languages such as ML, it is better to disable either @{system_option
  jedit_completion} or @{system_option jedit_completion_immediate}
  temporarily.  *}


section {* Isabelle symbols \label{sec:symbols} *}

text {* Isabelle sources consist of \emph{symbols} that extend plain
  ASCII to allow infinitely many mathematical symbols within the
  formal sources.  This works without depending on particular
  encodings and varying Unicode standards
  \cite{Wenzel:2011:CICM}.\footnote{Raw Unicode characters within
  formal sources would compromise portability and reliability in the
  face of changing interpretation of special features of Unicode, such
  as Combining Characters or Bi-directional Text.}

  For the prover back-end, formal text consists of ASCII characters
  that are grouped according to some simple rules, e.g.\ as plain
  ``@{verbatim a}'' or symbolic ``@{verbatim "\<alpha>"}''.

  For the editor front-end, a certain subset of symbols is rendered
  physically via Unicode glyphs, in order to show ``@{verbatim "\<alpha>"}''
  as ``@{text "\<alpha>"}'', for example.  This symbol interpretation is
  specified by the Isabelle system distribution in @{file
  "$ISABELLE_HOME/etc/symbols"} and may be augmented by the user in
  @{file_unchecked "$ISABELLE_HOME_USER/etc/symbols"}.

  The appendix of \cite{isabelle-isar-ref} gives an overview of the
  standard interpretation of finitely many symbols from the infinite
  collection.  Uninterpreted symbols are displayed literally, e.g.\
  ``@{verbatim "\<foobar>"}''.  Overlap of Unicode characters used in
  symbol interpretation with informal ones (which might appear e.g.\
  in comments) needs to be avoided!  Raw Unicode characters within
  prover source files should be restricted to informal parts, e.g.\ to
  write text in non-latin alphabets in comments.

  \medskip \paragraph{Encoding.} Technically, the Unicode view on
  Isabelle symbols is an \emph{encoding} in jEdit (not in the
  underlying JVM) that is called @{verbatim "UTF-8-Isabelle"}.  It is
  provided by the Isabelle/jEdit plugin and enabled by default for all
  source files.  Sometimes such defaults are reset accidentally, or
  malformed UTF-8 sequences in the text force jEdit to fall back on a
  different encoding like @{verbatim "ISO-8859-15"}.  In that case,
  verbatim ``@{verbatim "\<alpha>"}'' will be shown in the text buffer
  instead of its Unicode rendering ``@{text "\<alpha>"}''.  The jEdit menu
  operation \emph{File / Reload with Encoding / UTF-8-Isabelle} helps
  to resolve such problems, potentially after repairing malformed
  parts of the text.

  \medskip \paragraph{Font.} Correct rendering via Unicode requires a
  font that contains glyphs for the corresponding codepoints.  Most
  system fonts lack that, so Isabelle/jEdit prefers its own
  application font @{verbatim IsabelleText}, which ensures that
  standard collection of Isabelle symbols are actually seen on the
  screen (or printer).

  Note that a Java/AWT/Swing application can load additional fonts
  only if they are not installed on the operating system already!
  Some old version of @{verbatim IsabelleText} that happens to be
  provided by the operating system would prevents Isabelle/jEdit from
  its bundled version.  This could lead to missing glyphs (black
  rectangles), when the system version of @{verbatim IsabelleText} is
  older than the application version.  This problem can be avoided by
  refraining to ``install'' any version of @{verbatim IsabelleText} in
  the first place (although it might be occasionally tempting to use
  the same font in other applications).

  \medskip \paragraph{Input methods.} In principle, Isabelle/jEdit
  could delegate the problem to produce Isabelle symbols in their
  Unicode rendering to the underlying operating system and its
  \emph{input methods}.  Regular jEdit also provides various ways to
  work with \emph{abbreviations} to produce certain non-ASCII
  characters.  Since none of these standard input methods work
  satisfactorily for the mathematical characters required for
  Isabelle, various specific Isabelle/jEdit mechanisms are provided.

  Here is a summary for practically relevant input methods for
  Isabelle symbols:

  \begin{enumerate}

  \item The \emph{Symbols} panel with some GUI buttons to insert
  certain symbols in the text buffer.  There are also tooltips to
  reveal the official Isabelle representation with some additional
  information about \emph{symbol abbreviations} (see below).

  \item Copy / paste from decoded source files: text that is rendered
  as Unicode already can be re-used to produce further text.  This
  also works between different applications, e.g.\ Isabelle/jEdit and
  some web browser or mail client, as long as the same Unicode view on
  Isabelle symbols is used uniformly.

  \item Copy / paste from prover output within Isabelle/jEdit.  The
  same principles as for text buffers apply, but note that \emph{copy}
  in secondary Isabelle/jEdit windows works via the keyboard shortcut
  @{verbatim "C+c"}, while jEdit menu actions always refer to the
  primary text area!

  \item Completion provided by Isabelle plugin (see
  \secref{sec:completion}).  Isabelle symbols have a canonical name
  and optional abbreviations.  This can be used with the text
  completion mechanism of Isabelle/jEdit, to replace a prefix of the
  actual symbol like @{verbatim "\<lambda>"}, or its backslashed name
  @{verbatim "\\"}@{verbatim "lambda"}, or its ASCII abbreviation
  @{verbatim "%"} by the Unicode rendering.

  The following table is an extract of the information provided by the
  standard @{file "$ISABELLE_HOME/etc/symbols"} file:

  \medskip
  \begin{tabular}{lll}
    \textbf{symbol} & \textbf{backslashed name} & \textbf{abbreviation} \\\hline
    @{text "\<lambda>"} & @{verbatim "\\lambda"} & @{verbatim "%"} \\
    @{text "\<Rightarrow>"} & @{verbatim "\\Rightarrow"} & @{verbatim "=>"} \\
    @{text "\<Longrightarrow>"} & @{verbatim "\\Longrightarrow"} & @{verbatim "==>"} \\[0.5ex]
    @{text "\<And>"} & @{verbatim "\\And"} & @{verbatim "!!"} \\
    @{text "\<equiv>"} & @{verbatim "\\equiv"} & @{verbatim "=="} \\[0.5ex]
    @{text "\<forall>"} & @{verbatim "\\forall"} & @{verbatim "!"} \\
    @{text "\<exists>"} & @{verbatim "\\exists"} & @{verbatim "?"} \\
    @{text "\<longrightarrow>"} & @{verbatim "\\longrightarrow"} & @{verbatim "-->"} \\
    @{text "\<and>"} & @{verbatim "\\and"} & @{verbatim "&"} \\
    @{text "\<or>"} & @{verbatim "\\or"} & @{verbatim "|"} \\
    @{text "\<not>"} & @{verbatim "\\not"} & @{verbatim "~"} \\
    @{text "\<noteq>"} & @{verbatim "\\noteq"} & @{verbatim "~="} \\
    @{text "\<in>"} & @{verbatim "\\in"} & @{verbatim ":"} \\
    @{text "\<notin>"} & @{verbatim "\\notin"} & @{verbatim "~:"} \\
  \end{tabular}
  \medskip

  Note that the above abbreviations refer to the input method. The
  logical notation provides ASCII alternatives that often coincide,
  but deviate occasionally.  This occasionally causes user confusion
  with very old-fashioned Isabelle source that use ASCII replacement
  notation like @{verbatim "!"} or @{verbatim "ALL"} directly in the
  text.

  On the other hand, coincidence of symbol abbreviations with ASCII
  replacement syntax syntax helps to update old theory sources via
  explicit completion (see also @{verbatim "C+b"} explained in
  \secref{sec:completion}).

  \end{enumerate}

  \paragraph{Control symbols.} There are some special control symbols
  to modify the display style of a single symbol (without
  nesting). Control symbols may be applied to a region of selected
  text, either using the \emph{Symbols} panel or keyboard shortcuts or
  jEdit actions.  These editor operations produce a separate control
  symbol for each symbol in the text, in order to make the whole text
  appear in a certain style.

  \medskip
  \begin{tabular}{llll}
    \textbf{style} & \textbf{symbol} & \textbf{shortcut} & \textbf{action} \\\hline
    superscript & @{verbatim "\<^sup>"} & @{verbatim "C+e UP"} & @{action "isabelle.control-sup"} \\
    subscript & @{verbatim "\<^sub>"} & @{verbatim "C+e DOWN"} & @{action "isabelle.control-sub"} \\
    bold face & @{verbatim "\<^bold>"} & @{verbatim "C+e RIGHT"} & @{action "isabelle.control-bold"} \\
    reset & & @{verbatim "C+e LEFT"} & @{action "isabelle.control-reset"} \\
  \end{tabular}
  \medskip

  To produce a single control symbol, it is also possible to complete
  on @{verbatim "\\"}@{verbatim sup}, @{verbatim "\\"}@{verbatim sub},
  @{verbatim "\\"}@{verbatim bold} as for regular symbols.  *}


section {* Automatically tried tools \label{sec:auto-tools} *}

text {* Continuous document processing works asynchronously in the
  background.  Visible document source that has been evaluated already
  may get augmented by additional results of \emph{asynchronous print
  functions}.  The canonical example is proof state output, which is
  always enabled.  More heavy-weight print functions may be applied,
  in order to prove or disprove parts of the formal text by other
  means.

  Isabelle/HOL provides various automatically tried tools that operate
  on outermost goal statements (e.g.\ @{command lemma}, @{command
  theorem}), independently of the state of the current proof attempt.
  They work implicitly without any arguments.  Results are output as
  \emph{information messages}, which are indicated in the text area by
  blue squiggles and a blue information sign in the gutter (see
  \figref{fig:auto-tools}).  The message content may be shown as for
  other output (see also \secref{sec:prover-output}).  Some tools
  produce output with \emph{sendback} markup, which means that
  clicking on certain parts of the output inserts that text into the
  source in the proper place.

  \begin{figure}[htb]
  \begin{center}
  \includegraphics[scale=0.3]{auto-tools}
  \end{center}
  \caption{Results of automatically tried tools}
  \label{fig:auto-tools}
  \end{figure}

  \medskip The following Isabelle system options control the behavior
  of automatically tried tools (see also the jEdit dialog window
  \emph{Plugin Options / Isabelle / General / Automatically tried
  tools}):

  \begin{itemize}

  \item @{system_option auto_methods} controls automatic use of a
  combination of standard proof methods (@{method auto}, @{method
  simp}, @{method blast}, etc.).  This corresponds to the Isar command
  @{command "try0"}.

  The tool is disabled by default, since unparameterized invocation of
  standard proof methods often consumes substantial CPU resources
  without leading to success.

  \item @{system_option auto_nitpick} controls a slightly reduced
  version of @{command nitpick}, which tests for counterexamples using
  first-order relational logic. See also the Nitpick manual
  \cite{isabelle-nitpick}.

  This tool is disabled by default, due to the extra overhead of
  invoking an external Java process for each attempt to disprove a
  subgoal.

  \item @{system_option auto_quickcheck} controls automatic use of
  @{command quickcheck}, which tests for counterexamples using a
  series of assignments for free variables of a subgoal.

  This tool is \emph{enabled} by default.  It requires little
  overhead, but is a bit weaker than @{command nitpick}.

  \item @{system_option auto_sledgehammer} controls a significantly
  reduced version of @{command sledgehammer}, which attempts to prove
  a subgoal using external automatic provers. See also the
  Sledgehammer manual \cite{isabelle-sledgehammer}.

  This tool is disabled by default, due to the relatively heavy nature
  of Sledgehammer.

  \item @{system_option auto_solve_direct} controls automatic use of
  @{command solve_direct}, which checks whether the current subgoals
  can be solved directly by an existing theorem.  This also helps to
  detect duplicate lemmas.

  This tool is \emph{enabled} by default.

  \end{itemize}

  Invocation of automatically tried tools is subject to some global
  policies of parallel execution, which may be configured as follows:

  \begin{itemize}

  \item @{system_option auto_time_limit} (default 2.0) determines the
  timeout (in seconds) for each tool execution.

  \item @{system_option auto_time_start} (default 1.0) determines the
  start delay (in seconds) for automatically tried tools, after the
  main command evaluation is finished.

  \end{itemize}

  Each tool is submitted independently to the pool of parallel
  execution tasks in Isabelle/ML, using hardwired priorities according
  to its relative ``heaviness''.  The main stages of evaluation and
  printing of proof states take precedence, but an already running
  tool is not canceled and may thus reduce reactivity of proof
  document processing.

  Users should experiment how the available CPU resources (number of
  cores) are best invested to get additional feedback from prover in
  the background, by using a selection of weaker or stronger tools.
*}


section {* Sledgehammer \label{sec:sledgehammer} *}

text {* The \emph{Sledgehammer} panel (\figref{fig:sledgehammer})
  provides a view on some independent execution of the Isar command
  @{command sledgehammer}, with process indicator (spinning wheel) and
  GUI elements for important Sledgehammer arguments and options.  Any
  number of Sledgehammer panels may be active, according to the
  standard policies of Dockable Window Management in jEdit.  Closing
  such windows also cancels the corresponding prover tasks.

  \begin{figure}[htb]
  \begin{center}
  \includegraphics[scale=0.3]{sledgehammer}
  \end{center}
  \caption{An instance of the Sledgehammer panel}
  \label{fig:sledgehammer}
  \end{figure}

  The \emph{Apply} button attaches a fresh invocation of @{command
  sledgehammer} to the command where the cursor is pointing in the
  text --- this should be some pending proof problem.  Further buttons
  like \emph{Cancel} and \emph{Locate} help to manage the running
  process.

  Results appear incrementally in the output window of the panel.
  Proposed proof snippets are marked-up as \emph{sendback}, which
  means a single mouse click inserts the text into a suitable place of
  the original source.  Some manual editing may be required
  nonetheless, say to remove earlier proof attempts. *}


section {* Find theorems \label{sec:find} *}

text {* The \emph{Find} panel (\figref{fig:find}) provides an
  independent view for the Isar command @{command find_theorems}.  The
  main text field accepts search criteria according to the syntax
  @{syntax thmcriterium} given in \cite{isabelle-isar-ref}.  Further
  options of @{command find_theorems} are available via GUI elements.

  \begin{figure}[htb]
  \begin{center}
  \includegraphics[scale=0.3]{find}
  \end{center}
  \caption{An instance of the Find panel}
  \label{fig:find}
  \end{figure}

  The \emph{Apply} button attaches a fresh invocation of @{command
  find_theorems} to the current context of the command where the
  cursor is pointing in the text, unless an alternative theory context
  (from the underlying logic image) is specified explicitly. *}


chapter {* Miscellaneous tools *}

section {* SideKick *}

text {* The \emph{SideKick} plugin of jEdit provides some general
  services to display buffer structure in a tree view.

  Isabelle/jEdit provides SideKick parsers for its main mode for
  theory files, as well as some minor modes for the @{verbatim NEWS}
  file, session @{verbatim ROOT} files, and system @{verbatim
  options}.

  Moreover, the special SideKick parser @{verbatim "isabelle-markup"}
  provides access to the full (uninterpreted) markup tree of the PIDE
  document model of the current buffer.  This is occasionally useful
  for informative purposes, but the amount of displayed information
  might cause problems for large buffers, both for the human and the
  machine.
*}


section {* Timing *}

text {* Managed evaluation of commands within PIDE documents includes
  timing information, which consists of elapsed (wall-clock) time, CPU
  time, and GC (garbage collection) time.  Note that in a
  multithreaded system it is difficult to measure execution time
  precisely: elapsed time is closer to the real requirements of
  runtime resources than CPU or GC time, which are both subject to
  influences from the parallel environment that are outside the scope
  of the current command transaction.

  The \emph{Timing} panel provides an overview of cumulative command
  timings for each document node.  Commands with elapsed time below
  the given threshold are ignored in the grand total.  Nodes are
  sorted according to their overall timing.  For the document node
  that corresponds to the current buffer, individual command timings
  are shown as well.  A double-click on a theory node or command moves
  the editor focus to that particular source position.

  It is also possible to reveal individual timing information via some
  tooltip for the corresponding command keyword, using the technique
  of mouse hovering with @{verbatim CONTROL}/@{verbatim COMMAND}
  modifier key as explained in \secref{sec:tooltips-hyperlinks}.
  Actual display of timing depends on the global option
  @{system_option jedit_timing_threshold}, which can be configured in
  "Plugin Options / Isabelle / General".

  \medskip The \emph{Monitor} panel provides a general impression of
  recent activity of the farm of worker threads in Isabelle/ML.  Its
  display is continuously updated according to @{system_option
  editor_chart_delay}.  Note that the painting of the chart takes
  considerable runtime itself --- on the Java Virtual Machine that
  runs Isabelle/Scala, not Isabelle/ML.  Internally, the
  Isabelle/Scala module @{verbatim isabelle.ML_Statistics} provides
  further access to statistics of Isabelle/ML.  *}


section {* Isabelle/Scala console *}

text {* The \emph{Console} plugin of jEdit manages various shells
  (command interpreters), e.g.\ \emph{BeanShell}, which is the
  official jEdit scripting language, and the cross-platform
  \emph{System} shell.  Thus the console provides similar
  functionality than the special buffers @{verbatim "*scratch*"} and
  @{verbatim "*shell*"} in Emacs.

  Isabelle/jEdit extends the repertoire of the console by
  \emph{Scala}, which is the regular Scala toplevel loop running
  inside the \emph{same} JVM process as Isabelle/jEdit itself.  This
  means the Scala command interpreter has access to the JVM name space
  and state of the running Prover IDE application: the main entry
  points are @{verbatim view} (the current editor view of jEdit) and
  @{verbatim PIDE} (the Isabelle/jEdit plugin object).

  For example, the subsequent Scala snippet gets the PIDE document
  model of the current buffer within the current editor view:

  \begin{center}
  @{verbatim "PIDE.document_model(view.getBuffer).get"}
  \end{center}

  This helps to explore Isabelle/Scala functionality interactively.
  Some care is required to avoid interference with the internals of
  the running application, especially in production use.  *}


section {* Low-level output *}

text {* Prover output is normally shown directly in the main text area
  or secondary \emph{Output} panels, as explained in
  \secref{sec:prover-output}.

  Beyond this, it is occasionally useful to inspect low-level output
  channels via some of the following additional panels:

  \begin{itemize}

  \item \emph{Protocol} shows internal messages between the
  Isabelle/Scala and Isabelle/ML side of the PIDE editing protocol.
  Recording of messages starts with the first activation of the
  corresponding dockable window; earlier messages are lost.

  Actual display of protocol messages causes considerable slowdown, so
  it is important to undock all \emph{Protocol} panels for production
  work.

  \item \emph{Raw Output} shows chunks of text from the @{verbatim
  stdout} and @{verbatim stderr} channels of the prover process.
  Recording of output starts with the first activation of the
  corresponding dockable window; earlier output is lost.

  The implicit stateful nature of physical I/O channels makes it
  difficult to relate raw output to the actual command from where it
  was originating.  Parallel execution may add to the confusion.
  Peeking at physical process I/O is only the last resort to diagnose
  problems with tools that are not fully PIDE compliant.

  Under normal circumstances, prover output always works via managed
  message channels (corresponding to @{ML writeln}, @{ML warning},
  @{ML error} etc.\ in Isabelle/ML), which are displayed by regular
  means within the document model (\secref{sec:prover-output}).

  \item \emph{Syslog} shows system messages that might be relevant to
  diagnose problems with the startup or shutdown phase of the prover
  process; this also includes raw output on @{verbatim stderr}.

  A limited amount of syslog messages are buffered, independently of
  the docking state of the \emph{Syslog} panel.  This allows to
  diagnose serious problems with Isabelle/PIDE process management,
  outside of the actual protocol layer.

  Under normal situations, such low-level system output can be
  ignored.

  \end{itemize}
*}


chapter {* Known problems and workarounds \label{sec:problems} *}

text {*
  \begin{itemize}

  \item \textbf{Problem:} Odd behavior of some diagnostic commands with
  global side-effects, like writing a physical file.

  \textbf{Workaround:} Copy / paste complete command text from
  elsewhere, or discontinue continuous checking temporarily.

  \item \textbf{Problem:} No way to delete document nodes from the overall
  collection of theories.

  \textbf{Workaround:} Ignore unused files.  Restart whole
  Isabelle/jEdit session in worst-case situation.

  \item \textbf{Problem:} Keyboard shortcuts @{verbatim "C+PLUS"} and
  @{verbatim "C+MINUS"} for adjusting the editor font size depend on
  platform details and national keyboards.

  \textbf{Workaround:} Rebind keys via \emph{Global Options /
  Shortcuts}.

  \item \textbf{Problem:} The Mac OS X keyboard shortcut @{verbatim
  "COMMAND+COMMA"} for application \emph{Preferences} is in conflict
  with the jEdit default shortcut for \emph{Incremental Search Bar}
  (action @{verbatim "quick-search"}).

  \textbf{Workaround:} Rebind key via \emph{Global Options /
  Shortcuts} according to national keyboard, e.g.\ @{verbatim
  "COMMAND+SLASH"} on English ones.

  \item \textbf{Problem:} Mac OS X system fonts sometimes lead to
  character drop-outs in the main text area.

  \textbf{Workaround:} Use the default @{verbatim IsabelleText} font.
  (Do not install that font on the system.)

  \item \textbf{Problem:} Some Linux / X11 input methods such as IBus
  tend to disrupt key event handling of Java/AWT/Swing.

  \textbf{Workaround:} Do not use input methods, reset the environment
  variable @{verbatim XMODIFIERS} within Isabelle settings (default in
  Isabelle2013-2).

  \item \textbf{Problem:} Some Linux / X11 window managers that are
  not ``re-parenting'' cause problems with additional windows opened
  by Java. This affects either historic or neo-minimalistic window
  managers like @{verbatim awesome} or @{verbatim xmonad}.

  \textbf{Workaround:} Use regular re-parenting window manager.

  \item \textbf{Problem:} Recent forks of Linux / X11 window managers
  and desktop environments (variants of Gnome) disrupt the handling of
  menu popups and mouse positions of Java/AWT/Swing.

  \textbf{Workaround:} Use mainstream versions of Linux desktops.

  \item \textbf{Problem:} Full-screen mode via jEdit action @{verbatim
  "toggle-full-screen"} (default shortcut @{verbatim F11}) works on
  Windows, but not on Mac OS X or various Linux / X11 window managers.

  \textbf{Workaround:} Use native full-screen control of the window
  manager (notably on Mac OS X).

  \item \textbf{Problem:} Full-screen mode and dockable windows in
  \emph{floating} state may lead to confusion about window placement
  (depending on platform characteristics).

  \textbf{Workaround:} Avoid this combination.

  \end{itemize}
*}

end