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+% Copyright 2007 by Till Tantau
+%
+% This file may be distributed and/or modified
+%
+% 1. under the LaTeX Project Public License and/or
+% 2. under the GNU Public License.
+%
+% See the file doc/generic/pgf/licenses/LICENSE for more details.
+
+
+% This file is perfectly self-contained, except that the catcode of @ should be made a letter.
+
+
+% Guard against reading twice
+\ifx\pgfkeysloaded\undefined
+ \let\pgfkeysloaded=\relax
+\else
+ \expandafter\endinput
+\fi
+
+% The purpose of this file is to provide a general settings engine that
+% works with all TeX formats and has no save-stack impact
+
+
+% This is useful:
+
+\def\pgfkeys@ifcsname#1\endcsname#2\else#3\fi{\expandafter\ifx\csname#1\endcsname\relax#3\else#2\fi}%
+\ifx\eTeXrevision\undefined%
+\else%
+ \expandafter\let\expandafter\pgfkeys@ifcsname\csname ifcsname\endcsname%
+\fi
+
+\def\pgfkeys@empty{}
+
+% This also:
+
+\ifx\PackageError\undefined
+ \def\pgfkeys@error#1{\immediate\write-1{Package pgfkeys: Error! #1.}}%
+\else
+ \def\pgfkeys@error#1{\PackageError{pgfkeys}{#1}{}}%
+\fi
+
+% Set a key to a value
+%
+% #1 = key
+% #2 = tokens
+%
+% Description:
+%
+% This command sets the key to the given tokens. The tokens are stored as
+% is and can even contain things like #9.
+%
+% Keys are organized hierarchically using something similar to Unix
+% paths. Thus, a typically key might be called "/tikz/length" or
+% "/tikz/length dimension/.@cmd". Some keys starting with a dot are
+% special, so they should not be used as normal key names (they are
+% similar to Unix files starting with a dot -- you can use them, but
+% be careful).
+%
+% Keys are always local to the current TeX group.
+%
+% Example:
+%
+% \pgfkeyssetvalue{/tikz/length}{2cm-3cm}
+% \pgfkeyssetvalue{/algo/swap}{{#2}{#1}}
+
+\def\pgfkeyssetvalue#1#2{%
+ \pgfkeys@temptoks{#2}\expandafter\edef\csname pgfk@#1\endcsname{\the\pgfkeys@temptoks}%
+}
+
+
+
+% Add text to a key at the end
+%
+% #1 = key
+% #2 = a value to be added at the beginning
+% #3 = a value to be added at the end
+%
+% Description:
+%
+% This command adds #2 to the definition of the key. The key should
+% have been set previously using \pgfkeyssetvalue.
+%
+% Example:
+%
+% \pgfkeysaddvalue{/tikz/length}{}{-3cm}
+
+\def\pgfkeysaddvalue#1#2#3{%
+ {%
+ \toks0{#1}%
+ \pgfkeysifdefined{#1}
+ {\pgfkeys@temptoks\expandafter\expandafter\expandafter{\csname pgfk@#1\endcsname}}%
+ {\pgfkeys@temptoks{}}%
+ \toks1{#2}%
+ \xdef\pgfkeys@global@temp{\the\toks0 \the\pgfkeys@temptoks \the\toks1}% believe or don't: the spaces are important
+ }%
+ \pgfkeyslet{#1}\pgfkeys@global@temp%
+}
+
+
+
+% Makes a key equal a given code
+%
+% #1 = key
+% #2 = a code name
+%
+% Description:
+%
+% This command executes a \let command so that a key gets the same
+% value as the parameter #2.
+%
+% Keys are always local to the current TeX group.
+%
+% Example:
+%
+% \pgfkeyslet{/algo/swap}{\myswap}
+
+\def\pgfkeyslet#1#2{%
+ \expandafter\let\csname pgfk@#1\endcsname#2%
+}
+
+
+% Retrieve the code stored in a key into a code
+%
+% #1 = key
+% #2 = code
+%
+% Description:
+%
+% This command will set #2 to "point" to the value stored in the key.
+%
+% Example:
+%
+% \pgfkeysgetvalue{/tikz/swap}{\myswap}
+
+\def\pgfkeysgetvalue#1#2{\expandafter\let\expandafter#2\csname pgfk@#1\endcsname}
+
+
+
+% Retrieve the value stored in a key
+%
+% #1 = key
+%
+% Description:
+%
+% This command will expand to the value stored in the key. The key
+% should previously have been set using \pgfkeyasetkey or \pgfkeyslet.
+%
+% Example:
+%
+% The length is \pgfkeysvalue{/tikz/length}.
+
+\def\pgfkeysvalueof#1{\csname pgfk@#1\endcsname}
+
+
+
+% If for testing whether a key exists
+%
+% #1 = key
+% #2 = if-case
+% #3 = else-case
+%
+% Description:
+%
+% This if will be executed if the key exists. In eTeX mode this works
+% like a normal if, in normal TeX mode you need to provide an \else.
+%
+% Example:
+%
+% \pgfkeysifdefined{/tikz/length}{key exists}{does not exist}
+
+\def\pgfkeysifdefined#1#2#3{\pgfkeys@ifcsname pgfk@#1\endcsname#2\else#3\fi}
+
+
+
+
+% Execute settings
+%
+% #1 = list of settings
+%
+% Description:
+%
+% The list of settings should contain comma-separated settings. Each
+% setting has the following form:
+%
+% /path/key=value
+%
+% The parts "/path/" and "=value" are optional. When the path is not
+% specified, the value of the token register "\pgfkeypath" is used. If
+% "=value" is missing, the value of the setting "/path/key/.@def" is used
+% instead. If this key is set to "\pgfvaluerequired", the key
+% "/errors/value required/.@cmd" is executed. Theis error handler,
+% like all other error handlers, will get the current key as its first
+% parameter (unexpanded) and the current value as its second value
+% (also unexpanded).
+%
+% Any spaces at the beginning and at the end and around the
+% equals-sign are removed. The key with the complete path is set to
+% the code \pgfcurrentkey.
+%
+% The setting is then processed according to the following rules:
+%
+% 1) If the key /path/key/.@cmd" is present, its code is executed
+% with the value computed above, followed by \pgfeov (end of
+% value). So, to handle
+%
+% "/stuff/height= 1.5 ,"
+%
+% /stuff/height/.@cmd should be set to some code, that can
+% handle the parameter
+%
+% "1.5\pgfeov"
+%
+% For instance, saying
+%
+% \pgfkeys{/stuff/height/.@cmd}{#1\pgfeov}{\def\myheight{#1}}
+%
+% will do nicely.
+%
+% 2) Otherwise, if the key /path/key is present, this key is
+% set to the value computed above.
+%
+% 3) Otherwise, if the key /handlers/key/.@cmd is present, it is executed
+% with the same parameters as in 1). Additionally, the
+% token register \pgfcurrentkeypath will be set to "/path/" and the
+% macor \pgfcurrentkeywithoutpath to "key". So, in the above
+% example if neither "/stuff/height/.@cmd" nor
+% "/stuff/height" is present, but "/handlers/height" is,
+% then "/handlers/height" is executed with the parameters:
+%
+% "1.5\pgfeov"
+%
+% and \pgfcurrentkey is set to "/stuff/height" and \pgfcurrentkeypath
+% is set to "/stuff/" and \pgfcurrentkeywithoutpath to "height".
+%
+% 4) Otherwise, if the key "/path/.unknown/.@cmd" is present, its code is
+% executed with the same parameters as in 3).
+%
+% 5) Otherwise, the key "/handlers/.unknown/.@cmd" is executed with the same
+% parameters as in 1).
+%
+% After all settings have been processed, the value of the token
+% register \pgfdefaultkeypath is set to its original value. Thus, any local
+% change of this token register has no effect outside the call.
+%
+% Example:
+%
+% \pgfkeys{/tikz/.is family}
+% \pgfkeys{/tikz/line width/.cd,
+% .def=\pgfsetlinewidth{##1},
+% .set default=.4pt}
+% \pgfkeys{tikz,line width=1pt}
+
+\newtoks\pgfkeys@pathtoks
+\def\pgfkeyscurrentpath{\the\pgfkeys@pathtoks}
+\newtoks\pgfkeys@temptoks
+
+\def\pgfkeys@root{/}
+\let\pgfkeysdefaultpath\pgfkeys@root
+
+\def\pgfkeys{\expandafter\pgfkeys@@set\expandafter{\pgfkeysdefaultpath}}%
+\def\pgfkeys@@set#1#2{%
+ \let\pgfkeysdefaultpath\pgfkeys@root%
+ \pgfkeys@parse#2,\pgfkeys@mainstop%
+ \def\pgfkeysdefaultpath{#1}}
+
+\def\pgfkeys@parse{\futurelet\pgfkeys@possiblerelax\pgfkeys@parse@main}
+\def\pgfkeys@parse@main{%
+ \ifx\pgfkeys@possiblerelax\pgfkeys@mainstop%
+ \expandafter\pgfkeys@cleanup%
+ \else%
+ \expandafter\pgfkeys@normal%
+ \fi%
+}
+\def\pgfkeys@normal#1,{%
+ \pgfkeys@unpack#1=\pgfkeysnovalue=\pgfkeys@stop%
+ \pgfkeys@parse%
+}
+\def\pgfkeys@cleanup\pgfkeys@mainstop{}
+
+\def\pgfkeys@mainstop{\pgfkeys@mainstop} % equals only itself
+\def\pgfkeys@novalue{} % equals only itself
+\def\pgfkeysnovalue{\pgfkeys@novalue} % equals only itself
+\def\pgfkeysnovalue@text{\pgfkeysnovalue}
+\def\pgfkeysvaluerequired{\pgfkeysvaluerequired} % equals only itself
+
+\def\pgfkeys@unpack#1=#2=#3\pgfkeys@stop{%
+ \pgfkeys@spdef\pgfkeyscurrentkey{#1}%
+ \edef\pgfkeyscurrentkey{\pgfkeyscurrentkey}%
+ \ifx\pgfkeyscurrentkey\pgfkeys@empty%
+ % Skip
+ \else%
+ \pgfkeys@add@path@as@needed%
+ \pgfkeys@spdef\pgfkeyscurrentvalue{#2}%
+ \ifx\pgfkeyscurrentvalue\pgfkeysnovalue@text% Hmm... no value
+ \pgfkeysifdefined{\pgfkeyscurrentkey/.@def}%
+ {\pgfkeysgetvalue{\pgfkeyscurrentkey/.@def}{\pgfkeyscurrentvalue}}
+ {}% no default, so leave it
+ \fi%
+ \ifx\pgfkeyscurrentvalue\pgfkeysvaluerequired%
+ \pgfkeysvalueof{/errors/value required/.@cmd}\pgfkeyscurrentkey\pgfkeyscurrentvalue\pgfeov%
+ \else%
+ \pgfkeys@case@one%
+ \fi%
+ \fi}
+
+\def\pgfkeys@case@one{%
+ \pgfkeysifdefined{\pgfkeyscurrentkey/.@cmd}%
+ {\pgfkeysgetvalue{\pgfkeyscurrentkey/.@cmd}{\pgfkeys@code}%
+ \expandafter\pgfkeys@code\pgfkeyscurrentvalue\pgfeov}
+ {\pgfkeys@case@two}%
+}
+
+\def\pgfkeys@case@two{%
+ \pgfkeysifdefined{\pgfkeyscurrentkey}%
+ {\pgfkeys@case@two@extern}%
+ {\pgfkeys@case@three}%
+}
+
+\def\pgfkeys@case@two@extern{%
+ \ifx\pgfkeyscurrentvalue\pgfkeysnovalue@text%
+ \pgfkeysvalueof{\pgfkeyscurrentkey}%
+ \else%
+ \pgfkeyslet{\pgfkeyscurrentkey}\pgfkeyscurrentvalue%
+ \fi%
+}
+
+
+\def\pgfkeys@case@three{%
+ \pgfkeys@split@path%
+ \pgfkeysifdefined{/handlers/\pgfkeyscurrentname/.@cmd}%
+ {\pgfkeysgetvalue{/handlers/\pgfkeyscurrentname/.@cmd}{\pgfkeys@code}%
+ \expandafter\pgfkeys@code\pgfkeyscurrentvalue\pgfeov}
+ {\pgfkeys@unknown}%
+}
+
+\def\pgfkeys@unknown{%
+ \pgfkeysifdefined{\pgfkeyscurrentpath/.unknown/.@cmd}%
+ {%
+ \pgfkeysgetvalue{\pgfkeyscurrentpath/.unknown/.@cmd}{\pgfkeys@code}%
+ \expandafter\pgfkeys@code\pgfkeyscurrentvalue\pgfeov}
+ {%
+ \pgfkeysgetvalue{/handlers/.unknown/.@cmd}{\pgfkeys@code}%
+ \expandafter\pgfkeys@code\pgfkeyscurrentvalue\pgfeov%
+ }%
+}
+
+
+\def\pgfkey@argumentisspace#1{%
+ \def\pgfkeys@spdef##1##2{%
+ \futurelet\pgfkeys@possiblespace\pgfkeys@sp@a##2\pgfkeys@stop\pgfkeys@stop#1\pgfkeys@stop\relax##1}%
+ \def\pgfkeys@sp@a{%
+ \ifx\pgfkeys@possiblespace\pgfkeys@sptoken%
+ \expandafter\pgfkeys@sp@b%
+ \else%
+ \expandafter\pgfkeys@sp@b\expandafter#1%
+ \fi}%
+ \def\pgfkeys@sp@b#1##1 \pgfkeys@stop{\pgfkeys@sp@c##1}%
+}
+\pgfkey@argumentisspace{ }
+\def\pgfkeys@sp@c#1\pgfkeys@stop#2\relax#3{\pgfkeys@temptoks{#1}\edef#3{\the\pgfkeys@temptoks}}
+{\def\:{\global\let\pgfkeys@sptoken= } \: }
+
+
+
+\def\pgfkeys@add@path@as@needed{% Should add the path if the
+ % \pgfkeyscurrentkey does not start with /
+ \expandafter\futurelet\expandafter\pgfkeys@possibleslash\expandafter\pgfkeys@check@slash\pgfkeyscurrentkey\relax%
+}
+\def\pgfkeys@check@slash{%
+ \ifx\pgfkeys@possibleslash/%
+ \expandafter\pgfkeys@nevermind%
+ \else%
+ \expandafter\pgfkeys@addpath%
+ \fi%
+}
+
+\def\pgfkeys@nevermind#1\relax{}
+\def\pgfkeys@addpath#1\relax{\edef\pgfkeyscurrentkey{\pgfkeysdefaultpath#1}}
+
+\def\pgfkeys@split@path{% Should assign the two codes
+ % \pgfkeyscurrentname and \pgfcurrentlkeypath
+ \pgfkeys@pathtoks{}%
+ \expandafter\pgfkeys@splitter\pgfkeyscurrentkey//%
+}
+\def\pgfkeys@splitter#1/#2/{%
+ \def\pgfkeys@temp{#2}%
+ \ifx\pgfkeys@temp\pgfkeys@empty%
+ % Ah. done
+ \def\pgfkeyscurrentname{#1}%
+ \expandafter\pgfkeys@gobbletoslash%
+ \else%
+ \expandafter\pgfkeys@pathtoks\expandafter{\the\pgfkeys@pathtoks#1/}%
+ \fi%
+ \pgfkeys@splitter#2/%
+}
+\def\pgfkeys@gobbletoslash\pgfkeys@splitter/{\expandafter\pgfkeys@remove@slash\the\pgfkeys@pathtoks\relax}%
+\def\pgfkeys@remove@slash#1/\relax{\pgfkeys@pathtoks{#1}}
+
+
+
+% Quickly set keys
+%
+% #1 = default path
+% #2 = key-value pairs
+%
+% Desscription:
+%
+% This command starts the execution with the default path set to
+% #1. This command should only be used when speed is important (like
+% in a heavily used macro like \tikzset). Normally, keys should be
+% used to set the path. Note that if #1 equals /, then \pgfkeys will
+% actually be quicker!
+%
+% Example:
+%
+% \pgfqkeys{/tikz}{myother length/.code=\def\myotherlength{#1}\pgfkeysalso{length=#1}}
+
+\def\pgfqkeys{\expandafter\pgfkeys@@qset\expandafter{\pgfkeysdefaultpath}}%
+\def\pgfkeys@@qset#1#2#3{\def\pgfkeysdefaultpath{#2/}\pgfkeys@parse#3,\pgfkeys@mainstop\def\pgfkeysdefaultpath{#1}}
+
+
+% Sets keys while setting keys
+%
+% #1 = key-value pairs
+%
+% Desscription:
+%
+% This code may only be called inside the code that is executed for a
+% key. The #1 should be a list of settings pairs. They will be executed
+% as if they had been given as the argument to the \pgfkeys command.
+%
+% Example:
+%
+% \pgfkeys{tikz,myother length/.code=\def\myotherlength{#1}\pgfkeysalso{length=#1}}
+
+\def\pgfkeysalso#1{\pgfkeys@parse#1,\pgfkeys@mainstop}
+
+
+
+% Quickly sets keys while setting keys
+%
+% #1 = default path
+% #2 = key-value pairs
+%
+% Desscription:
+%
+% This command executes #2 with the default path set to #1. This
+% command will cause chaos if used incorrectly. The only safe
+% place to use it instead of \pgfkeys is at the beginning of a TeX group.
+%
+% Example:
+%
+% \begingroup
+% \pgfqkeysalso{/tikz}{myother length/.code=\def\myotherlength{#1}\pgfkeysalso{length=#1}}
+
+\def\pgfqkeysalso#1#2{\def\pgfkeysdefaultpath{#1/}\pgfkeys@parse#2,\pgfkeys@mainstop}
+
+
+
+
+% Now setup the default handelers and keys:
+
+% Define a key macro with one argument (\def or \edef)
+%
+% #1 = key
+% #2 = code
+%
+% Description:
+%
+% This command will setup things so the key/.@cmd contains a macro
+% that takes one parameter and has #2 as its code.
+%
+% Example:
+%
+% \pgfkeysdef{/my key}{\show#1}
+
+\def\pgfkeysdef#1#2{%
+ \def\pgfkeys@temp##1\pgfeov{#2}%
+ \pgfkeyslet{#1/.@cmd}{\pgfkeys@temp}%
+}
+\def\pgfkeysedef#1#2{%
+ \edef\pgfkeys@temp##1\pgfeov{#2}%
+ \pgfkeyslet{#1/.@cmd}{\pgfkeys@temp}%
+}
+
+
+% Define a key macro with mutliple arguments (\def or \edef)
+%
+% #1 = key
+% #2 = argument pattern
+% #2 = code
+%
+% Description:
+%
+% This command will setup things so the key/.@cmd contains a macro
+% that takes #2 as its parameter pattern and has #3 as its code.
+%
+% Example:
+%
+% \pgfkeysdefargs{/swap}{#1#2}{#2#1}
+
+\def\pgfkeysdefargs#1#2#3{%
+ \def\pgfkeys@temp#2\pgfeov{#3}%
+ \pgfkeyslet{#1/.@cmd}{\pgfkeys@temp}%
+ \pgfkeyssetvalue{#1/.@args}{#2\pgfeov}%
+ \pgfkeyssetvalue{#1/.@body}{#3}%
+}
+\def\pgfkeysedefargs#1#2#3{%
+ \edef\pgfkeys@temp#2\pgfeov{#3}%
+ \pgfkeyslet{#1/.@cmd}{\pgfkeys@temp}%
+ \pgfkeyssetvalue{#1/.@args}{#2\pgfeov}%
+ \pgfkeyssetvalue{#1/.@body}{#3}%
+}
+
+
+
+% Defining a key command
+
+\pgfkeysdef{/handlers/.code}{\pgfkeysdef{\pgfkeyscurrentpath}{#1}}
+\pgfkeysdef{/handlers/.code 2 args}{\pgfkeysdefargs{\pgfkeyscurrentpath}{##1##2}{#1}}
+\pgfkeysdef{/handlers/.ecode}{\pgfkeysedef{\pgfkeyscurrentpath}{#1}}
+\pgfkeysdef{/handlers/.ecode 2 args}{\pgfkeysedefargs{\pgfkeyscurrentpath}{##1##2}{#1}}
+\pgfkeysdefargs{/handlers/.code args}{#1#2}{\pgfkeysdefargs{\pgfkeyscurrentpath}{#1}{#2}}
+\pgfkeysdefargs{/handlers/.ecode args}{#1#2}{\pgfkeysedefargs{\pgfkeyscurrentpath}{#1}{#2}}
+
+% Adding to a key command
+
+\pgfkeys{/handlers/.add code/.code 2 args=%
+ % Find out, whether with args or not.
+ \pgfkeysifdefined{\pgfkeyscurrentpath/.@args}%
+ {% Yes, so add to body and reuse args
+ \pgfkeysaddvalue{\pgfkeyscurrentpath/.@body}{#1}{#2}%
+ % Redefine code
+ \pgfkeysgetvalue{\pgfkeyscurrentpath/.@args}{\pgfkeys@tempargs}
+ \pgfkeysgetvalue{\pgfkeyscurrentpath/.@body}{\pgfkeys@tempbody}
+ \expandafter\expandafter\expandafter\def\expandafter\pgfkeys@temp\expandafter\pgfkeys@tempargs\expandafter{\pgfkeys@tempbody}%
+ \pgfkeyslet{\pgfkeyscurrentpath/.@cmd}{\pgfkeys@temp}%
+ }%
+ {%
+ % No, so single argument. Redefine accordingly.
+ {%
+ \toks0{#1}%
+ \pgfkeysifdefined{\pgfkeyscurrentpath/.@cmd}%
+ {\pgfkeys@temptoks\expandafter\expandafter\expandafter{\csname pgfk@\pgfkeyscurrentpath/.@cmd\endcsname##1\pgfeov}}%
+ {\pgfkeys@temptoks{}}%
+ \toks1{#2}%
+ \xdef\pgfkeys@global@temp{\the\toks0 \the\pgfkeys@temptoks \the\toks1}%
+ }%
+ \expandafter\def\expandafter\pgfkeys@temp\expandafter##\expandafter1\expandafter\pgfeov\expandafter{\pgfkeys@global@temp}%
+ \pgfkeyslet{\pgfkeyscurrentpath/.@cmd}\pgfkeys@temp%
+ }%
+}
+\pgfkeys{/handlers/.prefix code/.code=\pgfkeys{\pgfkeyscurrentpath/.add code={#1}{}}}%
+\pgfkeys{/handlers/.append code/.code=\pgfkeys{\pgfkeyscurrentpath/.add code={}{#1}}}%
+
+
+% Defining a style
+
+\pgfkeys{/handlers/.style/.code=\pgfkeys{\pgfkeyscurrentpath/.code=\pgfkeysalso{#1}}}
+\pgfkeys{/handlers/.estyle/.code=\pgfkeys{\pgfkeyscurrentpath/.ecode=\noexpand\pgfkeysalso{#1}}}
+\pgfkeys{/handlers/.style args/.code 2 args=\pgfkeys{\pgfkeyscurrentpath/.code args={#1}{\pgfkeysalso{#2}}}}
+\pgfkeys{/handlers/.estyle args/.code 2 args=\pgfkeys{\pgfkeyscurrentpath/.ecode args={#1}{\noexpand\pgfkeysalso{#2}}}}
+\pgfkeys{/handlers/.style 2 args/.code=\pgfkeys{\pgfkeyscurrentpath/.code 2 args=\pgfkeysalso{#1}}}
+
+% Adding to a style
+
+\pgfkeys{/handlers/.add style/.code 2 args=\pgfkeys{\pgfkeyscurrentpath/.add code={\pgfkeysalso{#1}}{\pgfkeysalso{#2}}}}%
+\pgfkeys{/handlers/.prefix style/.code=\pgfkeys{\pgfkeyscurrentpath/.add code={\pgfkeysalso{#1}}{}}}%
+\pgfkeys{/handlers/.append style/.code=\pgfkeys{\pgfkeyscurrentpath/.add code={}{\pgfkeysalso{#1}}}}%
+
+
+% Defining a value
+
+\pgfkeys{/handlers/.initial/.code=\pgfkeyssetvalue{\pgfkeyscurrentpath}{#1}}
+\pgfkeys{/handlers/.add/.code 2 args=\pgfkeysaddvalue{\pgfkeyscurrentpath}{#1}{#2}}
+\pgfkeys{/handlers/.get/.code=\pgfkeysgetvalue{\pgfkeyscurrentpath}{#1}}
+
+% Defining a default
+
+\pgfkeys{/handlers/.default/.code=\pgfkeyssetvalue{\pgfkeyscurrentpath/.@def}{#1}}
+\pgfkeys{/handlers/.value required/.code=\pgfkeyssetvalue{\pgfkeyscurrentpath/.@def}{\pgfkeysvaluerequired}}
+\pgfkeys{/handlers/.value forbidden/.code=\pgfkeys{\pgfkeyscurrentpath/.add code=%
+{%
+ \ifx\pgfkeyscurrentvalue\pgfkeysnovalue@text%
+ \else%
+ \pgfkeysvalueof{/errors/value forbidden/.@cmd}\pgfkeyscurrentkey\pgfkeyscurrentvalue\pgfeov%
+ \fi%
+}{}}}
+
+
+% High-level cmds
+
+\pgfkeys{/handlers/.store in/.code=\pgfkeysalso{\pgfkeyscurrentpath/.code=\def#1{##1}}}
+\pgfkeys{/handlers/.estore in/.code=\pgfkeysalso{\pgfkeyscurrentpath/.code=\edef#1{##1}}}
+
+\pgfkeys{/handlers/.is if/.code=\pgfkeysalso{%
+ \pgfkeyscurrentpath/.code=\pgfkeys@handle@boolean{#1}{##1},
+ \pgfkeyscurrentpath/.default=true%
+ }%
+}
+\def\pgfkeys@handle@boolean#1#2{%
+ \pgfkeys@ifcsname#1#2\endcsname%
+ \csname#1#2\endcsname%
+ \else%
+ \pgfkeysvalueof{/errors/boolean expected/.@cmd}\pgfkeyscurrentkey{#2}\pgfeov%
+ \fi
+}
+
+\pgfkeys{/handlers/.is choice/.code=%
+ \pgfkeys{%
+ \pgfkeyscurrentpath/.cd,%
+ .code=\expandafter\pgfkeysalso\expandafter{\pgfkeyscurrentkey/##1},
+ .unknown/.style={/errors/unknown choice value=\pgfkeyscurrentkey\pgfkeyscurrentvalue}}}
+
+
+% Inspection handlers
+
+\pgfkeys{/handlers/.show value/.code=\pgfkeysgetvalue{\pgfkeyscurrentpath}{\pgfkeysshower}\show\pgfkeysshower} % inspect the value
+\pgfkeys{/handlers/.show code/.code=\pgfkeysgetvalue{\pgfkeyscurrentpath/.@cmd}{\pgfkeysshower}\show\pgfkeysshower} % inspect the body of the command
+
+
+% Path handling
+
+\pgfkeys{/handlers/.is family/.code=\pgfkeys{\pgfkeyscurrentpath/.ecode=\edef\noexpand\pgfkeysdefaultpath{\pgfkeyscurrentpath/}}}
+\pgfkeys{/handlers/.cd/.code=\edef\pgfkeysdefaultpath{\pgfkeyscurrentpath/}}
+
+
+% Value expansion
+
+\pgfkeys{/handlers/.expand once/.code=\expandafter\pgfkeys@exp@call\expandafter{#1}}
+\pgfkeys{/handlers/.expand twice/.code=\expandafter\expandafter\expandafter\pgfkeys@exp@call\expandafter\expandafter\expandafter{#1}}
+\pgfkeys{/handlers/.expanded/.code=\edef\pgfkeys@temp{#1}\expandafter\pgfkeys@exp@call\expandafter{\pgfkeys@temp}}
+
+\def\pgfkeys@exp@call#1{\pgfkeysalso{\pgfkeyscurrentpath=#1}}
+
+% Try to set a key and do nothing if not define
+
+\newif\ifpgfkeyssuccess
+\pgfkeys{/handlers/.try/.code=\pgfkeys@try}
+\pgfkeys{/handlers/.retry/.code=\ifpgfkeyssuccess\else\pgfkeys@try\fi}
+\def\pgfkeys@try{%
+ \pgfkeysifdefined{\pgfkeyscurrentpath/.@cmd}%
+ {%
+ \pgfkeysgetvalue{\pgfkeyscurrentpath/.@cmd}{\pgfkeys@code}%
+ \ifx\pgfkeyscurrentvalue\pgfkeysnovalue@text% Hmm... no value
+ \pgfkeysifdefined{\pgfkeyscurrentpath/.@def}%
+ {\pgfkeysgetvalue{\pgfkeyscurrentpath/.@def}{\pgfkeyscurrentvalue}}
+ {}% no default, so leave it
+ \fi%
+ \expandafter\pgfkeys@code\pgfkeyscurrentvalue\pgfeov%
+ \pgfkeyssuccesstrue%
+ }%
+ {%
+ \pgfkeysifdefined{\pgfkeyscurrentpath}%
+ {%
+ \ifx\pgfkeyscurrentvalue\pgfkeysnovalue@text%
+ \pgfkeysvalueof{\pgfkeyscurrentpath}%
+ \else%
+ \pgfkeyslet{\pgfkeyscurrentpath}\pgfkeyscurrentvalue%
+ \fi%
+ \pgfkeyssuccesstrue%
+ }%
+ {\pgfkeyssuccessfalse}%
+ }%
+}
+
+% Utilities
+
+\pgfkeys{/utils/exec/.code=#1} % simply execute the given code directly.
+
+
+% Errors
+
+\pgfkeys{/errors/boolean expected/.code 2 args=\pgfkeys@error{%
+ Boolean parameter of key '#1' must be 'true' or 'false', not
+ '#2'. I am going to ignore it}}
+\pgfkeys{/errors/value required/.code 2 args=\pgfkeys@error{%
+ The key '#1' requires a value. I am going to ignore this key}{}}
+\pgfkeys{/errors/value forbidden/.code 2 args=\pgfkeys@error{%
+ You may not specify a value for the key '#1'. I am going to ignore
+ the value '#2' that you provided}}
+\pgfkeys{/errors/unknown choice value/.code 2 args=\pgfkeys@error{%
+ Choice '\pgfkeyscurrentname' unknown in key
+ '\pgfkeyscurrentpath'. I am going to ignore this key}}
+\pgfkeys{/errors/unknown key/.code 2 args=\pgfkeys@error{%
+ I do not know the key '#1' and I am going to ignore it. Perhaps
+ you misspelled it}}
+
+\pgfkeys{/handlers/.unknown/.code=%
+ {%
+ \let\pgfkeys@orig@key=\pgfkeyscurrentkey%
+ \pgfkeysalso{/errors/unknown key=\pgfkeys@orig@key{}}%
+ }
+}
+
+
+
+\endinput