aud.util.Sys Class Reference

System related utilities. More...

Collaboration diagram for aud.util.Sys:

Classes
class	ExternalProgram
	Get path of an external program.

Static Public Member Functions
static synchronized String	env (String varname)
	Get environment variable varname. More...
static String	indent (int level)
	get indentation string filled with spaces More...
static File	writeToFile (File file, String text)
	write text to file @endiliteral More...
static File	writeToTempFile (String text, String suffix)
	write text to temporary file More...
static String	readFile (File file)
	read entire file and return contents as String More...
static void	execAndDetach (String command)
	Execute command in a new process and detach. More...
static void	viewPDFFile (String filename)
	open PDF viewer More...
static String	whereAmI (int depth)
	get code location (like __FILE__,__LINE__ More...
static String	whereAmI ()
	get code location (like __FILE__,__LINE__ More...
static void	emacsclient (String file, int line, int column)
	open emacs client (Un*x only) (or no action otherwise) More...
static void	openCallersSourceInEmacs (int depth)
	open emacs whereAmI (Un*x only) More...

Detailed Description

System related utilities.

Some functions require external tools. The paths of the tools can be set as envionment variables.

Required GraphViz binaries

tool	environment variable	default path (colon-separated list)	purpose
PDF viewer	AUD_PDFVIEWER	/usr/bin/evince	view PDF files
GraphViz dot	AUD_DOT	/usr/bin/dot:/usr/local/bin/dot:/local/usr/bin/dot:/opt/homebrew/bin	layout and render graphs
Emacs	AUD_EMACS	/usr/bin/emacs	editor (Un*x only)
Emacs client	AUD_EMACSCLIENT	/usr/bin/emacsclient	editor (Un*x only)

Notes

• This is not "production code"! There are tests missing, and not all potential errors are handled. In this sense, this is "bad" code!

• In particular, some functions just return null on error and use the fact that Java checks references and would raise a NullPointerException if return values are not checked. – Don't try this in C++! Never!

Definition at line 58 of file Sys.java.

Member Function Documentation

emacsclient()

static void aud.util.Sys.emacsclient ( String  file, int  line, int  column  )

static

open emacs client (Un*x only) (or no action otherwise)

Definition at line 273 of file Sys.java.

                                                                  {
    if (EMACS.isAvailable() && EMACSCLIENT.isAvailable()) {
      String command=
        EMACSCLIENT.getPath()+" -a "+EMACS.getPath()+" -n +"+line+
        (column>0 ? ":"+column+" " : " ")+file;
      System.err.println(command);
      execAndDetach(command);
    }
  }

Referenced by aud.util.Sys.openCallersSourceInEmacs().

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env()

static synchronized String aud.util.Sys.env ( String  varname )

static

Get environment variable varname.

Parameters

varname

variable name

Returns

value or null if undefined

Definition at line 176 of file Sys.java.

                                                        {
    if (env_==null)
      env_=System.getenv();
    return env_.get(varname);
  }

Referenced by aud.util.SingleStepper.SingleStepper().

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execAndDetach()

static void aud.util.Sys.execAndDetach ( String  command )

static

Execute command in a new process and detach.

Java seems unable to "really" detach processes, so we start the process within a new Java thread.

Parameters

command

same as for Runtime.exec

Definition at line 237 of file Sys.java.

                                                   {
    Thread t=new Thread(new Runnable()
    {
      public void run() {
        try {
          String cmd=Thread.currentThread().getName();
          //System.err.println(cmd);
          //Runtime.getRuntime().exec(cmd); // fix deprecation (since Java 18)
          new ProcessBuilder(cmd.split(" ")).start();
        } catch(IOException e) {
          e.printStackTrace();
        }
      }
    },command);
    t.start();
  }

Referenced by aud.util.Sys.viewPDFFile().

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indent()

static String aud.util.Sys.indent ( int  level )

static

get indentation string filled with spaces

Definition at line 183 of file Sys.java.

                                         {
    String spaces="";
    for (int i=0;i<level;++i) spaces+="  ";
    return spaces;
  }

Referenced by aud.BinaryTree< T >.toTikZ().

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openCallersSourceInEmacs()

static void aud.util.Sys.openCallersSourceInEmacs ( int  depth )

static

open emacs whereAmI (Un*x only)

Definition at line 284 of file Sys.java.

                                                         {
    StackTraceElement location=new Throwable().getStackTrace()[depth+1];
    File file=new File(location.getFileName().toString());
    if (file.exists())
      emacsclient(file.getPath(),location.getLineNumber(),0);
    else
      System.err.println("unknown path for source file '"+file+"'");
  }

References aud.util.Sys.emacsclient().

Referenced by aud.util.SingleStepper.showSource().

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readFile()

static String aud.util.Sys.readFile ( File  file )

static

read entire file and return contents as String

Definition at line 216 of file Sys.java.

                                           {
    byte[] buffer = new byte[(int) file.length()];
    BufferedInputStream f = null;
    try {
      f = new BufferedInputStream(new FileInputStream(file));
      f.read(buffer);
    } catch (IOException e) {
      System.err.println("ERROR: "+e.getMessage());
      return null; // note: probably triggers NullPointerException
    } finally {
      if (f != null) try { f.close(); } catch (IOException ignored) { }
    }
    return new String(buffer);
  }

Referenced by aud.example.graph.GraphParser.main(), aud.util.DotViewer.main(), aud.example.graph.MyGraph.MyGraph(), and aud.example.graph.GraphParser.parse().

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viewPDFFile()

static void aud.util.Sys.viewPDFFile ( String  filename )

static

open PDF viewer

Definition at line 255 of file Sys.java.

                                                  {
    Sys.execAndDetach(PDFVIEWER.getPath()+" "+filename);
  }

References aud.util.Sys.execAndDetach().

Referenced by aud.util.Graphviz.displayAsPDF().

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whereAmI() [1/2]

static String aud.util.Sys.whereAmI ( )

static

get code location (like __FILE__,__LINE__

Definition at line 268 of file Sys.java.

                                  {
    return whereAmI(0);
  }

References aud.util.Sys.whereAmI().

Referenced by aud.util.Sys.whereAmI().

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whereAmI() [2/2]

static String aud.util.Sys.whereAmI ( int  depth )

static

get code location (like __FILE__,__LINE__

Definition at line 260 of file Sys.java.

                                           {
    StackTraceElement location=new Throwable().getStackTrace()[depth+1];
    String rv=location.getFileName().toString()+":";
    rv+=location.getLineNumber()+" ";
    rv+=location.getClassName()+"#"+location.getMethodName();
    return rv;
  }

Referenced by aud.util.SingleStepper.halt(), and aud.util.SingleStepper.whereAmI().

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writeToFile()

static File aud.util.Sys.writeToFile ( File  file, String  text  )

static

write text to file @endiliteral


Returns

file

Definition at line 192 of file Sys.java.

                                                        {
    try {
      FileOutputStream f=new FileOutputStream(file);
      f.write(text.getBytes());
      f.close();
    } catch (IOException e) {
      System.err.println("ERROR: "+e.getMessage());
      return null; // note: probably triggers NullPointerException
    }
    return file;
  }

Referenced by aud.util.DotViewer.display(), and aud.util.Sys.writeToTempFile().

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writeToTempFile()

static File aud.util.Sys.writeToTempFile ( String  text, String  suffix  )

static

write text to temporary file

Returns

file

Definition at line 206 of file Sys.java.

                                                                {
    try {
      return writeToFile(File.createTempFile("aud-",suffix),text);
    } catch (IOException e) {
      System.err.println("ERROR: "+e.getMessage());
      return null; // note: probably triggers NullPointerException
    }
  }

References aud.util.Sys.writeToFile().

Referenced by aud.util.Graphviz.displayAsPDF().

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The documentation for this class was generated from the following file:

• Sys.java