edu.mit.ai.psg.jevaUI
Class JevaCLI

java.lang.Object
  |
  +--edu.mit.ai.psg.jevaUI.JevaCLI

public class JevaCLI

extends Object

JevaCLI is a command line (stream) interface for the Jeva Java evalator of expressions & statements. JevaCLI can be used as

• an application: main starts a top read-eval-print-loop (repl). Good for quickly trying out some class in the classpath. See main(java.lang.String[]).
• a breakpoint/stub: an application may call JevaCLI.repl(..) providing an environment of current names, and the user can evaluate Java expression and statements in that environment, including calling other stubs, returning values, and throwing exceptions.

JevaCLI invokes Jeva, which accepts Java 1.2 (except inner and anonymous classes). Previous results (including nulls) are stored in a Vector:

 
.  localResults.get(n) 

Jexa may be invoked programmatically:

.  import edu.mit.ai.psg.jexa.Jexa;
.  Jexa.examine(expression)

See Also:

JevaGUI, edu.mit.ai.psg.jeva

Field Summary

static String	continuePromptFormat
static String	promptFormat Format for the prompt; takes number as single (0th) argument.
static Vector	results Vector of result values from expressions typed at the window

Method Summary

static void	main(String[] arguments) Application Startup: Loops accepting top level statements and expressions from System.in .
static Object	repl() Read-Eval-Print-Loop: starts a loop which reads Java expressions and statements from System.in , including return statements to return a value.
static Object	repl(int options, String initialMessage, Reader inReader, PrintWriter outWriter, Class returnClass, Class[] throwsClasses, IEnv env, String initStatements) Read-Eval-Print-Loop: starts a loop which reads Java expressions and statements from inStream, including return statements to return a value.
static void	replTop() Top read-eval-print-loop: reads Java expressions and statements from System.in, evaluates them, and prints results of expressions on System.out.
static void	replTop(int options, String initStatements)
static void	replTop(int options, String initialMessage, String initStatements)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

results

public static Vector results

Vector of result values from expressions typed at the window

promptFormat

public static String promptFormat

Format for the prompt; takes number as single (0th) argument.

See Also:

MessageFormat

continuePromptFormat

public static String continuePromptFormat

Method Detail

main

public static void main(String[] arguments)

Application Startup: Loops accepting top level statements and expressions from System.in .

replTop

public static void replTop()

Top read-eval-print-loop: reads Java expressions and statements from System.in, evaluates them, and prints results of expressions on System.out.

replTop

public static void replTop(int options,
                           String initStatements)

replTop

public static void replTop(int options,
                           String initialMessage,
                           String initStatements)

repl

public static Object repl()
                   throws Throwable

Read-Eval-Print-Loop: starts a loop which reads Java expressions and statements from System.in , including return statements to return a value.

Throws:

Throwable - --- throws anything user throws.

repl

public static Object repl(int options,
                          String initialMessage,
                          Reader inReader,
                          PrintWriter outWriter,
                          Class returnClass,
                          Class[] throwsClasses,
                          IEnv env,
                          String initStatements)
                   throws Throwable

Read-Eval-Print-Loop: starts a loop which reads Java expressions and statements from inStream, including return statements to return a value.

Parameters:

options - Option flag bits or'ed together; 0 is default. Jeva options used only if env is null.

initialMessage - Non-null text replaces herald; if called from a breakpoint, a good practice is to show user contents of env.

inReader - Reader from which to read Java constructs. If null, uses new InputStreamReader(System.in).

outWriter - Writer to which to write messages, results. If null, uses new PrintWriter(System.out, true).

returnClass - user may only return a value of this class (like method return type); Object.class allows anything. Use void.class for void result. If null, never returns or throws (like a top level loop).

throwsClasses - user may only throw Throwables which are instances of these classes, or instances of Error or RuntimeException (like method throw declarations). If null, defaults to no declarations. If returnClass is not null, then throws are actually thrown; otherwise they are caught and displayed.

env - initial environment created with Jeva.makeDefaultEnv, Jeva.extendEnv(), or Jeva.parseEval..Statement If null, defaults to Jeva.makeDefaultEnv() .

initStatements - initial statements to run. (Convenience feature for extending env from command line or applet parameter, e.g., to specify default imports for user input.) If null, defaults to no statements.

Throws:

Throwable - --- throws anything user throws compatibile with throwsClasses