picocli

Interface CommandLine.IParameterPreprocessor

Enclosing class:

CommandLine

public static interface CommandLine.IParameterPreprocessor

Options, positional parameters and commands can be assigned a IParameterPreprocessor that implements custom logic to preprocess the parameters for this option, position or command. When an option, positional parameter or command with a custom IParameterPreprocessor is matched on the command line, picocli's internal parser is temporarily suspended, and this custom logic is invoked.

This custom logic may completely replace picocli's internal parsing for this option, positional parameter or command, or it may do some preprocessing before picocli's internal parsing is resumed for this option, positional parameter or command.

The "preprocessing" can include modifying the stack of command line parameters, or modifying the model.

This may be useful when disambiguating input for commands that have both a positional parameter and an option with an optional parameter.

Example usage:

 @Command(name = "edit")
 class Edit {
     @Parameters(index = "0", description = "The file to edit.")
     File file;

     enum Editor { defaultEditor, eclipse, idea, netbeans }

     @Option(names = "--open", arity = "0..1", preprocessor = Edit.MyPreprocessor.class,
         description = {
             "Optionally specify the editor to use; if omitted the default editor is used. ",
             "Example: edit --open=idea FILE opens IntelliJ IDEA (notice the '=' separator)",
             "         edit --open FILE opens the specified file in the default editor"
         })
     Editor editor = Editor.defaultEditor;

     static class MyPreprocessor implements IParameterPreprocessor {
         public boolean preprocess(Stack<String> args, CommandSpec commandSpec, ArgSpec argSpec, Map<String, Object> info) {
             // we need to decide whether the next arg is the file to edit or the name of the editor to use...
             if (" ".equals(info.get("separator"))) { // parameter was not attached to option
                 args.push(Editor.defaultEditor.name()); // act as if the user specified --open=defaultEditor
             }
             return false; // picocli's internal parsing is resumed for this option
         }
     }
 }

Since:

4.6

See Also:

CommandLine.Option.preprocessor(), CommandLine.Parameters.preprocessor()

Method Summary

Modifier and Type	Method and Description
boolean	preprocess(Stack<String> args, CommandLine.Model.CommandSpec commandSpec, CommandLine.Model.ArgSpec argSpec, Map<String,Object> info) Called when either the command, option or positional parameter that has this preprocessor configured was recognized by the picocli parser.

Method Detail

preprocess

boolean preprocess(Stack<String> args,
                   CommandLine.Model.CommandSpec commandSpec,
                   CommandLine.Model.ArgSpec argSpec,
                   Map<String,Object> info)

Called when either the command, option or positional parameter that has this preprocessor configured was recognized by the picocli parser.

Implementors are free to modify one or more of the specified command line arguments before they are processed by the picocli parser (or by the option's parameter consumer, if one is specified).

Implementors may optionally consume one or more of the specified command line arguments: a return value of true signals that the preprocessor consumed the parameter: picocli should skip further processing of this option or positional parameter, and the preprocessor implementation takes responsibility for assigning the option or positional parameter a value. A return value of false means that picocli should process the stack as usual for this option or positional parameter, and picocli is responsible for assigning this option or positional parameter a value.

For a command, returning true signals that the preprocessor takes responsibility for parsing all options and positional parameters for this command, and takes responsibility for validating constraints like whether all required options and positional parameters were specified. A return value of false means that picocli should process the stack as usual for this command, and picocli is responsible for validation. Command preprocessors can signal back to the picocli parser when they detect that the user requested version information or usage help by putting a value of true in the specified info map for keys versionHelpRequested or usageHelpRequested, respectively.

If the user input is invalid, implementations should throw a CommandLine.ParameterException with a message to display to the user.

Parameters:

args - the remaining command line arguments that follow the matched argument (the matched argument is not on the stack anymore)

commandSpec - the command or subcommand that was matched (if the specified argSpec is null), or the command that the matched option or positional parameter belongs to

argSpec - the option or positional parameter for which to pre-process command line arguments (may be null when this method is called for a subcommand that was matched)

info - a map containing additional information on the current parser state, including whether the option parameter was attached to the option name with a `=` separator, whether quotes have already been stripped off the option, etc. Implementations may modify this map to communicate back to the picocli parser. Supported values:

Supported values in the info Map

key	valid values	type
separator	'' (empty string): attached without separator, ' ' (space): not attached, (any other string): option name was attached to option param with specified separator	java.lang.String
negated	true: the option or positional parameter is a negated option/parameter, false: the option or positional parameter is not a negated option/parameter	java.lang.Boolean
unquoted	true: quotes surrounding the value have already been stripped off, false: quotes surrounding the value have not yet been stripped off	java.lang.Boolean
versionHelpRequested	true: version help was requested, false: version help was not requested	java.lang.Boolean
usageHelpRequested	true: usage help was requested, false: usage help was not requested	java.lang.Boolean

Returns:

true if the preprocessor consumed the parameter and picocli should skip further processing of the stack for this option or positional parameter; false if picocli should continue processing the stack for this option or positional parameter

Throws:

CommandLine.ParameterException - if the user input is invalid