DefaultLineExpander (JLine Bundle 4.1.3 API)

java.lang.Object

org.jline.shell.impl.DefaultLineExpander

All Implemented Interfaces:: LineExpander

public class DefaultLineExpander extends Object implements LineExpander

Default implementation of LineExpander that provides sane defaults for variable expansion.

Supported expansions:

$VAR and ${VAR} — variable expansion from session variables, then System.getenv()
~ at word start — expands to user.home system property
Single-quoted regions ('...') are not expanded
Double-quoted regions ("...") expand variables

Advanced braced forms:

${VAR:-default} — use default if VAR is unset or empty
${VAR:=default} — assign default if VAR is unset or empty
${VAR:+alt} — use alt if VAR is set and non-empty
${VAR:?error} — error if VAR is unset or empty

Deliberately not included (subclass for these):

${VAR//pattern/replacement} — pattern substitution
Glob expansion (*, ?)

Subclasses can override resolve(String, CommandSession) to customize how variable names are resolved.

Since:

4.0

See Also:

Constructor Summary

Constructors

Constructor

Description

DefaultLineExpander()

Creates a new DefaultLineExpander.
Method Summary

Modifier and Type

Method

Description

String

expand(String line, CommandSession session)

Expands variables and expressions in the given command line.

protected String

expandBracedExpression(String expr, CommandSession session)

Expands a braced expression such as VAR, VAR:-default, VAR:=default, VAR:+alt, or VAR:?error.

protected String

resolve(String name, CommandSession session)

Resolves a variable name to its value.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details
- DefaultLineExpander
  
  public DefaultLineExpander()
  
  Creates a new DefaultLineExpander.
Method Details
- expand
  
  public String expand(String line, CommandSession session)
  
  Description copied from interface: LineExpander
  
  Expands variables and expressions in the given command line.
  
  Specified by:
  
  expand in interface LineExpander
  
  Parameters:
  
  line - the command line to expand
  
  session - the current command session (for variable lookup)
  
  Returns:
  
  the expanded command line
- expandBracedExpression
  
  protected String expandBracedExpression(String expr, CommandSession session)
  
  Expands a braced expression such as VAR, VAR:-default, VAR:=default, VAR:+alt, or VAR:?error.
  
  Parameters:
  
  expr - the expression inside the braces (without ${ })
  
  session - the command session
  
  Returns:
  
  the expanded value, or null if the variable is unknown and no modifier applies
- resolve
  
  protected String resolve(String name, CommandSession session)
  
  Resolves a variable name to its value.
  The default implementation checks session variables first, then falls back to System.getenv().
  Subclasses can override this to provide custom resolution (e.g., Groovy evaluation, default values).
  
  Parameters:
  
  name - the variable name
  
  session - the current command session
  
  Returns:
  
  the resolved value as a string, or null if not found