VarExpansion.java

package org.xmlsh.sh.core;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.EnumSet;
import org.xmlsh.core.CoreException;
import org.xmlsh.core.EvalEnv;
import org.xmlsh.core.EvalFlag;
import org.xmlsh.core.XVariableExpr;
import org.xmlsh.sh.grammar.Token;
import org.xmlsh.sh.shell.ParseResult;
import org.xmlsh.sh.shell.Shell;
import org.xmlsh.util.Util;

/*
 * Variable Expansion detected at parser time
 * 
 * ${ [#|!] varname [ '[' index ']' ] [ ':' expr }
 * 
 */
public class VarExpansion extends Word {
  private final static EnumSet<EvalFlag> _indMskFlags = EnumSet.of(
      EvalFlag.EXPAND_VAR, EvalFlag.PARSE_QUOTES, EvalFlag.JOIN_VALUES,
      EvalFlag.OMIT_NULL);
  private String mPrefix; // "#" | "!"
  private String mVarname;
  private Word mIndex;
  private Word mField;

  // Single token expansion
  public VarExpansion(Token t, String simplevar) {
    super(t);
    mVarname = simplevar;
  }

  public VarExpansion(Token t, String prefix, String var, Word ind,
      Word field) {
    super(t);
    mPrefix = prefix;
    mVarname = var;
    mIndex = ind;
    mField = field;
  }

  @Override
  public void print(PrintWriter out) {
    out.print("${");
    if(mPrefix != null)
      out.print(mPrefix);
    out.print(mVarname);
    if(mIndex != null) {
      out.print("[");
      mIndex.print(out);
      out.print("]");
    }
    if(mField != null) {
      out.print(":");
      mField.print(out);
    }
    out.print("}");
  }

  @Override
  protected ParseResult expandToResult(Shell shell, EvalEnv env,
      ParseResult result) throws IOException, CoreException {
    String ind = mIndex != null ? mIndex.expandString(shell, indEnv(env))
        : null;
    String field = mField != null ? mField.expandString(shell, env) : null;
    XVariableExpr expr = new XVariableExpr(mPrefix, mVarname, ind, field);
    return EvalUtils.evalVarToResult(shell, expr, env, env.asCharAttrs(),
        result);
  }

  private EvalEnv indEnv(EvalEnv env) {
    return env.withFlagsMasked(_indMskFlags);
  }

  @Override
  public boolean isEmpty() {

    return Util.isEmpty(mVarname);

  }

  @Override
  String getSimpleName() {
    return mVarname;
  }

}