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package bjc.pratt.commands;
import bjc.data.Tree;
import bjc.pratt.tokens.Token;
/**
* Represents the result of executing a command.
*
* @author bjcul
*
* @param <K> The key type of the tokens
* @param <V> The value type of the tokens
*/
public class CommandResult<K, V> {
/**
* Represents the status of a command execution
*
* @author bjcul
*
*/
public static enum Status {
/**
* The command successfully parsed.
*/
SUCCESS,
/**
* The command failed, in a non-recoverable way
*/
FAIL,
/**
* The command failed. Attempt recovery via backtracking
*/
BACKTRACK
}
/**
* The status of this command.
*/
public final Status status;
private Tree<Token<K, V>> success;
private CommandResult(Status status) {
this.status = status;
}
/**
* Get the success value of this command, or null if it failed.
*
* @return The success value of the command
*/
public Tree<Token<K, V>> success() {
return success;
}
/**
* Create a success result
*
* @param <K2> The key type of the token
* @param <V2> The value type of the token
*
* @param succ The tree produced by the command
*
* @return A command result representing a success
*/
public static <K2, V2> CommandResult<K2, V2> success(Tree<Token<K2, V2>> succ) {
CommandResult<K2, V2> result = new CommandResult<>(Status.SUCCESS);
result.success = succ;
return result;
}
/**
* Create a non-backtracking failure result.
*
* @param <K2> The key type of the token
* @param <V2> The value type of the token
*
* @return A command result representing a non-backtracking fail
*/
public static <K2, V2> CommandResult<K2, V2> fail() {
CommandResult<K2, V2> result = new CommandResult<>(Status.FAIL);
return result;
}
/**
* Create a backtracking failure result.
*
* @param <K2> The key type of the token
* @param <V2> The value type of the token
*
* @return A command result representing a backtracking fail
*/
public static <K2, V2> CommandResult<K2, V2> backtrack() {
CommandResult<K2, V2> result = new CommandResult<>(Status.BACKTRACK);
return result;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("CommandResult [status=");
builder.append(status);
if (status == Status.SUCCESS) {
builder.append(", success=");
builder.append(success);
}
builder.append("]");
return builder.toString();
}
}
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