com.scalar.db.sql.Literal Maven / Gradle / Ivy
package com.scalar.db.sql;
import com.google.common.base.MoreObjects;
import java.util.Objects;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
/**
* A literal value, which is primarily used within SQL parsers. This class is needed because, based
* on the statement alone, the SQL parser cannot distinguish between certain value types, such as
* BIGINT vs. INT or FLOAT vs. DOUBLE. As a result, it retains these values as string
* representations. These string representations must be converted to their corresponding types when
* executing the statement.
*/
@Immutable
public class Literal implements Term {
public final Type type;
// The type of value depends on the type. If the type is BOOLEAN, the value should be of type
// java.lang.Boolean. If the type is DECIMAL, the value should be of type java.lang.String, and
// the content of the value should be a valid decimal number. If the type is FLOAT, the value
// should be of type java.lang.String, and the content of the value should be a valid float
// number. If the type is STRING, the value should be of type java.lang.String. If the type is
// NULL, the value should be null.
@Nullable public final Object value;
private Literal(Type type, @Nullable Object value) {
this.type = Objects.requireNonNull(type);
this.value = value;
}
@Override
public String toString() {
return MoreObjects.toStringHelper(this).add("type", type).add("value", value).toString();
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof Literal)) {
return false;
}
Literal literal = (Literal) o;
return type == literal.type && Objects.equals(value, literal.value);
}
@Override
public int hashCode() {
return Objects.hash(type, value);
}
/**
* Returns a {@code Literal} object for Boolean.
*
* @param value a boolean value
* @return a {@code Literal} object
*/
public static Literal ofBoolean(boolean value) {
return new Literal(Type.BOOLEAN, value);
}
/**
* Returns a {@code Literal} object for Decimal.
*
* @param value a decimal number as a string representation
* @return a {@code Literal} object
*/
public static Literal ofDecimal(String value) {
return new Literal(Type.DECIMAL, value);
}
/**
* Returns a {@code Literal} object for Float.
*
* @param value a float number as a string representation
* @return a {@code Literal} object
*/
public static Literal ofFloat(String value) {
return new Literal(Type.FLOAT, value);
}
/**
* Returns a {@code Literal} object for String.
*
* @param value a string value
* @return a {@code Literal} object
*/
public static Literal ofString(String value) {
return new Literal(Type.STRING, value);
}
/**
* Returns a {@code Literal} object for Null.
*
* @return a {@code Literal} object
*/
public static Literal ofNull() {
return new Literal(Type.NULL, null);
}
public enum Type {
BOOLEAN,
DECIMAL,
FLOAT,
STRING,
NULL
}
}