// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// =================================================================================================
package com.twitter.common.thrift.text;
import java.io.IOException;
import com.google.gson.JsonElement;
import com.google.gson.stream.JsonWriter;
/**
* A type parsing helper, knows how to parse a given type either from a string
* or from a JsonElement, and knows how to emit a given type to a JsonWriter.
*
* Clients should use the static members defined here for common types.
* Should be implemented for each integral type we need to read/write.
*
* @author Alex Roetter
*
* @param <T> The type we are trying to read.
*/
abstract class TypedParser<T> {
// Static methods clients can use.
static final TypedParser<Boolean> BOOLEAN = new TypedParser<Boolean>() {
@Override
public Boolean readFromString(String s) {
return Boolean.parseBoolean(s);
}
@Override
public Boolean readFromJsonElement(JsonElement elem) {
return elem.getAsBoolean();
}
@Override
public void writeValue(JsonWriter jw, Boolean val) throws IOException {
jw.value(val);
}
};
static final TypedParser<Byte> BYTE = new TypedParser<Byte>() {
@Override
public Byte readFromString(String s) {
return Byte.parseByte(s);
}
@Override
public Byte readFromJsonElement(JsonElement elem) {
return elem.getAsByte();
}
@Override
public void writeValue(JsonWriter jw, Byte val) throws IOException {
jw.value(val);
}
};
static final TypedParser<Short> SHORT = new TypedParser<Short>() {
@Override
public Short readFromString(String s) {
return Short.parseShort(s);
}
@Override
public Short readFromJsonElement(JsonElement elem) {
return elem.getAsShort();
}
@Override
public void writeValue(JsonWriter jw, Short val) throws IOException {
jw.value(val);
}
};
static final TypedParser<Integer> INTEGER = new TypedParser<Integer>() {
@Override
public Integer readFromString(String s) {
return Integer.parseInt(s);
}
@Override
public Integer readFromJsonElement(JsonElement elem) {
return elem.getAsInt();
}
@Override
public void writeValue(JsonWriter jw, Integer val) throws IOException {
jw.value(val);
}
};
static final TypedParser<Long> LONG = new TypedParser<Long>() {
@Override
public Long readFromString(String s) {
return Long.parseLong(s);
}
@Override
public Long readFromJsonElement(JsonElement elem) {
return elem.getAsLong();
}
@Override
public void writeValue(JsonWriter jw, Long val) throws IOException {
jw.value(val);
}
};
static final TypedParser<Double> DOUBLE = new TypedParser<Double>() {
@Override
public Double readFromString(String s) {
return Double.parseDouble(s);
}
@Override
public Double readFromJsonElement(JsonElement elem) {
return elem.getAsDouble();
}
@Override
public void writeValue(JsonWriter jw, Double val) throws IOException {
jw.value(val);
}
};
static final TypedParser<String> STRING = new TypedParser<String>() {
@Override
public String readFromString(String s) {
return s;
}
@Override
public String readFromJsonElement(JsonElement elem) {
return elem.getAsString();
}
@Override
public void writeValue(JsonWriter jw, String val) throws IOException {
jw.value(val);
}
};
/**
* Convert from a string to the given type
*/
abstract T readFromString(String s);
/**
* Read the given type from a JsonElement
*/
abstract T readFromJsonElement(JsonElement elem);
/**
* Write the given type out using a JsonWriter
*/
abstract void writeValue(JsonWriter jw, T val) throws IOException;
}