mirror of
https://github.com/amalthea-mc/ShopChest.git
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183 lines
7.3 KiB
Java
183 lines
7.3 KiB
Java
/*
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* Copyright (c) 2007 David Crawshaw <david@zentus.com>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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package org.sqlite;
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import java.sql.*;
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/** Provides an interface for creating SQLite user-defined functions.
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*
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* <p>A subclass of <tt>org.sqlite.Function</tt> can be registered with
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* <tt>Function.create()</tt> and called by the name it was given. All
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* functions must implement <tt>xFunc()</tt>, which is called when SQLite
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* runs the custom function.</p>
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*
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* Eg.
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*
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* <pre>
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* Class.forName("org.sqlite.JDBC");
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* Connection conn = DriverManager.getConnection("jdbc:sqlite:");
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*
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* Function.create(conn, "myFunc", new Function() {
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* protected void xFunc() {
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* System.out.println("myFunc called!");
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* }
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* });
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*
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* conn.createStatement().execute("select myFunc();");
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* </pre>
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*
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* <p>Arguments passed to a custom function can be accessed using the
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* <tt>protected</tt> functions provided. <tt>args()</tt> returns
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* the number of arguments passed, while
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* <tt>value_<type>(int)</tt> returns the value of the specific
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* argument. Similarly a function can return a value using the
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* <tt>result(<type>)</tt> function.</p>
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*
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* <p>Aggregate functions are not yet supported, but coming soon.</p>
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*
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*/
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public abstract class Function
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{
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private Conn conn;
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private DB db;
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long context = 0; // pointer sqlite3_context*
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long value = 0; // pointer sqlite3_value**
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int args = 0;
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/** Registers the given function with the Connection using the
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* provided name. */
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public static final void create(Connection conn, String name, Function f)
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throws SQLException {
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if (conn == null || !(conn instanceof Conn))
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throw new SQLException("connection must be to an SQLite db");
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if (conn.isClosed())
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throw new SQLException("connection closed");
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f.conn = (Conn)conn;
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f.db = f.conn.db();
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if (name == null || name.length() > 255)
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throw new SQLException("invalid function name: '"+name+"'");
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if (f.db.create_function(name, f) != Codes.SQLITE_OK)
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throw new SQLException("error creating function");
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}
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/** Removes the named function form the Connection. */
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public static final void destroy(Connection conn, String name)
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throws SQLException {
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if (conn == null || !(conn instanceof Conn))
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throw new SQLException("connection must be to an SQLite db");
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((Conn)conn).db().destroy_function(name);
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}
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/** Called by SQLite as a custom function. Should access arguments
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* through <tt>value_*(int)</tt>, return results with
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* <tt>result(*)</tt> and throw errors with <tt>error(String)</tt>. */
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protected abstract void xFunc() throws SQLException;
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/** Returns the number of arguments passed to the function.
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* Can only be called from <tt>xFunc()</tt>. */
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protected synchronized final int args()
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throws SQLException { checkContext(); return args; }
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/** Called by <tt>xFunc</tt> to return a value. */
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protected synchronized final void result(byte[] value)
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throws SQLException { checkContext(); db.result_blob(context, value); }
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/** Called by <tt>xFunc</tt> to return a value. */
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protected synchronized final void result(double value)
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throws SQLException { checkContext(); db.result_double(context,value);}
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/** Called by <tt>xFunc</tt> to return a value. */
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protected synchronized final void result(int value)
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throws SQLException { checkContext(); db.result_int(context, value); }
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/** Called by <tt>xFunc</tt> to return a value. */
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protected synchronized final void result(long value)
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throws SQLException { checkContext(); db.result_long(context, value); }
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/** Called by <tt>xFunc</tt> to return a value. */
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protected synchronized final void result()
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throws SQLException { checkContext(); db.result_null(context); }
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/** Called by <tt>xFunc</tt> to return a value. */
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protected synchronized final void result(String value)
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throws SQLException { checkContext(); db.result_text(context, value); }
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/** Called by <tt>xFunc</tt> to throw an error. */
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protected synchronized final void error(String err)
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throws SQLException { checkContext(); db.result_error(context, err); }
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final int value_bytes(int arg)
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throws SQLException {checkValue(arg); return db.value_bytes(this,arg);}
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final String value_text(int arg)
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throws SQLException {checkValue(arg); return db.value_text(this,arg);}
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final byte[] value_blob(int arg)
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throws SQLException {checkValue(arg); return db.value_blob(this,arg); }
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final double value_double(int arg)
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throws SQLException {checkValue(arg); return db.value_double(this,arg);}
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final int value_int(int arg)
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throws SQLException {checkValue(arg); return db.value_int(this, arg); }
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final long value_long(int arg)
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throws SQLException { checkValue(arg); return db.value_long(this,arg); }
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/** Called by <tt>xFunc</tt> to access the value of an argument. */
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protected synchronized final int value_type(int arg)
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throws SQLException {checkValue(arg); return db.value_type(this,arg); }
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private void checkContext() throws SQLException {
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if (conn == null || conn.db() == null || context == 0)
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throw new SQLException("no context, not allowed to read value");
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}
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private void checkValue(int arg) throws SQLException {
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if (conn == null || conn.db() == null || value == 0)
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throw new SQLException("not in value access state");
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if (arg >= args)
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throw new SQLException("arg "+arg+" out bounds [0,"+args+")");
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}
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public static abstract class Aggregate
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extends Function
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implements Cloneable
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{
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protected final void xFunc() {}
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protected abstract void xStep() throws SQLException;
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protected abstract void xFinal() throws SQLException;
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public Object clone() throws CloneNotSupportedException {
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return super.clone();
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}
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}
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}
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