--- /dev/null
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Copyright 2016 Guilherme Mansur<guilhermerpmansur@gmail.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License 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.
+
+# Services to manipulate a Postgres database
+#
+# For more information, refer to the documentation of http://www.postgresql.org/docs/manuals/
+#
+# ### Usage example
+#
+# ~~~
+# class Animal
+# var name: String
+# var kind: String
+# var age: Int
+# end
+#
+# var animals = new Array[Animal]
+# var dog = new Animal("Lassy", "dog", 10)
+# var cat = new Animal("Garfield", "cat", 3)
+# var turtle = new Animal("George", "turtle", 123)
+#
+# animals.add(dog)
+# animals.add(cat)
+# animals.add(turtle)
+#
+# var db = new Postgres.open("dbname=postgres")
+#
+# assert db_is_open: not db.is_closed
+# assert create_table: db.create_table("IF NOT EXISTS animals (aname TEXT PRIMARY KEY, kind TEXT NOT NULL, age INT NOT NULL)") else print db.error
+#
+# for animal in animals do
+# assert insert: db.insert("INTO animals VALUES('{animal.name}', '{animal.kind}', {animal.age})") else print db.error
+# end
+#
+# var result = db.raw_execute("SELECT * FROM animals")
+# assert result.is_ok
+# assert drop_table: db.execute("DROP TABLE animals")
+# db.finish
+# assert db_is_closed: db.is_closed
+# ~~~
+module postgres
+
+private import native_postgres
+
+# A connection to a Postgres database
+class Postgres
+ private var native_connection: NativePostgres
+
+ var is_closed = true
+
+ # Open the connnection with the database using the `conninfo`
+ init open(conninfo: Text)
+ do
+ init(new NativePostgres.connectdb(conninfo))
+ if native_connection.status.is_ok then is_closed = false
+ end
+
+ # Close this connection with the database
+ fun finish
+ do
+ if is_closed then return
+
+ is_closed = true
+
+ native_connection.finish
+ end
+
+ fun prepare(stmt_name:String, query:String, num_params: Int):PGResult do return new PGResult(native_connection.prepare(stmt_name, query, num_params))
+
+ fun exec_prepared(stmt_name: String, num_params: Int, values: Array[String], param_lengths: Array[Int], param_formats: Array[Int], result_format: Int):PGResult do
+ return new PGResult(native_connection.exec_prepared(stmt_name, num_params, values, param_lengths, param_formats, result_format))
+ end
+
+ # Executes a `query` and returns the raw `PGResult`
+ fun raw_execute(query: Text): PGResult do return new PGResult(native_connection.exec(query))
+
+ # Execute the `sql` statement and returns `true` on success
+ fun execute(query: Text): Bool do return native_connection.exec(query).status.is_ok
+
+ # Create a table on the DB with a statement beginning with "CREATE TABLE ", followed by `rest`
+ #
+ # This method does not escape special characters.
+ fun create_table(rest: Text): Bool do return execute("CREATE TABLE " + rest)
+
+ # Insert in the DB with a statement beginning with "INSERT ", followed by `rest`
+ #
+ # This method does not escape special characters.
+ fun insert(rest: Text): Bool do return execute("INSERT " + rest)
+
+ # Replace in the DB with a statement beginning with "REPLACE", followed by `rest`
+ #
+ # This method does not escape special characters.
+ fun replace(rest: Text): Bool do return execute("REPLACE " + rest)
+
+ # The latest error message on the connection an empty string if none
+ fun error: String do return native_connection.error
+
+ # The status of this connection
+ fun is_valid: Bool do return native_connection.status.is_ok
+
+ # Resets the connection to the database
+ fun reset do native_connection.reset
+end
+
+# The result of a given query
+class PGResult
+ private var pg_result: NativePGResult
+
+ fun clear do pg_result.clear
+
+ # Returns the number of rows in the query result
+ fun ntuples:Int do return pg_result.ntuples
+
+ # Returns the number of columns in each row of the query result
+ fun nfields:Int do return pg_result.nfields
+
+ # Returns the ExecStatusType of a result
+ fun is_ok:Bool do return pg_result.status.is_ok
+
+ # Returns the field name of a given `column_number`
+ fun fname(column_number:Int):String do return pg_result.fname(column_number)
+
+ # Returns the column number associated with the `column_name`
+ fun fnumber(column_name:String):Int do return pg_result.fnumber(column_name)
+
+ # Returns a single field value of one row of the result at `row_number`, `column_number`
+ fun value(row_number:Int, column_number:Int):String do return pg_result.value(row_number, column_number)
+
+ # Tests wether a field specified by the `row_number` and `column_number` is null.
+ fun is_null(row_number:Int, column_number: Int): Bool do return pg_result.is_null(row_number, column_number)
+end
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