linedb

Documentation

Overview

Package linedb provides an OO-like interface to operate on simple line-record databases backed by a plain text file.

The rules are as follows:

• One file, one database;
• One line, one record;
• An empty (0 bytes) database file contains exactly zero records;
• In all other cases, an empty line is a valid record;
• No assumptions are made about the inner structure of each record, even in terms of white space characters;
• The only special character is the record separator, '\n'.

Index

• type Database
  • func Open(filePath string) (*Database, error)
  • func (db *Database) All() []Rec
  • func (db *Database) Delete(number int) (string, error)
  • func (db *Database) Insert(number int, record string) error
  • func (db *Database) Length() int
  • func (db *Database) Record(number int) (string, error)
  • func (db *Database) Select(filter func(Rec) bool) []Rec
  • func (db *Database) Update(number int, record string) (string, error)
• type Rec

Types

type Database

type Database struct {
	// contains filtered or unexported fields
}

Database represents a handle to a given backing file.

func Open

func Open(filePath string) (*Database, error)

Open creates a handle to the given backing file.

func (*Database) All

func (db *Database) All() []Rec

All returns all the records with their respective number

func (*Database) Delete

func (db *Database) Delete(number int) (string, error)

Delete removes the number-th record from the database.

func (*Database) Insert

func (db *Database) Insert(number int, record string) error

Insert creates a new record at position n, pushing the n-th record and all subsequent records one position forward, i.e, Insert(1, ...) would create a new record at the beginning of the file.

Special case: Insert(0, ...) places the new record at the end of the file.

func (*Database) Length

func (db *Database) Length() int

Length returns the number of records in the database.

func (*Database) Record

func (db *Database) Record(number int) (string, error)

Record returns the number-th record in the database. Like lines in files, records are 1-indexed.

func (*Database) Select

func (db *Database) Select(filter func(Rec) bool) []Rec

Select returns the records which cause the filter function to return true.

func (*Database) Update

func (db *Database) Update(number int, record string) (string, error)

Update replaces the text of the number-th record, and returns the old text.

type Rec

type Rec struct {
	Number int
	Text   string
}

Rec pairs the text of a record with its line number in the backing file.