84 lines
1.8 KiB
Go
84 lines
1.8 KiB
Go
package airportsdb
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import (
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"fmt"
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"io/fs"
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"sync"
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)
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// Prm groups the required parameters of the DB's constructor.
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//
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// All values must comply with the requirements imposed on them.
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// Passing incorrect parameter values will result in constructor
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// failure (error or panic depending on the implementation).
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type Prm struct {
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// Path to OpenFlights Airport csv table.
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//
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// Must not be empty.
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AirportsPath string
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// Path to OpenFlights Countries csv table.
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//
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// Must not be empty.
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CountriesPath string
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}
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// DB is a descriptor of the OpenFlights database in csv format.
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//
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// For correct operation, DB must be created
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// using the constructor (New) based on the required parameters
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// and optional components. After successful creation,
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// The DB is immediately ready to work through API.
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type DB struct {
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airports, countries pathMode
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airportsOnce, countriesOnce sync.Once
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mCountries map[string]string
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mAirports map[string][]record
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}
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type pathMode struct {
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path string
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mode fs.FileMode
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}
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const invalidPrmValFmt = "invalid parameter %s (%T):%v"
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func panicOnPrmValue(n string, v any) {
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panic(fmt.Sprintf(invalidPrmValFmt, n, v, v))
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}
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// New creates a new instance of the DB.
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//
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// Panics if at least one value of the parameters is invalid.
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//
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// The created DB does not require additional
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// initialization and is completely ready for work.
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func New(prm Prm, opts ...Option) *DB {
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switch {
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case prm.AirportsPath == "":
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panicOnPrmValue("AirportsPath", prm.AirportsPath)
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case prm.CountriesPath == "":
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panicOnPrmValue("CountriesPath", prm.CountriesPath)
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}
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o := defaultOpts()
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for i := range opts {
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opts[i](o)
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}
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return &DB{
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airports: pathMode{
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path: prm.AirportsPath,
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mode: o.airportMode,
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},
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countries: pathMode{
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path: prm.CountriesPath,
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mode: o.countryMode,
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},
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}
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}
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