977229eb5a
Scanning subdivision csv-table entries one-by-one takes significant time and system resources. To speed up random access to table records, on the first call, the table is pumped into memory (map). On subsequent calls, I/O operations are not performed. Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
75 lines
1.6 KiB
Go
75 lines
1.6 KiB
Go
package csvlocode
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import (
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"fmt"
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"os"
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"sync"
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)
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// Prm groups the required parameters of the Table'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 UN/LOCODE csv table.
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//
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// Must not be empty.
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Path string
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// Path to csv table of UN/LOCODE Subdivisions.
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//
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// Must not be empty.
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SubDivPath string
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}
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// Table is a descriptor of the UN/LOCODE table in csv format.
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//
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// For correct operation, Table 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 Table is immediately ready to work through API.
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type Table struct {
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paths []string
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mode os.FileMode
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subDivPath string
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subDivOnce sync.Once
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mSubDiv map[subDivKey]subDivRecord
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}
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const invalidPrmValFmt = "invalid parameter %s (%T):%v"
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func panicOnPrmValue(n string, v interface{}) {
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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 Table.
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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 Table 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) *Table {
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switch {
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case prm.Path == "":
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panicOnPrmValue("Path", prm.Path)
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case prm.SubDivPath == "":
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panicOnPrmValue("SubDivPath", prm.SubDivPath)
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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 &Table{
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paths: append(o.extraPaths, prm.Path),
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mode: o.mode,
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subDivPath: prm.SubDivPath,
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}
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}
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