75 lines
2.8 KiB
Go
75 lines
2.8 KiB
Go
// In this example, a Parser is created that can parse and normalize Dutch postcodes
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// The implementation uses only TokenHandler functions and does not implement a
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// full-fledged state-based Parser for it.
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package examples
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import (
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"fmt"
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"git.makaay.nl/mauricem/go-parsekit"
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)
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func Example_dutchPostcodeUsingTokenizer() {
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parser := createPostcodeTokenizer()
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for i, input := range []string{
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"1234 AB",
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"2233Ab",
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"1001\t\tab",
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"1818ab",
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"1212abc",
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"1234",
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"huh",
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"",
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"\xcd2222AB",
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} {
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result, err := parser.Execute(input)
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if err != nil {
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fmt.Printf("[%d] Input: %q Error: %s\n", i, input, err.Full())
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} else {
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fmt.Printf("[%d] Input: %q Output: %s Tokens:", i, input, result)
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for _, t := range result.Tokens() {
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fmt.Printf(" %s(%s)", t.Type, t.Value)
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}
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fmt.Printf("\n")
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}
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}
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// Output:
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// [0] Input: "1234 AB" Output: 1234 AB Tokens: PCD(1234) PCL(AB)
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// [1] Input: "2233Ab" Output: 2233 AB Tokens: PCD(2233) PCL(AB)
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// [2] Input: "1001\t\tab" Output: 1001 AB Tokens: PCD(1001) PCL(AB)
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// [3] Input: "1818ab" Output: 1818 AB Tokens: PCD(1818) PCL(AB)
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// [4] Input: "1212abc" Error: unexpected character '1' (expected a Dutch postcode) at start of file
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// [5] Input: "1234" Error: unexpected character '1' (expected a Dutch postcode) at start of file
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// [6] Input: "huh" Error: unexpected character 'h' (expected a Dutch postcode) at start of file
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// [7] Input: "" Error: unexpected end of file (expected a Dutch postcode) at start of file
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// [8] Input: "\xcd2222AB" Error: unexpected character '<27>' (expected a Dutch postcode) at start of file
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}
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// ---------------------------------------------------------------------------
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// Implementation of the parser
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// ---------------------------------------------------------------------------
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func createPostcodeTokenizer() *parsekit.Tokenizer {
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// Easy access to the parsekit definitions.
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C, A, M, T := parsekit.C, parsekit.A, parsekit.M, parsekit.T
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// TokenHandler functions are created and combined to satisfy these rules:
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// - A Dutch postcode consists of 4 digits and 2 letters (1234XX).
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// - The first digit is never a zero.
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// - A space between letters and digits is optional.
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// - It is good form to write the letters in upper case.
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// - It is good form to use a single space between digits and letters.
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digitNotZero := C.Except(A.Rune('0'), A.Digit)
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pcDigits := C.Seq(digitNotZero, C.Rep(3, A.Digit))
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pcLetter := C.Any(A.ASCIILower, A.ASCIIUpper)
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pcLetters := M.ToUpper(C.Seq(pcLetter, pcLetter))
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space := M.Replace(C.Opt(A.Whitespace), " ")
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postcode := C.Seq(T.Str("PCD", pcDigits), space, T.Str("PCL", pcLetters), A.EndOfFile)
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// Create a Tokenizer that wraps the 'postcode' TokenHandler and allows
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// us to match some input against that handler.
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return parsekit.NewTokenizer(postcode, "a Dutch postcode")
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}
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