147 lines
3.0 KiB
Go
147 lines
3.0 KiB
Go
package rfc8259exponentnumber
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import (
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"io"
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"sourcecode.social/reiver/go-erorr"
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"sourcecode.social/reiver/go-rfc8259/errors"
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)
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// Parse tries to parse the JSON exponent-number literal.
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// If it succeeds, then it return nil.
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// If it failed, it returns an error.
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//
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// IETF RFC-8259 calls a exponent number an "int" with this definition:
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//
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// e = %x65 / %x45 ; e E
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//
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// exp = e [ minus / plus ] 1*DIGIT
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//
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// minus = %x2D ; -
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//
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// plus = %x2B ; +
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//
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// Example usage:
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//
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// var runescanner io.RuneScanner
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//
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// // ...
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//
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// var dst rfc8259exponentnumber.ExponentNumber
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// err := rfc8259exponentnumber.Parse(runescanner, &dst)
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//
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// if nil != err {
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// return err
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// }
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//
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// fmt.Printf("dst = %#v\n", dst)
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func Parse(runescanner io.RuneScanner, dst *ExponentNumber) error {
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if nil == runescanner {
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return rfc8259errors.ErrNilRuneScanner
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}
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if nil == dst {
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return rfc8259errors.ErrNilDestination
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}
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var buffer [256]byte
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var p []byte = buffer[0:0]
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{
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var r rune
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{
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var err error
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r, _, err = runescanner.ReadRune()
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if nil != err {
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if io.EOF == err {
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return rfc8259errors.ErrUnexpectedEndOfFile
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}
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return rfc8259errors.ErrProblemReadingRune(err)
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}
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}
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if 'E' != r && 'e' != r {
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return erorr.Errorf("rfc8259: JSON parser encountered a problem — when trying to parse a exponent-number, expected the first character to be 'E', or 'e', but actually was %q (%U)", r, r)
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}
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p = append(p, string(r)...)
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}
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{
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var r rune
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{
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var err error
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r, _, err = runescanner.ReadRune()
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if nil != err {
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if io.EOF == err {
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return rfc8259errors.ErrUnexpectedEndOfFile
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}
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return rfc8259errors.ErrProblemReadingRune(err)
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}
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}
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switch r {
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case '+', '-':
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p = append(p, string(r)...)
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default:
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if err := runescanner.UnreadRune(); nil != err {
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return rfc8259errors.ErrProblemUnreadingRune(err, r)
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}
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}
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}
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{
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var r rune
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{
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var err error
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r, _, err = runescanner.ReadRune()
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if nil != err {
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if io.EOF == err {
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return rfc8259errors.ErrUnexpectedEndOfFile
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}
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return rfc8259errors.ErrProblemReadingRune(err)
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}
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}
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switch r {
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case '0', '1','2','3','4','5','6','7','8','9':
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p = append(p, string(r)...)
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default:
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return erorr.Errorf("rfc8259: JSON parser encountered a problem — when trying to parse a exponent-number, expected the character after %q to be '0', '1', '2', '3', '4', '5', '6', '7', '8', or '9', but actually was %q (%U)", string(p), r, r)
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}
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}
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loop: for {
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var r rune
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{
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var err error
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r, _, err = runescanner.ReadRune()
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if nil != err && io.EOF != err {
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return rfc8259errors.ErrProblemReadingRune(err)
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}
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if io.EOF == err {
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/////////////////////// BREAK
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break loop
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}
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switch r {
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case '0','1','2','3','4','5','6','7','8','9':
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p = append(p, string(r)...)
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default:
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if err := runescanner.UnreadRune(); nil != err {
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return rfc8259errors.ErrProblemUnreadingRune(err, r)
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}
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/////////////////////// BREAK
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break loop
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}
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}
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}
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*dst = Something(string(p))
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return nil
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}
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