initial commits

number/parse.go

@@ -0,0 +1,110 @@
+package rfc8259number
+
+import (
+	"io"
+
+	"sourcecode.social/reiver/go-rfc8259/errors"
+	"sourcecode.social/reiver/go-rfc8259/exponentnumber"
+	"sourcecode.social/reiver/go-rfc8259/fractionalnumber"
+	"sourcecode.social/reiver/go-rfc8259/naturalnumber"
+)
+
+// Parse tries to parse a JSON number literal.
+// If it succeeds, then it return nil, and sets ‘dst’ to the parsed value.
+// If it failed, it returns an error.
+//
+// Example usage:
+//
+//	var rs io.RuneScaner
+//	
+//	// ...
+//	
+//	var value rfc8259number.Number
+//	err := rfc8259number.Parse(rs, &value)
+//	
+//	if nil != err {
+//		return err
+//	}
+//	
+//	fmt.Printf("value = %#v\n", value)
+func Parse(runescanner io.RuneScanner, dst *Number) error {
+	if nil == runescanner {
+		return rfc8259errors.ErrNilRuneScanner
+	}
+	if nil == dst {
+		return rfc8259errors.ErrNilDestination
+	}
+
+	var natPart rfc8259naturalnumber.NaturalNumber         // [ minus ] int
+	var fracPart rfc8259fractionalnumber.FractionalNumber  // [ frac ]
+	var expPart rfc8259exponentnumber.ExponentNumber       // [ exp ]
+
+	// [ minus ] int
+	{
+		if err := rfc8259naturalnumber.Parse(runescanner, &natPart); nil != err {
+			return err
+		}
+		if rfc8259naturalnumber.Nothing() == natPart {
+			return rfc8259errors.ErrInternalError("expected the result of a natural-number, but it is actually nothing")
+		}
+	}
+
+	// [ frac ]
+	{
+		var r rune
+		{
+			var err error
+
+			r, _, err = runescanner.ReadRune()
+			if nil != err {
+				if io.EOF == err {
+					natPart.WhenSomething(func(value string){
+						*dst = Something(value)
+					})
+					return nil
+				}
+
+				return rfc8259errors.ErrProblemReadingRune(err)
+			}
+			if err := runescanner.UnreadRune(); nil != err {
+				return rfc8259errors.ErrProblemUnreadingRune(err, r)
+			}
+		}
+
+		if '.' == r {
+			if err := rfc8259fractionalnumber.Parse(runescanner, &fracPart); nil != err {
+				return err
+			}
+		}
+	}
+
+	// [ exp ]
+	{
+		var r rune
+		{
+			var err error
+
+			r, _, err = runescanner.ReadRune()
+			if nil != err {
+				if io.EOF == err {
+					*dst = Something(natPart.GetElse("") + fracPart.GetElse(""))
+					return nil
+				}
+
+				return rfc8259errors.ErrProblemReadingRune(err)
+			}
+			if err := runescanner.UnreadRune(); nil != err {
+				return rfc8259errors.ErrProblemUnreadingRune(err, r)
+			}
+		}
+
+		if 'E' == r || 'e' == r {
+			if err := rfc8259exponentnumber.Parse(runescanner, &expPart); nil != err {
+				return err
+			}
+		}
+	}
+
+	*dst = Something(natPart.GetElse("") + fracPart.GetElse("") + expPart.GetElse(""))
+	return nil
+}