Merge pull request #6 from launchdarkly/eb/ch110425/float-exp-parsing

fix float parsing when there's an exponent but no decimal

Author: eli-darkly

internal/commontest/test_values.go

@@ -47,10 +47,14 @@ func makeNumberTestValues(encodingBehavior encodingBehavior) []testValue {
 		{"int large", 1603312301195, "1603312301195", ""}, // enough magnitude for a millisecond timestamp
 		{"float", 3.5, "3.5", ""},
 		{"float negative", -3.5, "-3.5", ""},
-		{"float with exp", 3500, "3.5e3", "3500"},
-		{"float with Exp", 3500, "3.5E3", "3500"},
-		{"float with exp+", 3500, "3.5e+3", "3500"},
-		{"float with exp-", 0.0035, "3.5e-3", "0.0035"},
+		{"float with exp and decimal", 3500, "3.5e3", "3500"},
+		{"float with Exp and decimal", 3500, "3.5E3", "3500"},
+		{"float with exp+ and decimal", 3500, "3.5e+3", "3500"},
+		{"float with exp- and decimal", 0.0035, "3.5e-3", "0.0035"},
+		{"float with exp but no decimal", 5000, "5e3", "5000"},
+		{"float with Exp but no decimal", 5000, "5E3", "5000"},
+		{"float with exp+ but no decimal", 5000, "5e+3", "5000"},
+		{"float with exp- but no decimal", 0.005, "5e-3", "0.005"},
 	} {
 		enc := v.encoding
 		if !encodingBehavior.forParsing && v.simplestEncoding != "" {

jreader/token_reader_default.go

@@ -380,21 +380,22 @@ func (r *tokenReader) consumeASCIILowercaseAlphabeticChars() int {
 
 func (r *tokenReader) readNumber(first byte) (float64, bool) {
 	startPos := r.lastPos
-	hasDecimal := false
+	isFloat := false
 	var ch byte
 	var ok bool
 	for {
 		ch, ok = r.readByte()
 		if !ok {
 			break
 		}
-		if (ch < '0' || ch > '9') && !(ch == '.' && !hasDecimal) {
+		if (ch < '0' || ch > '9') && !(ch == '.' && !isFloat) {
 			break
 		}
 		if ch == '.' {
-			hasDecimal = true
+			isFloat = true
 		}
 	}
+	hasExponent := false
 	if ch == 'e' || ch == 'E' {
 		// exponent must match this regex: [eE][-+]?[0-9]+
 		ch, ok = r.readByte()
@@ -407,7 +408,6 @@ func (r *tokenReader) readNumber(first byte) (float64, bool) {
 		} else {
 			return 0, false
 		}
-		haveExpDigits := false
 		for {
 			ch, ok = r.readByte()
 			if !ok {
@@ -417,18 +417,19 @@ func (r *tokenReader) readNumber(first byte) (float64, bool) {
 				r.unreadByte()
 				break
 			}
-			haveExpDigits = true
+			hasExponent = true
 		}
-		if !haveExpDigits {
+		if !hasExponent {
 			return 0, false
 		}
+		isFloat = true
 	} else {
 		if ok {
 			r.unreadByte()
 		}
 	}
 	chars := r.data[startPos:r.pos]
-	if hasDecimal {
+	if isFloat {
 		// Unfortunately, strconv.ParseFloat requires a string - there is no []byte equivalent. This means we can't
 		// avoid a heap allocation here. Easyjson works around this by creating an unsafe string that points directly
 		// at the existing bytes, but in our default implementation we can't use unsafe.