vendor/google.golang.org/protobuf/internal/encoding/text/decode_number.go
changeset 256 6d9efbef00a9
child 260 445e01aede7e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/google.golang.org/protobuf/internal/encoding/text/decode_number.go	Sun Jul 11 10:35:56 2021 +0200
@@ -0,0 +1,190 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package text
+
+// parseNumberValue parses a number from the input and returns a Token object.
+func (d *Decoder) parseNumberValue() (Token, bool) {
+	in := d.in
+	num := parseNumber(in)
+	if num.size == 0 {
+		return Token{}, false
+	}
+	numAttrs := num.kind
+	if num.neg {
+		numAttrs |= isNegative
+	}
+	strSize := num.size
+	last := num.size - 1
+	if num.kind == numFloat && (d.in[last] == 'f' || d.in[last] == 'F') {
+		strSize = last
+	}
+	tok := Token{
+		kind:     Scalar,
+		attrs:    numberValue,
+		pos:      len(d.orig) - len(d.in),
+		raw:      d.in[:num.size],
+		str:      string(d.in[:strSize]),
+		numAttrs: numAttrs,
+	}
+	d.consume(num.size)
+	return tok, true
+}
+
+const (
+	numDec uint8 = (1 << iota) / 2
+	numHex
+	numOct
+	numFloat
+)
+
+// number is the result of parsing out a valid number from parseNumber. It
+// contains data for doing float or integer conversion via the strconv package
+// in conjunction with the input bytes.
+type number struct {
+	kind uint8
+	neg  bool
+	size int
+}
+
+// parseNumber constructs a number object from given input. It allows for the
+// following patterns:
+//   integer: ^-?([1-9][0-9]*|0[xX][0-9a-fA-F]+|0[0-7]*)
+//   float: ^-?((0|[1-9][0-9]*)?([.][0-9]*)?([eE][+-]?[0-9]+)?[fF]?)
+// It also returns the number of parsed bytes for the given number, 0 if it is
+// not a number.
+func parseNumber(input []byte) number {
+	kind := numDec
+	var size int
+	var neg bool
+
+	s := input
+	if len(s) == 0 {
+		return number{}
+	}
+
+	// Optional -
+	if s[0] == '-' {
+		neg = true
+		s = s[1:]
+		size++
+		if len(s) == 0 {
+			return number{}
+		}
+	}
+
+	// C++ allows for whitespace and comments in between the negative sign and
+	// the rest of the number. This logic currently does not but is consistent
+	// with v1.
+
+	switch {
+	case s[0] == '0':
+		if len(s) > 1 {
+			switch {
+			case s[1] == 'x' || s[1] == 'X':
+				// Parse as hex number.
+				kind = numHex
+				n := 2
+				s = s[2:]
+				for len(s) > 0 && (('0' <= s[0] && s[0] <= '9') ||
+					('a' <= s[0] && s[0] <= 'f') ||
+					('A' <= s[0] && s[0] <= 'F')) {
+					s = s[1:]
+					n++
+				}
+				if n == 2 {
+					return number{}
+				}
+				size += n
+
+			case '0' <= s[1] && s[1] <= '7':
+				// Parse as octal number.
+				kind = numOct
+				n := 2
+				s = s[2:]
+				for len(s) > 0 && '0' <= s[0] && s[0] <= '7' {
+					s = s[1:]
+					n++
+				}
+				size += n
+			}
+
+			if kind&(numHex|numOct) > 0 {
+				if len(s) > 0 && !isDelim(s[0]) {
+					return number{}
+				}
+				return number{kind: kind, neg: neg, size: size}
+			}
+		}
+		s = s[1:]
+		size++
+
+	case '1' <= s[0] && s[0] <= '9':
+		n := 1
+		s = s[1:]
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+			n++
+		}
+		size += n
+
+	case s[0] == '.':
+		// Set kind to numFloat to signify the intent to parse as float. And
+		// that it needs to have other digits after '.'.
+		kind = numFloat
+
+	default:
+		return number{}
+	}
+
+	// . followed by 0 or more digits.
+	if len(s) > 0 && s[0] == '.' {
+		n := 1
+		s = s[1:]
+		// If decimal point was before any digits, it should be followed by
+		// other digits.
+		if len(s) == 0 && kind == numFloat {
+			return number{}
+		}
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+			n++
+		}
+		size += n
+		kind = numFloat
+	}
+
+	// e or E followed by an optional - or + and 1 or more digits.
+	if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
+		kind = numFloat
+		s = s[1:]
+		n := 1
+		if s[0] == '+' || s[0] == '-' {
+			s = s[1:]
+			n++
+			if len(s) == 0 {
+				return number{}
+			}
+		}
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+			n++
+		}
+		size += n
+	}
+
+	// Optional suffix f or F for floats.
+	if len(s) > 0 && (s[0] == 'f' || s[0] == 'F') {
+		kind = numFloat
+		s = s[1:]
+		size++
+	}
+
+	// Check that next byte is a delimiter or it is at the end.
+	if len(s) > 0 && !isDelim(s[0]) {
+		return number{}
+	}
+
+	return number{kind: kind, neg: neg, size: size}
+}