diff options
Diffstat (limited to 'vendor/google.golang.org/protobuf/internal/encoding/json/decode_number.go')
-rw-r--r-- | vendor/google.golang.org/protobuf/internal/encoding/json/decode_number.go | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/vendor/google.golang.org/protobuf/internal/encoding/json/decode_number.go b/vendor/google.golang.org/protobuf/internal/encoding/json/decode_number.go new file mode 100644 index 000000000..2999d7133 --- /dev/null +++ b/vendor/google.golang.org/protobuf/internal/encoding/json/decode_number.go @@ -0,0 +1,254 @@ +// 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 json + +import ( + "bytes" + "strconv" +) + +// parseNumber reads the given []byte for a valid JSON number. If it is valid, +// it returns the number of bytes. Parsing logic follows the definition in +// https://tools.ietf.org/html/rfc7159#section-6, and is based off +// encoding/json.isValidNumber function. +func parseNumber(input []byte) (int, bool) { + var n int + + s := input + if len(s) == 0 { + return 0, false + } + + // Optional - + if s[0] == '-' { + s = s[1:] + n++ + if len(s) == 0 { + return 0, false + } + } + + // Digits + switch { + case s[0] == '0': + s = s[1:] + n++ + + case '1' <= s[0] && s[0] <= '9': + s = s[1:] + n++ + for len(s) > 0 && '0' <= s[0] && s[0] <= '9' { + s = s[1:] + n++ + } + + default: + return 0, false + } + + // . followed by 1 or more digits. + if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' { + s = s[2:] + n += 2 + for len(s) > 0 && '0' <= s[0] && s[0] <= '9' { + s = s[1:] + n++ + } + } + + // e or E followed by an optional - or + and + // 1 or more digits. + if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') { + s = s[1:] + n++ + if s[0] == '+' || s[0] == '-' { + s = s[1:] + n++ + if len(s) == 0 { + return 0, false + } + } + for len(s) > 0 && '0' <= s[0] && s[0] <= '9' { + s = s[1:] + n++ + } + } + + // Check that next byte is a delimiter or it is at the end. + if n < len(input) && isNotDelim(input[n]) { + return 0, false + } + + return n, true +} + +// numberParts is the result of parsing out a valid JSON number. It contains +// the parts of a number. The parts are used for integer conversion. +type numberParts struct { + neg bool + intp []byte + frac []byte + exp []byte +} + +// parseNumber constructs numberParts from given []byte. The logic here is +// similar to consumeNumber above with the difference of having to construct +// numberParts. The slice fields in numberParts are subslices of the input. +func parseNumberParts(input []byte) (numberParts, bool) { + var neg bool + var intp []byte + var frac []byte + var exp []byte + + s := input + if len(s) == 0 { + return numberParts{}, false + } + + // Optional - + if s[0] == '-' { + neg = true + s = s[1:] + if len(s) == 0 { + return numberParts{}, false + } + } + + // Digits + switch { + case s[0] == '0': + // Skip first 0 and no need to store. + s = s[1:] + + case '1' <= s[0] && s[0] <= '9': + intp = s + n := 1 + s = s[1:] + for len(s) > 0 && '0' <= s[0] && s[0] <= '9' { + s = s[1:] + n++ + } + intp = intp[:n] + + default: + return numberParts{}, false + } + + // . followed by 1 or more digits. + if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' { + frac = s[1:] + n := 1 + s = s[2:] + for len(s) > 0 && '0' <= s[0] && s[0] <= '9' { + s = s[1:] + n++ + } + frac = frac[:n] + } + + // e or E followed by an optional - or + and + // 1 or more digits. + if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') { + s = s[1:] + exp = s + n := 0 + if s[0] == '+' || s[0] == '-' { + s = s[1:] + n++ + if len(s) == 0 { + return numberParts{}, false + } + } + for len(s) > 0 && '0' <= s[0] && s[0] <= '9' { + s = s[1:] + n++ + } + exp = exp[:n] + } + + return numberParts{ + neg: neg, + intp: intp, + frac: bytes.TrimRight(frac, "0"), // Remove unnecessary 0s to the right. + exp: exp, + }, true +} + +// normalizeToIntString returns an integer string in normal form without the +// E-notation for given numberParts. It will return false if it is not an +// integer or if the exponent exceeds than max/min int value. +func normalizeToIntString(n numberParts) (string, bool) { + intpSize := len(n.intp) + fracSize := len(n.frac) + + if intpSize == 0 && fracSize == 0 { + return "0", true + } + + var exp int + if len(n.exp) > 0 { + i, err := strconv.ParseInt(string(n.exp), 10, 32) + if err != nil { + return "", false + } + exp = int(i) + } + + var num []byte + if exp >= 0 { + // For positive E, shift fraction digits into integer part and also pad + // with zeroes as needed. + + // If there are more digits in fraction than the E value, then the + // number is not an integer. + if fracSize > exp { + return "", false + } + + // Make sure resulting digits are within max value limit to avoid + // unnecessarily constructing a large byte slice that may simply fail + // later on. + const maxDigits = 20 // Max uint64 value has 20 decimal digits. + if intpSize+exp > maxDigits { + return "", false + } + + // Set cap to make a copy of integer part when appended. + num = n.intp[:len(n.intp):len(n.intp)] + num = append(num, n.frac...) + for i := 0; i < exp-fracSize; i++ { + num = append(num, '0') + } + } else { + // For negative E, shift digits in integer part out. + + // If there are fractions, then the number is not an integer. + if fracSize > 0 { + return "", false + } + + // index is where the decimal point will be after adjusting for negative + // exponent. + index := intpSize + exp + if index < 0 { + return "", false + } + + num = n.intp + // If any of the digits being shifted to the right of the decimal point + // is non-zero, then the number is not an integer. + for i := index; i < intpSize; i++ { + if num[i] != '0' { + return "", false + } + } + num = num[:index] + } + + if n.neg { + return "-" + string(num), true + } + return string(num), true +} |