Files
nim-web3/web3/ethhexstrings.nim
T
2023-12-12 12:15:34 +07:00

105 lines
3.2 KiB
Nim

# nim-web3
# Copyright (c) 2019-2023 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
# * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.
import
std/[json, strutils]
from json_rpc/jsonmarshal import expect
export json
type
HexQuantityStr* = distinct string
HexDataStr* = distinct string
# Hex validation
template stripLeadingZeros(value: string): string =
var cidx = 0
# ignore the last character so we retain '0' on zero value
while cidx < value.len - 1 and value[cidx] == '0':
cidx.inc
value[cidx .. ^1]
func encodeQuantity*(value: SomeUnsignedInt): string =
var hValue = value.toHex.stripLeadingZeros
result = "0x" & hValue.toLowerAscii
func hasHexHeader*(value: string): bool =
value.len >= 2 and value[0] == '0' and value[1] in {'x', 'X'}
template hasHexHeader*(value: HexDataStr|HexQuantityStr): bool =
value.string.hasHexHeader
func isHexChar*(c: char): bool =
if c notin {'0'..'9'} and
c notin {'a'..'f'} and
c notin {'A'..'F'}: false
else: true
func validate*(value: HexQuantityStr): bool =
template strVal: untyped = value.string
if not value.hasHexHeader:
return false
# No leading zeros (but allow 0x0)
if strVal.len < 3 or (strVal.len > 3 and strVal[2] == '0'): return false
for i in 2..<strVal.len:
let c = strVal[i]
if not c.isHexChar:
return false
return true
func validate*(value: HexDataStr): bool =
template strVal: untyped = value.string
if not value.hasHexHeader:
return false
# Leading zeros are allowed
for i in 2..<strVal.len:
let c = strVal[i]
if not c.isHexChar:
return false
# Must be even number of digits
if strVal.len mod 2 != 0: return false
return true
# Initialisation
template hexDataStr*(value: string): HexDataStr = value.HexDataStr
template hexQuantityStr*(value: string): HexQuantityStr = value.HexQuantityStr
# Converters
func `%`*(value: HexDataStr): JsonNode =
if not value.validate:
raise newException(ValueError, "HexDataStr: Invalid hex for Ethereum: " & value.string)
else:
result = %(value.string)
func `%`*(value: HexQuantityStr): JsonNode =
if not value.validate:
raise newException(ValueError, "HexQuantityStr: Invalid hex for Ethereum: " & value.string)
else:
result = %(value.string)
func fromJson*(n: JsonNode, argName: string, result: var HexDataStr) =
# Note that '0x' is stripped after validation
n.kind.expect(JString, argName)
let hexStr = n.getStr()
if not hexStr.hexDataStr.validate:
raise newException(ValueError, "Parameter \"" & argName & "\" value is not valid as a Ethereum data \"" & hexStr & "\"")
result = hexStr[2..hexStr.high].hexDataStr
func fromJson*(n: JsonNode, argName: string, result: var HexQuantityStr) =
# Note that '0x' is stripped after validation
n.kind.expect(JString, argName)
let hexStr = n.getStr()
if not hexStr.hexQuantityStr.validate:
raise newException(ValueError, "Parameter \"" & argName & "\" value is not valid as an Ethereum hex quantity \"" & hexStr & "\"")
result = hexStr[2..hexStr.high].hexQuantityStr