nim-web3/web3/ethhexstrings.nim

96 lines
2.8 KiB
Nim

import strutils
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]
proc encodeQuantity*(value: SomeUnsignedInt): string =
var hValue = value.toHex.stripLeadingZeros
result = "0x" & hValue
func hasHexHeader*(value: string): bool =
if value != "" and value[0] == '0' and value[1] in {'x', 'X'} and value.len > 2: true
else: false
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
proc validate*(value: HexQuantityStr): bool =
template strVal: untyped = value.string
if not value.hasHexHeader:
return false
# No leading zeros
if strVal[2] == '0': return false
for i in 2..<strVal.len:
let c = strVal[i]
if not c.isHexChar:
return false
return true
proc 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
import json
from json_rpc/rpcserver import expect
proc `%`*(value: HexDataStr): JsonNode =
if not value.validate:
raise newException(ValueError, "HexDataStr: Invalid hex for Ethereum: " & value.string)
else:
result = %(value.string)
proc `%`*(value: HexQuantityStr): JsonNode =
if not value.validate:
raise newException(ValueError, "HexQuantityStr: Invalid hex for Ethereum: " & value.string)
else:
result = %(value.string)
proc 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
proc 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