Add parse bin int, fixes #8018 (#8020)

* clarify `parseHexInt`, `parseOctInt` docstring and exception msgs

* add `parseBinInt` based on `parseutil.parseBin` implementation

Adds a `parseBinInt`, which parses a binary integer string and returns
it as an integer. This is based on the implementation of
`parseutil.parseBin`, removing the unnecessary parts.

* add tests for all `parse(Hex|Oct|Bin)Int` procs

* replace `parse*Int` proc impls by call to parseutil procs

Replaces the `parse(Hex|Oct|Bin)Int` procedure implementation by calls
to the `parseutil` procs, which receive a mutable argument.

Has the main advantage that the empty string as well as a "prefix
only" string, e.g. "0x" counts as an invalid integer.

Also moves the `parseOctInt` proc further up in the file so that all
`parse` procs are below one another.

* replace `var L` by `let L` in `parse` procs

There's no reason for the usage of `var` here.

* add `maxLen` optional arg for `parseutil.parse(Oct|Bin)`

Plus small change to test cases.

* update changelog about `parse*Int` procs

* fix `rejectParse` template in `tstrutils`

* make sure only `s.len` chars are parsed, if `maxLen+start` > s.len

Fixes a previous bug in `parseHex` (and now affected `parseOct` and
`parseBin`), which allowed to set `start + maxLen` to be larger than
the strings length. This resulted in an out of bounds access.

* move `parse*Int` proc change to breaking changes, add double `

2 files changed, 57 insertions, 51 deletions

diff --git a/lib/pure/parseutils.nim b/lib/pure/parseutils.nim
index d54f1454b..e633d8cf7 100644
--- a/lib/pure/parseutils.nim
+++ b/lib/pure/parseutils.nim
@@ -47,12 +47,14 @@ proc parseHex*(s: string, number: var int, start = 0; maxLen = 0): int {.
   ##   discard parseHex("0x38", value)
   ##   assert value == -200
   ##
-  ## If 'maxLen==0' the length of the hexadecimal number has no
-  ## upper bound. Not more than ```maxLen`` characters are parsed.
+  ## If ``maxLen == 0`` the length of the hexadecimal number has no upper bound.
+  ## Else no more than ``start + maxLen`` characters are parsed, up to the
+  ## length of the string.
   var i = start
   var foundDigit = false
-  let last = if maxLen == 0: s.len else: i+maxLen
-  if i+1 < last and s[i] == '0' and (s[i+1] == 'x' or s[i+1] == 'X'): inc(i, 2)
+  # get last index based on minimum `start + maxLen` or `s.len`
+  let last = min(s.len, if maxLen == 0: s.len else: i+maxLen)
+  if i+1 < last and s[i] == '0' and (s[i+1] in {'x', 'X'}): inc(i, 2)
   elif i < last and s[i] == '#': inc(i)
   while i < last:
     case s[i]
@@ -70,14 +72,20 @@ proc parseHex*(s: string, number: var int, start = 0; maxLen = 0): int {.
     inc(i)
   if foundDigit: result = i-start
 
-proc parseOct*(s: string, number: var int, start = 0): int  {.
+proc parseOct*(s: string, number: var int, start = 0, maxLen = 0): int  {.
   rtl, extern: "npuParseOct", noSideEffect.} =
-  ## parses an octal number and stores its value in ``number``. Returns
+  ## Parses an octal number and stores its value in ``number``. Returns
   ## the number of the parsed characters or 0 in case of an error.
+  ##
+  ## If ``maxLen == 0`` the length of the octal number has no upper bound.
+  ## Else no more than ``start + maxLen`` characters are parsed, up to the
+  ## length of the string.
   var i = start
   var foundDigit = false
-  if i+1 < s.len and s[i] == '0' and (s[i+1] == 'o' or s[i+1] == 'O'): inc(i, 2)
-  while i < s.len:
+  # get last index based on minimum `start + maxLen` or `s.len`
+  let last = min(s.len, if maxLen == 0: s.len else: i+maxLen)
+  if i+1 < last and s[i] == '0' and (s[i+1] in {'o', 'O'}): inc(i, 2)
+  while i < last:
     case s[i]
     of '_': discard
     of '0'..'7':
@@ -87,14 +95,20 @@ proc parseOct*(s: string, number: var int, start = 0): int  {.
     inc(i)
   if foundDigit: result = i-start
 
-proc parseBin*(s: string, number: var int, start = 0): int  {.
+proc parseBin*(s: string, number: var int, start = 0, maxLen = 0): int  {.
   rtl, extern: "npuParseBin", noSideEffect.} =
-  ## parses an binary number and stores its value in ``number``. Returns
+  ## Parses an binary number and stores its value in ``number``. Returns
   ## the number of the parsed characters or 0 in case of an error.
+  ##
+  ## If ``maxLen == 0`` the length of the binary number has no upper bound.
+  ## Else no more than ``start + maxLen`` characters are parsed, up to the
+  ## length of the string.
   var i = start
   var foundDigit = false
-  if i+1 < s.len and s[i] == '0' and (s[i+1] == 'b' or s[i+1] == 'B'): inc(i, 2)
-  while i < s.len:
+  # get last index based on minimum `start + maxLen` or `s.len`
+  let last = min(s.len, if maxLen == 0: s.len else: i+maxLen)
+  if i+1 < last and s[i] == '0' and (s[i+1] in {'b', 'B'}): inc(i, 2)
+  while i < last:
     case s[i]
     of '_': discard
     of '0'..'1':
diff --git a/lib/pure/strutils.nim b/lib/pure/strutils.nim
index bea0a0243..5de013c26 100644
--- a/lib/pure/strutils.nim
+++ b/lib/pure/strutils.nim
@@ -844,7 +844,7 @@ proc parseInt*(s: string): int {.noSideEffect, procvar,
   ## Parses a decimal integer value contained in `s`.
   ##
   ## If `s` is not a valid integer, `ValueError` is raised.
-  var L = parseutils.parseInt(s, result, 0)
+  let L = parseutils.parseInt(s, result, 0)
   if L != s.len or L == 0:
     raise newException(ValueError, "invalid integer: " & s)
 
@@ -853,7 +853,7 @@ proc parseBiggestInt*(s: string): BiggestInt {.noSideEffect, procvar,
   ## Parses a decimal integer value contained in `s`.
   ##
   ## If `s` is not a valid integer, `ValueError` is raised.
-  var L = parseutils.parseBiggestInt(s, result, 0)
+  let L = parseutils.parseBiggestInt(s, result, 0)
   if L != s.len or L == 0:
     raise newException(ValueError, "invalid integer: " & s)
 
@@ -862,7 +862,7 @@ proc parseUInt*(s: string): uint {.noSideEffect, procvar,
   ## Parses a decimal unsigned integer value contained in `s`.
   ##
   ## If `s` is not a valid integer, `ValueError` is raised.
-  var L = parseutils.parseUInt(s, result, 0)
+  let L = parseutils.parseUInt(s, result, 0)
   if L != s.len or L == 0:
     raise newException(ValueError, "invalid unsigned integer: " & s)
 
@@ -871,7 +871,7 @@ proc parseBiggestUInt*(s: string): BiggestUInt {.noSideEffect, procvar,
   ## Parses a decimal unsigned integer value contained in `s`.
   ##
   ## If `s` is not a valid integer, `ValueError` is raised.
-  var L = parseutils.parseBiggestUInt(s, result, 0)
+  let L = parseutils.parseBiggestUInt(s, result, 0)
   if L != s.len or L == 0:
     raise newException(ValueError, "invalid unsigned integer: " & s)
 
@@ -880,33 +880,42 @@ proc parseFloat*(s: string): float {.noSideEffect, procvar,
   ## Parses a decimal floating point value contained in `s`. If `s` is not
   ## a valid floating point number, `ValueError` is raised. ``NAN``,
   ## ``INF``, ``-INF`` are also supported (case insensitive comparison).
-  var L = parseutils.parseFloat(s, result, 0)
+  let L = parseutils.parseFloat(s, result, 0)
   if L != s.len or L == 0:
     raise newException(ValueError, "invalid float: " & s)
 
+proc parseBinInt*(s: string): int {.noSideEffect, procvar,
+  rtl, extern: "nsuParseBinInt".} =
+  ## Parses a binary integer value contained in `s`.
+  ##
+  ## If `s` is not a valid binary integer, `ValueError` is raised. `s` can have
+  ## one of the following optional prefixes: ``0b``, ``0B``. Underscores within
+  ## `s` are ignored.
+  let L = parseutils.parseBin(s, result, 0)
+  if L != s.len or L == 0:
+    raise newException(ValueError, "invalid binary integer: " & s)
+
+proc parseOctInt*(s: string): int {.noSideEffect,
+  rtl, extern: "nsuParseOctInt".} =
+  ## Parses an octal integer value contained in `s`.
+  ##
+  ## If `s` is not a valid oct integer, `ValueError` is raised. `s` can have one
+  ## of the following optional prefixes: ``0o``, ``0O``.  Underscores within
+  ## `s` are ignored.
+  let L = parseutils.parseOct(s, result, 0)
+  if L != s.len or L == 0:
+    raise newException(ValueError, "invalid oct integer: " & s)  
+
 proc parseHexInt*(s: string): int {.noSideEffect, procvar,
   rtl, extern: "nsuParseHexInt".} =
   ## Parses a hexadecimal integer value contained in `s`.
   ##
-  ## If `s` is not a valid integer, `ValueError` is raised. `s` can have one
+  ## If `s` is not a valid hex integer, `ValueError` is raised. `s` can have one
   ## of the following optional prefixes: ``0x``, ``0X``, ``#``.  Underscores
   ## within `s` are ignored.
-  var i = 0
-  if i+1 < s.len and s[i] == '0' and (s[i+1] == 'x' or s[i+1] == 'X'): inc(i, 2)
-  elif i < s.len and s[i] == '#': inc(i)
-  while i < s.len:
-    case s[i]
-    of '_': inc(i)
-    of '0'..'9':
-      result = result shl 4 or (ord(s[i]) - ord('0'))
-      inc(i)
-    of 'a'..'f':
-      result = result shl 4 or (ord(s[i]) - ord('a') + 10)
-      inc(i)
-    of 'A'..'F':
-      result = result shl 4 or (ord(s[i]) - ord('A') + 10)
-      inc(i)
-    else: raise newException(ValueError, "invalid integer: " & s)
+  let L = parseutils.parseHex(s, result, 0)
+  if L != s.len or L == 0:
+    raise newException(ValueError, "invalid hex integer: " & s)
 
 proc generateHexCharToValueMap(): string =
   ## Generate a string to map a hex digit to uint value
@@ -1616,23 +1625,6 @@ proc delete*(s: var string, first, last: int) {.noSideEffect,
     inc(j)
   setLen(s, newLen)
 
-proc parseOctInt*(s: string): int {.noSideEffect,
-  rtl, extern: "nsuParseOctInt".} =
-  ## Parses an octal integer value contained in `s`.
-  ##
-  ## If `s` is not a valid integer, `ValueError` is raised. `s` can have one
-  ## of the following optional prefixes: ``0o``, ``0O``.  Underscores within
-  ## `s` are ignored.
-  var i = 0
-  if i+1 < s.len and s[i] == '0' and (s[i+1] == 'o' or s[i+1] == 'O'): inc(i, 2)
-  while i < s.len:
-    case s[i]
-    of '_': inc(i)
-    of '0'..'7':
-      result = result shl 3 or (ord(s[i]) - ord('0'))
-      inc(i)
-    else: raise newException(ValueError, "invalid integer: " & s)
-
 proc toOct*(x: BiggestInt, len: Positive): string {.noSideEffect,
   rtl, extern: "nsuToOct".} =
   ## Converts `x` into its octal representation.