lib/strings: Update docs and restructured code to improve readability of toInt and toIntBase10.

This commit is contained in:
Jacob Abel 2022-07-09 20:12:31 -04:00
parent 88b18dcf44
commit ed71173841
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GPG key ID: C41690827135AD22
3 changed files with 42 additions and 22 deletions

View file

@ -784,7 +784,7 @@ rec {
false;
/* Parse a string as an int. Does not support parsing of integers with preceding zero due to
ambiguity between zero-padded and octal numbers.
ambiguity between zero-padded and octal numbers. See toIntBase10.
Type: string -> int
@ -805,25 +805,35 @@ rec {
toInt "3.14"
=> error: floating point JSON numbers are not supported
*/
# Obviously, it is a bit hacky to use fromJSON this way.
toInt = str:
let
# RegEx: Match any leading whitespace, then any digits, and finally match any trailing
# whitespace.
strippedInput = match "[[:space:]]*([[:digit:]]+)[[:space:]]*" str;
# RegEx: Match any leading whitespace, then a leading '0', then at least one digit following
# after, and finally match any trailing whitespace.
isLeadingZero = match "[[:space:]]*0[[:digit:]]+[[:space:]]*" str == [];
# RegEx: Match a leading '0' then one or more digits.
isLeadingZero = match "0[[:digit:]]+" (head strippedInput) == [];
# Attempt to parse input
parsedInput = fromJSON (elemAt strippedInput 0);
parsedInput = fromJSON (head strippedInput);
generalError = "toInt: Could not convert ${escapeNixString str} to int.";
octalAmbigError = "toInt: Ambiguity in interpretation of ${escapeNixString str}"
+ " between octal and zero padded integer.";
in
if isLeadingZero
then throw "Ambiguity in interpretation of ${str} between octal and zero padded integer."
else if strippedInput != null && isInt parsedInput
then parsedInput
else throw "Could not convert ${str} to int.";
# Error on presence of non digit characters.
if strippedInput == null
then throw generalError
# Error on presence of leading zero/octal ambiguity.
else if isLeadingZero
then throw octalAmbigError
# Error if parse function fails.
else if !isInt parsedInput
then throw generalError
# Return result.
else parsedInput;
/* Parse a string as a base 10 int. This supports parsing of zero-padded integers.
@ -846,26 +856,32 @@ rec {
toIntBase10 "3.14"
=> error: floating point JSON numbers are not supported
*/
# Obviously, it is a bit hacky to use fromJSON this way.
toIntBase10 = str:
let
# RegEx: Match any leading whitespace, then match any zero padding, capture any remaining
# digits after that, and finally match any trailing whitespace.
strippedInput = match "[[:space:]]*0*([[:digit:]]+)[[:space:]]*" str;
# RegEx: Match any leading whitespace, at least one '0', and any trailing whitespace.
isZero = match "[[:space:]]*0+[[:space:]]*" str == [];
# RegEx: Match at least one '0'.
isZero = match "0+" (head strippedInput) == [];
# Attempt to parse input
parsedInput = fromJSON (elemAt strippedInput 0);
parsedInput = fromJSON (head strippedInput);
generalError = "toIntBase10: Could not convert ${escapeNixString str} to int.";
in
# Value is zero
if isZero
# Error on presence of non digit characters.
if strippedInput == null
then throw generalError
# In the special case zero-padded zero (00000), return early.
else if isZero
then 0
else
if strippedInput != null && isInt parsedInput
then parsedInput
else throw "Could not convert ${str} to int.";
# Error if parse function fails.
else if !isInt parsedInput
then throw generalError
# Return result.
else parsedInput;
/* Read a list of paths from `file`, relative to the `rootPath`.
Lines beginning with `#` are treated as comments and ignored.

View file

@ -346,6 +346,8 @@ runTests {
( builtins.tryEval (toInt "123 123") == { success = false; value = false; } )
( builtins.tryEval (toInt "0 123") == { success = false; value = false; } )
( builtins.tryEval (toInt " 0d ") == { success = false; value = false; } )
( builtins.tryEval (toInt " 1d ") == { success = false; value = false; } )
( builtins.tryEval (toInt " d0 ") == { success = false; value = false; } )
( builtins.tryEval (toInt "00") == { success = false; value = false; } )
( builtins.tryEval (toInt "01") == { success = false; value = false; } )
( builtins.tryEval (toInt "002") == { success = false; value = false; } )
@ -388,6 +390,8 @@ runTests {
( builtins.tryEval (toIntBase10 "123 123") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 "0 123") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 " 0d ") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 " 1d ") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 " d0 ") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 " foo ") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 " foo 123 ") == { success = false; value = false; } )
( builtins.tryEval (toIntBase10 " foo 00123 ") == { success = false; value = false; } )

View file

@ -162,7 +162,7 @@ checkConfigError 'A definition for option .* is not.*string or signed integer co
# Check coerced value with unsound coercion
checkConfigOutput '^12$' config.value ./declare-coerced-value-unsound.nix
checkConfigError 'A definition for option .* is not of type .*. Definition values:\n\s*- In .*: "1000"' config.value ./declare-coerced-value-unsound.nix ./define-value-string-bigint.nix
checkConfigError 'Could not convert .* to int' config.value ./declare-coerced-value-unsound.nix ./define-value-string-arbitrary.nix
checkConfigError 'toInt: Could not convert .* to int' config.value ./declare-coerced-value-unsound.nix ./define-value-string-arbitrary.nix
# Check mkAliasOptionModule.
checkConfigOutput '^true$' config.enable ./alias-with-priority.nix