75 lines
1.6 KiB
Nix
75 lines
1.6 KiB
Nix
# Functions for working with paths, see ./path.md
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{ lib }:
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let
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inherit (builtins)
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isString
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match
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;
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inherit (lib.strings)
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substring
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;
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inherit (lib.asserts)
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assertMsg
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;
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# Return the reason why a subpath is invalid, or `null` if it's valid
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subpathInvalidReason = value:
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if ! isString value then
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"The given value is of type ${builtins.typeOf value}, but a string was expected"
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else if value == "" then
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"The given string is empty"
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else if substring 0 1 value == "/" then
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"The given string \"${value}\" starts with a `/`, representing an absolute path"
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# We don't support ".." components, see ./path.md#parent-directory
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else if match "(.*/)?\\.\\.(/.*)?" value != null then
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"The given string \"${value}\" contains a `..` component, which is not allowed in subpaths"
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else null;
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in /* No rec! Add dependencies on this file at the top. */ {
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/* Whether a value is a valid subpath string.
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- The value is a string
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- The string is not empty
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- The string doesn't start with a `/`
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- The string doesn't contain any `..` path components
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Type:
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subpath.isValid :: String -> Bool
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Example:
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# Not a string
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subpath.isValid null
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=> false
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# Empty string
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subpath.isValid ""
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=> false
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# Absolute path
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subpath.isValid "/foo"
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=> false
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# Contains a `..` path component
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subpath.isValid "../foo"
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=> false
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# Valid subpath
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subpath.isValid "foo/bar"
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=> true
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# Doesn't need to be normalised
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subpath.isValid "./foo//bar/"
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=> true
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*/
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subpath.isValid = value:
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subpathInvalidReason value == null;
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}
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