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Merge pull request #9115 from fricklerhandwerk/lookup-algorithm

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reword documentation on lookup path resolution
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John Ericson 2023-10-10 10:44:32 -04:00 committed by GitHub
parent 4b1a97338f 7642894a4e
commit c7f1d86b80
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1 changed files with 11 additions and 11 deletions
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22
src/libexpr/primops.cc
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@ -1698,13 +1698,14 @@ static void prim_findFile(EvalState & state, const PosIdx pos, Value * * args, V
static RegisterPrimOp primop_findFile(PrimOp {
.name = "__findFile",
.args = {"search path", "lookup path"},
.args = {"search-path", "lookup-path"},
.doc = R"(
Look up the given path with the given search path.
Find *lookup-path* in *search-path*.
A search path is represented list of [attribute sets](./values.md#attribute-set) with two attributes, `prefix`, and `path`.
`prefix` is a relative path.
`path` denotes a file system location; the exact syntax depends on the command line interface.
A search path is represented list of [attribute sets](./values.md#attribute-set) with two attributes:
- `prefix` is a relative path.
- `path` denotes a file system location
The exact syntax depends on the command line interface.
Examples of search path attribute sets:
@ -1722,13 +1723,12 @@ static RegisterPrimOp primop_findFile(PrimOp {
}
```
The lookup algorithm checks each entry until a match is found, returning a [path value](@docroot@/language/values.html#type-path) of the match.
The lookup algorithm checks each entry until a match is found, returning a [path value](@docroot@/language/values.html#type-path) of the match:
This is the process for each entry:
If the lookup path matches `prefix`, then the remainder of the lookup path (the "suffix") is searched for within the directory denoted by `patch`.
Note that the `path` may need to be downloaded at this point to look inside.
If the suffix is found inside that directory, then the entry is a match;
the combined absolute path of the directory (now downloaded if need be) and the suffix is returned.
- If *lookup-path* matches `prefix`, then the remainder of *lookup-path* (the "suffix") is searched for within the directory denoted by `path`.
Note that the `path` may need to be downloaded at this point to look inside.
- If the suffix is found inside that directory, then the entry is a match.
The combined absolute path of the directory (now downloaded if need be) and the suffix is returned.
[Lookup path](@docroot@/language/constructs/lookup-path.md) expressions can be [desugared](https://en.wikipedia.org/wiki/Syntactic_sugar) using this and [`builtins.nixPath`](@docroot@/language/builtin-constants.md#builtins-nixPath):