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Implement --raw for nix-instantiate --eval #12119

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mergify merged 2 commits into from
Dec 31, 2024
Merged

Implement --raw for nix-instantiate --eval #12119

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1a402e0
test: test eval of newlines with raw output
not-my-profile Dec 31, 2024
7a8a286
feat(nix-instantiate): add --raw flag
not-my-profile Dec 31, 2024
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8 changes: 8 additions & 0 deletions doc/manual/rl-next/nix-instantiate-raw.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
---
synopsis: "`nix-instantiate --eval` now supports `--raw`"
prs: [12119]
---

The `nix-instantiate --eval` command now supports a `--raw` flag, when used
the evaluation result must be a string, which is printed verbatim without
quotation marks or escaping.
2 changes: 1 addition & 1 deletion doc/manual/source/command-ref/nix-copy-closure.md
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Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,7 @@ When using public key authentication, you can avoid typing the passphrase with `
> Copy GNU Hello from a remote machine using a known store path, and run it:
>
> ```shell-session
> $ storePath="$(nix-instantiate --eval '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable -A hello.outPath | tr -d '"')"
> $ storePath="$(nix-instantiate --eval --raw '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable -A hello.outPath)"
> $ nix-copy-closure --from alice@itchy.example.org "$storePath"
> $ "$storePath"/bin/hello
> Hello, world!
Expand Down
7 changes: 6 additions & 1 deletion doc/manual/source/command-ref/nix-instantiate.md
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Expand Up @@ -5,7 +5,7 @@
# Synopsis

`nix-instantiate`
[`--parse` | `--eval` [`--strict`] [`--json`] [`--xml`] ]
[`--parse` | `--eval` [`--strict`] [`--raw` | `--json` | `--xml`] ]
[`--read-write-mode`]
[`--arg` *name* *value*]
[{`--attr`| `-A`} *attrPath*]
Expand Down Expand Up @@ -102,6 +102,11 @@ standard input.
> This option can cause non-termination, because lazy data
> structures can be infinitely large.

- `--raw`

When used with `--eval`, the evaluation result must be a string,
which is printed verbatim, without quoting, escaping or trailing newline.

- `--json`

When used with `--eval`, print the resulting value as an JSON
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10 changes: 8 additions & 2 deletions src/nix-instantiate/nix-instantiate.cc
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Expand Up @@ -24,7 +24,7 @@ static Path gcRoot;
static int rootNr = 0;


enum OutputKind { okPlain, okXML, okJSON };
enum OutputKind { okPlain, okRaw, okXML, okJSON };

void processExpr(EvalState & state, const Strings & attrPaths,
bool parseOnly, bool strict, Bindings & autoArgs,
Expand All @@ -50,7 +50,11 @@ void processExpr(EvalState & state, const Strings & attrPaths,
vRes = v;
else
state.autoCallFunction(autoArgs, v, vRes);
if (output == okXML)
if (output == okRaw)
std::cout << *state.coerceToString(noPos, vRes, context, "while generating the nix-instantiate output");
// We intentionally don't output a newline here. The default PS1 for Bash in NixOS starts with a newline
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@roberth roberth Dec 31, 2024

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newline

This should be documented in the manual, perhaps without the reasoning.

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@roberth roberth Dec 31, 2024

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idea (no action required)
--lines to allow multiple arguments and stream them to stdout, each on their own line. This would always add a newline, so --raw --lines would output a line. Perhaps also implicitly flattening lists as well, printing a line for each item.

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@not-my-profile not-my-profile Dec 31, 2024

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I mentioned the absence of a trailing newline in the manual.

// and other interactive shells like Zsh are smart enough to print a missing newline before the prompt.
else if (output == okXML)
printValueAsXML(state, strict, location, vRes, std::cout, context, noPos);
else if (output == okJSON) {
printValueAsJSON(state, strict, vRes, v.determinePos(noPos), std::cout, context);
Expand Down Expand Up @@ -132,6 +136,8 @@ static int main_nix_instantiate(int argc, char * * argv)
gcRoot = getArg(*arg, arg, end);
else if (*arg == "--indirect")
;
else if (*arg == "--raw")
outputKind = okRaw;
else if (*arg == "--xml")
outputKind = okXML;
else if (*arg == "--json")
Expand Down
2 changes: 1 addition & 1 deletion tests/functional/eval.nix
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
{
int = 123;
str = "foo";
str = "foo\nbar";
attr.foo = "bar";
}
7 changes: 4 additions & 3 deletions tests/functional/eval.sh
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Expand Up @@ -16,8 +16,8 @@ EOF
nix eval --expr 'assert 1 + 2 == 3; true'

[[ $(nix eval int -f "./eval.nix") == 123 ]]
[[ $(nix eval str -f "./eval.nix") == '"foo"' ]]
[[ $(nix eval str --raw -f "./eval.nix") == 'foo' ]]
[[ $(nix eval str -f "./eval.nix") == '"foo\nbar"' ]]
[[ $(nix eval str --raw -f "./eval.nix") == $'foo\nbar' ]]
[[ "$(nix eval attr -f "./eval.nix")" == '{ foo = "bar"; }' ]]
[[ $(nix eval attr --json -f "./eval.nix") == '{"foo":"bar"}' ]]
[[ $(nix eval int -f - < "./eval.nix") == 123 ]]
Expand All @@ -28,7 +28,8 @@ nix eval --expr 'assert 1 + 2 == 3; true'

nix-instantiate --eval -E 'assert 1 + 2 == 3; true'
[[ $(nix-instantiate -A int --eval "./eval.nix") == 123 ]]
[[ $(nix-instantiate -A str --eval "./eval.nix") == '"foo"' ]]
[[ $(nix-instantiate -A str --eval "./eval.nix") == '"foo\nbar"' ]]
[[ $(nix-instantiate -A str --raw --eval "./eval.nix") == $'foo\nbar' ]]
[[ "$(nix-instantiate -A attr --eval "./eval.nix")" == '{ foo = "bar"; }' ]]
[[ $(nix-instantiate -A attr --eval --json "./eval.nix") == '{"foo":"bar"}' ]]
[[ $(nix-instantiate -A int --eval - < "./eval.nix") == 123 ]]
Expand Down
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