forked from lix-project/lix
eldritch horrors
512c1f05c3
Previously, there were two mostly-identical value printers -- one in
`libexpr/eval.cc` (which didn't force values) and one in
`libcmd/repl.cc` (which did force values and also printed ANSI color
codes).
This PR unifies both of these printers into `print.cc` and provides a
`PrintOptions` struct for controlling the output, which allows for
toggling whether values are forced, whether repeated values are tracked,
and whether ANSI color codes are displayed.
Additionally, `PrintOptions` allows tuning the maximum number of
attributes, list items, and bytes in a string that will be displayed;
this makes it ideal for contexts where printing too much output (e.g.
all of Nixpkgs) is distracting. (As requested by @roberth in
https://github.com/NixOS/nix/pull/9554#issuecomment-1845095735)
Please read the tests for example output.
Future work:
- It would be nice to provide this function as a builtin, perhaps
`builtins.toStringDebug` -- a printing function that never fails would
be useful when debugging Nix code.
- It would be nice to support customizing `PrintOptions` members on the
command line, e.g. `--option to-string-max-attrs 1000`.
(cherry picked from commit 0fa08b451682fb3311fe58112ff05c4fe5bee3a4, )
===
Restore ambiguous value printer for `nix-instantiate`
The Nix team has requested that this output format remain unchanged.
I've added a warning to the man page explaining that `nix-instantiate
--eval` output will not parse correctly in many situations.
(cherry picked from commit df84dd4d8dd3fd6381ac2ca3064432ab31a16b79)
Change-Id: I7cca6b4b53cd0642f2d49af657d5676a8554c9f8
53 lines
1.2 KiB
C++
53 lines
1.2 KiB
C++
#pragma once
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/**
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* @file
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* @brief Options for printing Nix values.
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*/
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#include <limits>
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namespace nix {
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/**
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* Options for printing Nix values.
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*/
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struct PrintOptions
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{
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/**
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* If true, output ANSI color sequences.
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*/
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bool ansiColors = false;
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/**
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* If true, force values.
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*/
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bool force = false;
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/**
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* If true and `force` is set, print derivations as
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* `«derivation /nix/store/...»` instead of as attribute sets.
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*/
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bool derivationPaths = false;
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/**
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* If true, track which values have been printed and skip them on
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* subsequent encounters. Useful for self-referential values.
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*/
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bool trackRepeated = true;
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/**
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* Maximum depth to evaluate to.
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*/
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size_t maxDepth = std::numeric_limits<size_t>::max();
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/**
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* Maximum number of attributes in an attribute set to print.
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*/
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size_t maxAttrs = std::numeric_limits<size_t>::max();
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/**
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* Maximum number of list items to print.
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*/
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size_t maxListItems = std::numeric_limits<size_t>::max();
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/**
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* Maximum string length to print.
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*/
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size_t maxStringLength = std::numeric_limits<size_t>::max();
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};
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}
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