0fa08b4516
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`.
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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