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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
96964ee534
Note, this supports plurals, but doesn't apply it anywhere. I'm mainly doing that to demonstrate the approach regarding syntax. See format_providers.h for details.
77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_TOOLCHAIN_DIAGNOSTICS_FORMAT_PROVIDERS_H_
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#define CARBON_TOOLCHAIN_DIAGNOSTICS_FORMAT_PROVIDERS_H_
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#include "common/ostream.h"
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#include "llvm/Support/FormatVariadicDetails.h"
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namespace Carbon {
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// Selects a formatv string based on the value. If the format style is not
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// provided, as in `{0}`, the value uses standard formatting.
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//
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// When used, the true and false outputs are separated by a `|`.
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//
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// For example, `{0:true|false}` would yield standard bool formatting.
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//
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// If needed, the _full_ style string can be wrapped with `'` in order to
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// preserve prefix or suffix whitespace (which is stripped by formatv). For
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// example, `{0:' true | false '}` retains whitespace which would be dropped
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// before `true` and after `false`.
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struct BoolAsSelect {
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// NOLINTNEXTLINE(google-explicit-constructor)
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BoolAsSelect(bool value) : value(value) {}
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bool value;
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};
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// Selects a formatv string based on the value. If the format style is not
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// provided, as in `{0}`, the value uses standard formatting.
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//
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// The style is a series of match cases, separated by `|`. Each case is a pair
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// formatted as `<selector>:<output string>`.
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//
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// Supported selectors are:
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// - `=<value>`: Matches when the value is correct.
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// - Empty for the default. This is optional, although it's a fatal error to not
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// handle a value. If provided, it must be last.
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//
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// For example, `{0:=0:zero|=1:one|:other}` breaks down into:
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// - `=0` -> `zero`
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// - `=1` -> `one`
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// - default -> `other`
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//
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// As another example, `{0:=1:is|:are}` is a way to handle plural-based output.
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//
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// If needed, the _full_ style string can be wrapped with `'` in order to
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// preserve prefix or suffix whitespace (which is stripped by formatv). For
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// example, `{0:'=0: zero |=1: one '}` retains whitespace which would be dropped
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// after `one`.
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struct IntAsSelect {
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// NOLINTNEXTLINE(google-explicit-constructor)
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IntAsSelect(int value) : value(value) {}
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int value;
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};
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} // namespace Carbon
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// See BoolAsSelect.
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template <>
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struct llvm::format_provider<Carbon::BoolAsSelect> {
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static auto format(const Carbon::BoolAsSelect& wrapper, raw_ostream& out,
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StringRef style) -> void;
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};
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// See IntAsSelect.
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template <>
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struct llvm::format_provider<Carbon::IntAsSelect> {
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static auto format(const Carbon::IntAsSelect& wrapper, raw_ostream& out,
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StringRef style) -> void;
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};
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#endif // CARBON_TOOLCHAIN_DIAGNOSTICS_FORMAT_PROVIDERS_H_
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