mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-03 13:25:50 +01:00
Jon Ross-Perkins
35d15a390c
Per [#toolchain discussion](https://discord.com/channels/655572317891461132/655578254970716160/1176632520834560211) We'd at one point been trying to put `[[nodiscard]]` everywhere, but then we stopped because it had felt verbose without finding many issues (plus, people plain forgot to add it). Some history in #888. Since newer code gets added without it, we now have code like: ``` auto GetLineInfo(Line line) -> LineInfo&; [[nodiscard]] auto GetLineInfo(Line line) const -> const LineInfo&; auto AddLine(LineInfo info) -> Line; auto GetTokenInfo(Token token) -> TokenInfo&; [[nodiscard]] auto GetTokenInfo(Token token) const -> const TokenInfo&; auto AddToken(TokenInfo info) -> Token; [[nodiscard]] auto GetTokenPrintWidths(Token token) const -> PrintWidths; ``` Here, the lack of `[[nodiscard]]` doesn't mean anything: for example, `GetLineInfo` should not have its result discarded if it's called. But the mix could be confusing for readers. As a resolution, remove the attribute. `[[nodiscard]]` should be treated like other attributes going forward, which essentially means "avoid in general, add a comment to explain why the attribute is needed" rather than use-as-default.
84 lines
3.1 KiB
C++
84 lines
3.1 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_LEX_STRING_LITERAL_H_
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#define CARBON_TOOLCHAIN_LEX_STRING_LITERAL_H_
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#include <optional>
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Allocator.h"
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#include "toolchain/diagnostics/diagnostic_emitter.h"
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namespace Carbon::Lex {
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class StringLiteral {
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public:
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// Extract a string literal token from the given text, if it has a suitable
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// form. Returning std::nullopt indicates no string literal was found;
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// returning an invalid literal indicates a string prefix was found, but it's
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// malformed and is returning a partial string literal to assist error
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// construction.
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static auto Lex(llvm::StringRef source_text) -> std::optional<StringLiteral>;
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// Expand any escape sequences in the given string literal and compute the
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// resulting value. This handles error recovery internally and cannot fail.
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//
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// When content_needs_validation_ is false and the string has no indent to
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// deal with, this can return the content directly. Otherwise, the allocator
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// will be used for the StringRef.
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auto ComputeValue(llvm::BumpPtrAllocator& allocator,
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DiagnosticEmitter<const char*>& emitter) const
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-> llvm::StringRef;
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// Get the text corresponding to this literal.
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auto text() const -> llvm::StringRef { return text_; }
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// Determine whether this is a multi-line string literal.
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auto is_multi_line() const -> bool { return multi_line_; }
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// Returns true if the string has a valid terminator.
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auto is_terminated() const -> bool { return is_terminated_; }
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private:
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enum MultiLineKind : int8_t {
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NotMultiLine,
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MultiLine,
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MultiLineWithDoubleQuotes
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};
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struct Introducer;
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explicit StringLiteral(llvm::StringRef text, llvm::StringRef content,
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bool content_needs_validation, int hash_level,
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MultiLineKind multi_line, bool is_terminated)
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: text_(text),
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content_(content),
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content_needs_validation_(content_needs_validation),
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hash_level_(hash_level),
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multi_line_(multi_line),
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is_terminated_(is_terminated) {}
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// The complete text of the string literal.
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llvm::StringRef text_;
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// The content of the literal. For a multi-line literal, this begins
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// immediately after the newline following the file type indicator, and ends
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// at the start of the closing `"""`. Leading whitespace is not removed from
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// either end.
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llvm::StringRef content_;
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// Whether content needs validation, in particular due to either an escape
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// (which needs modifications) or a tab character (which may cause a warning).
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bool content_needs_validation_;
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// The number of `#`s preceding the opening `"` or `"""`.
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int hash_level_;
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// Whether this was a multi-line string literal.
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MultiLineKind multi_line_;
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// Whether the literal is valid, or should only be used for errors.
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bool is_terminated_;
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};
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} // namespace Carbon::Lex
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#endif // CARBON_TOOLCHAIN_LEX_STRING_LITERAL_H_
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