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https://github.com/carbon-language/carbon-lang.git
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Geoff Romer
80f035874d
* Move nontrivial logic out of `parser.ypp` into `FieldList`, rename it to `ParenContents`, make it a class, and add tests * Use a `FieldInitializer` struct instead of `std::pair<std::string, Expression*>` to represent the fields of a tuple
62 lines
2.1 KiB
C++
62 lines
2.1 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 EXECUTABLE_SEMANTICS_SYNTAX_PAREN_CONTENTS_H_
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#define EXECUTABLE_SEMANTICS_SYNTAX_PAREN_CONTENTS_H_
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#include <list>
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#include "executable_semantics/ast/expression.h"
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namespace Carbon {
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// A FieldInitializer represents the initialization of a single tuple field.
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struct FieldInitializer {
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// The field name. An empty string indicates that this represents a
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// positional field.
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std::string name;
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// The expression that initializes the field.
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Expression* expression;
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};
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// Represents the syntactic contents of an expression delimited by
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// parentheses. Such expressions can be interpreted as either tuples or
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// arbitrary expressions, depending on their context and the syntax of their
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// contents; this class helps calling code resolve that ambiguity. Since that
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// ambiguity is purely syntactic, this class should only be needed during
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// parsing.
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class ParenContents {
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public:
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// Indicates whether the paren expression's contents end with a comma.
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enum class HasTrailingComma { Yes, No };
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// Constructs a ParenContents representing the contents of "()".
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ParenContents() : fields_({}), has_trailing_comma_(HasTrailingComma::No) {}
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// Constructs a ParenContents representing the given list of fields,
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// with or without a trailing comma.
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ParenContents(std::vector<FieldInitializer> fields,
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HasTrailingComma has_trailing_comma)
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: fields_(fields), has_trailing_comma_(has_trailing_comma) {}
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ParenContents(const ParenContents&) = default;
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ParenContents& operator=(const ParenContents&) = default;
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// Returns the paren expression, interpreted as a tuple.
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Expression* AsTuple(int line_number) const;
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// Returns the paren expression, with no external constraints on what kind
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// of expression it represents.
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Expression* AsExpression(int line_number) const;
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private:
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std::vector<FieldInitializer> fields_;
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HasTrailingComma has_trailing_comma_;
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};
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} // namespace Carbon
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#endif // EXECUTABLE_SEMANTICS_SYNTAX_PAREN_CONTENTS_H_
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