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111 lines
3.7 KiB
C++
111 lines
3.7 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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#include "executable_semantics/ast/pattern.h"
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#include <string>
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#include "common/ostream.h"
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#include "executable_semantics/ast/expression.h"
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#include "executable_semantics/common/arena.h"
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#include "executable_semantics/common/error.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Support/Casting.h"
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namespace Carbon {
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using llvm::cast;
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void Pattern::Print(llvm::raw_ostream& out) const {
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switch (kind()) {
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case Kind::AutoPattern:
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out << "auto";
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break;
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case Kind::BindingPattern: {
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const auto& binding = cast<BindingPattern>(*this);
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if (binding.Name().has_value()) {
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out << *binding.Name();
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} else {
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out << "_";
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}
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out << ": " << *binding.Type();
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break;
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}
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case Kind::TuplePattern: {
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const auto& tuple = cast<TuplePattern>(*this);
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out << "(";
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llvm::ListSeparator sep;
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for (const TuplePattern::Field& field : tuple.Fields()) {
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out << sep << field.name << " = " << *field.pattern;
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}
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out << ")";
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break;
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}
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case Kind::AlternativePattern: {
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const auto& alternative = cast<AlternativePattern>(*this);
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out << *alternative.ChoiceType() << "." << alternative.AlternativeName()
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<< *alternative.Arguments();
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break;
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}
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case Kind::ExpressionPattern:
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out << *cast<ExpressionPattern>(*this).Expression();
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break;
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}
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}
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auto PatternFromParenContents(Nonnull<Arena*> arena, SourceLocation source_loc,
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const ParenContents<Pattern>& paren_contents)
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-> Nonnull<Pattern*> {
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std::optional<Nonnull<Pattern*>> single_term = paren_contents.SingleTerm();
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if (single_term.has_value()) {
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return *single_term;
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} else {
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return TuplePatternFromParenContents(arena, source_loc, paren_contents);
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}
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}
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auto TuplePatternFromParenContents(Nonnull<Arena*> arena,
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SourceLocation source_loc,
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const ParenContents<Pattern>& paren_contents)
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-> Nonnull<TuplePattern*> {
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return arena->New<TuplePattern>(
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source_loc,
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paren_contents.TupleElements<TuplePattern::Field>(source_loc));
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}
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// Used by AlternativePattern for constructor initialization. Produces a helpful
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// error for incorrect expressions, rather than letting a default cast error
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// apply.
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static auto RequireFieldAccess(Nonnull<Expression*> alternative)
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-> FieldAccessExpression& {
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if (alternative->kind() != Expression::Kind::FieldAccessExpression) {
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FATAL_PROGRAM_ERROR(alternative->source_loc())
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<< "Alternative pattern must have the form of a field access.";
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}
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return cast<FieldAccessExpression>(*alternative);
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}
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AlternativePattern::AlternativePattern(SourceLocation source_loc,
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Nonnull<Expression*> alternative,
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Nonnull<TuplePattern*> arguments)
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: Pattern(Kind::AlternativePattern, source_loc),
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choice_type(&RequireFieldAccess(alternative).aggregate()),
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alternative_name(RequireFieldAccess(alternative).field()),
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arguments(arguments) {}
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auto ParenExpressionToParenPattern(Nonnull<Arena*> arena,
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const ParenContents<Expression>& contents)
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-> ParenContents<Pattern> {
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ParenContents<Pattern> result = {
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.elements = {}, .has_trailing_comma = contents.has_trailing_comma};
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for (const auto& element : contents.elements) {
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result.elements.push_back(
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{.name = element.name,
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.term = arena->New<ExpressionPattern>(element.term)});
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}
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return result;
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}
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} // namespace Carbon
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